All branches of the food industry are inextricably linked with the development of chemistry. The level of development of biochemistry in most industries Food Industry also characterizes the level of development of the industry. As we have already said, the main technological processes of the wine-making, bakery, brewing, tobacco, food-acid, juice, leavening and alcohol industries are based on biochemical processes. That is why the improvement of biochemical processes and, in accordance with this, the implementation of measures to improve the entire production technology is the main task of scientists and industrial workers. Workers in a number of industries are constantly engaged in selection - selection of highly active races and yeast strains. After all, the yield and quality of wine, beer depend on this; yield, porosity and taste of bread. Serious results have been achieved in this area: our domestic yeast in terms of its "efficiency" meets the increased requirements of technology.
An example is the yeast of the K-R race, developed by the workers of the Kiev factory of sparkling wines in collaboration with the Academy of Sciences of the Ukrainian SSR, which perform well the functions of fermentation under the conditions of a continuous process of champagne wine; thanks to this, the champagne production process was reduced by 96 hours.
For the needs of the national economy, tens and hundreds of thousands of tons of edible fats are consumed, including a significant share for the production of detergents and drying oils. Meanwhile, in the production of detergents, a significant amount of edible fats (at the current level of technology, up to 30 percent) can be replaced with synthetic fatty acids and alcohols. This would release a very significant amount of valuable fats for food purposes.
For technical purposes, for example, for the production of adhesives, it is also consumed a large number of(many thousands of tons!) food starch and dextrin. And here chemistry comes to the rescue! Back in 1962, some plants began to use a synthetic material, polya-krlamide, for labeling instead of starch and dextrin. ... Currently, most factories - wineries, non-alcoholic beer, champagne, canned food, etc. - are switching to synthetic adhesives. Thus, synthetic glue AT-1, consisting of MF-17 resin (urea with formaldehyde) with the addition of CMC (carboxymethyl cellulose), is increasingly being used. The food industry processes a significant amount of food liquids (wine materials, wine, food). in, beer wort, kvass wort, fruit and berry juices), which by their nature have aggressive properties in relation to metal. These liquids are sometimes in the process of technological processing contained in unsuitable or poorly adapted containers (metal, reinforced concrete and other containers), which degrades the quality of the finished product. Today chemistry has presented to the food industry a variety of different means for coating the inner surfaces of various containers - tanks, tanks, apparatuses, cisterns. These are eprosin, varnish XC-76, KhVL and others, which completely protect the surface from any impact and are completely neutral and harmless. Widespread use in the food industry is synthetic films, plastic products, synthetic closures. , the canning, food concentrate, bakery industry, cellophane is successfully used for packaging various products. Plastic wrap is used to wrap bakery products, they keep freshness better and longer, and stale slowly.
Plastics, cellulose acetate film and polystyrene are increasingly used every day for the manufacture of containers for the packaging of confectionery products, for the packaging of sawdust, jam, preserves and for the preparation of various boxes and other types of packaging.
Expensive imported raw materials - cork seals for wine, beer, soft drinks, mineral waters- perfectly replace various types of gaskets made of polyethylene, polyisobutylene and other synthetic masses.
Chemistry is actively serving food engineering. Nylon is used for the manufacture of high-wear parts, caramel stamping machines, bushings, clamps, silent gears, nylon meshes, filter cloth; in the wine-making, liqueur-vodka and beer-non-alcoholic industries, nylon is used for parts for labeling, rejection and filling machines.
Every day, more and more plastics are being "introduced" into food machine-building - for the manufacture of various conveyor tables, bunkers, receivers, elevator buckets, pipes, cassettes for proofing bread and many other parts and assemblies.
The contribution of great chemistry to the food industry is steadily growing. In 1866, German chemist Ritthausen obtained an organic acid from the breakdown products of wheat protein, which he called glutamic acid. This discovery had little practical significance for almost half a century. Later, however, it was found that glutamic acid, although not an essential amino acid, is still contained in relatively large quantities in such vital organs and tissues as the brain, heart muscle, and blood plasma. For example, 100 grams of brain matter contains 150 milligrams of glutamic acid.
"Scientific research has established that glutamic acid actively participates in biochemical processes in the central nervous system, participates in intracellular protein and carbohydrate metabolism, stimulates oxidative processes. Of all amino acids, only glutamic acid is intensively oxidized by the brain tissue, while a significant amount is released. energy necessary for the processes occurring in the brain tissues.
Hence, the most important area of application of glutamic acid is in medical practice, for the treatment of diseases of central nervous system.
At the beginning of the 20th century, the Japanese scientist Kikunae Ikeda, studying the composition of soy sauce, seaweed (kelp) and other foods characteristic of East Asia, decided to find an answer to the question of why food flavored with dried seaweed (for example, kelp) becomes more tasty and appetizing. It was unexpectedly found out that kelp "ennobles" food because "it contains glutamic acid.
In 1909, Ikede was granted a British patent for a method for the production of flavoring preparations. According to this method, Ikeda, by electrolysis, isolated monosodium glutamate from the protein hydrolyzate, that is, the sodium salt of glutamic acid. It turned out that monosodium glutamate has the ability to improve the taste of food.
Monosodium glutamate is a yellowish fine-crystalline powder; at the present time it is being produced in increasing quantities both in our country and abroad - especially in the countries of East Asia. It is mainly used in the food industry as a taste reducing agent for products, which is lost during the preparation of certain products. Monosodium glutamate is used in the industrial production of soups, sauces, meat and sausage products, canned vegetables, etc.
For food, the following dosage of sodium glutamate is recommended: 10 grams of the drug is enough as a seasoning for 3-4 kilograms of meat or meat dishes, as well as dishes prepared from fish and poultry, for 4-5 kilograms of vegetable products, for 2 kilograms of legumes and rice, as well as cooked from dough, for 6-7 liters of soup, sauces, meat oulop. The importance of sodium glutamate is especially great in the manufacture of canned food, since during heat treatment the products lose their taste to a greater or lesser extent. In these cases, they usually give 2 grams of the drug per 1 kilogram of canned food.
If the taste of any product deteriorates as a result of storage or cooking, then glutamate restores it. Monosodium glutamate increases the sensitivity of the gustatory nerves - making them more receptive to the taste of food. In some cases, it even enhances the flavor, such as overriding unwanted bitterness and earthy flavors in various vegetables. The pleasant taste of fresh vegetable dishes is due to the high content of glutamic acid in them. One has only to add a small pinch of glutamate to the steamed vegetarian soup - well, lo and behold, the dish acquires a full flavor, you get the feeling that you are eating a fragrant meat broth. And another "magical" effect is monosodium glutamate. The fact is that during long-term storage of meat and fish products, their freshness is lost, taste and appearance deteriorate. If these products are moistened with a solution of sodium glutamate before storage, they will remain fresh, while the control germs lose their original taste and turn rancid.
In Japan, MSG is marketed under the name aji-no-moto, which means the essence of taste. Sometimes this word is translated differently - "soul of taste". In China, this drug is called "wei-shu", that is, "gastronomic powder", the French call it "mind serum", clearly hinting at the role of glutamic acid in brain processes.
And what is monosodium glutamate and glutamic acid made of? Each country chooses the most profitable raw material for itself. For example, in the United States, more than 50 percent of monosodium glutamate is produced from sugar beet waste, about 30 percent from wheat gluten, and about 20 percent from corn gluten. In China, monosodium glutamate is produced from soy protein, in Germany from wheat protein. In Japan, a method has been developed for the biochemical synthesis of glutamic acid from glucose and mineral salts using a special race of microorganisms (micrococcus glutamicus), which was reported in Moscow at the V International Biochemical Congress by the Japanese scientist Kinoshita.
A number of new workshops for the production of glutamic acid and sodium glutamate have been organized in our country in recent years. The main raw materials for these purposes are wastes from corn-starch production, waste from sugar production (beet syrup) and waste from alcohol production (stillage).
At present, tens of thousands of tons of glutamic acid and monosodium glutamate are produced annually all over the world, and the scope of their application is expanding every day.
Wonderful Accelerators - Enzymes
Most of the chemical reactions that take place in the body involve enzymes. Enzymes are specific proteins produced by a living cell and capable of accelerating chemical reactions. The enzymes got their name from the Latin word, which means "fermentation". Alcoholic fermentation is one of the oldest examples of the action of enzymes. All manifestations of life are due to the presence of enzymes;
IP Pavlov, who made an exceptionally great contribution to the development of the theory of enzymes, considered them to be the causative agents of life: “All these substances play a huge role, they determine the processes due to which life is manifested, they are in the full sense pathogens of life. ”The experience of changes occurring in living organisms, a person learned to transfer to the industrial sphere - for the technical processing of raw materials in the food and other industries. The use of enzymes and enzyme preparations in technology is based on their ability to accelerate the transformation of many individual organic and mineral substances, thus accelerating the most diverse technological processes.
Currently, 800 different enzymes are already known.
The action of various enzymes is very specific. This or that enzyme acts only on a certain substance or on a certain type of chemical bond in a * molecule.
Depending on the action of enzymes, they are divided into six classes.
Enzymes are able to break down various carbohydrates, protein: protein substances, hydrolyze fats, break down other organic substances, catalyze redox reactions, transfer various chemical groups of molecules of some organic compounds to molecules of others. It is very important that enzymes can accelerate processes not only in the forward direction, but also in the opposite direction, that is, enzymes can carry out not only decomposition reactions of complex organic molecules, but also their synthesis. It is also interesting that enzymes act in extremely small doses on a huge amount of substances. At the same time, enzymes act very quickly, One catalyst molecule converts thousands of substrate particles, in one second. So, 1 gram of pepsin is able to break down 50 kilograms of coagulated egg white; salivary amylase, saccharifying starch, exerts its effect when diluted one in a million, and 1 gram of crystalline rennin makes 12 tons of milk curd!
All naturally occurring enzymes are non-toxic. This advantage is very valuable in almost all food processing industries.
How enzymes are obtained
Enzymes are widespread in nature and are found in all tissues and organs of animals, in plants, as well as in microorganisms - in fungi, bacteria, yeast. Therefore, they can be obtained from a wide variety of sources. Scientists have found an answer to the most interesting questions: how to obtain these miraculous substances artificially, how can they be used in everyday life and in production? , then molds, as it turned out, are truly a "treasure trove" of various biological catalysts. Enzyme preparations obtained from microorganisms began to gradually replace preparations of animal and vegetable origin in most industries.
The advantages of this type of raw material include, first of all, the high reproduction rate of microorganisms. Within a year, under certain conditions, it is possible to harvest 600-800 "harvests" of artificially grown molds or other microorganisms. On a certain environment ( wheat bran, grape or fruit pomace, that is, the remnants after juicing) are sown and, under artificially created conditions (the required humidity and temperature), microorganisms rich in certain enzymes or containing an enzyme of specific properties are grown. To stimulate the production of an increased amount of the enzyme, various salts, acids and other ingredients are added to the mixture. Then a complex of enzymes or individual enzymes are isolated from the biomass,
Enzymes and food
The targeted use of the activity of enzymes contained in raw materials or added in the required quantities is the basis for the production of many food products. Ripening of meat, minced meat sausage, ripening of herring after salting, ripening of tea, tobacco, wines, after which there appears in each of these products an amazing taste and aroma peculiar only to them - is the result of the "work" of enzymes. The process of malt germination, when small starch, insoluble in water, turns into soluble, and the grain acquires a specific aroma and taste - this is also the work of enzymes! In today's view, the further development of the food industry is unthinkable without the use of enzymes and enzyme preparations (a complex of enzymes various actions) Take, for example, bread - the most massive food product. Under normal conditions, the production of bread, or rather the process of dough preparation, also takes place with the participation of enzymes found in flour. What if you add only 20 grams of amylase enzyme preparation per ton of flour? Then we will get bread with improved; taste, aroma, with a beautiful crust, more porous, more voluminous and even sweeter! The enzyme, breaking down to a certain extent the starch contained in the flour, increases the sugar content in the flour; the processes of fermentation, gassing and others are more intensive - and the quality of the bread becomes better.
The same enzyme, amylase, is used in the brewing industry. With his assistance, part of the malt used to make beer wort is replaced with ordinary grain. It turns out a fragrant, frothy, tasty beer. With the help of the enzyme amylase, you can get a water-soluble form of starch, molasses and glucose from cornmeal.
Freshly made chocolate products, soft sweets with filling, marmalade and others are a delicacy not only for kids, but also for adults. But after lying for some time in a store or at home, these products lose their charming taste and appearance - they begin to harden, sugar crystallizes, and the aroma is lost. How to extend the life of these products? Enzyme invertase! It turns out that invertase prevents "stale" confectionery products, rough crystallization of sugar; products remain completely "fresh" for a long time. And what about ice cream with cream? With the use of the lactase enzyme, it will never be grainy or "gritty", because milk sugar will not crystallize.
Enzymes need to work to prevent store-bought meat from being tough. After the slaughter of the animal, the properties of meat change: at first the meat is tough and tasteless, fresh meat has a weak aroma and taste, over time the meat becomes soft, the intensity of the aroma of boiled meat and broth increases, the taste becomes more pronounced and acquires new shades. The meat is ripening.
Changes in meat hardness during maturation are associated with changes in muscle and connective tissue proteins. The characteristic taste of meat and meat broth depends on the content of glutamic acid in the composition of muscle tissue, which, like its salts - glutamates, has a specific taste of meat broth. Therefore, the weakly expressed taste of fresh meat is partly explained by the fact that glutamine during this period is associated with some component, being released as the meat matures.
The change in the aroma and taste of meat during maturation is also associated with the accumulation of low molecular weight volatile fatty acids, which are formed as a result of the hydrolytic breakdown of muscle fiber lipids under the action of lipase.
The difference in the fatty acid composition of muscle fiber lipids of different animals gives specificity to the aroma and taste shades of different types of meat.
Due to the enzymatic nature of meat changes, temperature has a decisive influence on their speed. The activity of enzymes slows down sharply, but does not stop even at very low temperatures: they are not destroyed at minus 79 degrees. Enzymes in a frozen state can be stored for many months without losing activity. In some cases, their activity increases after defrosting.
The scope of application of enzymes and their preparations is expanding every day.
Our industry increases from year to year the processing of grapes, fruits and berries for the production of wine, juices, canned food. In this production, difficulties sometimes lie in the fact that the initial raw material - fruits and berries - does not "give away" all the juice contained in it during the pressing process. Adding an insignificant amount (0.03-0.05 percent) of the enzyme preparation of pectinase to wine, hail, apples, plums, and various berries when crushing or crushing them gives a very sensitive increase in juice yield - by 6-20 percent. Pectinase can also be used to lighten juices, in the production of fruit jellies, fruit purees. The enzyme glucose oxidase is of great practical interest for the protection of products from the oxidizing effect of oxygen - fats, food concentrates and other fat-containing products. The issue of long-term storage of products, which now have a short "lifespan" due to rancidity or other oxidative changes, is being addressed. Removal of oxygen or protection. Those from him are very important in the cheese-making, non-alcoholic, brewing, wine, fat industries, in the production of products such as milk powder, may-one, food concentrates and flavoring products. In all cases, the use of the glucose oxidase-catalase system turns out to be simple and very effective remedy improving the quality and shelf life of products.
The future of the food industry, and indeed of nutritional science in general, is unthinkable without deep study and widespread use of enzymes. Many of our research institutes are engaged in improving the production and use of enzyme preparations. In the coming years, it is planned to dramatically increase the production of these wonderful substances.
1. Carbohydrates, their classification. Content in food. Significance in nutrition
Carbohydrates are organic compounds containing aldehyde or ketone and alcohol groups. Under the general name carbohydrates unite compounds that are widespread in nature, which include both sweet-tasting substances called sugars, and chemical related substances, but much more complex in composition, insoluble and non-sweet-tasting compounds, for example, starch and cellulose. (cellulose).
Carbohydrates are part of many food products, since they make up 80-90% of the dry matter of plants. In animal organisms, carbohydrates contain about 2% of body weight, but their value is great for all living organisms, since they are part of the nucleotides from which nucleic acids are built, which carry out protein biosynthesis and the transfer of hereditary information. Many carbohydrates play an important role in the processes that prevent blood clotting and the penetration of pathogens into macroorganisms, in the phenomena of immunity.
The formation of organic substances in nature begins with the photosynthesis of carbohydrates by the green parts of plants, their CO2 and H2O. In the leaves and other green parts of plants, in the presence of chlorophyll from carbon dioxide from the air and water from the soil, carbohydrates are formed under the influence of sunlight. The synthesis of carbohydrates is accompanied by the absorption of large amounts of solar energy and the release of oxygen into the environment.
Light 12 H2O + 6 CO2 - C6 H12 O6 + 6O2 + 6 H2O chlorophyll
Sugars in the process of further changes in living organisms give rise to other organic compounds - polysaccharides, fats, organic acids, and in connection with the assimilation of nitrogenous substances from the soil - proteins and many others. Under certain conditions, many complex carbohydrates undergo hydrolysis and decompose into less complex carbohydrates; some of the carbohydrates are not degraded by water. The classification of carbohydrates is based on this, which are divided into two main classes:
Simple carbohydrates or simple sugars or monosaccharides. Monosaccharides contain from 3 to 9 carbon atoms, the most common are pentoses (5C) and hexose (6C), and the functional group is aldose and ketose.
Well-known monosaccharides are glucose, fructose, galactose, rabinose, arabinose, xylose and D-ribose.
Glucose (grape sugar) is found in free form in berries and fruits (in grapes - up to 8%; in plums, cherries - 5-6%; in honey - 36%). Starch, glycogen, maltose are built from glucose molecules; glucose is the main part of sucrose, lactose.
Fructose (fruit sugar) is contained in pure form in bee honey (up to 37%), grapes (7.7%), apples (5.5%); is the main part of sucrose.
Galactose - component milk sugar (lactose), which is found in mammalian milk, plant tissues, seeds.
Arabinose is found in conifers, beet pulp, pectin, mucus, gum (gum), hemicellulose.
