Physiological value of milk. Nutritional and biological value of milk

Milk and dairy products are essential food products. They are staples of the diet and medical nutrition and differ from other food products in that they contain all the substances necessary for the body in an optimally balanced state. Milk provides normal growth, development and vital activity of the organism. High nutritional, biological and medicinal properties milk has long been valued; in ancient times, milk was given names such as “juice of life”, “ White blood”, “source of health”, etc.

The great Russian physiologist I.P. Pavlov viewed milk as amazing food prepared by nature itself and characterized by easy digestibility and nutritional value. digestibility of milk and dairy products in the human body is 95-98%. The inclusion of dairy products in any diet increases its usefulness and quality indicators, contributes to better assimilation other components.

Physiological value(FC) - the ability of food components to activate the activity of the main body systems. FC is provided by physiologically active substances (PAS).

Depending on the effect on the human body physiologically active substances can be divided into the following groups:

1. PAS that have an exciting effect on nervous system person. These include alkaloids: nicotine, caffeine, theobromine, as well as ethyl alcohol.

2. PAS affecting cardiovascular system. This group includes minerals, potassium, magnesium, calcium; vitamins B1, PP,

3. PAS, activating digestive system. Include minerals: sodium, chlorine, enzymes, phospholipids, vitamins, fiber, hemicelluloses, pectin, aromatic substances, glycosides, nitrogenous and nitrogen-free extractives, hop resins and acids.

4. FAW, enhancing immune system. These include substances with a pronounced bactericidal and fungicidal action: polyphenols, dyes, aromatics, vitamins: B 1 , PP, glycosides, organic acids, among which benzoic, salicylic, gallic, citric, and lactic acids are distinguished by the greatest bactericidal activity.

5. PAS that promote excretion from the body harmful substances: slags, toxic elements, bacterial etc. poisons. This group is represented by pectins, fiber, and some proteins.

It should be noted that substances that are of no value to the human body (for example, bacterial and fungal toxins) are considered harmful, as well as useful material, which provide negative impact on the human body in doses exceeding the MPC.

The above list of PAS belonging to different groups indicates that many food substances are multifunctional.

Nutraceutical components in milk favorably affect the human body: calcium, lactoferrin, lactoperoxidase, immunoglobulins, whey proteins, linolenic acid, oligosaccharides, phospholipids, etc.

There are many more nutraceutical components in colostrum, and some of them are present in much higher concentrations than in regular milk.

Milk and dairy products are extremely valuable and indispensable products in the prevention and treatment of diseases such as gastrointestinal, heart and blood vessels, liver, kidneys, diabetes mellitus, obesity, acute gastritis, etc. They should be consumed as part of a balanced diet to maintain tone and as a factor in increasing life expectancy.

Dairy products are of exceptional importance in the nutrition of children, especially in the initial period of their life, because. contains a significant amount of phospholipids, essential amino acids, normalizing the processes of growth and development of the body.

The physiological value of milk increases significantly when consumed in the form of fermented milk drinks. Their use contributes to the creation acid environment in the intestinal tract and, as a result, the suppression of putrefactive microflora and the normalization of digestion. Therefore, dairy products are widely used as a remedy for intoxication of the body with poisonous products of putrefactive microflora. Dairy products are digested much easier and faster than milk. In addition, they contain a large number of antibiotic substances with bactericidal action.

Milk (in the amount of 1l) satisfies daily requirement human in animal fat, calcium, phosphorus; 53% - in animal protein; 35% - in essential fatty acids and vitamins A, C, thiamine; 12.6% in phospholipids and 26% in energy.

Thanks to its unique chemical composition dairy products can replace all other food products. The chemical composition of milk and dairy products is extremely diverse, and all of their components are essential in nutritional physiology.

Dairy products contain water, proteins, fats, carbohydrates, minerals, vitamins, organic acids, dyes, immune bodies, enzymes, gases, etc. Various factors influence the chemical composition: type of animal, age, conditions of feeding and keeping, period years, etc. (Table 2)

table 2

Chemical composition cow's milk

Protein substances of dairy products. They are the most nutritionally valuable part of dairy products, they consist of casein and whey proteins - albumin and globulin. In addition to them, dairy products contain shell proteins of fat globules and some other little-studied protein substances, as well as nitrogenous compounds.

Squirrels dairy products have an extremely favorable quantitative and qualitative composition amino acids, including all essential amino acids. Therefore, dairy proteins are considered complete. In addition, milk proteins, unlike other animal proteins, are relatively easily reproducible and are recognized as the cheapest, which allows them to be used more and more widely every year as food additives to non-dairy products.

Milk protein surpasses the ideal protein in amino acid composition, which determines its high physiological value (see table 3).

“Milk,” wrote academician I.P. Pavlov, “is an amazing food prepared by nature itself.” It has been established that this product contains over a hundred of the most valuable components. It includes all the substances necessary for the life of the body: proteins, fats, carbohydrates, mineral salts, vitamins. These components of milk are well balanced, making them easily and completely digestible.

Milk, like bread, mankind began to use in writing more than five thousand years ago. Milk - the only product nutrition in the first months of a person's life. Importance it has in the diet of an adult. For old, weakened and sick people, milk is an indispensable food.

Since ancient times, milk has been used as remedy from many diseases in the treatment of the heart, kidneys and other organs.

Inclusion of dairy products in diet increases its usefulness and contributes to a better assimilation of all components.

Milk has a beneficial effect on the secretion of the digestive glands. For its assimilation by the body, energy is required 3-4 times less than for the assimilation of, for example, bread.

