Introduction

Milk is the only food product in the first months of human life. For old, weak and sick people, milk is an indispensable food.

“Milk,” wrote academician I.P. Pavlov, “is an amazing food prepared by nature itself.” I.P. Pavlov believed that milk is in an exceptional position among other products of our diet, it is the easiest food.

Properly organized nutrition of the patient not only satisfies the needs of the body, but also actively influences the course of the disease. Taking this into account, a therapeutic nutrition system has been developed, the principles of which are widely used in medical practice. The amount of food consumed, as well as its temperature, is of great importance. The latter should not exceed 60°C and be below 15°C, with the exception of special cold dishes, such as cold milk or sour cream for stomach bleeding. The frequency of meals is no less than 4 times, and in some diseases, in particular with peptic ulcers of the stomach and duodenum, up to 5-6 times a day.

Milk. Nutritional and biological value of milk and dairy products

It is well known that milk is the most important baby food product. Milk is an extremely valuable product in the diet of adults. Very often, milk and dairy products are underestimated in our diet and are preferred to meat, fish, and eggs.

The main qualities of milk are its easy digestibility, the content of high-value proteins and fat in quite significant quantities, the presence of various mineral salts, as well as vitamins.

The nutritional and biological value of milk lies in the optimal balance of its components, easy digestibility (95-98%) and high utilization of all plastic and energy substances necessary for the body. Milk contains all the nutrients the body needs, so milk and dairy products are indispensable in the diet of sick people, children and the elderly. It contains complete proteins, fats, vitamins, and 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 proteins throughout the diet and significantly increases the body's supply of calcium.

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, time of year, nature of feed, age of animals, lactation period, milk processing technology.

Milk proteins are represented by casein, albumin (lactoalbumin) and globulin (lactoglobulin). Milk proteins contain amino acids necessary for the body (tryptophan, phenylalanine, methionine, valine, lysine, threonine, histidine, isoleucine and leucine).

Milk proteins are easily accessible to digestive enzymes, and casein has a regulatory effect on increasing the digestibility of other nutrients. When milk sours, casein splits off calcium and curdles. Albumin is the most valuable protein in milk; when boiled, it coagulates, forming foam, and partially precipitates.

Cow, goat, sheep, mare, donkey, deer, camel, and buffalo milk are used in human nutrition. Buffalo and sheep milk have particularly high nutritional and energy properties. The most nutritious is reindeer milk, containing up to 20% fat, 10.5% protein, and 3 times more vitamins than cow's milk. Human milk contains 1.25% protein, therefore, cow's and any other milk requires dilution when feeding infants. Based on the nature of the proteins, the milk of various animals can be divided into casein (75% casein or more) and albumin (50% casein or less). Casein milk includes the milk of most lactating farm animals, including cows and goats. Albumin milk includes mare's and donkey's milk. The peculiarities of albumin milk are its higher biological and nutritional value, due to a better balance of amino acids, high sugar content and the ability to form small, tender flakes when soured. Albumin milk has properties similar to human milk and is its best substitute. Albumin particles are 10 times smaller than casein, whose particles are larger and when curdled in the stomach of an infant, cow's milk protein forms large, dense, coarse flakes that are difficult to digest.

The main protein in cow's milk is casein, which makes up 81.9% of the total milk proteins. Lactoalbumin is contained in milk in the amount of 12.1%, lactoglobulin 6%. Milk fat is one of 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 has high taste properties. 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 is higher in autumn, winter and spring 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. This is the only milk carbohydrate found nowhere else. Lactose is a disaccharide; upon hydrolysis, it breaks down into glucose and galactose. The entry of lactose into the intestines has a normalizing effect on the composition of beneficial intestinal flora. Milk intolerance, which occurs in many people, is caused by the lack of enzymes in the body that break down galactose.

Milk sugar is of great importance in the production of lactic acid products. Under the influence of lactic acid bacteria, it is converted into lactic acid; this causes casein to coagulate. This process is observed in the production of sour cream, yogurt, cottage cheese, and kefir.