Xylose (wood sugar) is found in cotton husks, corn stubs. Xylose is part of pentosans. Combining with phosphorus, xylose passes into active compounds that play an important role in the interconversion of sugars.
D-ribose occupies a special place among monosaccharides. Why nature preferred ribose to all sugars is not yet clear, but it is this that serves as a universal component of the main biologically active molecules responsible for the transmission of hereditary information - ribonucleic (RNA) and deoxyribonucleic (DNA) acids; it is also a part of ATP and ADP, with the help of which chemical energy is stored and transferred in any living organism. The replacement of one of the phosphate residues in ATP with a pyridine fragment leads to the formation of another important agent - NAD - a substance that is directly involved in vital redox processes. Another key agent is ribulose 1,5 diphosphate. This compound is involved in the assimilation of carbon dioxide by plants.
Complex carbohydrates, or complex sugars, or polysaccharides (starch, glycogen and non-starch polysaccharides - fiber (cellulose and hemicellulose, pectins).
Distinguish between polysaccharides (oligosaccharides) of I and II orders (polyoses).
Oligosaccharides are polysaccharides of the first order, the molecules of which contain from 2 to 10 monosaccharide residues connected by glycosidic bonds. In accordance with this, disaccharides, trisaccharides, etc. are distinguished.
Disaccharides are complex sugars, each molecule of which, upon hydrolysis, breaks down into two molecules of monosaccharides. Disaccharides, along with polysaccharides, are one of the main sources of carbohydrates in human and animal food. By their structure, disaccharides are glycosides in which two monosaccharide molecules are linked by a glycosidic bond.
Among the disaccharides, maltose, sucrose and lactose are especially well known. Maltose, which is a-glucopyranosyl - (1,4) - a-glucopyranose, is formed as an intermediate in the action of amylases on starch (or glycogen).
One of the most common disaccharides is sucrose, a common food sugar. The sucrose molecule consists of one a-E-glucose residue and one P-E-fructose residue. Unlike most disaccharides, sucrose does not have free hemiacetal hydroxyl and does not have reducing properties.
Disaccharide lactose is found only in milk and consists of RE-galactose and E-glucose.
Polysaccharides of the second order are divided into structural and reserve ones. The former includes cellulose, and the reserve ones include glycogen (in animals) and starch (in plants).
Starch is a complex of linear amylose (10-30%) and branched amylopectin (70-90%), built from the residues of the glucose molecule (α-amylose and amylopectin in linear chains a - 1,4 - bonds, amylopectin at branch points by interchain a - 1.6 - bonds), the general formula of which is С6Н10О5п.
Bread, potatoes, cereals and vegetables are the main energy resource of the human body.
Glycogen is a polysaccharide widely distributed in animal tissues, similar in structure to amylopectin (highly branched chains every 3-4 links, the total number of glycosidic residues is 5-50 thousand)
Cellulose (cellulose) is a common plant homopolysaccharide that serves as a supporting material for plants (plant skeleton). Wood is half composed of fiber and lignin associated with it; it is a linear biopolymer containing 600-900 glucose residues linked by P - 1,4 - glycosidic bonds.
Monosaccharides include compounds that have at least 3 carbon atoms in a molecule. Depending on the number of carbon atoms in the molecule, they are called trioses, tetroses, pentoses, hexoses and heptoses.
In human and animal nutrition, carbohydrates constitute the bulk of food. Due to carbohydrates, 1/2 of the daily energy requirement of the human diet is provided. Carbohydrates help keep protein from being wasted for energy purposes.
An adult needs 400-500 g of carbohydrates per day (including starch - 350-400 g, sugars - 50-100 g, other carbohydrates - 25 g), which must be supplied with food. With heavy physical exertion, the need for carbohydrates increases. With excessive introduction into the human body, carbohydrates can be converted into fats or deposited in small amounts in the liver and muscles in the form of animal starch - glycogen.
In terms of nutritional value, carbohydrates are classified as digestible and non-digestible. Digestible carbohydrates - mono and disaccharides, starch, glycogen. Indigestible - cellulose, hemicelluloses, inulin, pectin, gum, mucus. In the human digestive tract, digestible carbohydrates (with the exception of monosaccharides) are broken down by enzymes to monosaccharides, which are absorbed into the bloodstream through the intestinal walls and carried throughout the body. With excess simple carbohydrates and in the absence of energy expenditure, part of the carbohydrates is converted to fat or stored in the liver as a reserve source of energy for temporary storage in the form of glycogen. Indigestible carbohydrates are not utilized by the human body, but they are extremely important for digestion and constitute the so-called "dietary fiber". Dietary fibers stimulate the intestinal motor function, prevent the absorption of cholesterol, play a positive role in the normalization of the intestinal microflora composition, in inhibiting putrefactive processes, and contribute to the elimination of toxic elements from the body.
Daily rate dietary fiber is 20-25 g. Animal products contain little carbohydrates, therefore, plant food is the main source of carbohydrates for humans. Carbohydrates make up three quarters of the dry mass of plants and algae, they are found in grains, fruits, vegetables. In plants, carbohydrates accumulate as storage substances (for example, starch) or they play the role of a supporting material (fiber).
The main digestible carbohydrates in the human diet are starch and sucrose. Starch accounts for approximately 80% of all carbohydrates consumed by humans. Starch is the main human energy resource. Sources of starch are grains, legumes, potatoes. Monosaccharides and oligosaccharides are present in cereals in relatively small amounts. Sucrose usually enters the human body with products to which it is added (confectionery, drinks, ice cream). High sugar foods are the least valuable of all carbohydrate foods. It is known that it is necessary to increase the content of dietary fiber in the diet. The source of dietary fiber is rye and wheat bran, vegetables, fruits. Whole grain bread is much more valuable in terms of dietary fiber content than premium flour bread. Fruit carbohydrates are mainly represented by sucrose, glucose, fructose, as well as fiber and pectin substances. There are products that consist of almost the same carbohydrates: starch, sugar, honey, caramel. Animal products contain significantly less carbohydrates than plant foods. One of the most important representatives of animal starches is glycogen. Meat and liver glycogen are similar in structure to starch. And milk contains lactose: 4.7% - in cow, 6.7% - in human.
The properties of carbohydrates and their transformation are of great importance in the storage and production of food products. So, during the storage of fruits and vegetables, weight loss occurs as a result of the consumption of carbohydrates for the respiration processes. Transformations of pectin substances cause a change in the consistency of the fruit.
2. Antienzymes. Content in food. Operating principle. Factors that reduce the inhibitory effect
Antienzymes (inhibitors of protennases). Protein substances that block the activity of enzymes. Contained in raw legumes, egg white, wheat, barley, other products of plant and animal origin, not subjected to heat treatment. The effect of antienzymes on digestive enzymes, in particular pepsin, trypsin, and a-amylase, has been studied. An exception is human trypsin, which is in a cationic form and therefore is not sensitive to legume antiprotease.
Currently, several tens of natural inhibitors of proteinases, their primary structure and mechanism of action have been studied. Trypsin inhibitors, depending on the nature of the diaminomonocarboxylic acid they contain, are divided into two types: arginine and lysine. The arginine type includes: soy Kunitz inhibitor, inhibitors of wheat, corn, rye, barley, potatoes, chicken egg ovomucoid, etc. isolated from cow colostrum.
The mechanism of action of these anti-alimentary substances is the formation of persistent enzyme inhibitory complexes and the suppression of the activity of the main proteolytic enzymes of the pancreas: trypsin, chymotrypsin and elastase. The result of this blockade is a decrease in the absorption of protein substances in the diet.
The considered inhibitors of plant origin are characterized by a relatively high thermal stability, which is not typical for protein substances. Heating dry plant products containing these inhibitors to 130 ° C or boiling for half an hour does not lead to a significant decrease in their inhibitory properties. Complete destruction of the soybean trypsin inhibitor is achieved by 20 minutes autoclaving at 115 ° C or boiling the soybeans for 2-3 hours.
Inhibitors of animal origin are more sensitive to heat. At the same time, the consumption of raw eggs in large quantities can have a negative effect on the absorption of the protein part of the diet.
Certain enzyme inhibitors can play a specific role in the body under certain conditions and at certain stages of the body's development, which in general determines the ways of their study. Heat treatment of food raw materials leads to denaturation of the protein antienzyme molecule, i.e. it affects digestion only when raw food is consumed.
Substances that block the assimilation or exchange of amino acids. This is the effect on amino acids, mainly lysine, from the side of reducing sugars. The interaction takes place under conditions of severe heating according to the Maillard reaction, therefore, gentle heat treatment and the optimal content of sources of reducing sugars in the diet ensure good absorption of essential amino acids.
carbohydrate taste antienzyme acid
3. The role of acids in the formation of the taste and smell of food. The use of food acids in food production.
Almost all foods contain acids or acidic and medium salts. In processed products, acids come from raw materials, but they are often added during the production process or they are formed during fermentation. Acids give the food a specific taste and thus facilitate their better assimilation.
Food acids are a group of substances of organic and inorganic nature, diverse in their properties. The composition and features of the chemical structure of food acids are different and depend on the specifics of the food object, as well as the nature of acid formation.
In plant products, organic acids are most often found - malic, citric, tartaric, oxalic, pyruvic, lactic. Lactic, phosphoric and other acids are common in animal products. In addition, fatty acids are found in a free state in small quantities, which sometimes impair the taste and smell of products. Typically, food contains mixtures of acids.
Due to the presence of free acids and acidic salts, many products and their aqueous extracts are acidic.
The sour taste of a food product is determined by hydrogen ions formed as a result of the electrolytic dissociation of the acids and acid salts contained in it. The activity of hydrogen ions (active acidity) is characterized by the pH indicator (negative logarithm of the concentration hydrogen ions).
Almost all food acids are weak and dissociate slightly in aqueous solutions. In addition, the food system may contain buffer substances, in the presence of which the activity of hydrogen ions will remain approximately constant due to its connection with the equilibrium of dissociation of weak electrolytes. Milk is an example of such a system. In this regard, the total concentration of acidic substances in a food product is determined by the indicator of potential, total or titratable (alkali) acidity. For different products, this value is expressed through different indicators. For example, in juices, the total acidity is determined in g per 1 liter, in milk - in Turner's degrees, etc.
Food acids in food raw materials and products perform various functions related to the quality of food items. As part of the complex of flavoring substances, they participate in the formation of taste and aroma, which are among the main indicators of the quality of a food product. It is the taste, along with the smell and appearance, that to this day has a more significant impact on the consumer's choice of a particular product in comparison with such indicators as composition and nutritional value. Changes in taste and aroma are often signs of incipient deterioration of the food product or the presence of foreign substances in its composition.
The main taste sensation caused by the presence of acids in the composition of the product is sour taste, which is generally proportional to the concentration of H ions +(taking into account the differences in the activity of substances that cause the same taste perception). For example, the threshold concentration (the minimum concentration of a flavoring agent perceived by the senses), which allows you to feel a sour taste, is 0.017% for citric acid, and 0.03% for acetic acid.
In the case of organic acids, the anion of the molecule also influences the perception of sour taste. Depending on the nature of the latter, combined taste sensations may occur, for example, citric acid has a sweet and sour taste, and picric acid has a sour - bitter. A change in taste sensations also occurs in the presence of salts of organic acids. Thus, ammonium salts impart a salty taste to the product. Naturally, the presence of several organic acids in the composition of the product in combination with taste organic substances of other classes determine the formation of original taste sensations, often inherent exclusively to one, specific type of food products.
The participation of organic acids in the formation of aroma in different products is not the same. The share of organic acids and their lactones in the complex of aromatic substances, such as strawberries, is 14%, in tomatoes - about 11%, in citrus fruits and beer - about 16%, in bread - more than 18%, while acids account for less than 6%.
The composition of the aromatic complex of fermented milk products includes lactic, citric, acetic, propionic and formic acids.
The quality of a food product is an integral value that includes, in addition to organoleptic properties (taste, color, aroma), indicators characterizing its colloidal, chemical and microbiological stability.
The formation of the quality of the product is carried out at all stages of the technological process of its production. At the same time, many technological indicators that ensure the creation of a high-quality product depend on the active acidity (pH) of the food system.
In general, the pH value affects the following technological parameters:
-the formation of flavor and aroma components characteristic of a particular type of product;
-colloidal stability of a polydisperse food system (for example, the colloidal state of milk proteins or a complex of protein-tannins in beer);
thermal stability of the food system (for example, the thermal stability of protein substances in dairy products, depending on the state of equilibrium between ionized and colloidly distributed calcium phosphate);
biological resistance (eg beer and juices);
enzyme activity;
conditions for the growth of beneficial microflora and its influence on the maturation processes (for example, beer or cheese).
The presence of food acids in a product may result from the deliberate introduction of acid into the food system during the technological process to regulate its pH. In this case, food acids are used as technological food additives.
In general, there are three main purposes of adding acids to the food system:
-imparting certain organoleptic properties (taste, color, aroma) characteristic of a particular product;
-influence on colloidal properties, which determine the formation of a consistency inherent in a particular product;
increase in stability, ensuring the preservation of product quality for a certain time.
Acetic acid (glacial) E460 is the most famous food acid and is produced in the form of an essence containing 70-80% of the actual acid. In everyday life, vinegar essence diluted with water is used, called table vinegar. Using vinegar to preserve food is one of the oldest preserving methods. Depending on the raw material from which acetic acid is obtained, a distinction is made between wine, fruit, malic, alcoholic vinegar and synthetic acetic acid. Acetic acid is produced by acetic acid fermentation. Salts and esters of this acid are called acetates. Potassium and sodium acetates (E461 and E462) are used as food additives.
Along with acetic acid and acetates, sodium and potassium diacetates are also used. These substances are composed of acetic acid and acetates in a molar ratio of 1: 1. Acetic acid is a colorless liquid that is miscible with water in all respects. Sodium diacetate is a white crystalline powder, soluble in water, with strong smell acetic acid.
Acetic acid has no legal restrictions; its action is mainly based on lowering the pH of the canned product, manifests itself at a content above 0.5% and is directed mainly against bacteria . The main area of use is canned vegetables and pickled products. It is used in mayonnaise, sauces, for marinating fish products and vegetables, berries and fruits. Acetic acid is also widely used as a flavoring agent.
Lactic acid is produced in two forms, differing in concentration: a 40% solution and a concentrate containing at least 70% acid. Obtained by lactic acid fermentation of sugars. Its salts and esters are called lactates. As a food additive E270 is used in the production of soft drinks, caramel masses, fermented milk products. Lactic acid has restrictions on its use in baby food.
Lemon acid - citric acid fermentation product of sugars. Has the mildest taste in comparison with other food acids and does not irritate the mucous membranes of the digestive tract. Salts and esters of citric acid - citrates. It is used in the confectionery industry, in the production of soft drinks and some types of canned fish (food additive E330).
Apple acid has a less sour taste than lemon and wine. For industrial use, this acid is synthetically obtained from maleic acid, and therefore the purity criteria include restrictions on the content of toxic maleic acid impurities in it. Malic acid salts and esters are called malates. Malic acid has the chemical properties of hydroxy acids. When heated to 100 ° C, it turns into anhydride. It is used in the confectionery industry and in the production of soft drinks (food additive E296).
Wine acid is a product of processing waste of winemaking (wine yeast and tartar). It does not have any significant irritating effect on the mucous membranes of the gastrointestinal tract and does not undergo metabolic transformations in the human body. The main part (about 80%) is destroyed in the intestine by bacteria. Salts and esters of tartaric acid are called tartrates. It is used in confectionery and soft drinks (food additive E334).
succinic acid is a by-product of the production of adipic acid. There is also known a method for its isolation from amber waste. It has chemical properties characteristic of dicarboxylic acids, forms salts and esters, which are called succinates. At 235 ° C, succinic acid splits off water, turning into succinic anhydride. It is used in the food industry to regulate the pH of food systems (food additive E363).
Succinic anhydride is a product of high-temperature dehydration of succinic acid. Also obtained by catalytic hydrogenation of maleic anhydride. Poorly soluble in water, where it is very slowly hydrolyzed to succinic acid.
Adipic acid obtained in industry, mainly by two-stage oxidation of cyclohexane. Possesses all chemical properties characteristic of carboxylic acids, in particular, forms salts, most of which are soluble in water. Easily esterified into mono- and diesters. Salts and esters of adipic acid are called adipates. It is a food additive (E355) that provides sour taste of products, in particular, soft drinks.
Fumaric acid found in many plants and fungi, formed during the fermentation of carbohydrates in the presence of Aspergillus fumaricus. The industrial method of production is based on the isomerization of maleic acid under the action of HC1 containing bromine. Salts and esters are called fumarates. In the food industry, fumaric acid is used as a substitute for citric and tartaric acids (food additive E297). Possesses toxicity, and therefore the daily intake with food is limited to the level of 6 mg per 1 kg of body weight.
Glucono delta lactone - the product of enzymatic aerobic oxidation (, D-glucose. In aqueous solutions, glucono-delta-lactone is hydrolyzed into gluconic acid, which is accompanied by a change in the pH of the solution. It is used as an acidity regulator and baking powder (food additive E575) in dessert mixtures and products based on minced meat, such as sausages.
Phosphoric acid and its salts - phosphates (potassium, sodium and calcium) are widespread in food raw materials and products of its processing. Phosphates are found in high concentrations in dairy, meat and fish products, in some types of cereals and nuts. Phosphates (food additives E339 - 341) are introduced into soft drinks and confectionery. The permissible daily dose, in terms of phosphoric acid, corresponds to 5-15 mg per 1 kg of body weight (since an excessive amount of it in the body can cause an imbalance of calcium and phosphorus).
Bibliography
1.A.P. Nechaev Food chemistry / A.P. Nechaev, S.E. Traubenberg, A.A. Kochetkova and others; under. Ed. A.P. Nechaev. SPb .: GIORD, 2012 .-- 672 p.