From cows of the same breed, depending on climatic conditions, feeding, maintenance, different amounts of milk are obtained, its quality is also different. The composition of milk varies depending on the time of year, the age of the cow, her individual features and many other factors. Employees of the All-Union Scientific Research Dairy Institute (VNIIMI) conducted a study of milk supplied to 220 dairy enterprises in 55 zones of the RSFSR and 12 union republics. In total, about 80,000 samples of milk were studied, accounting for about 25-30% of its total procurement in the studied areas. The studies were carried out monthly. With an average fat content in milk of 3.55%, the fluctuations were in the range of 3.36-3.86%, i.e., at the level of existing basic indicators. The amount of total protein was 3.13% with fluctuations from 2.96 to 3.30%. The density of milk averaged 1.0283 (23.3%) with fluctuations from 27.4 to 29.4%. The content of solids in milk on average turned out to be 11.93% with fluctuations from 11.60 to 12.36%.

In addition to cow's milk, milk and other types of farm animals are used for food, and both in whole, and in the form of dairy products: cheese, made mainly from sheep milk, koumiss - from mare.

1. Nutritional value of milk

biological value

The most important component of milk are proteins, the total amount of which in cow's milk averages 3.2% (2.7% - casein and 0.5% - whey proteins - albumins and globulins). Half a liter of milk is almost 1/3 of a person's daily requirement for animal protein. According to the balance of amino acids and digestibility, milk proteins are among the most valuable. They have practically no amino acids that limit biological value. True, there is a certain deficiency of sulfur-containing amino acids (mainly cystine) in casein, but they are rich in whey milk proteins, which are characterized by high content the other two most deficient amino acids, lysine and tryptophan, are often deficient in human diets. Milk proteins, under the influence of hydrochloric acid and digestive enzymes produced in the stomach, coagulate into small flakes, which greatly facilitates their digestion and assimilation. Whey proteins are especially well absorbed. The digestibility of milk proteins is 96--98%. It should be noted that it is whey proteins that are carriers of special protective factors - immunoglobulins, which are involved in the production of antibodies against pathogens and viruses.

From caseins in the process of digestion, physiologically active peptides are formed, one of which, the so-called casein glycomacropeptide, inhibits gastric secretion and motility. In the process of digestion of cow's milk, peptides with opioid (narcotic) activity (β-casomorphins) can be released, which have a regulatory effect on cerebral circulation. Substances that lower blood pressure have been isolated from bovine casein, so milk, dairy products and dishes from them are used in the complex treatment of coronary heart disease, atherosclerosis of the coronary, cerebral, peripheral vessels, stage II-III hypertension. In addition, food peptides isolated from milk casein can be used as promising medicines for the treatment of gastroduodenal pathology associated with hyperfunction of the stomach, to reduce the feeling of hunger and as anti-stress drugs. However, there is scientific evidence that milk casein increases blood cholesterol levels and promotes atherosclerosis. Therefore, abuse dairy products, especially fat-free cottage cheese, consisting of almost pure casein, is not worth it.

Compared to other fats of animal origin, milk fat is better absorbed in the human body, which is facilitated by relatively low temperature its melting (28--33 °C) and finely dispersed state. The digestibility of milk fat is 97--99%. It contains relatively few essential polyunsaturated fatty acids, but when drinking half a liter of milk, about 20% of a person's daily need for them is covered. Presence in milk fat deficient arachidonic acid, short-chain fatty acids (and in total milk fat includes more than 30 different fatty acids), as well as significant amounts of phospholipids and vitamins A and D, increases its biological value. In addition, the ratio of fat and protein in milk is close to optimal (1:1). Milk, especially fat, is a weak causative agent of gastric secretion and motility, has a pronounced antacid effect, that is, it directly interacts with hydrochloric acid in the stomach, inactivating it. Therefore, it is recommended to use milk for hyperacid (with high acidity) gastritis, gastric ulcer and duodenal ulcer.

Due to the fact that fats slow down the evacuation from the stomach, inhibit gastric secretion and cause a feeling of satiety, for more fat milk less gastric juice is secreted at the beginning of digestion and it lingers longer in the stomach. Therefore, full-fat milk (and cream) has a more pronounced therapeutic effect in these diseases than fat-free.

Carbohydrates in milk are represented mainly by lactose (milk sugar), the amount of which is on average 4.5--5%. Unlike other sugars, it is relatively poorly soluble in water, is slowly absorbed in the intestine, stimulates the development of lactic acid sticks in it, which, by forming lactic acid, suppress putrefactive microflora and contribute to better absorption of calcium and phosphorus. Lactose is 5-6 times less sweet than sucrose (beet sugar), so milk does not have a pronounced sweet taste. Under the influence of enzymes of the stomach and intestines, lactose is broken down into glucose and galactose, which are absorbed into the blood and serve as a source of energy. The role of lactose in the nutrition of infants is especially important.

However, children and adults may have milk intolerance (so-called selective lactose malabsorption), associated with a deficiency of the intestinal enzyme lactase, which leads to impaired digestion. milk sugar, its fermentation in the gastrointestinal tract, accompanied by bloating, abdominal pain and other symptoms of indigestion. Moreover, primary lactase deficiency is a genetically determined condition and depends on belonging to different ethnic groups. So, lactase deficiency occurs in 15-20% of adult residents of Northern and Central Europe and in 75-100% of indigenous peoples of Northern and South America, Africa, Southeast Asia. In Russians, the frequency of lactase deficiency is 12.5-16.3%, in Belarusians - 13%, in Ukrainians - 5.8%.