Minerals. Milk contains a wide range of macro- and microelements. Calcium and phosphorus are of particular importance in the mineral composition of milk. It also contains potassium, sodium, iron, and sulfur. They are found in milk in an easily digestible form. Microelements include 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 contains some amounts of ascorbic acid, thiamine, riboflavin, and nicotinic acid. In the summer, when animals eat succulent green food, the content of vitamins in milk increases. The calorie content of milk is low and averages 66 kcal per 100 g of product. Milk contains a number of enzymes.

Milk causes weak secretion of the gastric glands and is therefore indicated for peptic ulcers and hyperacid gastritis. Due to the presence of lactose, when milk is consumed, microflora develops in the intestines, delaying putrefactive processes. Milk contains little salt, and therefore it is recommended for people suffering from nephritis and edema. Milk does not contain nucleic compounds, therefore, it is indicated for persons with impaired purine metabolism. For feverish patients, milk is both a light food and drink.

One of the common health problems in old age is blood vessel disease - atherosclerosis. Among the nutrients that have preventive and therapeutic value for atherosclerosis, especially noteworthy are vitamins A, E, B vitamins, choline and the amino acid methionine. All these substances are found in milk.

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

Due to the easy digestibility of milk, it is widely used in the treatment of patients with gastric ulcers and gastritis with high acidity of gastric juice. In recent years, the beneficial effect of milk on the nervous system has been established. The famous Russian doctor S.P. Botkin believed that milk is a precious remedy in the treatment of heart and kidney diseases. Milk protein promotes better liver function in a healthy person, and is also used in therapeutic nutrition for liver diseases, infectious diseases, etc.

The value of lactic acid products also lies in the fact that lactic acid bacteria prevent the development of putrefactive pathogenic bacteria in the intestines. Therefore, these products are widely used for preventive and therapeutic purposes for diseases of the gastrointestinal tract.

Milk plays an important role in the nutrition of a pregnant woman, as the most perfect source of providing the body with the “building material” necessary for the normal development of the fetus. During breastfeeding, the mother's milk supply provides the baby with the necessary substances.

Physiological norms of the daily diet (total 3000--3200 calories) include the consumption of 400--500 g of milk (fresh and sour), 25--30 g of cottage cheese, 15--20 g of cheese and 15--20 g of sour cream on average . Milk and lactic acid products should receive a much wider use than is currently the case in the daily nutrition of adults.

Introduction

Theoretical part

1 Nutritional value of milk, nutritional significance

2 Classification, characteristics of milk assortment

3 Quality requirements, defects

4 Packaging, labeling, storage of milk

Practical part

1 Assortment of milk sold by the Rublevsky store in Gomel. Suppliers

2 Quality of milk sold by a trading enterprise

3 Packaging, labeling, transportation and storage conditions ensuring the quality of milk

Conclusions and offers

Literature

Applications

Introduction

Milk is a product of the secretory activity of the mammary gland of mammals. I.P. Pavlov called milk an amazing food prepared by nature itself. It contains in optimal proportions all the substances necessary for the normal development of the body: water, proteins, fats, milk sugar, mineral compounds, organic acids, vitamins, enzymes, hormones, gases and other components, of which there are more than 100. Milk digestibility 98-99 %.

The natural purpose of milk is to feed babies who are not yet able to digest other food.

The history of milk is as ancient as the history of humanity itself. As soon as he appeared on earth, man immediately learned the taste of dairy products. Milk was consumed as food more than 6,000 years ago. The most consumed type of milk is cow's milk.

Currently, milk is part of many products used by humans, and its production has become a large industry, new technologies and a new range have also appeared, so it is necessary to study this product in more depth.

The purpose of my course work is to study the nutritional value of milk, its importance in nutrition, study the classification and characteristics of the range of milk, quality requirements. And also study all types of packaging, labeling and storage of milk.

The objectives of my course work are: to study the range of milk sold by a trading company; study and analyze the quality of milk sold by a trading enterprise; study packaging, labeling, transportation conditions, storage, ensuring the quality of milk.