2.Dudkin M.S. New food products / M.S. Dudkin, L.F. Shchelkunov. M .: MAIK "Nauka", 1998. - 304 p.
.Nikolaeva M.A. Theoretical foundations of commodity research / M.A. Nikolaev. M .: Norma, 2007 .-- 448 p.
.Rogov I.A. Chemistry of food. / I.A. Rogov, L.V. Antipova, N.I. Dunchenko. - M .: Colossus, 2007 .-- 853 p.
.The chemical composition of Russian food products / ed. THEM. Skurikhin. M .: DeLiprint, 2002 .-- 236 p.
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1. Food chemistry and its main directions.
Food chemistry- the science of chemistry. the composition of food systems, its change in the course of the technological flow under the influence of various factors, the general laws of these transformations.
The main directions of development of food chemistry:
1). Chem. composition of food systems raw materials, their usefulness and safety.
Food composition. products and raw materials:
Macronutrients (vitamins, minerals)
Micronutrients (organic to-you)
Alimentary nutritional factors (some PUFA, non-replaceable amino acids - cannot be synthesized in org.)
Non-standard
Antialimentary - food components. products or raw materials that do not have nutritional or biological value for us, but are part of food.
Alimentary fiber
Xenobiotics are foreign chemical substances that should not be included in food.
2). Conversion of micro- and macronutrients, non-nutritional substances in the process stream.
3). Fundamentals of isolation, fractionation of components of raw materials, food systems and their modification.
4). Tech. obtaining and using food additives.
Food additives are components introduced into food products to give them the desired properties.
5). Tech. obtaining and using dietary supplements
6). Methods of analysis and research of food systems, their components and additives.
2. Human food - the most important social and economic problem of society. Two categories of food problems.
The main problems facing humanity:
1). Providing the population with food is the main problem.
2). Energy supply.
3). Supply of raw materials, including water.
4). Environmental protection.
Prod. should not only satisfy a person's need for the basics. Pete. in-wah, but also to carry out the basic medical and profile. functions.
There are 2 types of food problems:
1. Needed. production as much food as is required to provide everyone with sufficient food.
2. Create conditions to ensure that everyone gets enough. amount of food. Compliance with this condition depends on the political decisions of the world community.
As for solving the first problem, the ways are as follows:
1). Increase the efficiency of agriculture.
2). Reduce losses during technological processing of raw materials.
3). Reduce losses during storage, transportation, sales.
4). Increase the efficiency of using raw materials by creating closed technological cycles.
5). Development of ways to obtain new food products as a result of microbiological, organic synthesis.
6). Shrinking the food chain is to remove the consumption of animal proteins from it, immediately eating vegetable proteins.
3. Basic terms and definitions used in food chemistry.
Manufacturing raw materials - objects of plant, live, microbe, min. origin and water used for food production.
Food products- products made from food raw materials and used for food in natural or processed form.
Food quality- a set of product properties, reflecting the ability of the product to provide organoleptic characteristics, to ensure the body's need for nutrients, to ensure health safety and reliability during manufacture and storage.
Food safety- absence of toxic, carcinogenic, mutagenic and any other adverse effects on the human body when eating food in generally accepted quantities.
The nutritional value- a concept that reflects the entirety useful properties product, including the degree of satisfaction of the physiological needs for basic nutrients and energy, as well as organoleptic advantages.
Biological value- an indicator of the quality of food protein, reflecting the degree of compliance of its amino acid composition with the body's needs for amino acids for protein synthesis.
Energy value- the amount of energy in kilocalories. released in the human body from food. product to meet its physiological needs.
Biological effectiveness - an indicator of the quality of the fatty components of the product, reflecting the content of PUFA in it.
PUFA - acids with 2 or more double bonds.
Counterfeiting of food products and food raw materials–Production and sale of counterfeit food products and food raw materials that do not correspond to their name and recipe.
Identification of food products and food raw materials- Establishing the compliance of food products and food raw materials with their names in accordance with regulatory documents for given view product (technical regulations of the Customs Union, technical conditions).
Shelf life - the period of time during which, subject to certain conditions, food raw materials and food products retain the quality established by the regulatory documentation (TU, GOST, technical regulations).
Packaging and auxiliary materials- in contact with food products at different stages of the technological process of production, transportation, storage and sale.
4. Functions of water in raw materials and food products.
Water, not being a food product - a nutrient, a substance is extremely important for life: a stabilizer of body temperature, a carrier of nutrients and waste products, a component of reactions and a reaction medium, a stabilizer of the conformation of biopolymers (proteins, fats, carbohydrates). Water is a substance that facilitates the dynamic behavior of macromolecules, incl. and catalytic properties.
Functions of water in food systems:
1) Present as an intracellular and intercellular component of plant and animal objects.
2) Present as a dispersing medium and solvent in many food systems.
3) Determines the consistency of the products.
4) Provides the appearance and taste of food.
5) Affects the stability of the food during storage.
Based on the fact that many types of food products contain a large amount of moisture that affects preservation, methods are needed for long-term storage of products.
Water is a direct participant in all hydrolytic processes, therefore, its removal or binding with salt or sugar will slow down many reactions and inhibit the growth of microorganisms.
5. Free and bound moisture in food. Methods for the determination of free and bound water.
The value of water in food is determined by its association with the food. Total moisture, determined simple method drying, simply indicates the amount of moisture in the product, but does not characterize its involvement in hydrolytic, biochemical and microbiological processes. Free moisture not associated with biopolymers (proteins, lipids, carbohydrates) and is available for chemical, biochemical and microbiological reactions.
Bound moisture firmly associated with biopolymers by physical, chemical bonds: hydrogen, covalent, ionic and hydrophobic interactions.
Bound moisture is moisture that exists near the dissolved non-aqueous component, has low molecular mobility and does not freeze at 40 ° C. Some types of bound moisture do not freeze even at temperatures of -60 ° C.
The amount and strength of the bond of water with other components depends on: the nature of the non-aqueous component, the composition of the salt, pH, t.
Consider the distribution of free and bound moisture in food systems. The total grain moisture is 15-20%, of which 10-15% is associated moisture. If the moisture content of the stored grain rises, free moisture will appear and biochemical processes will intensify, the grain will begin to germinate.
While fruits and vegetables have a moisture content of 75-90%. This is mainly free moisture and only about 5% bound moisture held by colloids (proteins and carbohydrates). This is a very firmly bound moisture, so fruits and vegetables are easily dried to a moisture content of 10-15%, and further drying requires special methods.
Methods for determining free and bound moisture:
1) Differential scanning calorimetry. The sample is cooled to a temperature below 0 ° C, under such conditions free moisture freezes. When this sample is heated, the calorimeter can measure the amount of heat expended to melt the frozen part. Then unfrozen moisture will be defined as the difference between total and frozen moisture.
2)Thermogravimetric method... Based on the determination of the drying rate. V controlled conditions trace the boundary between the area of constant drying rate and the area where this rate decreases. This boundary indicates or characterizes the bound moisture.
3) Dielectric measurements... The method is based on the fact that at 0оС the values of the dielectric constant of water and ice are approximately the same, but the dielectric behavior of bound moisture differs significantly from the dielectric behavior of the bulk of water and ice.
4) Heat capacity measurement... The heat capacity of water is greater than the heat capacity of ice, i.e., as the temperature rises, the hydrogen bonds of water are broken. This property is used to determine the mobility of molecules. If the moisture content of the product is low and the moisture is specifically bound, then its contribution to the heat capacity is insignificant. In areas of high moisture content, there is mainly free water and its contribution to the heat capacity is more significant.
5) Nuclear magnetic resonance method... A study of the mobility of water in a stationary matrix is carried out. In the presence of free and bound moisture, 2 spectral lines are obtained instead of 1, which characterizes the bulk moisture.
6. Water activity. Water activity and food stability.
Water activity ( aw ) –
ROV- characterizes the state of equilibrium in which the product does not absorb moisture and does not lose it to the atmosphere.
Water activity characterizes the state of water in the food system, its involvement in chemical and biological changes in the product. By the value of water activity, it is customary to distinguish between products:
1-0.9 high humidity
aw = 0.9-0.6 products with intermediate moisture
aw = 0.6-0 low humidity
The relationship between water activity and food stability is manifested in the following:
1 ) In products with low humidity, fat oxidation processes occur, non-enzymatic browning , loss of water-soluble substances (vitamins) and enzyme-controlled processes can take place. The activity of microorganisms is minimal here.
2) In products with intermediate humidity, various of the above processes can occur, including with the participation of microorganisms.
3) In products with high humidity, water activity 0.9-1 is mainly caused by microorganisms.
During storage, the following changes can occur in food products: darkening of the product as a result of non-enzymatic reactions (aw = 0.6-0.75).
Enzymatic reactions occurring in the presence of free moisture necessary for the transfer of the substrate: enzymatic reactions, reactions involving lipases occur at aw = 0.1-0.2. Such low values are explained by the fact that lipids require less water as a vehicle and their mobility is sufficient for enzymatic reactions to occur.
Most bacteria multiply at aw = 0.85-0.95, molds at aw = 0.6-0.8, and yeast at aw = 0.8-0.9, so low aw values inhibit the growth of any microorganisms.
Deterioration of products with intermediate moisture content is caused to a greater extent by yeasts and molds, to a lesser extent - by bacteria. Yeast causes mischievous jams, syrups, dried fruits, confectionery. Molds cause spoilage of meat, cheeses, biscuits, jams, dried fruits.
7. Water activity. Methods for reducing the activity of water in food.
Water activity () - an indicator representing the ratio of the vapor pressure of water over a given solvent to the vapor pressure over pure water. Or the ratio of the equilibrium relative humidity of the product / 100.
To increase the shelf life, it is necessary to prevent a number of chemical, biochemical and microbiological reactions, i.e. reduce water activity in food. To do this, use drying, drying, adding various substances: sugar or salt, freezing.
Adsorption method consists in drying the product, followed by moistening to the specified moisture content.
Osmosis drying- food products are immersed in a solution, the water activity of which is lower than aw of the product. There are 2 countercurrents: the dissolved substance diffuses from the solution into the product, and water diffuses from the product into the solution. Salt and sugar are used as solutions.
Application of potential humidifiers... They can be used to increase the moisture content of the product, but reduce aw. Potential moisturizers are: sugar, starch, lactic acid, glycerin.
In dry products, allowed without loss of the desired properties aw = 0.35-0.5, depending on the type of product (crackers, crispbread, milk powder). Products with a softer texture will have an even higher aw.
8. The role of proteins in human nutrition.
Proteins - high-molecular nitrogen-containing compounds built from alpha-amino acid residues.
The biological significance of proteins is that genetic information is transmitted through them.
The contractile function of proteins is muscle tissue proteins.
Proteins play the role of catalysts and regulators of biochemical processes.
Carry out a transport function - they carry iron, lipids, hormones, oxygen.
The protective function of proteins is realized in the synthesis of antibodies.
The need for protein in the human body is explained by the following:
1) Protein is essential for growth and development.
2) Protein controls metabolism (metabolism consists of 2 processes: catabolism (complex organic compounds decompose with the release of energy - dissimilation) and anabolism (synthesis of complex compounds from simple ones with energy absorption - assimilation).
3) Proteins have a strong dynamic effect on metabolism.
4) Proteins regulate water balance in the body i.e. proteins and some minerals control the water content in various parts of the body. As soon as there are fewer proteins, water flows into the intercellular space, edema appears.
5) Proteins strengthen the immune system - antibodies in the blood.
Proteins are not stored in the store, so they must be taken with food daily. To study the body's needs for protein, a balance is calculated - the amount of proteins that have entered the body and the products of their decay released from the body are compared.
Normally, an adult (20-35 years old) has a nitrogen balance. In a young growing organism, less nitrogen is excreted than it enters. plastic processes prevail. In old age, with a lack of protein, a negative nitrogen balance is observed - more is excreted than it is received.
Norms daily requirement in protein.
The need for protein depends on: age, gender, character labor activity, climatic living conditions, national dietary habits.
Recommended consumption rates vary widely, with different rates in different countries. The Russian School of Nutrition recommends 70-120 grams per day for men, 60-90 grams per day for women; including animal protein for men 49-65 grams, women - 43-49 grams per day.
For people who have undergone infectious diseases or surgery, the amount of protein increases to 110-120 grams.
A high-protein diet is typical for a diabetic diet - 140 grams of protein per day. Limit protein content in renal failure.
Babies - 3 g per kg of body weight.
Children 4-6 years old - 2.5 g per kg of body weight.
Children 10-15 years old - 1.5 g per kg of body weight.
Young people under 18 years old - 1-1.5 g per kg of body weight.
Adults 25-45 - 0.9 g per kg of body weight.
People over 60 and pregnant women - 1.5 g per kg of body weight.
The high dose of protein for the elderly is attributed to poor digestibility and low absorption of protein by the elderly. Deviation in one direction or another from the norm has negative consequences.
Excessive protein intake leads to:
1) Increased formation of ammonia in tissues.
2) The accumulation of toxic products in the large intestine. decay processes intensify.
3) An increase in the load on the liver (disinfection) and on the kidneys (removal of decay products).
4) Overexcitation of the nervous system.
5) Hypoavitaminosis of vitamin A, B6.
10. The biological value of proteins. Indicators of biological value: amino acid speed, INAC, CEB, protein digestibility.
The biological value of proteins is determined:
1) The presence in their composition of essential amino acids and their ratio with non-essential.
2) The digestibility of proteins by enzymes in the digestive tract.
Distinguish between biologically valuable and biologically defective proteins. Biologically valuable, they are balanced in amino acid composition and contain the necessary essential amino acids in the required quantities.
In terms of amino acid composition, animal proteins are well balanced and close to the composition of human proteins. They contain enough essential amino acids and are complete. And plant proteins are poor in many essential amino acids. Especially lysine, threonine, tryptophan, therefore, are considered inferior.
Indicators of the biological value of protein:
AKC - is calculated as the ratio of mg of amino acid in 1 g of protein to mg of amino acid in 1 g of reference protein.
AKC is calculated in% or is a dimensionless value. AKC is close to 100% protein in chicken eggs and breast milk.
INAK- is calculated as the n-th power from the product of the ratio of the amino acid of the protein under study to the amino acid of the standard, the n-th power shows the calculated number of amino acids.
The limiting amino acid is the amino acid whose quickest is the lowest. The value of this scor determines the biological value and the degree of digestibility of the protein.
CEB (Protein Efficiency Ratio)- an indicator determined by the ratio of the weight gain of animals (grams) to the amount of consumed protein (grams). The control group for determining the CEB is a group of animals fed with casein.
The degree of digestibility depends on: structural features, enzyme activity, the depth of hydrolysis in the gastrointestinal tract, the type of preliminary processing.
The digestibility of animal proteins is higher than plant proteins. That is due to the presence of fiber in plant tissues (makes it difficult to digest, extracting proteins; promotes the rapid movement and elimination of food from the body).
In decreasing rate of assimilation of proteins in the human gastrointestinal tract, the products are arranged in the sequence: fish => dairy products => meat => bread => cereals.
The diet of plant proteins should be 45%, and animals - 55%.
11. The problem of protein deficiency on Earth and ways to solve it. New forms of protein foods. Potential raw material sources of protein components of food.
Some areas of the earth are still severely protein deficient.
Lack of protein in the diet:
1) Decreases the protective function of lymphocytes (immunity).
2) The activity of leukocytes decreases (the risk of bacterial infections increases).
3) Facilitates the formation of malignant tumors.
4) If the lack of protein was in childhood, then the loss of mental and physical development is never recoverable.
The consequences of protein-caloric insufficiency in childhood are diseases: alimentary marasmus, kwashiorkor, with characteristic symptoms that are fatal.
To overcome the protein deficiency in the diet of the population, it is necessary:
1) Increase the productivity of crop production - high-yielding varieties.
2) Develop animal husbandry.
3) Reduce processing and storage losses.
4) Create new technologies for new forms of protein foods.
New forms of protein foods.
The main direction of scientific and technological progress in the field of food production is the intensification of food production processes with the simultaneous imparting of properties to products that reflect the modern requirement of nutritional science. Such new food production is mainly about obtaining protein products, the reasons for this approach are:
=> Population growth.
=> Awareness of the limited resources of the planet.
=> The need to manufacture products that meet modern image life.
Potential raw material sources of new forms of protein foods:
1) Legumes: soybeans, peas, lentils.
2) Cereals and cereal products: wheat, rye, oats.
3) Oilseeds: sunflower, flax, rapeseed.
4) Vegetative mass of plants: alfalfa, clover.
5) By-products of fruits and berries: apricot pits, plums.
6) Nuts: pine nuts, hazelnuts, walnuts, Brazil nuts.
The traditional raw materials are soybeans and wheat.
A feature of the processing technology is the use of an integrated approach, waste-free technology, the desire to extract all potential resources from raw materials.
New food products derived from the protein fractions of raw materials are called new forms of protein food, textured, structured artificial foods.
12. The concept of essential amino acids. The problem of protein enrichment with amino acids.
The problem of protein enrichment with amino acids.
To eliminate the lack of amino acids, it was proposed to enrich products containing protein with free amino acids obtained by microbiological and chemical methods.
The industrial production of essential amino acids has been established: lysine, glutamic acid.
But it turns out that there is a difference in time between the entry into the bloodstream of free amino acids introduced into the product and amino acids released as a result of digestion. Untimely intake of amino acids causes an imbalance in the blood, therefore, without participating in biosynthesis, they can undergo transformations, including the formation of toxins.
13,14,15. Protein determination methods, isolation, purification.
1) Qualitative reactions
2) quantitation protein by the Kjeldahl method - a classical method with which the results of all modern and its modifications are compared (GOST); Lowry method; biuret method. The last two are easy for serial analyzes.
3) Isolation and purification of protein:
The first stage is the destruction of the cellular structure of the material (homogenizers, disintegrators). It should be noted that mechanical stress may be accompanied by partial denaturation.