It should be noted the high content in milk and dairy products of such mineral elements as calcium and phosphorus. Both of them are found in milk in well-balanced proportions, which determines their relatively high digestibility. Thus, the ratio between calcium and phosphorus in milk is 1:1 - 1.4:1 (in cottage cheese and cheese - 1: 1.5 - 1: 2), while in meat and fish it is equal, respectively, 1:13 and 1:11. About 80% of a person's daily calcium requirement is met by milk and dairy products. At the same time, milk is relatively poor in some trace elements: iron, copper, manganese, iodine, and fluorine. Therefore, when eating predominantly dairy products, especially children, anemia may develop. Milk and dairy products are a constant source of almost all vitamins. They are especially rich in riboflavin, which is relatively deficient in food products; about 50% of a person’s daily requirement for this vitamin is met by milk and dairy products.

The biological value of milk is supplemented by a variety of enzymes, hormones, antibodies, antibiotics and other biologically active substances. Thus, food and biological value milk is indisputable, and it is an indispensable human food product. However, not everything is so perfect with milk: it is low in iron, which even calves replenish with grass; for those who, starting from infancy add cow's or goat milk, more often develop diathesis, anemia, dysfunction of the gastrointestinal tract. In addition, as I.P. Neumyvakin points out, casein (protein) contained in mother's milk is broken down using the so-called rennet, and when the need for casein disappears (the foundation for the formation of nails and hair is laid) - and this usually happens at 1-2 years of age - it disappears. In addition, milk, entering the stomach, under the influence of acidic contents, coagulates, forming, as it were, cottage cheese, envelops particles of other food and isolates it from gastric juice. And until curdled milk is digested, the process of processing other food will not begin, which is why milk should be drunk separately from other food.

Energy value and digestibility

biological The value of milk is that:

Its components are well balanced

They are easily digestible

Milk components are mainly used for synthetic and "construction" (plastic) purposes.

The amino acids of milk are so well balanced that its proteins are digested by 98%. According to this indicator, they are inferior (and only by 2%) to egg proteins, the amino acid balance of which is accepted by the World Health Organization (WHO) as a standard (100%). In addition, some substances necessary for the body are found only in milk. Let us name only the deficient arachidonic acid and the biologically active protein-lecithin complex. Both of these components prevent the development of atherosclerotic processes in the body.

Milk calcium is the most easily digestible calcium in nature. The complex of vitamins A, B2, D3, carotene, choline, tocopherols, thiamine and ascorbic acid. All this has a normalizing effect on the level of cholesterol in the blood serum.

The composition of the mineral substances of milk includes all the elements of the periodic system of Mendeleev. It contains salts of potassium, sodium, magnesium, iron, citric, phosphoric and hydrochloric acids and a number of others. All of them are found in milk in an easily digestible form.

IN most Milk contains carbohydrates, fats, proteins and mineral salts. Vitamins, enzymes, trace elements, hormones, immune bodies and other substances are contained in milk in very small quantities, but they have high biological activity and their role in human nutrition is enormous.

PART I GENERAL DAIRY TECHNOLOGY

Chapter 1. Milk as a raw material for the dairy industry

Nutritional and biological value of milk

Milk (lactate) is a biological product of the secretory activity of the mammalian mammary gland. It provides all the necessary nutrients normal development of the newborn. Possessing immunological and bactericidal properties (the ability to destroy and suppress the development of extraneous microflora), milk protects it from diseases, participates in the formation of its enzyme and immune systems.

The composition of milk in optimally harmonic combinations includes: proteins, lipids, carbohydrates, minerals, water, organic acids, gases, pigments, vitamins, enzymes, hormones, immune bodies and others. essential components for normal feeding and metabolism of the cub. Milk, containing in a balanced qualitative and quantitative composition more than 250 vital substances with easy and almost complete digestibility (96-98%), has no equal product in nature in terms of nutritional and biological value.

Since ancient times, milk has been used not only for nutrition, but also in medicinal and preventive purposes, therefore it was called the "source of health", "food of the gods".

According to the definition of the great Russian physiologist I.P. Pavlov, "milk is an amazing food prepared by nature itself." He pointed out that milk has the ability to independently, without the participation of the cerebral cortex and in the absence of appetite, excite the digestive tract, cause the separation of digestive juices and be absorbed, “without which the digestion of other food cannot occur”; this is especially healing properties milk for sick and weakened organisms; in addition, milk proteins are easier and more fully digested than the proteins of other products, and contribute to the absorption of the latter.

All components of milk are complete and play an important role in the physiology of human nutrition.

Milk proteins are the most biologically valuable component. The amino acids formed during the breakdown of proteins are the material for building body cells, enzymes, hormones, antibodies during manifestations of immunity, etc. Of all animal proteins, milk proteins are the most complete. Casein, albumin and globulin contain all essential amino acids (lysine, tryptophan, methionine, phenylalanine, leucine, isoleucine, threonine, valine). A dietary deficiency of at least one essential amino acid causes a metabolic disorder in the human body. Whey proteins are more valuable than casein because they contain more lysine, tryptophan and other essential amino acids. Milk proteins have lipotropic properties, regulating fat metabolism, increase the balance of food and the absorption of other proteins. With amphoteric properties, milk protein protects the body from toxic substances. When the body is poisoned with heavy metals, casein reacts with them, forming insoluble salts that are excreted from the body.

It is important that the proteins in milk are in a dissolved state, therefore they are easily attacked and digested by proteolytic enzymes. digestive tract. The digestibility of milk proteins is 96-98%.

The sulfur-containing amino acid methionine is a source of the formation of choline and phosphatides, which play an important role in metabolism, preventing fatty degeneration of the liver, atrophy of the endocrine glands, changes in the transmission of nerve excitations, etc. Milk protein amino acids arginine and threonine normalize the processes of growth and development and are therefore especially important for the child's body.

The daily requirement of an adult in amino acids (28.4 g of milk proteins or 14.5 g of whey proteins) is fully provided by consuming 0.5 liters of milk.