1. Theoretical part

.1 Nutritional value of milk, nutritional significance

Milk- a biological fluid that is synthesized in the mammary glands of mammals from blood components. The mammary glands are located in the tissues of the udder. The udder is divided into two parts. Each part contains two independent glands (anterior and posterior), not connected by ducts, which allows each part of the udder to be milked separately.

Milk contains physiologically valuable nutrients that are well balanced and easily and completely absorbed by the human body.

Milk is an indispensable product of mass and everyday consumption, and also serves as a raw material for the production of butter, fermented milk products, cheeses, ice cream, and canned milk.

A person per day should consume almost 1.5 liters of dairy products (in terms of milk), including 0.5 liters of milk, 15-20 g of cow’s butter, 18 g of cheese, 20 g of sour cream and cottage cheese.

More than 120 chemical substances have been found in milk, including: proteins, fats, minerals, vitamins, enzymes, etc. The energy value of cow's milk is 2797 kJ. One liter of milk satisfies an adult’s daily need for fat, calcium and phosphorus, 53% for protein, 35% for vitamins A, C, B1 (thiamine), and 25% for energy.

The chemical composition of milk depends on the species and animals, time of year, livestock feeding conditions and other factors. Milk in its composition is a complex system consisting of organic and inorganic compounds. Organic substances: proteins, carbohydrates, fats, enzymes, vitamins. Inorganic: water, mineral salts, gases.

An important indicator of the chemical composition of milk is dry skimmed milk residue (SMR), the content of which is used to judge the naturalness (undiluted) of milk. SMR is determined by subtracting the percentage of fat from the percentage of milk dry matter.

Protein substancesare the most valuable component of milk, since the amino acids formed during their breakdown are a good plastic material for building body tissues. The milk protein is called casein.Casein is a complex phosphoprotein protein; it is found in milk in the form of a calcium salt, which is responsible for its white color. Casein coagulates under the action of rennet and forms a dense clot, which is used in the production of rennet cheeses and cottage cheese.

The simple proteins remaining in the serum - albumin and globulin - are called whey, they do not precipitate under the influence of rennet and remain in the whey.

Milk fat(average 3.8%) is in the form of fat globules covered with lecithin-protein shells. Which prevent them from sticking together. 1 ml of milk contains 3 billion fat globules with a diameter of 0.5 to 10 microns. When their shells are destroyed during processing and storage, free fat appears, which deteriorates the quality of the product. Milk fat is the best known food fat in terms of taste, composition, and digestibility. However, its disadvantages should also be noted. Milk fat is poorly resistant to high temperatures, light rays, air oxygen, water vapor, alkali and acid solutions. Under the influence of various factors, it hydrolyzes, oxidizes, becomes salty, and as a result deteriorates.

Milk sugarhas a beneficial property for humans, it penetrates through the intestinal walls into the blood more slowly than others, stays in the intestines for a longer time and can be used to feed lactic acid bacteria, the development of which has a healing effect on the human body. When heating milk to a temperature above 95°C its color varies from pale cream to brown.

Milk sugar plays an important role in the production technology of fermented milk products and cheeses. In addition to lactic acid, carbon dioxide, alcohol, butyric acid and other compounds can be formed from milk sugar in these products.

Mineralsare of great importance in the formation of new tissue cells, enzymes, vitamins, hormones, as well as in the mineral metabolism of the body. The content of minerals in milk is up to 1%. After burning milk, 0.7% ash is obtained. The ash contains salts of organic and inorganic acids, mainly phosphoric, citric and hydrochloric.

Among the mineral salts contained in milk, calcium and phosphorus salts occupy a special place. Calcium milk is well absorbed and is essentially the main source of providing the body with this element. Milk calcium is absorbed better than calcium from cereals, bread and vegetables. 1 liter of milk contains 1.2 g of calcium. Calcium is essential for bone formation, regulating blood pressure, and reducing the risk of certain types of cancer.