The second stage is the extraction of proteins, i.e. extraction, transfer of proteins into solution (water-albumin, salt-globulins, alcohol-prolamins, alkaline solution-gluteins)
The third stage is deposition, the choice of method and mode depends on the task and individual characteristics of the object:
A) Precipitation with trichloroacetic acid allows the separation of proteins from a.to. and peptides, but is accompanied by irreversible denaturation.
B) Precipitation with organic solvents - widely used to obtain enzyme preparations.
C) Salting out the protein with aluminum sulfate while preserving the native structure.
D) Deposition at the isoelectric point, by changing the pH of the protein solution, we achieve sedimentation with the preservation of the structure.
E) Precipitation of thermal coagulation - carry out by varying the heat treatment of the protein product. Heat-labile proteins in the sediment, heat-stable - in solution.
The fourth step is protein purification. If in the future it is necessary to obtain a protein preparation of a high degree of purity, then fractionation methods based on individual f.-kh. properties of various proteins:
a) Gel filtration method (molecular sieve method) with its help separate the components by molecular weight. Sefedax preparations are used as a gel. From a separation column filled with granules with a certain cell size, proteins of high molecular weight will come out earlier, low molecular weight - later.
b) electrophoretic separation of proteins - separation in electric field direct current. In buffer solutions, amphoteric protein molecules have a charge and in a direct current electric field move to the anode (-) or to the cathode (+)
c) isoelectric focusing - the method is based on volume. That different proteins have different isoelectric points. Separation is carried out in a column along the height of which a pH gradient is created. Protein moves under the influence of email. Fields until it reaches the area of the column that corresponds to its isoelectric point. The total charge of the protein becomes 0, the protein loses its mobility and remains in this pH zone.
d) affinity chromatography (by affinity) - based on the ability of proteins to specifically and reversibly bind to ligands.
16. proteins of food raw materials: proteins of cereals. Proteins of wheat, rye, oats, barley, corn, rice, buckwheat.
A. to. the composition of the total proteins of cereal crops is determined by a.-k. the composition of individual fractions: albumin (H2O), globulins (salt), prolamins (alcohol) and glutelins (NaOH).
Albumin high content of lysine, threonine, methionine, isoleucine and tryptophan. Globulin poorer than albumin in the content of lysine, tryptophan and methionine. But both fractions have a high content of glutamic and aspartic acid but low in proline. V prolaminic fractions high in lysine, little threonine, tryptophan, arginine and histidine. Glutelinic by A.-K. composition occupies an intermediate position between prolamins and globulins, i.e. they contain more arginine, histidine and lysine than prolamins.
Proteins are unevenly distributed between morphological parts of the grain. Their main amount (up to 70%) is localized in the endosperm, less in the aleurone layer (15%) and the embryo (20%). In the endosperm, proteins are distributed in such a way that their concentration decreases as they move from the subaleuron layer towards the center. The proteins of the embryo and the aleurone layer are mainly represented by albumin and globulins, which perform a catalytic function (enzymes responsible for grain germination). Endosperm proteins are albumins, globulins, prolamins and glutelins. These are mainly storage proteins (up to 80%), most of which are prolamins and glutelins. When studying the protein complex of any culture, the natural structure of the protein molecule is destroyed. Non-covalent bonds are destroyed or changed, i.e. primary denaturation occurs. Further, the extraction of albumin, associated with a violation of the hydrophobic interaction, changes the structure of the protein molecule. When alkali-soluble proteins are extracted, disulfide bonds break.
Wheat protein(albumins 5%, globulins 13%, prolamins 36%, glutelins 28%). In wheat grain, prolamins and glutelins form gluten. Wheat prolamine is called gliadin (it is better soluble in alcohol 60%, isoel. Point pH = 7.0). It contains little lysine and tryptophan, but a lot of proline and glutamic acid. Wheat glutelin is called glutenin, contains a lot of glutamic acid. Wheat alubumin is called leucosin. Easily denatures with loss of solubility. Wheat is characterized by a low content of lysine, isoleucine and threonine, a little methionine. The main advantage of gluten is a complex protein complex, consisting of two fractions of gliadin and glutenic (1: 1). The protein content is 85%, carbohydrates 15%, lipids from 2 to 8%.
Different qualities of gluten have the same a.-k. composition and consists of the same protein compounds. In strong gluten, the packing density of protein components is higher than in weak gluten. Disulfide and hydrogen bonds are involved in the formation of gluten. The strength and mobility of the gluten structure is created by specific rheological properties (elasticity, viscosity, extensibility), which is explained by the presence of non-covalent, easily torn and easily arising properties. The quality of gluten is related to the number of disulfide bonds and is assessed by the ratio of –S-S- bonds and the number of –SH- groups. Depending on the rheological groups. Depending on the rheological properties of gluten, wheat varieties are divided into hard and soft. In firm - gluten is strong, short-torn, the dough is strong, with high elasticity, low-stretch (pasta, semolina). In soft wheat, gluten is resilient, elastic and stretchable. The dough has a good gas-holding capacity and has a porous structure. The soft wheat group is divided into strong, weak and medium varieties. Flour from strong varieties gives firm elastic dough, good shape with porous bread. The dough has limited elongation and lowers gas retention. ability. When strong wheat is mixed with flour with low baking properties, we get flour of good quality. Strong wheat improver varieties. Medium wheat flour is a relatively good bread, but it is not an improver. Weak varieties produce low, loose bread with poor porosity.
Rye grain proteins. (alb.-24%, glob.-14%, prol.-31%, gluten-23%) Rye is poor in lysine and isoleucine, insignificant. the content of methionine. Well balanced. By A.K. composition. Grain contains gliadin and glutenin; under normal conditions, gluten is not washed, because A.-K. the composition of rye proteins differs from a.k.w. wheat, contains fewer hydrogen and -S-S- bonds. Prolamins of rye are called sekamin. Bread made from pure rye flour needs improvers.
Barley proteins.(alb.-6%, glob.-7%, prol.-42%, gluten-27%) barley is poor in leucine and isoleucine. Prolamins of barley are called hordein. Gluten is similar to weak short-tear wheat gluten (gray in color, poor elasticity). Flour tastes bad. It is used where there is no wheat and rye.
Oat proteins(alb.-8, glob.-32, pr.-14, glut.-34) are rich in lysine. Prolamine fraction (avelin), contains a large amount of it. The predominant fraction is glutelin. According to the content of separate a.k. oat proteins are distinguished by their high biological value.
Corn proteins(a-10%, glob-5, n-30, gluten-40) Prolamin corn-zein. By A.K. composition poorly balanced. It can be used in the manufacture of paper and plastics, because contains no lysine or tryptophan at all.
Rice(a-11, glob.-5, prol.-4, glute.-63.) The bulk of proteins is represented by glutelins (orisein), all irreplaceable amino acids are included in the composition of rice proteins, which determines its high biological value. The first limiting acid is lysine, the second is trionine. Such a.s.s. makes rice an integral component of children's and dietary food, a.s.s. rice is approaching buckwheat.
Buckwheat(a.-22, glob.-47, pr.-1, glut.-12) The predominant fraction is globulin. The second is albumin. Buckwheat proteins have an excellent composition of a.k. In terms of lysine content, it surpasses the grain of wheat, rye and rice, approaching soybeans. In terms of soda, valine is equated to milk, in terms of leucine soda to beef, in terms of phenylalanine and tryptophan, they are not inferior to proteins of animal origin (milk, meat.)
17. Proteins of legumes.
It is distinguished by a high protein content in soybeans up to 40% and a good balance of a.s.s. The amount of methionine and cystine is considered the limiting one. Up to 80% of legumes fall on the albumin and globulin fraction. A distinctive feature is the presence of inhibitors of proteolytic enzymes and lectins. Protease inhibitors can be of various types, with the Marten inhibitors being the most researched. Removing them from legume proteins during heat treatment. Their presence in plants is due to the biochemical characteristics of plants. Inhibitors control the course of seed germination processes. For human health, the presence of inhibitors is undesirable; legumes that have not undergone heat treatment are not allowed for food. Lectins cause selective agglutination of red blood cells. Agglutination-gluing, aggregation of particles or cells, is selective, depending on the individual characteristics of a person.
18. Proteins of oilseeds.
Proteins make up a significant portion of the dry matter. The content in some oilseeds varies from 16 to 28%. In sunflower seeds, soda protein is about 15%, flax-25%, cotton-20%, castor oil-16%, labor up to 28%. Most of the proteins of oil crops belong to the globulin fraction-80%, to the albumin and globulin fractions equally-1%, the prolamin fraction is absent. sunflower seeds are well balanced in a.s.s. Cotton is high in glutamic, aspartic and lysine. The content of the rest of the irreplaceable (phenylalanine, trionin) is not great. High balance of oilseeds by a.s.s. allows us to consider them as a valuable source in the production of vegetable protein, new forms of protein food.
19. Proteins of potatoes, vegetables and fruits.
Most of the nitrogenous substances contained in fruits and vegetables are proteins, a smaller part is free amino acids and even less amides: asparagine and glutamine. In general, vegetables are low in storage proteins. Most of them are in green peas - on average 5.0%, in vegetable beans - 4.0, spinach - 2.9, cauliflower - 2.5, potatoes - 2.0, carrots - 1.5, tomatoes - 0 , 6%. Even less protein in many fruits. But some fruits contain no less protein than vegetables. So, the olive contains an average of 7% proteins, blackberries - 2%, bananas - 1.5%. All essential amino acids are present in vegetables and fruits, and therefore they can play a role in the protein balance of our diet. First of all, this concerns potatoes due to their relatively high consumption. In relation to the proteins of a chicken egg, the biological value of potato proteins is 85%, in relation to the ideal protein - 70%. The first limiting amino acids of potato proteins are methionine and cysteine, the second is leucine. Potatoes are a widespread culture that is part of the daily diet of the population, a source of cheap raw materials for many food industries: alcohol (molasses, starch, alcohol). The average protein content in potatoes is about 2%, in wheat about 15%, however, due to the fact that the yield of potatoes is higher, it can provide no less protein than wheat. On average, a person eats about 300g. At the same time, less than 7% of the protein requirement is satisfied. Potato protein has a high biological value, because contains all essential a.k. and is called tuberin. By the content of irreplaceable a.k. surpasses wheat protein and is close to soy protein in composition. If we take the biological value of chicken egg proteins as 100%, then the biological value of potato protein will be about 85%. All potato proteins are represented by globulin and albumin fractions in a ratio of 7: 3.
20. Milk proteins.
Milk contains more than 100 components. Some of its main ingredients (lactose and casein) are not found anywhere else. Cow's milk contains on average 2.5-4% protein, which contains about 20 protein components. Many of which are capable of forming antibodies. The main proteins in milk are casein and whey proteins (alpha-lactoglobulin, beta-lactoglobulin and immunoglobulin). Casein makes up milk protein, it accounts for about 3%. Phosphoproteins are present in milk as their precursor, caseinogen, which contains a full complement of essential amino acids. especially a lot of methionine, lysine and tryptophan. Under the action of proteolytic enzymes of the stomach in the presence of calcium ions, caseinogen is converted into casein and in the form of a curdled sediment is further retained in the stomach and is more fully absorbed.
21. Change of proteins during technological processes.
Any technological impact leads to the destruction of the structure of the protein molecule, which is accompanied by the loss of biological value (denaturation). Thermal denaturation is the basis for baking bread, biscuits, biscuits, cakes, drying pasta, cooking and frying fish, meat, vegetables, canning and pasteurization, sterilization of milk. These processes are considered useful, because accelerate the digestion of protein and determine the consumer properties of the product (texture, appearance, organoleptic). However, due to the fact that the degree of denaturation can be different, the digestibility of products can not only improve, but also worsen. Moreover, the physicochemical properties of proteins can change. Long-term heat treatment at t 100-120 gr. leads to denaturation of micromolecules with cleavage of functional groups, rupture of peptide bonds and the formation of hydrogen sulfide, ammonia and carbon dioxide. Among the degradation products, some may have mutagenic properties (smoking, deep-fried, baked goods, broths, fried beef, pork, smoked and dried fish). Toxic properties of proteins during heat treatment over 200 gr. can give not only destruction, but also isomerization of a.k. from LVD form. The presence of D isomers reduces protein absorption. Mechanical denaturation - dough kneading, homogenization, grain grinding, - denaturation with the possibility of destruction.
22. Carbohydrates and from physiological purposes. Distribution in food raw materials and food products.
U. are widespread in nature; they are present in free or bound form in plants, animals, and bacterial organisms. U. make up 60-80% of the calorie content of the daily diet. In conjunction with proteins and lipids, they form complexes-subcellular structures - the basis of living matter.
The role of carbohydrates in nutrition: 1) energy - the main source of energy for muscles, brain, heart, cells and tissues. Energy is released during the oxidation of U. (1r-4kCall) and is stored in ATP molecules. 2) U. and their derivatives are part of a variety of tissues and fluids, i.e. are plastic material. In the composition of the plant cell, U. is about 90%, in animals, about 20%. They are part of the supporting tissues of plants and the human skeleton. 3) U. are regulators of a number of biochemical processes. 4) Tones up the central nervous system. 5) Perform specialized tasks (heparin prevents blood coagulation. 6) Protective - is realized by galacturonic acid. Non-toxic water-soluble ester compounds are formed with toxins and are excreted from the body.
In the human body, the reserves of uranium do not exceed 1%. They are quickly consumed during physical exertion, so they must be taken with food daily. The daily requirement of U. is 400-500g, of which 80% is starch. The main sources of carbohydrates are plant products: products from grains and flour (baked goods, cereals, pasta), sugar, vegetables and fruits. Animal products contain small amounts of lactose, glycogen, glucose. Dietary fiber is found exclusively in plant products: vegetables, fruits, legumes and grain products. A proper healthy diet involves the obligatory consumption of dietary fiber (about 25 g per day).
23. Digestible and indigestible carbohydrates, their physiological role. The metabolism of carbohydrates in the body.
Digestible includes mono- and oligosaccharides, starch and glycogen. Indigestible - cellulose, hemicellulose, pectin, inulin, mucus and gum. Indigestible carbohydrates include dietary fiber. They are very important for human health. In the human body, they perform the following functions: prevent the absorption of cholesterol; stimulate intestinal motor function; participate in the normalization of the composition intestinal microflora by inhibiting putrefactive processes; adsorb bile acids, promote the elimination of toxic elements and radionuclides from the body; normalize lipid metabolism, preventing obesity. When ingested. assimilated U. are broken down (except for monosaccharides), absorbed, then utilized in the form of glucose or converted into fat, or deposited for temporary storage in the form of glycogen. Fat accumulation is most intense when there is an excess of simple sugars in the diet.
U. exchange: 1) splitting in the gastrointestinal tract, received with food dipolyoligosaccharides to monosaccharides. 2) absorption of monosaccharides from the intestine into the blood. 3) synthesis and breakdown of glycogen in the liver. 4) anaerobic breakdown of glucose to PVC - glycolysis and anaerobic metabolism of PVC - Krebs cycle. 5) The secondary pathway of glucose catabolism is pentose phosphate. 6) Interconversion of hexoses 7) Formation of carbohydrates from non-carbohydrate components (PVC, glycerin, a.c.) - gluconeogenesis.
24. The physiological significance of some carbohydrates: glucose, fructose, lactose. Indigestible carbohydrates.
Indigestible - cellulose, hemicellulose, pectin, inulin, mucus and gum. Indigestible carbohydrates include dietary fiber. They are very important for human health. In the human body, they perform the following functions: prevent the absorption of cholesterol; stimulate intestinal motor function; participate in the normalization of the composition of the intestinal microflora, inhibiting putrefactive processes; adsorb bile acids, promote the elimination of toxic elements and radionuclides from the body; normalize lipid metabolism, preventing obesity.
Glucose- the main form in the form of which U. circulate in the blood and provide the energy needs of a person. Normal blood glucose is 80-100 mg per 100 ml. Excess sugar is converted into glycogen, which is a reserve substance and is used when there is a lack of U. in the diet. The process of glucose utilization is slowed down if the pancreas does not produce enough of the hormone insulin. Consequently, the blood sugar level rises 200-400mg per 100ml. The kidneys are unable to retain such an amount, and diabetes mellitus develops. A rapid increase in blood glucose is caused by mono- and disaccharides, especially sucrose.
Fructose- when it is consumed, the sugar level does not rise so quickly, it is more retained by the liver, once it enters the bloodstream, it enters into metabolic processes, insulin does not participate in its transformation. To a lesser extent, caries is produced. The sweetness is greater. Provides 4 kcal on oxidation.
Lactose found in milk, gives a sweetish taste. She also ferments c.m. bacteria in the manufacture of dairy products. Used in baby food. When lactose is broken down, galactose is formed.
24. The physiological significance of individual carbohydrates: glucose, fructose, lactose. Indigestible carbohydrates.
Glucose. The main form, to the form of a cat. carbohydrates circulate in the blood and provide a person's energy needs. Normal blood glucose is 80-100 mg / 100 ml. Excess sugar turns into glycogen, cat. is a reserve substance and is used when there is a lack of carbohydrates in the diet. The process of glucose utilization slows down if the pancreas does not produce an insufficient amount of the hormone insulin, therefore, the sugar level rises to 200-400 mg / 100 ml, the kidneys are unable to retain this amount, sugar appears in the urine, and diabetes mellitus develops. Mono- and disaccharides, especially sucrose, cause rapid increases in blood glucose levels.
Fructose. When consumed, the sugar level does not rise so quickly, it is more retained in the liver. Once in the blood, it enters into metabolic processes, insulin does not participate in its transformations. It causes less tooth decay, more sweetness, but also gives 4 kcal when oxidized and contributes to obesity.
Galactose. Formed by the breakdown of lactose, it does not occur in free form. Lactose is found in milk, giving it a sweetish taste. It is also fermented by lactic acid bacteria in the manufacture of dairy products, and is used in baby food.