Milk proteins have a water-binding, emulsifying, foaming ability, which allows them to be used in the production of combined biologically valuable products.

Milk fat, compared with other natural fats, has the most complex chemical composition (more than 157 fatty acids are involved in the formation of its glycerides). Its qualitative and quantitative glyceride composition is optimally balanced. Of the natural fats, it has the most valuable nutritional properties, is a source of energy for biochemical processes in the body.

Milk fat is highly digestible. This is due to the fact that it is found in milk in the form of easily digestible microscopic fat globules in liquid state. The melting point of milk fat is 27-34 °C. The biological value of milk fat is due to the content of fat-soluble vitamins (A, E, D) and essential polyunsaturated fatty acids (linoleic, linolenic, arachidonic). However, milk fat contains an insufficient amount of polyunsaturated fatty acids, covering the need human body by one third. Therefore, it is recommended to add to food vegetable oil rich in linoleic and linolenic fatty acids. The lack of polyunsaturated fatty acids in the body contributes to the development of atherosclerosis, vascular thrombosis, dry skin, eczema and other diseases. The lipoids associated with milk fat (phospholipids, lecithin, cerobrosides, stearins, waxes) play an important role in cellular metabolism, the intensity of fat absorption, and in the formation of adrenal hormones.

The pleasant taste of milk fat ennobles the taste of dairy products, determines the homogeneity and plasticity of their structure and consistency.

Milk sugar (lactose) is a source of energy for biological processes in the body, promotes the absorption of calcium, phosphorus, magnesium, barium. Possessing less solubility than sucrose, it causes less irritation of the digestive tract, and due to delayed hydrolysis, it reaches the large intestine, where it is used by lactic acid microflora, which creates a favorable acidic environment. Having 5 times less sweet taste than sucrose, lactose does not reduce appetite.

Milk minerals play a significant role in the plastic processes of the formation of new tissue cells, the synthesis of enzymes, vitamins, hormones, as well as in the mineral metabolism of the body. Milk contains a lot of calcium and phosphorus salts, which are in an optimally balanced ratio and easily digestible form. These elements are necessary for the body to form bone tissue, blood formation, brain activity, etc. Approximately 80% of a person's daily need for easily digestible calcium is met by dairy products. Calcium is needed to regulate blood pressure, reduce the risk of certain types of cancer; iodine is involved in the synthesis of the thyroid hormone - thyroxine; iron is part of hemoglobin and some enzymes; cobalt is part of vitamin B12; copper catalyzes redox processes in the body; sodium and potassium chlorides, phosphates are involved in the construction of blood and plasma elements; sulfur - in the synthesis of most proteins, a number of vitamins, hormones and other biologically active substances.

The biological value of milk is complemented by the presence of almost the entire complex of vitamins known and necessary for the human body, the content of which varies depending on the period of the year, on animal feeding rations; it, as a rule, rises in the summer when livestock is kept on green pastures.

One liter of milk fully satisfies the daily requirement of an adult for animal fat, calcium, phosphorus; 53% in animal protein; 35% - in biologically active essential fatty acids and vitamins A, C, thiamine; 12.6% in phospholipids and 26% in energy. The energy value of milk is 2720 kJ/kg.

The presence of all components in an optimal combination and easily digestible form makes milk an extremely valuable, indispensable product for dietary and therapeutic nutrition, especially for gastrointestinal diseases (colitis, cholecystitis, acute gastritis), diseases of the heart and blood vessels, liver, kidneys, diabetes, obesity. Milk should be consumed daily to maintain tone and increase life expectancy.

Milk is of exceptional importance in the nutrition of children, especially in the first period of their life. The shell protein of fat globules contains a significant amount of phospholipids, arginine and threonine - amino acids that normalize the processes of growth and development of the body. Milk is the main source of easily digestible phosphorus and calcium for building bone tissues of a growing organism.

The biological value of milk is complemented by the fact that it helps to create an acidic environment in the intestinal tract and suppress the development of putrefactive microflora.

Milk plays an equally important role as a dietary and medicinal product for the elderly, this was pointed out by Avicenna, who lived over 1000 years ago. Milk and dairy products must account for at least 20% daily diet old people. For an aging body, the nature of nutrition is a very important factor in health and life extension. This is due to the fact that in people over 60 years of age, the intensity of metabolic processes and the digestibility of food are reduced, there is a lack of digestive enzymes, and the secretory and motor functions of the gastrointestinal tract are weakened.

They have a depletion of the skeleton with mineral salts, a change in vitamin metabolism, and fluctuations in the composition of the blood. The body's resistance to the effects of adverse weather conditions and the body's resistance to diseases decrease over the years. A balanced and rational diet can largely counteract these processes.

With age, not only the intensity of metabolic processes in the body decreases, but also the need for nutrients decreases, selectivity appears in their choice. The need for meat is sharply reduced and the need for vegetable and dairy products increases.

Milk and dairy products are essential in the diet of the elderly. In this case, it is advisable to give preference to low-fat or low-fat dairy products. The desired ratio of animal and vegetable proteins and fats is 1:1.

Currently, dairy and vegetable-dairy products are being created for the therapeutic and prophylactic nutrition of the elderly.

A very important role in the nutrition of the elderly is given to dietary fermented milk products, which are most easily and quickly absorbed by the body, require less digestive juices, and improve health. gastrointestinal tract. Dietary fermented milk products with therapeutic and prophylactic properties, fortified, with vegetable biologically valuable fillers are being created.

To fully meet the needs of the population Russian Federation in dairy products, it is necessary to process more than 50 million tons of milk per year with an increase in capacity for the production of dietary fermented milk products, cottage cheese, cheese and canned milk.