Sorbitol and xylitol. Refers to carbohydrate derivatives. They are found in small quantities in human tissues. They have a sweet taste and are used as sweeteners. Indigestible carbohydrates are not utilized by the body, but are important for the digestion process, they make up the so-called dietary fiber.
Indigestible carbohydrates: cellulose, hemicellulose, pectin, gum, mucus, inulin.
25. The technological role of carbohydrates.
Carbohydrates form the nutritional, biological and energy properties of products, because affect the formation of taste, aroma and color, affect the stability of products during storage.
There are the following functions of mono- and oligosaccharides in the food system:
1. Hydrophilicity - due to the presence of a large number of –OH groups, which leads to the dissolution of sugars when interacting with water.
2. Binding of aromas - Carbohydrates are an important component for maintaining color and volatile aroma components. This is more characteristic of disaccharides than mono-. It appears when drying food. Carbohydrates are involved in the formation of non-enzymatic products - melanoidin pigments and volatile aromatic substances.
3. Non-oxidative or non-enzymatic browning - very common in foods. It is associated with the reactions of carbohydrates, namely the process of caramelization, as well as the process of interaction of carbohydrates with amino acids and proteins.
4. Sweetness - the coefficient of sweetness of sucrose is 100%, glucose is about 70%, galactose - 30%, fructose - 70%, lactose - 17%.
The functions of polysaccharides in food products are related to their structural and functional properties: molecular architecture, size and the presence of intermolecular interactions. Polysachars provide the formation of the structure and quality of food products - fragility, stickiness, hardness, density, viscosity, gloss, etc.
26. Hydrolysis of starch - types, regimes, participation and role in food production.
Hydrolysis occurs in many food systems, depends on pH, t o, enzyme activity, etc. It is important not only during the preparation of products, but also during storage: hydrolysis reactions can lead to undesirable color changes, hydrolysis of polysaccharides can reduce the ability to form gels.
Starch hydrolysis.
1. Acid hydrolysis. Under the action of acids, the associative bonds between the molecules of amylopectin and amylose are weakened and broken. This leads to disruption of the structure of the starch grain with the formation of a homogeneous mass. Further, the bonds α1-4 and α1-6 are broken, water joins at the place of the break. The end product is glucose. At intermediate stages, dextrins, tetra- and trisugars, and maltose are formed. The disadvantage of this process is the use of concentrated acids, high t about, which leads to thermal degradation and transglycosylation reactions.
2. Enzymatic hydrolysis. It is under the action of amylolytic enzymes: α and β amylases, glucoamylases, polypases. The enzymatic process of starch hydrolysis ensures the quality of the following products: in baking, it is the process of making dough and baking; in beer production, this is the process of obtaining beer wort and drying malt; in obtaining kvass, it is a product of the production of kvass loaves; alcohol production - preparation of raw materials for fermentation.
27. Reactions of formation of brown products. Melanoid formation reaction. Factors affecting the intensity of the formation of melanoidin pigments.
Darkening of food. products can take place as a result of oxidative and non-oxidative reactions.
Oxidative (enzymatic) darkening is a reaction between a phenolic substrate and atmospheric oxygen. It is catalyzed by the enzyme polyphenol oxidase (darkening on cuts of apples, bananas, pears). But this process is not related to carbohydrates!
Non-oxidative (non-enzymatic) browning is very common in foods. It is associated with the reactions of carbohydrates, namely the process of caramelization, as well as the process of interaction of carbohydrates with amino acids and proteins.
Caramelization - direct heating of carbohydrates (sugars, sugar syrups). Promotes a complex of reactions. The reaction rate increases with the addition of small concentrations of acids and alkalis and some salts. This produces brown products with a caramel flavor. The main process is dehydration. As a result, dehydrofuranones, cyclopentanones, pyrones, etc. are formed. By adjusting the reaction conditions, they can be directed to obtain, mainly, aroma or dark-colored compounds. Typically, sucrose is used to produce caramel color and flavor. Heating a sucrose solution in the presence of H 2 SO 4 or acidic ammonium salts gives intensely colored polymers (sugar color).
The melanoidin reaction is the first step in the non-enzymatic browning reaction of food. As a result of this process, yellow-brown substances with a specific aroma are formed. They can be desirable and undesirable. The formation of melanoidins is the cause of changes in the organoleptic properties of food products (fermentation of tea, aging of wines, cognac).
Factors affecting the M&E process:
1.) the influence of the pH of the medium (darkening is less significant at pH less than 6; the optimum of the reaction is from 7.8 to 9.2).
2.) humidity - this process is not observed at very low and high moisture content. Max darkening at intermediate moisture content.
3.) temperature - an increase in the reaction rate with increasing t o. An increase in t o by 10 about C increases the reaction rate by 2-3 times.
4.) the presence of some Me ions - intense darkening occurs in the presence of Cu and Fe ions.
5.) sugar structure - there is a decrease in the ability to form brown pigments in the series pentose - hexose - disachar.
7.) fermentation.
8.) oxidation of carbohydrates.
28. Lipids in food, lipid function in the human body.
Lipids are a group of compounds of animal, plant and microbiological origin. Practically insoluble in water, but readily soluble in non-polar organic solvents. Widely distributed in nature. In plants, they mainly accumulate in seeds and fruits (up to 50%), the vegetative part contains less than 5% lipids. In animals and fish, lipids are concentrated in the subcutaneous tissues surrounding the internal organs (liver, kidneys), and are also contained in the brain and nerve tissues.
The lipid content depends on genetic characteristics, on the variety and place of growth, in animals, on the species, on the diet. In the human body, with normal health indicators, adipose tissue in men is 10-15%, in women - 15-20%. 1 kg of adipose tissue contains about 800 g of fat, the rest is protein and water. Obesity begins when the adipose tissue content is 50% or more.
Lipid functions:
1.) energy (1 g = 9 kcal).
2.) structural (plastic) - are part of the cellular and extracellular membranes of all tissues.
3.) solvents and carriers of fat-soluble vitamins (K, E, D, A).
4.) provide the direction of the streams of nerve signals, because are part of nerve cells.
5) participate in the synthesis of hormones, vitamin D. Steroid hormones ensure the adaptation of the body to stress.
6.) protective - realized by lipids of the skin (elasticity), internal organs, the synthesis of substances that protect the body from the adverse effects of the environment.
Sturgeon fish - 20%;
Pork - about 30%;
Beef - about 10%;
Cow's milk - 5%;
Goat milk - 5-7%.
Lipids are widely used to obtain many types of fatty products, determining nutritional value and taste.
The bulk of lipids is represented by acylglycerols - esters of glycerol and fatty acids.
Usually fats are a mixture of TAGs of different composition, as well as the corresponding substances of a lipid nature.
Fats are obtained from plant materials - fatty oils that are rich in unsaturated fatty acids. Fats from land animals contain saturated fatty acids and are called animal fats.
Fats of marine mammals and fish are distinguished into a special group.
Saturated fatty acids (palmitic, stearic, myristic) are used mainly as an energetic material, they are found in large quantities in animal fats, determining their plasticity and t 0 melting.
An increased content of saturated fatty acids in the diet is undesirable because with their excess, lipid metabolism is disturbed, the level of cholesterol in the blood rises, the risk of developing atherosclerosis, obesity and gallstone disease increases.
Vegetable fats are a source of energy and plastic material for the body. They supply a number of essential substances to the human body, PUFA, MUFA, phospholipids, fat-soluble vitamins, sterols. All these compounds determine the biological effectiveness and nutritional value of the product.
For the southern zones of the country 27-28%.
For the northern zones of the country 38-40%.
With a low fat content in the diet, dryness and pustular skin diseases appear, then hair falls out, digestion is disturbed, resistance to infections decreases, the activity of the central nervous system is disrupted, and life expectancy is reduced.
Excessive consumption leads to their accumulation in the liver and other organs. The blood becomes viscous, which contributes to the blockage of blood vessels and the development of atherosclerosis.
Obesity leads to development cardiovascular disease, premature aging.
The development of malignant neoplasms is possible due to excessive consumption of food rich in fats. A large amount of bile acids for the emulsification of fats, which negatively affects the intestinal walls.
And with an excess of unsaturated fatty acids. the amount of free radicals in the blood can increase, which contributes to the accumulation of carcinogens and poison the liver and kidneys.
30. Polyunsaturated fatty acids, their physiological significance. The daily consumption rate of PUFA. Distribution in raw materials and foodstuffs.
Polyunsaturated fatty acids containing 2 or more double bonds are of particular biological importance. Saturated acids, such as linoleic and linolenic, are not synthesized in humans and animals, while arachidonic acids are synthesized from linoleic in the presence of biotin and vitamin B 6. The complex of NK linoleic + linolenic in their biological effect is equated to vitamin F.
PUFAs are essential for growth and metabolism in all living organisms, because:
1.) are structural components of phospholipids, lipoproteins of cell membranes. They are a part of connective tissues and nerve cell sheaths.
2.) are involved in the transport and oxidation of cholesterol.
3.) prevent blood clots.
4.) provide elasticity of blood vessels.
5.) participate in the exchange of B vitamins.
6.) stimulate protective functions organism.
7.) participate in the formation of hormones and hormone-like substances.
PUFAs are divided into families depending on the position of the first double bond.
If the first double bond is in the 6th position, then this is ω-6, linoleic and linolenic acids, which prevail in vegetable oils, belong.
PUFAs of the ω-3 family predominate in the fats of marine mammals and fish: docosahexagenic, docosopentagenic, eicosopentane, α-linoleic. PUFA ω-6 and ω-3 in the human diet should be in a ratio of 10: 1. For medical nutrition, the ratio of ω-6 and ω-3 is from 3: 1 to 5: 1. Diseases: bronchial asthma, skin diseases, diabetes, hypertension, immunodeficiency diseases.
Lack of PUFA in the body leads to eczema, impaired cholesterol transport, and impaired renal function.
Complete absence of PUFA: impaired growth, necrotic skin changes, impaired capillary permeability. For such manifestations, a person must be on a fat-free diet for up to six months.
The biological activity of PUFA is not the same. The most active are arachidonic acid. Linoleic has a high activity, linolenic activity is lower.
Among the products, the most rich in PUFA are vegetable oils: corn, sunflower, olive.
Animal fats contain few of these acids. Beef fat contains 0.6% PUFA.
Wholemeal baked goods are a good source of these acids.
Arachidonic acid is found in small quantities in products, and is completely absent in vegetable oils. Its significant amounts in the brain - 0.5%, in offal 0.2-0.3%.
The need for PUFA is from 3 to 6 g per day, often used as dietary supplements for food.
The daily requirement for linoleic acid is 4-10 g.
According to modern concepts, the following TAG composition is considered balanced: PUFA - 10%, monounsaturated - 60%, saturated - 10%. This ratio is achieved by 1/3 vegetable and 2/3 animal fats.
31. Phospholipids, their physiological significance, functions. Distribution in raw materials and foodstuffs.
The main component of biomembranes, plays an important role in the permeability of cell membranes and in intracellular metabolism. The most important of the phospholipids is lecithin (phosphatidylcholine). Lecithin prevents fatty liver and promotes better fat metabolism.
Functions of phospholipids:
1.) participate in the formation of cellular biomembranes not only of the cells themselves, but also of intracellular organelles.
2.) Promote the transport of fat in the body.
3.) promote the absorption of fats, prevent obesity of internal organs.
4.) participate in the processes of blood clotting.
5.) prevent the deposition of cholesterol on the walls of blood vessels, thereby preventing atherosclerosis.
Phospholipids are found in unrefined vegetable oils, as well as in animal products - liver, kidneys, cream, yolks, sour cream, meat. The daily requirement is 5-10 g.
32. Sterols of plant and animal origin. Cholesterol, its physiological significance. Distribution in raw materials and foodstuffs.
Animal fats contain zoosterols, and vegetable fats contain phytosterols. Phytosterols include: β-sitastirol, brassicostyrene, stigmastirol. Cholesterol belongs to animal sterols. Plant styrenes are biologically active compounds (β-sitastirol prevents the absorption of cholesterol in the intestine, ergostyrene is a precursor of vitamin D 3).
Cholesterol functions. It enters the body with food of animal origin, but can also be synthesized from intermediate metabolic products of carbohydrates and fats. Therefore, it is necessary for the body to perform certain functions:
1.) serves as a precursor of some other steroids - bile acids, steroid hormones, vitamin D 3.
2.) is a part of cellular biomembranes.
Peculiarity: in the blood and bile, cholesterol is retained in the form colloidal solution... With an increase in the content of cholesterol in an unhealthy body in violation of metabolic processes, cholesterol falls out in the form of small atherosclerotic plaques on the walls of blood vessels in the biliary tract, which leads to the formation of cholelithiasis and atherosclerosis.
By-products (lungs and brains) - more than 2000 mg;
Kidneys, liver - from 400 to 700 mg;
One egg yolk - 250 mg;
Beef, pork - about 80 mg;
Lamb - 100 mg;
Chicken and chicken meat - about 70 mg.
33. Prostaglandins, their functions in the human body.
Tissue hormones. Found in the body in minimal amounts. The source of their formation is PUFA with a carbon chain of 20 or more atoms.
Functions:
1.) regulate the flow of venous blood in the vessels.
2.) counteract arrhythmias.
3.) maintain the balance of the autonomic nervous system of the heart.
4.) counteract the formation of blood clots.
5.) contribute to the preservation of pregnancy and the normal course of childbirth.
6.) have an anti-stress effect.
34. The concept of visible and invisible fats.
In the composition of food products are distinguished:
1.) visible fats - vegetable oils, animal fats, butter, margarine.
2.) invisible fats - fat of meat and meat products, fat of fish, milk, dairy products, fat of cereals and bakery products, fat of confectionery.
The most important source of fat in the diet are vegetable oils - the fat content is 99.9%, butter - 60-80%, dairy products - up to 3.5%, chocolate - up to 40%, cookies - 10%, buckwheat - 3% , oatmeal - 6%, cheeses - from 25 to 50%, pork and sausage products - up to 25%.
35. Changes and transformations of fats during storage and processing of raw materials and food. Reactions of acylglycerols with the participation of ester groups.
Fats are not stable during storage and are the most labile component of food products and raw materials. The instability of fats is due to their chemical structure, therefore, the conversion of acylglycerols is divided into 2 groups:
1.) reactions of acylglycerols with the participation of ester groups;
2.) reactions of acylglycerols with the participation of hydrocarbon radicals.
Reactions of acylglycerols with the participation of ester groups.
1.) Hydrolysis of TAGs. Under the influence of alkalis, acids, and the enzyme TAG lipases are hydrolyzed to form diacyl-, monoacylglycerols, and ultimately fatty acids and glycerol.
Hydrolysis of TAGs can proceed under the following conditions:
A.) in the presence of acid catalysts (H 2 SO 4); hydrolysis is carried out at t = 100 0 C and with an excess of water.
B.) in the absence of catalysts - non-reactive cleavage; t = 220-250 0 C, P = 2-2.5 MPa.
C.) hydrolysis with concentrated sodium hydroxide solutions (saponification); as a result we get soaps (sodium salts of fatty acids).
Hydrolysis is widely used in the food industry to obtain DAGs, MAGs, glycerol and fatty acids.
Hydrolytic breakdown of fats is one of the reasons for the deterioration of the quality of lipid-containing products - their spoilage. Damage intensifies at increased t 0, increased humidity, with an increase in lipase activity.
2.) Reaction of transesterification.
The reaction of exchange of acyl groups (acyl migration), leading to the production of new molecules of acylglycerols. Distinguish between intramolecular and intermolecular.
TAGs at t = 80-90 0 C in the presence of catalysts (sodium methylate or ethylate, aluminosilicates) exchange acyls. In this case, the fatty acid composition does not change, but a statistical redistribution of acyl residues in the TAG mixture occurs, which leads to a change in the physicochemical properties of fat mixtures: melting t 0 decreases, fat plasticity increases.
Transesterification of solid animal fats with liquid vegetable oils makes it possible to obtain plastic edible fats with a high content of linoleic acid.
The main active ingredient in the reaction mechanism is Na glycerate. It is its formation that makes the transfer of acyl groups possible. Transesterified fats are used in the production of bread, milk fat analogs, confectionery fat, etc.
36. Changes and transformations of fats during storage and processing of raw materials and food. Reactions of acylglycerols with the participation of hydrocarbon radicals.
1.) Hydrogenation of TAGs.
The selectivity of this reaction is achieved through the selection of the reaction conditions. First, linoleic acyls are hydrogenated to linolenic, then to oleic, then to stearic. In parallel with the addition of hydrogen, structural isomerization occurs and, possibly, geometric. From cis isomers to trans isomers.
Trans-isomers act as false competing substrates in the synthesis of hormones and prostaglandins, leading to the formation of unwanted compounds.
Legislation limits the content of trans-isomers in hydrogenated products to 40%, EU - 20%, for baby food not more than 4%.
2.) Oxidation of AG.
Fats and oils containing radicals of unsaturated fatty acids are oxidized by atmospheric oxygen. The primary products of oxidation are hydroperoxides of various structures, which are not stable and as a result of various transformations give secondary products - oxy-, epixiso compounds, alcohols, ketones, which lead to spoilage, polymerization, triggering autooxidation processes.
Primary oxidation products - hydroperoxides:
Enzymatic rancidity begins with the hydrolysis of TAG by lipase. The resulting fatty acids containing double bonds are oxidized by lipoxygenase. Secondary oxidation products are formed and cause spoilage.
37. Features of the processes occurring in the process flow (diagram with explanations) and during the storage of animal and vegetable fats. Spoilage of fats and oils.
During storage, vegetable and animal fats gradually acquire an unpleasant taste and smell under the influence of light, temperature, humidity and enzymes. Organoleptic properties decrease and compounds dangerous for the human body accumulate.
The depth and intensity of the spoilage process depends on:
The chemical composition of the food system;
The nature of the accompanying substances present and added antioxidants;
Humidity;
The presence of microorganisms;
Enzyme activity;
Contact with O 2 air (type of packaging).
Vegetable oils contain a significant amount of unsaturated fatty acids; mainly, autooxidation processes with atmospheric oxygen take place.
But! Due to low humidity, lack of minerals, oils are not affected by microorganisms and can be stored in the dark for a long time.
Animal fats contain an insignificant amount of free FAs, but they are practically free of antioxidants and this reduces their stability during storage, and high humidity and the presence of mineral substances, proteins contribute to the development of microflora and biochemical rancidity.
38. Vitamins, their role in nutrition. The degree of vitamin deficiency and excess vitamins.
Vitamins - these are low molecular weight organic compounds of various chemical non-protein nature. They are not synthesized in the human body or are synthesized in insignificant quantities. Enzymes that come with food and are necessary for capitalist activity, which determine the biochemical and physiological processes in the animal body.
Vitamins are indispensable microcomponents of food.
They are classified into 2 groups:
Fat soluble;
Water soluble.
A person's need for vitamins depends on age, health status, nature of work, time of year and the content of basic macronutrients in food.
There are 2 degrees of vitamin deficiency: vitamin deficiency and hypovitaminosis.
Avitaminosis - a state of deep deficiency of this vitamin, with a detailed clinical picture of its insufficiency (lack of vitamin D - rickets).
To hypovitaminosis include a state of moderate deficiency with erased nonspecific manifestations (loss of appetite, irritability, fatigue) and individual microsymptoms (violation of the skin). However, the expanded clinical picture absent.
In practice, polyhypovitaminosis and polyavitaminosis are more common, in which the body lacks several vitamins.
Hypo and avitaminosis associated with insufficient intake of vitamins from food is called primary or exogenous.
A deficiency of vitamins can also be observed with a sufficient intake of food, but as a result, a violation of their utilization or a sharp increase in needs, such hypovitaminosis is called secondary or exogenous.
Hypervitaminosis - excess of incoming vitamins. The potential toxicity of excess fat- and water-soluble vitamins is different. Fat-soluble vitamins are able to accumulate in the body's fatty tissues. Their increased intake can lead to symptoms of toxic effects. Increased reception water-soluble vitamins mainly leads only to the release of their excess from the body, sometimes allergies.
39. Causes of hypo- and avitaminosis.
Causes of hypo- and avitaminosis.
1. Insufficient intake of vitamins from food:
2) a decrease in the total amount of food consumed, due to low energy consumption;
3) loss and destruction of vitamin in the process of food production and storage;
4) unbalanced diets;
5) anorexia;
2. Suppression of intestinal microflora producing some vitamins.
1) gastrointestinal diseases.
2) the consequences of chemotherapy.
3. Impaired assimilation of vitamins.
1) impaired absorption of vitamins in the gastrointestinal tract;
3) violation of the volume of vitamins and the formation of their biologically inactive forms, with various diseases.
4. Increased need for vitamins.
1) a special physiological state of the body;
2) certain climatic conditions;
3) intense physiological stress;
4) significant neuropsychological stress;
5) harmful production conditions;
6) bad habits;
7) infectious diseases;
8) increased extraction of vitamins.
5. Congenital genetically determined disorders of the metabolism and functions of vitamins.
1) congenital malabsorption of vitamins in the intestine;
2) congenital impairment of the transport of vitamins by blood.
40. Change of vitamins in the technological stream.
The conditions and duration of storage of raw materials, storage of food products, as well as their production contributes to a decrease in the content of vitamins.
Vitamin A (retinol).
In prepared foods, vitamin A and carotenoids are dissolved in fats.
The rate of their oxidation and loss vitamin properties depends on the rate of fat oxidation. Antioxidants that protect fats from oxidation also help preserve vitamin A and carotenoids. Welding products in water, after 30 minutes 16% of vit. A is destroyed, after an hour - 40%, after 2 - 70%.
Vitamin B1 (thiamine).
Unstable in neutral and alkaline environments. Losses occur during extraction with water. Destroyed by sulfur dioxide. Vitamin B1 is stable in an acidic environment, withstands t = 120 0 С, resistant to oxygen, but sensitive to light. Thiaminase and polyphenol oxidase - destroy VitB1. Grinding food results in a loss of 20 to 70%. Some phenolic substances (chloragenic and pyrocatechic acids) destroy VitB1.
Vitamin B2 (riboflavin).
In food, they are found both in a free and in a bound state. Being water-soluble, it is easily extracted by washing, blanching and boiling. It is resistant to low pH values and does not degrade in an acidic environment, even at temperatures above 130 0 С. It is sensitive to the action of light, especially if it is a part of milk and dairy products.
Folic acid.
It occurs in the food industry as free and bound folates. In the technological process, when processing vegetables, fruits, dairy products, about 70% of free and about 40% of bound folates are lost. With blanching, the loss is about 10%. When cooking under pressure, about 20% is lost.
Vitamin B6 (pyridoxine).
Stable in acidic and alkaline environments. The main losses occur in the aquatic environment. when cooking frozen fruits and vegetables, losses range from 20-40%. On average, about 50% is lost during cooking.
Vitamin C (ascorbic acid).
It is easily extracted with water and oxidized by enzymes: ascorbate oxidase, cytochrome oxidase, polyphenol oxidase, and is also oxidized by atmospheric oxygen. Oxidation is accelerated in the presence of iron and copper. The presence of Vit B2 also leads to destruction. The classic preservation method is sulfitation. Losses occurring during cooking and blanching depend on the amount of water, the degree of grinding. Under anaeronic conditions, the destruction of VitC occurs as quickly as in the presence of sucrose and fructose, furfural is formed.
Proceeding from the fact that vitamins are unstable both during storage and in the process flow, it is necessary to fortify food products by fortification, because vitamins are of great biological importance. It is worth noting that a person needs all vitamins in full. Therefore, in a number of countries there are legislatively established norms for the fortification of food products.
41. minerals and their role in human nutrition. Physiological functions of the main mineral elements. The concepts of acidic and alkaline compounds in the human body from the point of view of food chemistry.
Minerals are also essential, like proteins, fats, carbohydrates and vitamins. They make up a small part of the human body, namely 3 kg of ash. In bones, minerals are presented in the form of crystals, and in soft tissues in the form of a colloidal solution with proteins or a true solution.
Functions of minerals:
1) Plastic - participate in the formation of inert tissue (P, Ca).
2) Enzymatic - make up 1/3 of enzymes, acting as a prosthetic group or are activated by Me enzymes.
3) Participate in the metabolic processes of the body: water-salt balance, acid-base balance, maintaining osmotic pressure.
4) Affect immunity.
5) Participate in the processes of hematopoiesis.
6) I participate in the mechanism of blood clotting.
Depending on the content of microelements in the body, they are divided into macro- and microelements.
Macronutrients: Na, K, Ca, Mg, S, P, Se.
Trace elements: Fe, Cu, Zn, I, F, Cr, Ni, Co, St, Se, Si.
In micro amounts, they stimulate biological processes, and a large number of them has a toxic effect on the body, therefore the content of some trace elements is regulated by medical and biological requirements and quality indicators.
In the course of complex transformations in the body of foods rich in Ca, K, Mg or Na, alkaline compounds can be formed. Sources of alkali-forming elements include fruits, vegetables, legumes, milk and dairy products. Other products: meat, eggs, fish, bread, cereals, pasta, in the process of transformation, give acidic compounds. The human body must maintain a balance of acidic and alkaline. The predominance of acidic compounds leads to health problems.
42. Groups of mineral elements, their occurrence in nature and ways of entering the human body.
Sources of entry of microelements into the human body: food, water, rarely inhaled air and skin.
Trace elements are divided into the following groups:
1. Natural. Their number is due to the content of trace elements in the environment.
2. Industrial. Mostly they are in excess. Their content is due to hazardous industries.
3. Iatrogenic. Trace elements that cause diseases that arise as a result of medical staff errors.
4. Endogenous. Cause hereditary or congenital disorders of digestibility or an increased ability to accumulate one or more mineral elements.
43. Causes of metabolic disorders. Deficient and excess mineral components of food.
Reasons for metabolic disorders of mineral substances.
1) Unbalanced diet.
2) Application of methods of culinary processing of food products that cause the loss of minerals: defrosting food in hot water and removing decoctions of vegetables and fruits.
3) the lack of timely correction of the composition of the diet with a change in the body's need for minerals associated with physiological reasons.
4) violation of the process of absorption of minerals in the gastrointestinal tract or increased fluid loss.
Lack or excess of minerals in the diet leads to the development of a number of diseases:
1. Ca - lack of growth retardation.
2. Mg - deficiency causes muscle cramps.
3. Fe - deficiency causes disruption of the immune system.
4. Zn - deficiency leads to the development of skin diseases, growth retardation.
5. Cu - deficiency leads to disruption of the liver, anemia, loss of elasticity of the artery.
6. Mn - deficiency leads to a deterioration in the formation and growth of the skeleton. Can cite infertility.
7. Mo - deficiency leads to the development of caries and slowing of cell growth.
8. Co - pernicious anemia.
9. Ni - depression and dermatitis.
10. Cr - development of diabetes.
11. Si - impaired growth of the skeleton.
12. P - caries
13. I - disruption of the thyroid gland.
14. Se - inhibits the work of the heart muscle.
The most deficient are Ca and Fe, and excess Na and Cl, F.
44. Influence of technological processing on the mineral composition of food products.
Change in minerals during technological processing:
Mineral elements are found in products and raw materials in the form of organic and inorganic compounds, therefore they are part of proteins, fats and carbohydrates.
Boiling vegetables and fruits in water leads to more significant losses than steaming. With an increase in duration, losses and an increase in temperature increase.
The presence of Fe, Cu, Mn in vegetable oils increases the rate of oxidative processes of thermal oxidation of fat-containing products. In plant products, minerals are lost during: peeling potatoes and vegetables 10-30%, grain crumbling about 15%, during heat treatment of vegetable raw materials, losses are from 5-30%, animal - 5-50%. When using low-quality technological equipment, some minerals can migrate into food products. This is undesirable. When kneading the dough, the iron content increases by 30%. When storing canned food in cans with poor-quality solder or a violation of the integral coating, lead, cadmium, tin can pass into the products.
45. The main food groups recommended for fortification and mineralization.
46. Principles of food fortification with micronutrients - vitamins and mineral elements.
Principles underlying fortification and mineralization in general.
1) For food enrichment. products, you should use those vitamins and minerals that are really deficient, whose deficiency is widespread and significantly affects the state of health:
Vitamin C;
B vitamins;
Folic acid;
Calcium.
2) Vitamins and minerals should be enriched first of all with products of mass consumption, available for all groups of children and adults, regularly used in the diet (daily and dietary).
3) Enrichment with vitamins and minerals should not impair the organoleptic qualities and properties of the fortified products: aroma, taste, color, odor, shelf life should not be reduced.
Fortification should not reduce the digestibility of other food components.
4) When enriching with micronutrients, it is necessary to take into account the possibility of chemical interaction of enriching additives with each other and with food components. It is necessary to choose such combinations, forms, and stages of application, which will ensure maximum safety during production and storage. Such special selected formulations of vitamin and mineral supplements are called primexes.
5) Regulated, i.e. the manufacturer's guaranteed micronutrient content must meet 30 to 50% of the daily micronutrient requirements of the food product.
6) The amount of micronutrients introduced into the product for enrichment should be calculated in accordance with their initial content in this product, but taking into account the loss of these micronutrients during production and storage.
7) The regulated content of micronutrients in fortified foods is controlled by state supervisory authorities and is placed on the product label per 100 g of the product.
8) The effectiveness of fortification of products should be confirmed by testing a control batch on a group of volunteers, which should confirm an improvement in the supply of minerals and vitamins to the body, complete safety, and good digestibility of the food product as a whole.
9) An important technological aspect of production is the choice of the stage of introducing the premix, which ensures the complete safety of the introduced micronutrients.
Enrichment of food with vitamins and minerals helps to improve the health status of all segments of the population, including the socially unprotected, and to save medical costs.
47. The food ration of a modern person. The main food groups. "Formula" of the modern diet.
Food products and ingredients.
Eating a variety of foods;
Maintaining ideal body weight;
Decreased consumption of sugar and salt;
Increased intake of carbohydrates (fiber and starch);
Decreased intake of saturated fat and cholesterol.
The daily diet should include foods from 4 groups:
1) meat, fish, eggs - sources of proteins and mineral compounds.
2) Potatoes, cereals, bread - sources of proteins and carbohydrates.
3) Milk and dairy products are sources of protein, carbohydrates, vitamins and minerals.
4) Fruits and vegetables - sources of vitamins and minerals.
Based on the changed perceptions and the changed need for energy, the modern diet recommended by experts is significantly different from the diet that existed 50-30 years ago. Taking into account the tendencies towards a decrease in calorie content without losing the main alimentary nutritional factors.
"Formula" of food 21c. is considered as the sum of 3 components:
1. Natural traditional products.
2. Natural modified products of a given composition.
48. The concept of healthy eating. Functional ingredients (dietary fiber, vitamins, minerals, PUFA, antioxidants, oligosaccharides, bifidobacteria, etc.)
Healthy food concept. Functional ingredients and products.
The concept of healthy eating was formulated at the end of the last century by Japanese nutritionists. It was in Japan that functional products became very popular, i.e. products containing ingredients beneficial to human health, increasing its resistance to diseases, capable of improving many physiological processes in the body, allowing you to extend the time of a person's active life.
The use of such products reduces cholesterol, keeps bones and teeth healthy, and reduces the risk of developing certain forms of cancer.
Functional foods are intended for the general population - everyone, and have the appearance of regular food, should be consumed regularly as part of the daily diet.
Traditional food products solve 3 problems: provide nutritional value, organoleptic properties and taste; and functional ones solve the problem of physiological interaction on the body.
Functional ingredients.
All functional products contain ingredients that give them these properties.
Dietary fiber distinguishes between soluble and insoluble;
Vitamins;
Minerals;
Antioxidants (vitamin C, vitamin E; β-carotene);
Oligosaccharides serving as a substrate for the development of beneficial microflora.
Bifidobacteria.
49. The concept of healthy eating. Requirements for functional ingredients. Functional products.
The concept of healthy eating was formulated at the end of the last century by Japanese nutritionists. It was in Japan that functional products became very popular, i.e. products containing ingredients that benefit human health, increase their resistance to disease, can improve many physiological processes in the body, allowing you to extend the active life of a person. The use of such products reduces cholesterol content, maintains healthy bones, teeth, and reduces the risk of developing certain cancers.
Requirements for functional ingredients:
1. Must be beneficial to nutrition and health.
2. Must be safe from the point of view balanced nutrition.
3. Exact physical and chemical indicators and methods for their determination.
4. Should not reduce the nutritional value of the product.
5. Have the appearance of regular food and be eaten like regular food.
6. Natural origin.
Examples of functional products:
1. Breakfast cereals.
2. Dairy and fermented milk products.
3. Fat emulsion products and vegetable oils.
4. Specialized non-alcoholic drinks (fruit drink, kvass, herbal infusions).
50. Physiological aspects of the chemistry of nutrients. Three classes of food chemicals.
The component composition of a food product consists of food raw materials, food additives and dietary supplements.
All substances that make up a food product can be summarized into three classes:
1. Nutrients:
a) macronutrients (proteins, lipids, carbohydrates). They perform plastic and energy functions.
b) micronutrients (vitamins, minerals). have a pronounced biological effect.
2. Substances involved in the formation of taste and aroma of products. They are the precursors of the main nutrients, or their breakdown products. This also includes: anti-alimentary substances that prevent the exchange of basic nutrients and toxic substances natural origin.
3. Alien, potentially hazardous substances anthropogenic or natural origin - xenobiotics, cantominants, PCI (foreign chemicals).
51. The theory of balanced nutrition, formulated by A.A. Pokrovsky. Three main points. "Formula" of balanced nutrition.
The first concept, the so-called nutritional paradigm, implied enriching the body with nutrients necessary for its energy and plastic needs, first freeing the food from ballast substances. On the basis of this paradigm, by the beginning of the 20th century, the theory of balanced nutrition was formulated, which is based on 3 main provisions:
1. With ideal nutrition, the influx of substances into the body exactly matches their loss (balance).
2. The influx of nutrients is provided by the destruction of complex food structures and the use of the body of the released organic and inorganic substances.
3. The energy expenditure of the body must be balanced with the incoming energy.
According to this theory, the normal functioning of the body is ensured when it is supplied with the necessary amount of energy and nutrients, as well as compliance with certain ratios between the numerous indispensable nutritional factors, each of which plays a specific role in metabolism.
One of the main laws on which this theory is based is the rule of correspondence of the enzyme sets of the body to the chemical structures of food.
Academician Pokrovsky calculated a balanced nutrition formula, which is a table that includes a list of food components in accordance with the body's needs for these components. This formula has been compiled for a total energy value of 3000 kcal per day.
In line with the downward trend in the energy requirements of modern humans, the normal consumption of macronutrients is being revised. Pokrovsky believed that a complete diet should contain nutrients of 5 classes:
1. Sources of energy (proteins, fats, carbohydrates).
2. Essential amino acids.
3. Vitamins.
5. Inorganic substances + water, which, being not a food component, is necessary for the human body. On average, a person uses 300-400 mg of metabolic, i.e. endogenous water... The rest of 1200-1700 ml is provided by food.
Thus, a balanced diet takes into account all nutritional factors, their interrelation in metabolic processes and the correspondence of enzymatic systems of chemical transformations in the body.
The mistake of this concept is that only the digestible components of food were considered valuable, the rest were considered and called ballast.
52. The theory of adequate nutrition A.М. Ugolev. Four principles of the theory of adequate nutrition.
In the 80s of the last century, a new concept of nutrition was formulated based on the theory of balanced nutrition, but taking into account new knowledge about the role and function of ballast substances and intestinal microflora.
1. Food is assimilated both by the absorbing organism and by the bacteria that inhabit it.
2. The influx of nutrients in the body is ensured by extracting them from food and as a result of the activity of bacteria synthesizing additional nutrients.