Milk and dairy products

Topic 5. Sanitary and hygienic assessment of milk

and dairy products

Nutritional and biological value of milk and dairy products. The nutritional and biological value of milk lies in the optimal balance of its components, easy digestibility (by 95-98%) and high use of all plastic and energy substances. Milk contains all the nutritional substances necessary for the body, therefore milk and dairy products are indispensable in the nutrition of patients, children and the elderly. It contains high-grade proteins, fats, vitamins, mineral salts. In total, about 100 biologically important substances have been found in milk. The inclusion of milk and dairy products in the diet improves the balance of the amino acid composition of the proteins of the entire diet and significantly increases the supply of calcium to the body. The chemical composition of cow's milk is as follows: proteins 3.5%, fats 3.4% (not less than 3.2%), carbohydrates in the form of milk sugar (lactose) - 4.6%, mineral salts 0.75%, water 87, 8%. The chemical composition of milk varies depending on the breed of animals, the season, the nature of the feed, the age of the animals, the lactation period, and the technology of milk processing.

Squirrels milk presented casein, albumin(lactoalbumin) and globulin(lactoglobulin). They are complete and contain all the amino acids necessary for the body. Milk proteins are readily available for digestive enzymes, and casein has a regulatory effect on increasing the digestibility of other nutrients. Casein, when souring milk, splits off calcium and curdles. Albumin is the most valuable milk protein; when boiled, it coagulates, forming foam, and partially precipitates.

In human nutrition, cow, goat, sheep, mare, donkey, deer, camel, buffalo milk is used. Buffalo and sheep milk has especially high nutritional and energy properties. The most nutritious is reindeer milk, which contains up to 20% fat, protein - 10.5%, vitamins 3 times more than in cow's milk. Women's milk contains 1.25% protein, therefore, cow's and any other milk requires dilution when feeding infants. According to the nature of the proteins, the milk of various animals can be divided into casein(casein 75% or more) and albuminous(casein 50% or less). Casein milk includes the milk of most lactating farm animals, including cows and goats. Albumin milk includes mare and donkey milk. The peculiarities of albumin milk are its higher biological and nutritional value, due to the better balance of amino acids, high sugar content and the ability to form small, tender flakes when soured. Albumin milk in properties approaches women's milk and is the best substitute for it. Albumin particles are 10 times smaller than casein, the particles of which are larger even when curdling in the stomach baby cow's milk protein forms hard-to-digest large, dense, coarse flakes.

Main protein cow's milk is casein, which in milk is 81.9% of the total amount of milk proteins. Lactoalbumin found in milk in an amount of 12.1%, lactoglobulin 6%.milk fat belongs to the most valuable fats in terms of nutritional and biological properties. It is in a state of emulsion and a high degree of dispersion. This fat is highly palatable. Milk fat contains phospholipids (0.03 g per 100 g of cow's milk) and cholesterol (0.01 g). Due to the low melting point (within 28-36˚C) and high dispersion, milk fat is absorbed by 94-96%. As a rule, the fat content of milk in autumn, winter and spring is higher than in summer. With good animal care, the amount of fat in cow's milk can reach 6-7%. Carbohydrates in milk are in the form of milk sugar - lactose. It is the only milk carbohydrate found anywhere else. Lactose refers to disaccharides; upon hydrolysis, it breaks down into glucose and galactose. The intake of lactose into the intestines has a normalizing effect on the composition of the beneficial intestinal flora. Milk intolerance, noted in many people, is caused by the absence in the body of enzymes that break down galactose.

Milk sugar is of great importance in the production of lactic acid products. Under the action of lactic acid bacteria, it turns into lactic acid; while curdling the casein. This process is observed in the production of sour cream, curdled milk, cottage cheese, kefir.

Minerals. Milk contains a wide range of macro- and microelements. In the mineral composition of milk, calcium and phosphorus are of particular importance. It also contains potassium, sodium, iron, sulfur. They are found in milk in an easily digestible form. Microelements contain zinc, copper, iodine, fluorine, manganese, etc. The calcium content in milk is 1.2 g/kg.

Vitamins. Almost all known vitamins are present in milk in small quantities. The main vitamins of milk are vitamins A and D, and also contain some amounts of ascorbic acid, thiamine, riboflavin, nicotinic acid. In summer, when animals eat juicy green fodder, the content of vitamins in milk increases. The calorie content of milk is low and averages 66kcal per 100g of product. Milk contains a number of enzymes.

Milk causes a weak secretion of the gastric glands and is therefore indicated for peptic ulcer and hyperacid gastritis. Due to the presence of lactose, when drinking milk, a microflora develops in the intestines, delaying putrefactive processes. There is little salt in milk, and therefore it is recommended for people suffering from nephritis and edema. There are no nucleic compounds in milk, therefore, it is indicated for persons with impaired purine metabolism. For febrile patients, milk is both light food and drink.

The overall balance of all substances that make up milk is characterized by an anti-sclerotic orientation, which has a normalizing effect on the level of cholesterol in the blood serum.

TO fermented milk products include: sour cream, curdled milk, cottage cheese, acidophilus milk, kefir, koumiss and others. They are obtained by fermenting pre-pasteurized milk with ferments of lactic acid microbes. The medicinal properties of lactic acid products are explained by the fact that they are digested 2-3 times easier and faster than milk, which forms dense large clots in the stomach, suppression of the growth of putrefactive intestinal microflora, and the presence of antibiotics produced by the lactic fermentation bacillus that affect pathogenic microbes. I.I. Mechnikov attached great importance to fermented milk products in preventing premature aging, one of the reasons for which he saw in the “self-poisoning” of the body by products formed during the processes of putrefaction in the intestines.