3. Normal nutrition is conditioned not by one, but by several flows of nutrients and regulatory substances.
4. Physiologically important components food are ballast substances - dietary fiber (DF).
PV - biopolymer components of plant food, these are indigestible polysaccharides (cellulose, hemicellulose, pectin).
Pectin substances - to soluble biopolymers.
Functions PV:
1. Stimulation of intestinal peristalsis.
2. Adsorption of toxic products.
3. Incomplete digestion of radiation, carcinogens.
4. Intensification of bile acid metabolism, which regulates cholesterol levels.
5. Reducing the availability of macronutrients, fats and carbohydrates to the action of enzymes, which prevents a sharp increase in their content in the blood.
6. Is a nutrient substrate for the intestinal microflora.
The theory of adequate nutrition formulates the basic principles of rational nutrition, which take into account the whole complex of nutritional factors, their relationship in metabolic processes and the correspondence of the body's enzyme systems to the individual characteristics of the reactions taking place in it.
53. Rational nutrition. The first principle of good nutrition.
A balanced diet is based on three main principles:
1. The balance of energy assuming the intake of energy with food and consumed in the process of life.
2. Satisfaction of the body's needs in the optimal amount and ratio of nutrients.
3. Diet, implying compliance with the time and number of meals, as well as its rational distribution at each meal.
1st principle of rational nutrition.
The role of the main sources of energy belongs to proteins, lipids, carbohydrates. The energy released during their breakdown, 4.9 calories, characterizes the calorie content of the product.
By calorie content, foods are divided into:
1. Especially high-calorie fats (butter, chocolate, etc.) - 400-900 calla / 100 g.
2. High-calorie (sugar, cereals, flour, pasta from soft wheat) - 250 - 400 calla / 100 g.
3. Medium energy (bread, meat, eggs, sausages, spirits) - 100 - 250 calla / 100 g.
4. Low-calorie (milk, not fatty fish, vegetables, potatoes, fruits, white wine, beer) - up to 100 calla.
1. Basic exchange.
2. Digestion of food.
3. Muscular activity.
· Muscular activity.
54. The second principle of good nutrition.
In accordance with the second principle of rational nutrition, the body's needs for basic nutrients must be satisfied: proteins, fats, carbohydrates, essential amino acids, essential PUFAs, vitamins, and minerals.
Carbohydrates are a common nutrient, energy value coefficient = 4 kcal. They are essential nutrients by themselves, but:
1. Serve as precursors of many intracellular components.
2. They are widespread and very cheap, therefore they take up a significant part (from 70 - 90%) of the diet. Under ideal conditions, 45% of carbohydrates in the daily diet, with 80% starch, sugar - 50 - 100 g, dietary fiber - 25 g, pectin substances - 5-6 g. 400 - 500 g - total carbohydrates.
Fats are products of animal and vegetable origin, as well as carbohydrates are a source of energy = 9 kalla. Unlike carbohydrates, they digest much longer, being a source of polyunsaturated fatty acids, and take part in the synthesis of steroids (cholesterol) acting as a source of carbon atoms.
The daily requirement is 60 - 80 g, i.e. 30 - 35% of the total diet, in the ratio of rast. to alive. 7: 3, LCD: sat. 30%, monounsaturated. 60% polyunsaturated. ten%.
Physiological value of fats - phospholipids required for the renewal of intracellular structures, days. Consumption - 5 g.
Proteins. The main functions of proteins from the point of view of the second principle:
1. Source of 10 essential and 10 nonessential amino acids for building.
2. Amino acids are precursors of hormones and other physiologically active components.
The daily requirement for protein is 60-90 g. The indicator of protein quality is biological value.
Vitamins. Essential components of enzymes and coenzymes are involved in metabolism, in many specialized reactions. In accordance with the WHO recommendations, the daily need for vitamins should be met by natural products, however, in some cases, multivitamin complexes can be used in the daily diet.
Inorganic substances and trace elements. Essential for the normal functioning of the body. Micro and macro elements are required.
55. The third principle of good nutrition.
It is based on 4 rules:
1. Regularity of food, taking into account the factors ensuring normal digestion.
2. Food fractionality during the day, at least 3 - 4 times, in Europe 6 - 7 times.
3. Rational support of food at every meal.
4. Optimal distribution of food during the day, in which dinner should not exceed 1/3 of the diet.
Regularity of nutrition is associated with adherence to food intake, in which it forms a reflex for the production of digestive juice, which ensures normal digestion.
Rational distribution of food, i.e. the fragmentation of nutrition by quantity and energy value provides a uniform load on the digestive tract, the necessary energy and nutrients that have entered the body in a timely manner.
The optimal combination of foods during the day should provide conditions for the digestion of food, so foods containing animal protein should be eaten rationally in the first half of the day. Vegetable and dairy in the afternoon.
Distribution of food during the day differenti. Depending on age, physical activity and daily routine. 3 meals a day is considered less correct. The intervals between meals are 3.5 - 5 hours.
Long-term unhealthy diet is seen as a factor in increasing the risk of typical diseases of our time.
· Oncology - increased consumption of salt, fats, the presence of carcinogens in food.
· Cardiovascular diseases - high blood cholesterol, excess fat intake.
· Dysfunction of the gastrointestinal tract - lack of dietary fiber.
· Osteoporosis - changes in bone composition are associated with a lack of absorption or loss of calcium.
· Obesity - increased consumption of fat and alcohol.
To correct nutritional status:
1. Enrichment of food with essential nutrients - vitominization and mineralization.
2. Increasing physical activity with proper diet planning.
3. Reducing energy value should take into account the need for adequate intake of proteins, fats, carbohydrates and vitamins.
56. Norms of consumption of nutrients and energy.
Energy value is one of the properties that determine the nutritional value of a product, because nutritional value is a set of st-in products that satisfy the body's need for nutrients and energy. The energy in which the body is provided during the consumption and assimilation of nutrients is spent on the implementation of 3 main functions of the body associated with its vital activity:
4. Basic exchange.
5. Digestion of food.
6. Muscular activity.
· Basal metabolism is the amount of energy a person needs to maintain vital processes in a state of complete rest. This amount of energy depends on gender, age, external conditions, and other factors. On average, 1 calla / 1 kg of body weight and the average parameter of age and sex are consumed per 1 g.
Female org. - 1200 calla. Husband. org. - 1500.
· Digestion is associated with its dynamic effect in the absence of muscle activity. The greatest energy expenditures are in the digestion of protein food, the smallest - carbohydrate. The amount of energy spent on the digestion of food is about 150 calla per day.
· Muscular activity.
Determines the activity of a person's lifestyle and requires a different amount of energy. On average, muscular activity daily picks up from 1000 - 2500 calla lilies.
An objective physiological criterion that determines the amount of energy adequate to the nature of human activity, the ratio of total energy consumption for all types of activity, taking into account the basal metabolism, is called the coefficient of physical activity (CFA).
With a prolonged daily excess of food over energy consumption, accumulation of reserve fat occurs.
57. The structure of the digestive system. Macronutrient metabolism.
The human digestive system includes the alimentary canal (GIT) 8-12 meters long, which includes the oral cavity, pharynx, esophagus, stomach, duodenum, thin and colon with the rectum and the main glands - salivary glands, liver, pancreas.
The gastrointestinal tract has three main functions:
1. Digestive
2. Excretory.
3. Regulatory
Main departments alimentary canal(esophagus, stomach and intestines) have three membranes:
1. Internal mucous membrane, with glands located in it, secreting mucus, and in some organs - and food juices.
2. The middle muscle, the contraction of which ensures the passage of the food lump through the alimentary canal.
3. External serous, which serves as the outer layer.
The main end products of hydrolytic breakdown contained in food macronutrients are monomers (sugars, amino acids, higher fatty acids), which, being absorbed at the level of digestive-transport complexes, are, in most cases, the main elements of metabolism (intermediate metabolism) and of which v various bodies and the tissues of the body are synthesized again complex organic compounds.
In this case, metabolism (from the Greek metaboli - change) means the transformation of substances inside the cell from the moment of their arrival until the formation of final products. During these chemical transformations, energy is released and absorbed.
The bulk of the nutrients absorbed in the digestive tract enters the liver, which is the main center of their distribution in the human body. There are five possible metabolic pathways in the liver of essential nutrients.
The metabolism of carbohydrates is associated with the formation of glucose-6-phosphate, which occurs during phosphorylation with the help of ATP, which enters the liver of free D-glucose.
The main metabolic pathway through D-glucose-6-phosphate is associated with its conversion to D-glucose, which enters the bloodstream, where its concentration must be maintained at the level necessary to provide the brain and other tissues with energy. The concentration of glucose in blood plasma should normally be 70-90 mg / 100 ml. Glucose-6-phosphate, which was not used for the formation of blood glucose, is converted into glycogen as a result of the action of two specific enzymes and stored in the liver.
Excess glucose-6-phosphate, not converted into blood glucose or glycogen, through the stage of formation of acetyl-CoA can be converted into fatty acids (with subsequent synthesis of lipids) or cholesterol, and also undergo decomposition with the accumulation of energy ATP or the formation of pentose phosphates.
Amino acid metabolism can occur through pathways including:
Transport through the circulatory system to other organs, where the biosynthesis of tissue proteins is carried out;
Synthesis of liver proteins and plasma;
Conversion to glucose and glycogen during gluconeogenesis;
Deamination and decomposition with the formation of acetyl-CoA, which can undergo oxidation with the accumulation of energy stored in the form of ATP, or be converted into storage lipids; ammonia formed during the deamination of amino acids is included in the composition of urea;
Conversion to nucleotides and other products, in particular hormones. Fatty acid metabolism by the main pathway involves
their use as a substrate for energy metabolism in the liver.
Free acids undergo activation and oxidation to form acetyl-CoA and ATP. Acetyl-CoA is further oxidized in the citric acid cycle, where ATP is re-formed during oxidative phosphorylation.
Excess acetyl-CoA released during acid oxidation can be converted to ketone bodies(acetoacetate and p-0-hydroxybutyrate), which are the transport form of acetyl groups to peripheral tissues, or used in the biosynthesis of cholesterol, a precursor of bile acids involved in the digestion and absorption of fats.
Two other pathways of fatty acid metabolism are associated with the biosynthesis of plasma lipoproteins, which function as carriers of lipids in adipose tissue, or with the formation of free fatty acids in blood plasma, which are transported to the heart and skeletal muscle as the main "fuel".
Thus, performing the functions of a "distribution center" in the body, the liver ensures the delivery of the necessary amounts of nutrients to other organs, smooths metabolic fluctuations caused by uneven food intake, converts excess amino groups into urea and other products that are excreted by the kidneys.
In addition to the transformation and distribution of macronutrients, the liver is actively involved in the processes of enzymatic detoxification of foreign organic compounds (non-nutritional substances) - drugs, food additives, preservatives and other potentially harmful substances,
Detoxification consists in the fact that relatively insoluble compounds undergo biotransformation, as a result of which they become more soluble, more easily broken down and excreted from the body. Most of the biotransformation processes are associated with enzymatic oxidation reactions involving the cytochrome P 450 enzyme. In general, the biotransformation process includes two phases: the formation of metabolites and their subsequent binding in various reactions with the formation of soluble conjugates.
58. The main ways of contamination of food and raw materials with contaminants.
Safety - the absence of danger to human health during their use, both from the point of view of acute exposure (poisoning) and from the point of view of long-term effects (carcinogenic, mutagenic).
Quality is a combination of properties and characteristics of a product that gives it the ability to satisfy condition or presume needs.
Food products are complex multicomponent systems that include, in addition to alimentary, anti-alimentary and foreign chemical substances - PCI - can be organic and inorganic in nature, products of microbiological synthesis.
The main ways of pollution:
1) the use of unauthorized food additives or the use of them in high doses.
2) the use of new, non-traditional technologies for the production of food products or individual food components, including chemical and microbiological synthesis.
3) contamination of crops and livestock products with pesticides (for pest control), veterinary drugs.
4) violation of hygienic rules for the use in crop production of fertilizers, irrigation water, solid and liquid waste from industry and animal husbandry, wastewater, sludge from treatment facilities.
5) use in animal husbandry and poultry farming of food and feed additives, growth stimulants, prophylactic and therapeutic drugs.
6) migration into food products of toxic substances from the equipment of the inventory of containers and packaging, due to the use of indestructible polymer and metal materials.
7) the formation of endogenous toxic compounds in food products during heat exposure, boiling, frying, etc.
8) failure to comply with sanitary requirements in the technology of production and storage of food products, which leads to the formation of toxins.
9) intake of toxic substances into food products, including radionuclides from the environment, atmosphere, soil, water bodies.
In descending order of toxicity, contaminants are arranged in the following order:
1. Toxins of microorganisms.
2. Toxic elements.
3. Antibiotics.
4. Pesticides.
5. Nitrates, nitrites, nitrosamines.
6. Dioxins and dioxin-like substances
7. Polycyclic and aromatic hydrocarbons formed as a result of natural and man-made processes.
8. Radionuclides.
9. Nutritional supplements.
59. Contamination of food with substances used in crop production.
Pesticides. Pesticides are substances of various chemical nature used in agriculture to protect cultivated plants from weeds, pests and diseases, i.e., chemical plant protection products. World production of pesticides (in terms of active substances) is more than 2 million tons per year, and this figure is constantly growing. Currently, in world practice, about 10 thousand names of pesticide preparations based on 1500 active substances are used, which belong to various chemical groups. The most common are the following: organochlorine, organophosphorus, carbamates (derivatives of carbamic acid), organomercury, synthetic pyrethroids and copper-containing fungicides.
Violations of hygienic standards for storage, transportation and use of pesticides, low culture of work with them lead to their accumulation in feed, food raw materials and food products, and the ability to accumulate and be transmitted along food chains - to their widespread distribution and negative impact on human health. The use of pesticides and their role in the fight against various pests in increasing the productivity of agricultural crops, their impact on the environment and human health cause controversial assessments of various specialists.
Nitrates, nitrites, nitrosamines. Nitrates are widespread in nature, they are normal metabolites of any living organism, both plant and animal, even in the human body more than 100 mg of nitrates are formed and used in metabolic processes per day.
When consumed in increased number nitrates (NO 3 -) in the digestive tract are partially reduced to nitrites (NO 2 -). The mechanism of the toxic action of nitrites in the body lies in their interaction with blood hemoglobin and in the formation of methemoglobin, which is unable to bind and carry oxygen. 1 mg of sodium nitrite (NaNO 2) can convert about 2000 mg of hemoglobin into methemoglobin.
The toxicity of nitrites will depend on the diet, individual characteristics of the organism, in particular, on the activity of the enzyme methemoglobin reductase, which is capable of reducing methemoglobin to hemoglobin.
Chronic exposure to nitrites leads to a decrease in vitamins A, E, C, B 1, B 6 in the body, which in turn affects the decrease in the body's resistance to the effects of various negative factors, including oncogenic ones. Nitrates, as noted above, by themselves do not have pronounced toxicity, however, a single intake of 1-4 g of nitrates causes acute poisoning in people, and a dose of 8-14 g can be fatal. ADI, in terms of nitrate ion, is 5 mg / kg of body weight, MPC for nitrates in drinking water is 45 mg / l.
In addition, N-nitrosamines can be formed from nitrites in the presence of various amines. Depending on the nature of the radical, various nitrosoamines can be formed, 80% of which have a carcinogenic, mutagenic, teratogenic effect, and the carcinogenic effect of these compounds is decisive.
As a result of technological processing of raw materials, semi-finished products (intensive heat treatment, smoking, salting, long-term storage, etc.), wide range nitroso compounds. In addition, nitrosoamines are formed in the human body as a result of endogenous synthesis from precursors (nitrates, nitrites).
The most widespread are the following nitroso compounds:
1. Nitrosodimitylamine
2. Nitrosodiethylamine
3. Nitrosodipropylamine
4. Nitrosodibutylamine
5. Nitrosodiperidin.
6. The main sources of nitrates and nitrites in the human body are, first of all, plant products. And since nitrates, as noted above, are normal product nitrogen exchange in plants, it is easy to assume that their content depends on the following factors:
7. · individual characteristics of plants; there are so-called "nitrate storage plants", these are, first of all, leafy vegetables, as well as root crops, such as beets, etc .;
8. · degree of fruit ripeness; unripe vegetables, potatoes, as well as vegetables of early ripening periods may contain more nitrates than those that have reached normal harvest maturity;
9. · increasing and often uncontrolled use of nitrogenous fertilizers (meaning the wrong dosage and timing of fertilization);
10. · The use of certain herbicides and the deficiency of molybdenum in the soil disrupt the metabolism in plants, which leads to the accumulation of nitrates.
In addition to plants, sources of nitrates and nitrites for humans are meat products, as well as sausages, fish, cheeses, to which sodium or potassium nitrite is added as a food additive - as a preservative or to preserve the usual color of meat products, since the resulting NO -myoglobin retains its red color even after thermal denaturation, which significantly improves the appearance and marketability of meat products.
To prevent the formation of N-nitroso compounds in the human body, it is really only possible to reduce the content of nitrates and nitrites, since the spectrum of nitrosated amines and amides is too extensive. A significant decrease in the synthesis of nitroso compounds can be achieved by adding ascorbic or iso ascorbic acid or their sodium salts.
Plant growth regulators. Plant growth regulators (PPP) are compounds of various chemical nature that affect the processes of plant growth and development and are used in agriculture to increase yields, improve the quality of crop products, facilitate harvesting, and in some cases to increase the shelf life of plant products ...
Plant growth regulators can be divided into two groups: natural and synthetic.
Natural PPP- these are natural components of plant organisms that perform the function of phytohormones: auxins, hiberrels, cytokinins, abscissic acid, endogenous ethylene, etc. During evolution, the human body has developed appropriate biotransformation mechanisms, and therefore natural PPR do not pose any danger to the human body ...