Yogurt is close to milk in its nutritional properties. Fresh one-day yogurt enhances intestinal motility and has a laxative effect. Two - three-day yogurt can have a fixing effect. Under the influence of ordinary curdled milk, the intestinal microflora changes, however, lactic acid microbes contained in curdled milk do not find favorable conditions for engraftment in the intestines.

Acidophilus bacillus takes root well in the human intestine and is used to make acidophilic lactic acid products. It is more effective in the fight against putrefactive microflora. Acidophilic milk is used to prepare patients for surgery, to treat putrefactive colitis, dyspepsia in children, constipation and other diseases. If regular milk after an hour, it is absorbed by 32%, then lactic acid products during this time by 91%.

To make kefir, milk is fermented with kefir mushrooms. In the manufacture of koumiss, milk (mare or cow) is fermented with pure cultures of Bulgarian sticks or lactic yeast. Depending on the timing of maturation, kefir and koumiss are divided into weak (one-day), medium (two-day) and strong (three-day). The alcohol content in weak kefir is 0.2%, on average - 0.4%, in strong - 0.6%. Weak kefir has a laxative property, is used to eliminate and prevent constipation. Kumis is a well-carbonated drink due to the presence of carbon dioxide. The alcohol content in koumiss is from 1 to 2.5%. It has a strengthening effect, improves digestion, metabolism and is widely used for medicinal purposes in chronic bronchitis, pulmonary tuberculosis and anacid gastritis.

Cottage cheese is a kind of concentrate of protein and calcium, therefore it has a high biological value. It helps prevent fatty liver disease. It has anti-sclerotic properties, increases diuresis and is widely used in the nutrition of children and the elderly.

Milk is a good environment for the development of microorganisms. The main diseases transmitted to humans through milk are tuberculosis, brucellosis, foot-and-mouth disease and coccal infections. Intestinal infections (dysentery), poliomyelitis can be transmitted through milk, which can be introduced into milk at all stages of its production, transportation, processing and distribution. With milk, infectious agents can be transferred to butter, cottage cheese, curdled milk and other dairy products. In curdled milk, the causative agents of typhoid fever survive up to 5 days, in cottage cheese up to 26 days, in oil up to 21 days. The causative agent of poliomyelitis remains viable in dairy products for up to 3 months. The possibility of transmission through milk of diphtheria and scarlet fever has been proven. Milk contamination is usually associated with bacillus carriers working in dairies and other dairy facilities.

Especially dangerous infections. The milk of animals suffering from anthrax, rabies, infectious jaundice, rinderpest and other diseases is subject to destruction on the spot in the presence of representatives of the veterinary and sanitary supervision.

Tuberculosis. The greatest danger to humans is milk from animals with severe clinical manifestations of the disease, especially with udder tuberculosis. The milk of such animals is not allowed to be used for food. Animals with a positive reaction to tuberculosis are allocated to special herds, and milk on farms must be disinfected by heating to 85 ° C for 30 minutes.

Brucellosis. Brucellosis affects cows, sheep and goats. Milk from animals suffering from brucellosis is subjected to mandatory boiling at the place of receipt for 5 minutes, followed by re-pasteurization at dairies.

foot and mouth disease- the disease is caused by a filter virus that is not resistant to heat. Heating milk to 80°C for 30 minutes or boiling it for 5 minutes kills the virus. Milk is allowed to be sold on the farm only after heat treatment.

Topic 3. Sanitary and hygienic assessment of meat

and meat products

Sanitary and hygienic examination of food products carried out by a sanitary doctor in a planned manner and outside the plan in the presence of special epidemiological indications. The purpose of the sanitary examination is to establish the qualitative state of food products and to identify properties that may adversely affect the health of the population. The quality of food products produced by food enterprises is regulated by the standards and regulations established in the country.

During storage, transportation and sale, food products can change their original properties: taste, appearance, smell; products can get into harmful impurities or microorganisms that make them hazardous to health. All products, depending on their quality, are usually divided into the following categories:

Benign (standard)– products that meet all the requirements of the standard. Their use in food does not cause concern. Such products are allowed to be used for food without restrictions.

Conditionally fit- products with certain defects, which in their natural form pose a danger to human health and require mandatory (most often thermal) treatment to neutralize them. For example, fresh fish, in the muscle tissue of which larvae of a wide tapeworm were found; meat of animals suffering from brucellosis, leukemia, tuberculosis, foot and mouth disease, etc.

Products with reduced nutritional value (non-standard)- these are products that have defects that reduce their nutritional value, but do not prevent them from being eaten when normal conditions i.e. not hazardous to human health. These products are prepared in violation of the technological processing regime, storage conditions and terms, or other reasons. For example, low-fat milk, high-moisture bread.

falsified products are products that are artificially given some properties and characteristics in order to hide flaws (or for the purpose of profit). For example, baking soda can be added to milk to hide hyperacidity. Neutralizing lactic acid, soda does not delay the development of putrefactive microorganisms and contributes to the destruction of vitamin C. Such milk is not suitable for human consumption.

Surrogates- products similar to natural ones in terms of organoleptic characteristics (smell, taste, color, appearance), but prepared artificially with a corresponding indication on the label. These are coffee surrogates made from cereals; fruit essences instead of natural juices; soy meat, mayonnaise, black caviar.

Poor quality products- these are products that are not suitable for food in both natural and processed form, as they are dangerous to human health or unsuitable for consumption due to unsatisfactory organoleptic properties. Violation of the quality of food products may be due to the decomposition of their constituent parts, in particular protein under the influence of putrefactive microflora, fat under the influence of physical and chemical factors. Poor-quality products can become due to infection with helminth larvae, as well as contamination with pesticides and other toxic substances above the MPC. Examples of poor quality products are rancid fats, moldy bread, rotting meat, flour with a high content of ergot.