Synthetic PPP- these are compounds that are, from a physiological point of view, analogs of endogenous phytohormones, or compounds that can affect the hormonal status of plants. They are obtained chemically or microbiologically. The most important PPPs produced industrially under various commercial names, are basically derivatives of aryl- or aryloxy-aliphatic carboxylic acids, indole, pyrimidine, pyridazine, pyradol. For example, sulfonylurea derivatives are widely used.
Synthetic PPRs, unlike natural ones, have a negative effect on the human body as xenobiotics. However, the degree of danger of most RRRs has not been fully understood; it is assumed that they may negatively affect intracellular metabolism due to the formation of toxic intermediates. In addition, some synthetic PPPs may themselves exhibit toxic properties. They are highly persistent in the environment and agricultural products, where they are found in residues. This, in turn, increases their potential health risks.
Fertilizers are used to increase soil fertility, therefore, to increase yields and increase the nutritional value of plants. Violation of agrochemical recommendations for the use of fertilizers leads to their accumulation in agricultural crops. They contaminate food, raw materials and get into food, having a toxic effect on the human body. Depending on the chemical composition, they are distinguished: nitrogenous, phosphoric, potassium, calcareous, bacterial, micronutrient fertilizers, complex, etc. They are divided into mineral and organic.
The need to use fertilizers is explained by the fact that the natural cycle of nitrogen, potassium, phosphorus cannot compensate for the losses.
60. Nutritional factors of nutrition.
Three kilograms of chemicals. This is the amount that is swallowed per year by the average consumer of a variety of, sometimes completely familiar products: muffins, for example, or marmalade. Colorants, emulsifiers, sealants, thickeners are now literally in everything. Naturally, the question arises: why do manufacturers add them to food and how harmless are these substances?
Experts agreed to consider that “food additives are a general name for natural or synthetic chemicals added to food with the aim of imparting certain properties (improving taste and smell, increasing nutritional value, preventing product spoilage, etc.) are used as independent food products. " The wording is clear and understandable. However, not everything in this matter is simple. Much depends on the honesty and elementary decency of manufacturers, on what exactly and in what quantities they use to give the products a presentation.
Taste serial number
Nutritional supplements are not an invention of our high-tech age. Salt, soda, spices have been known to people since time immemorial. But the real flourishing of their use nevertheless began in the twentieth century - the century of food chemistry. There were high hopes for supplements. And they met expectations in full. With their help, it was possible to create a large assortment of mouth-watering, long-lasting and at the same time less labor-intensive products in production. Having won recognition, the "improvers" were put on stream. The sausages are pale pink, the yoghurts are fresh fruit, and the muffins are lusciously non-hardening. The “youth” and attractiveness of the products was ensured by the additives that are used as colorants, emulsifiers, sealants, thickeners, gelling agents, glazing agents, flavor and odor enhancers, preservatives.
Their presence in mandatory is indicated on the packaging in the list of ingredients and are designated by the letter "E" (the initial letter in the word "Europe" individuals can cause individual intolerance.
The letter is followed by a number. It allows you to navigate in the variety of additives, being, according to the Unified European Classification, the code of a specific substance. For example, E152 is completely harmless activated carbon, E1404 is starch, and E500 is soda.
Codes E100 – E182 designate dyes that enhance or restore the color of the product. Codes E200 – E299 are preservatives that increase the shelf life of products by protecting them from microbes, fungi and bacteriophages. This group also includes chemical sterilizing additives used in the maturation of wines, as well as disinfectants. Е300 – Е399 - antioxidants that protect food from oxidation, for example, from rancid fat and discoloration of chopped vegetables and fruits. Е400 – Е499 - stabilizers, thickeners, emulsifiers, the purpose of which is to maintain a given consistency of the product, as well as to increase its viscosity. E500 – E599 - pH regulators and anti-caking agents. Е600 – Е699 - flavors that enhance the taste and aroma of the product. Е900 – Е999 - anti-flaming agents (defoamers), Е1000 – Е1521 - everything else, namely - glazing agents, separators, sealants, flour and bread improvers, texturing agents, packing gases, sweeteners. Food additives under the numbers E700 – E899 do not yet exist, these codes are reserved for new substances, the appearance of which is not far off.
The secret of the crimson kermes
The story of such a food coloring as cochineal, aka carmine (E120), is reminiscent of a detective novel. People learned to receive it in ancient times. Biblical legends mention a purple dye obtained from a red worm, which was used by the descendants of Noah. Indeed, carmine was obtained from cochineal insects, also known as oak bugs, or kermes. They lived in the Mediterranean countries, met in Poland and Ukraine, but the Ararat cochineal was most famous. Back in the 3rd century, one of the Persian kings presented the Roman emperor Aurelian with a scarlet dyed woolen fabric, which became a landmark of the Capitol. Ararat cochineal is also mentioned in medieval Arab chronicles, where it is said that Armenia produces "kirmiz" paint, used for dyeing down and woolen products, writing book engravings. However, in the 16th century, a new type of cochineal appeared on the world market - Mexican. The famous conquistador Hernan Cortes brought it from the New World as a gift to his king. The Mexican cochineal was smaller than the Ararat, but it multiplied five times a year, there was practically no fat in its thin bodies, which simplified the paint production process, and the coloring pigment was brighter. In a few years, a new type of carmine conquered all of Europe, while the Ararat cochineal was simply forgotten for many years. It was only at the beginning of the 19th century that the archimandrite of the Echmiadzin Monastery Isaak Ter-Grigoryan, who is also the miniaturist Sahak Tsakhkarar, managed to restore the recipes of the past. In the 30s of the XIX century, academician of the Russian Imperial Academy of Sciences Joseph Hamel became interested in his discovery, who devoted a whole monograph to "living dyes". They even tried to breed cochineal on an industrial scale. However, the appearance at the end of the 19th century of cheap aniline dyes discouraged domestic entrepreneurs from tinkering with worms. However, it quickly became clear that the need for cochineal paint would not disappear very soon, because, unlike chemical dyes, it is absolutely harmless to the human body, which means it can be used in cooking. In the 30s of the twentieth century, the Soviet government decided to reduce the import of imported food and obliged the famous entomologist Boris Kuzin to establish the production of domestic cochineal. The expedition to Armenia was crowned with success. A valuable insect has been found. However, his breeding was prevented by the war. The project for the study of the Ararat cochineal was resumed only in 1971, but it never came to breeding it on an industrial scale.
August 2006 was marked by two sensations at once. At the International Congress of Mycologists, held in the Australian city of Cairns, Dr. Martha Taniwaki from the Brazilian Institute of Food Technology said that she had solved the secret of coffee. Its unique taste is due to the activity of fungi that enter the coffee beans during their growth. At the same time, what the fungus will be and how much it will develop depends on natural conditions the area in which coffee is grown. That is why different types of invigorating drink are so different from each other. This discovery, according to scientists, has a great future, because if you learn to cultivate fungi, you can give a new taste not only to coffee, but if you go further, then wine and cheese.
But the American biotechnology company Intralytix proposed using viruses as food additives. This know-how will allow you to cope with outbreaks of such a dangerous disease as listeriosis, which, despite all the efforts of sanitary doctors, annually kills about 500 people in the United States alone. Biologists have created a cocktail of 6 viruses that are harmful to the bacterium Listeria monocytogenes, but absolutely safe for humans. The US Food and Drug Administration (FDA) has already approved the processing of ham, hot dogs, sausages, sausages and other meats.
The saturation of foods with special nutrients, practiced in recent decades in developed countries, has made it possible to almost completely eliminate diseases associated with a lack of one or another element. This is how cheilosis, angular stomatitis, glossitis, seborrheic dermatitis, conjunctivitis and keratitis associated with a lack of vitamin B2, riboflavin (dye E101, which gives products a beautiful yellow color), are a thing of the past; scurvy caused by a deficiency of vitamin C, ascorbic acid (antioxidant E300); anemia caused by a lack of vitamin E, tocopherol (antioxidant E306). It is logical to assume that in the future it will be enough to drink a special vitamin-mineral cocktail or take an appropriate pill, and nutritional problems will be solved.
However, scientists do not even think to stop there, some even predict that by the end of the XXI century our diet will consist entirely of food additives. It sounds fantastic and even a little creepy, but we must remember that such products already exist. Thus, chewing gum and Coca Cola, super popular in the twentieth century, got their unique taste precisely thanks to food additives. But the society does not share such enthusiasm. The army of opponents of food additives is growing by leaps and bounds. Why?
SPECIALIST OPINION
Olga Grigoryan, Leading Researcher, Department of Preventive and Rehabilitation Dietetics, Clinic of Medical Nutrition, State Research Institute of Nutrition, Russian Academy of Medical Sciences, Candidate of Medical Sciences.
- In principle, there is nothing strange in the fact that any chemical fillers, without which the modern food industry is unthinkable, are fraught with allergic reactions, disorders of the gastrointestinal tract. However, it is extremely difficult to prove that this or that nutritional supplement was the cause of the disease. You can, of course, exclude a suspicious product from the diet, then introduce it and see how the body perceives it, but the final verdict: which particular substance caused the allergic reaction is possible only after a series of expensive tests. And how will this help the patient, because next time he can buy a product on which this substance will simply not be indicated? I can only recommend avoiding beautiful food of unnatural color with too intrusive taste. Manufacturers are well aware of the possible risks of using food additives and take them quite deliberately. The appetizing type of meat products, which is due to the use of sodium nitrite (preservative E250), has long been the talk of the town. Its excess has a negative effect on metabolic processes, has a depressing effect on the respiratory system, and has an oncological effect. On the other hand, it is enough to look once at the gray-colored homemade sausage to understand that in this case the lesser of two evils is chosen. And, in order not to create problems for yourself and not to exceed the maximum permissible concentration of sodium nitrite, do not eat sausage every day, especially smoked sausage, and everything will be fine.
The problem is that not all dietary supplements used in industry are well understood. A typical example is sweeteners, artificial sweeteners: sorbitol (E420), aspartame (E951), saccharin (E954) and others. For a long time, doctors considered them absolutely safe for health and prescribed them both to patients with diabetes mellitus and to those who simply wanted to lose weight. However, in the past two decades, saccharin has emerged as a carcinogen. In any case, the laboratory animals that consumed it suffered from cancer, however, only if they ate saccharin in a volume comparable to their own weight. Not a single person is capable of this, which means that the risk is much less. But a large amount of sorbitol (about 10 grams or more) can cause gastrointestinal failure and cause diarrhea. In addition, sorbitol can aggravate irritable bowel syndrome and malabsorption of fructose.
The history of food supplements in the 21st century has also been marked by a scandal. In July 2000, representatives of the American Society for the Protection of Consumer Rights, with the support of Connecticut Attorney Richard Blumenthal, appealed to the US Food and Drug Administration (FDA) with a request to suspend the sale of food fortified with certain substances. They included, in particular, orange juice with calcium, biscuits with antioxidants, margarine, which lowers the level of "bad" cholesterol, pies with dietary fiber, as well as drinks, cereals and chips with additives based on vegetable raw materials. Arguing his claim, Richard Blumenthal stated, based on some evidence, that “certain additives can interfere with the action of drugs. Obviously there are others side effects that have not yet been discovered. " As I looked into the water. Three months later, a group of French researchers studying the properties of dietary fiber said that not only did they not protect against bowel cancer, but could also provoke it. For three years, they followed 552 volunteers with precancerous changes in the intestines. Half of the subjects ate as usual, while the other half received an isphagula husk-based supplement. And what? In the first group, only 20% fell ill, in the second - 29%. In August 2002, Belgian Health Minister Magda Elvoert added fuel to the fire by calling on the EU leadership to ban chewing gum and fluoride tablets in the EU, which, of course, protect against caries, but, on the other hand, provoke osteoporosis.
In January 2003, food colors, more precisely one of them, canthaxanthin, became the focus of public attention. People do not use it for food, but they add it to salmon, trout, and chickens so that their meat acquires a beautiful color. An EU special commission found that "there is an irrefutable link between increased consumption of canthaxanthin in animals and vision problems in humans."
However, the report of the British professor Jim Stevenson, released in the spring of 2003, made a splash. The research object of scientists from the University of Southampton (UK) was the five-year-old twins Michael and Christopher Parker. For two weeks, Michael was not allowed to eat Smarties and Sunny Delight candies, Irn Bru and Tizer red beverages, sodas and other chemical additives. The mother of twins, Lynn Parker, described the results of the experiment as follows: “On the second day I saw a change in Michael's behavior. He has become much more obedient, he has developed a sense of humor, he is willing to talk. The level of stress in the house has decreased, there is less aggressiveness in the relationship between the boys, they hardly fight or quarrel. " Scientists from Australia have also reported on the effects of nutritional supplements on adolescent behavior. They determined that calcium propionate (E282), added to bread as a preservative, can lead to severe mood swings, sleep disturbances and impaired concentration in children.In April 2005, an international team of researchers led by Malcolm Greaves stated that food additives (dyes, condiments, and preservatives) are responsible for 0.6–0.8% of chronic urticaria cases.
Black list
Food additives prohibited for use in the food industry of the Russian Federation
E121- Citrus red 2
E123- Red amaranth
E216- Parahydroxybenzoic acid propyl ether
E217- Parahydroxybenzoic acid propyl ester sodium salt
E240- Formaldehyde
Just a few years ago, illicit, life-threatening additives were used heavily. Dyes E121 and E123 contained in soda, candy, colored ice cream, and a preservative E240- in various canned food (compotes, jams, juices, mushrooms, etc.), as well as in almost all widely advertised imported chocolate bars. In 2005, preservatives were banned E216 and E217, which were widely used in the production of sweets, filled chocolates, meat products, pates, soups and broths. Studies have shown that all of these supplements can contribute to the formation of malignant tumors.
Food additives prohibited for use in the EU food industry, but allowed in the Russian Federation
E425- Konzhak (Konzhak flour):
(I) Konjac gum,
(Ii) Konjac glucomannan
E425 are used to speed up the process of combining poorly miscible substances. They are included in many products, especially the Light type, such as chocolate, in which vegetable fat is replaced with water. It is simply impossible to do this without such additives.
E425 does not cause serious illnesses, but in the EU countries, konjac flour is not used. She was withdrawn from production after several cases of suffocation of young children were recorded, in whose respiratory tract poorly soluble saliva got into gummy, the high density of which was achieved by means of this additive.
We must also take into account the fact that, due to his psychology, a person often cannot refuse what is harmful, but tasty. The story with the flavor enhancer monosodium glutamate (E621) is indicative in this regard. In 1907, an employee of the Imperial University of Tokyo (Japan) Kikunae Ikeda first obtained a white crystalline powder, which enhanced the taste sensation by increasing the sensitivity of the papillae of the tongue. In 1909, he patented his invention, and monosodium glutamate began a triumphant march around the world. Currently, the inhabitants of the Earth annually consume more than 200 thousand tons of it, without thinking about the consequences. Meanwhile, more and more data appear in the special medical literature that monosodium glutamate negatively affects the brain, worsens the condition of patients. bronchial asthma, leads to destruction of the retina and glaucoma. It is monosodium glutamate that some researchers blame for the spread of the Chinese restaurant syndrome. For several decades, a mysterious disease has been recorded in various parts of the world, the nature of which is still unclear. For absolutely healthy people, for no reason at all, the temperature rises, the face turns red, and chest pains appear. The only thing that unites the victims is that not long before the illness they all visited Chinese restaurants, whose chefs tend to abuse the "tasty" substance. Meanwhile, according to the WHO, taking more than 3 grams of monosodium glutamate a day "is very dangerous to health."
And yet we must face the truth. Today, humanity cannot do without food additives (preservatives, etc.), since it is they, and not agriculture, that are capable of providing 10% of the annual increase in food, without which the world's population will simply be on the verge of starvation. Another question is that they should be as safe as possible for health. Sanitary doctors, of course, take care of this, but everyone else should not lose their vigilance, carefully reading what is written on the package.
Please fill it out according to the rules of article formatting.
Food chemistry- a section of experimental chemistry dealing with the creation of high-quality food products and methods of analysis in the chemistry of food production.
The chemistry of food additives controls their introduction into food products to improve the production technology, as well as the structure and organoleptic properties of the product, increase its shelf life, and increase the biological value. These additives include:
- stabilizers
- flavors and aromas
- intensifiers of taste and smell
- spices
The creation of artificial food is also a subject of food chemistry. These are products that are obtained from proteins, amino acids, lipids and carbohydrates, previously isolated from natural raw materials or obtained by directed synthesis from mineral raw materials. Food additives are added to them, as well as vitamins, mineral acids, trace elements and other substances that give the product not only nutritional value, but also color, smell and the necessary structure. As natural raw materials, secondary raw materials from the meat and dairy industries, seeds, green mass of plants, hydrobionts, and biomass of microorganisms, for example, yeast, are used. High-molecular substances (proteins, polysaccharides) and low-molecular substances (lipids, sugars, amino acids and others) are isolated from them by means of chemistry. Low molecular weight nutrients are also obtained by microbiological synthesis from sucrose, acetic acid, methanol, hydrocarbons, enzymatic synthesis from precursors, and organic synthesis (including asymmetric synthesis for optically active compounds). Distinguish between synthetic food obtained from synthesized substances, for example, diets for therapeutic nutrition, combined products from natural products with artificial food additives, for example, sausages, sausages, minced meat, pates, and food analogs that imitate any natural products, for example , black caviar.
Literature
- Nesmeyanov A.N. Food of the future. M .: Pedagogika, 1985 .-- 128 p.
- Tolstoguzov VB New forms of protein food. M .: Agropromizdat, 1987 .-- 303 p.
- Ablesimov N.E. Synopsis of Chemistry: Reference and Study Guide for General Chemistry - Khabarovsk: Publishing House of the Far Eastern State University of Economics, 2005. - 84 p. - http://www.neablesimov.narod.ru/pub04c.html
- Ablesimov N.E. How many chemicals are there in the world? Part 2. // Chemistry and Life - XXI Century. - 2009. - No. 6. - S. 34-37.
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