Nutritional and biological value of meat and meat products. The meat of warm-blooded animals is the most important food product, which is a source of complete protein, fat, vitamins, mineral salts, as well as extractive substances (creatine, purine bases, lactic acid, glycogen, glucose, lactic acid, etc.). According to its chemical composition, animal meat provides the body with vital proteins and contains all the essential amino acids in a favorable balance. Compared with plant products, meat has a higher digestibility, low "puffiness", high saturation.

The chemical composition, organoleptic properties and nutritional value of meat vary significantly depending on the type, age and nature of the animal's nutrition, as well as on the part of the carcass. The content of proteins in meat is 11-21%. The amount of fat varies depending on the fatness of the animal, for example, in beef from 3 to 23%, in pork up to 37%. The meat of well-fed animals not only has a large energy value, but also contains more essential amino acids and biologically valuable fats. There are few carbohydrates (glycogen) in meat, less than 1%. Of the minerals, macronutrients such as phosphorus, magnesium, potassium, sodium are of primary importance, the content of which differs little in various types meat. Meat is also a source of some trace elements - gland, copper, zinc, iodine, etc. Iron is 3 times better absorbed from meat than from plant products. Meat contains various vitamins: thiamine, riboflavin, pyridoxine, nicotinic and pantothenic acids, as well as choline. The entrails (offal) - liver, kidneys, etc. contain less protein, but are very rich in vitamins A, group B and others.

Water-soluble nitrogenous extractives of meat give it a peculiar aroma and taste and excite the secretion of digestive juices and the activity of the nervous system. When cooking meat, from 1/3 to 2/3 of the extractives goes into the broth, so boiled meat is preferable in chemically sparing diets. Boiled meat is widely used in diet food with gastritis, peptic ulcer, liver diseases and other diseases of the digestive system.

The digestibility of meat is high: fats are digested by 94%; proteins of lean pork and veal by 90%, beef - 75%, lamb - 70%.

The main feature of meat fats is their refractoriness. Meat fats are distinguished by a significant content of solid, saturated fatty acids with a high melting point. With a decrease in fatness, significant changes occur in the composition of fat: the content of polyunsaturated fatty acids (PUFAs) decreases and the content of saturated, solid fatty acids sharply increases, and therefore the melting point of fats increases. Lean cattle meat fat has a lower biological value and is characterized by low digestibility. Beef and lamb are dominated by saturated fatty acid, and the content of essential polyunsaturated fatty acids (linoleic, linolenic) is insignificant. There are a lot of PUFAs in pork. According to biological properties, pork fat is the best. Cholesterol in the muscle tissue of warm-blooded animals is 1.5 times less than in adipose tissue.

poultry meat contains more proteins: chickens - 18-20%, turkey - 24.7% and extractives; proteins and fats are better digested. There are more PUFAs in the lipids of poultry meat than in beef and lamb. White meat is rich in phosphorus, sulfur and iron. The meat of ducks and geese is not used in dietary nutrition, since the fat content is 36 - 38%.

Meat is a perishable product. When it rots, decomposition of amino acids occurs with the release of ammonia, hydrogen sulfide and other foul-smelling gases. When fats are oxidized, volatile fatty acids are released. This not only worsens the organoleptic properties of the product, but also reduces its nutritional value.

Meat can cause food poisoning, most commonly caused by salmonella. Infectious animal diseases (zoonoses) can be transmitted to humans through meat. The meat of animals suffering from anthrax and other especially dangerous infections is not allowed for food and must be destroyed. With less dangerous infections (brucellosis, tuberculosis, foot and mouth disease, leukemia, etc.), meat is used as conditionally fit. Such meat can only be sold through public catering establishments, where it is most often thoroughly boiled for 2.5 - 3 hours in pieces weighing no more than 2 kg and up to 8 cm thick. Animal meat can also be a source of human infection with certain helminths (Finnosis , trichinosis).

Health protection of consumers from these diseases is provided by veterinary supervision. Livestock is slaughtered at meat processing plants and slaughterhouses under the supervision and control of the veterinary and sanitary service.

Infection of animal meat can be intravital or post-mortem. In malnourished and overworked animals, intravital bacteremia and the penetration of salmonella and other microflora from the intestine into muscle tissue and internal organs. In the process of slaughtering animals and removing the viscera, direct contamination of the carcass with intestinal contents is possible. To avoid this, the intestine should be removed only after applying double ligatures to both ends. To prevent the proliferation of microbes, meat should be stored at an air temperature of 0˚ to +4˚C, and frozen meat - at a temperature below 0˚C.

BREAD

Nutritional and biological value of bread. Flour is made from cereals (wheat, rye, corn, oats, barley), from which bread, cakes are baked, and used in the preparation of various dishes. The properties of flour depend on the quality of grinding and the % "yield" (the ratio of the mass of the obtained flour to the mass of the initial grain): flour coarse grinding(yield - 95-99%) contains bran, with finer grinding (yield 10-75%) Wheat flour the whiter and softer, the lower the % output. 74-85% of proteins are absorbed from wholemeal flour, up to 92% from fine flour, but at the same time, flour contains less B vitamins and minerals. When baking bread and bakery products, yeast is used, as well as milk, eggs, flavoring and aromatic substances.

Belkov in rye bread 5.0-5.2%, in rye-wheat - 6.3%, in wheat bread and buns - from 6.7 to 8.7%; fats in rye, rye-wheat and wheat bread 0.7-1.2%, in white buns - up to 1.9%; carbohydrates from 42.5% in rye to 52.7% in wheat flour products premium. Calorie black bread - 204-221 kcal, white - 229-266 kcal.

Diet varieties of bakery products are produced: protein-wheat bread and crackers are recommended for diabetes, obesity, diathesis; protein-bran bread - for the same diseases accompanied by constipation; salt-free (achloride) bread and crackers - for diseases of the kidneys, heart, hypertension, as well as for various inflammatory processes accompanied by edema. Wheat bran (doctor's) bread is recommended for pregnant women and nursing mothers, as well as for constipation and nervous diseases; bread from crushed wheat grain - with obesity and habitual constipation. With exacerbations of hyperacid gastritis, gastric and duodenal ulcers, crackers with low acidity are used. Dairy and high-calorie buns are used for the same diseases of the stomach, as well as in the nutrition of pregnant and lactating women, in baby food, for rickets, tuberculosis, and bone fractures.

During storage, the bread becomes stale as a result of a change in the colloidal structure of starch (synersis) and the release of water. Delay the staleness of bread stabilizers or freezing. Bread should be stored in well-ventilated rooms at a temperature of 16-18ºС. Bread and bakery products are transported in trays by specialized vehicles.

Freshly baked bread does not contain microorganisms, but with high humidity, low acidity and long-term storage, bacteria (spore-forming "potato stick" - Bac.Mesentericus, conditionally pathogenic vegetative anaerobe "wonderful stick" -Bac.prodegiosus,) and mold fungi ( Aspergillus, Penicillium, Fusarium, Cephalosporium, Trichoderma, Stachibotris). The crumb of bread affected by the “potato stick” is translucent, viscous, sticky, brownish in color with an unpleasant smell of rotting potatoes or fruits (irritates the stomach, causing dyspepsia). With the defeat of the “wonderful stick”, bright red mucous spots appear in the crumb. mold mushrooms can cause severe food poisoning(mycotoxicosis): ergotism, fusarium, aflatoxicosis.

food poisoning (BY) - diseases caused by the consumption of foods richly contaminated with microorganisms or containing toxic substances of a microbial or chemical nature. Food poisoning is not transmitted from a sick person to a healthy person.

Microbial food poisoning. Microorganisms (bacteria and microscopic mold fungi) and/or toxic products of their vital activity serve as the cause of microbial PD.

Food poisoning of a bacterial nature represented by toxic infections and bacterial toxicosis.

Food poisoning are a group of acute bacterial intestinal infections caused by pathogenic and opportunistic bacteria that produce endotoxins. In the gastrointestinal tract of a sick person, pathogens remain alive for 7-15 days, causing symptoms characteristic of infectious diseases with severe toxic manifestations. The main signs of food poisoning: simultaneous illness of a group of persons who consumed the same food; territorial limitation of the disease; a clear association with food intake; the suddenness of the onset (outbreak) of the disease with an incubation period of 6-24 hours, the rapid cessation of the outbreak after the withdrawal of an epidemically dangerous product. Prevention: 1. prevention of contamination of food and prepared foods; 2. ensuring storage conditions that exclude massive reproduction of microorganisms; 3. Reliable heat treatment before eating questionable (contaminated) foods.

Salmonellosis. The endogenous route of infection of meat and eggs of poultry can be associated with a lifetime disease of primary salmonellosis (infectious abortion and paratyphoid enteritis of cattle, typhoid of piglets, paratyphoid fever of calves and waterfowl) of animals intended for slaughter and secondary salmonellosis of weakened animals. The exogenous pathway is due to a violation sanitary regulations when cutting carcasses, transporting, storing and cooking, as well as bacteriocarrier of an employee of a public catering enterprise. Survival of Salmonella: 1) in the refrigerator at 7-10°C 6-13 days in sausages and sausages, 45 days in pasteurized milk, 60-65 days in raw eggs, scrambled eggs and raw pork; 2) in the freezer up to 13 months. in frozen meat. Salmonella persist at high concentrations of salt and acids in foods. Salmonella die instantly when boiled, at 56 0 C - after 1-2 minutes. However, to eliminate Salmonella in large pieces Meat and dense foods require a longer processing time. Most cases of salmonellosis are associated with meat (70-80%), milk (10%), fish (3.5%). There are frequent cases of infection through the eggs of lively infected waterfowl (ducks, geese), as well as confectionery products prepared using chicken eggs with a contaminated surface without heat treatment. If the source of salmonella is a bacteriocarrier, then any food can cause salmonellosis.

Characteristic signs of salmonellosis: incubation period 12-24 hours; sudden acute onset; bacteremia with the release of Salmonella exotoxin and the release of endotoxin into the blood after the death of Salmonella; the patient's body temperature is 38-40 0 С; repeated vomiting; stool for 1-3 days is plentiful, liquid, with green mucus and streaks of blood (especially often the appearance of blood in the stool in children, due to the involvement of the large intestine in the infectious process); dehydration of the body; signs of general toxicosis (pallor, weakness, loss of appetite, headache, muscle cramps and pain); the duration of the disease is 3-5 days, followed by a long-term isolation of bacteria with feces. There are 2 fundamentally different clinical forms of salmonellosis: typhoid-like (with all signs of gastroenteritis) and flu-like (along with dyspeptic disorders, catarrhal phenomena). Mortality is about 1%.

Prevention of salmonellosis: 1). Strict sanitary and veterinary supervision over the health of slaughtered livestock, compliance with sanitary rules for the process and conditions at slaughterhouses. 2). Prohibition on free sale raw eggs waterfowl and sale only after boiling for 15 minutes. 3). Health control of workers at food enterprises (regular preventive medical examinations with the identification of bacteria carriers, production control and health education of workers). 4). Proper heat treatment and storage of meat and dairy products, separate processing of boiled and raw meat, rejection of creams and dishes where eggs are used without heat treatment.