Of the trace elements found in milk, manganese, copper, iron, cobalt, iodine, zinc, tin, vanadium, silver, etc. Manganese catalyzes oxidative processes in the cell and is necessary for the synthesis of vitamins C, B and D. Copper and iron are involved in hematopoiesis, iodine - in the synthesis of the thyroid hormone thyroxine.

Enzymescontained in milk such as: peroxidase, reductase, phosphatase, catalase, lipase, lactase.

Lipasebreaks down fat glycerides into fatty acids and glycerol, and is destroyed at temperatures of 75-80°C.

Phosphatasecauses hydrolysis of phosphoric acid esters, is destroyed at 75°C . By its presence in pasteurized milk, one can judge whether it contains raw milk.

Peroxidasedecomposes hydrogen peroxide with the release of active oxygen, destroyed at 80-82°C. The peroxidase reaction tests the effectiveness of high pasteurization of milk.

Catalasebreaks down hydrogen peroxide into water and molecular oxygen. There is a lot of it in the milk of animals with mastitis.

Reductase- a reducing enzyme that accumulates in milk during the development of microflora, and its quantity is used to judge the bacterial contamination of milk.

Lactasebreaks down lactose into glucose and galactose.

Vitaminscan be: fat-soluble(A, D, E, K) and water-soluble(B1, B2, B3, B6, B12, PP, C, H - biotin), folic acid.

Vitamin A(0.03 mg%) is formed in the animal’s body from carotene in feed, is resistant to heat treatment, and is easily oxidized in light and in the presence of air.

Vitamin D(0.00005 mg%) is formed in the animal body from ergosterol under the influence of ultraviolet rays, resistant to heat treatment.

Vitamin E(0.15 mg%) is resistant to high temperatures (up to 170°C), is an antioxidant for fats.

Vitamin WITH(2 mg%) is significantly destroyed during storage, transportation and pasteurization.

Vitamin IN 1(0.04 mg%) can withstand heating up to 120°C in an acidic environment, but is less stable in neutral and alkaline environments.

Vitamin AT 2(0.05 mg%) is destroyed in a slightly alkaline environment, stable in an acidic environment, when heated to 120 ° C , collapses in the light.

Vitamin AT 3(0.38 mg%) is heat resistant and stimulates the development of bacteria.

Vitamins AT 6(0.05 mg%) and AT 12(0.0004 mg%) are preserved during pasteurization of milk.

Vitamin RRstable during technological processing of milk.

Vitamin Hstimulates the activity of microorganisms, is resistant to oxidation and heat.

Bactericidal substances- immune bodies (lysines, agglutins, antitoxins) have a destructive or suppressive effect on microorganisms that get into milk. The time during which the bactericidal properties of milk appear is called bactericidal phase(or period). The bactericidal period lasts at 30°C for 3 hours, at 15°C for 12 hours, at 5°C for 36 hours. Foreign substances (pesticides, nitrites, etc.) may enter milk; their content and control are regulated by standards.

Hormonessecrete endocrine glands. They are regulators of complex biochemical processes and communicate between individual organs. Under the influence of the hormones prolactin and thyroxine, lactic acid secretes milk.

Dyes- carotene, chlorophyll, xanthophyll enter milk from feed.

Water- the main part of milk, the amount of water determines the physical state of the product, physicochemical and biochemical processes in it.

Along with cow's milk, the national economy uses the milk of other farm animals. The average chemical composition of milk from various animals is given in Table 1.1.

Average chemical composition of milk from various animals.

Table 1.1

Sheep milk -Compared to cow's, it is richer in fat and protein and is characterized by higher acidity and density. Fat globules are larger. It is not used as a drink due to its specific smell. It is used for the production of feta cheese and other types of pickled cheeses.

Goat milk -its composition is similar to that of cow milk, but contains more albumin. Goat's milk fat globules are smaller. Due to the lack of coloring substances, it is paler, but contains more vitamin C. It is used in a mixture with sheep for the production of cheeses.

Mares' milk -called albumin. It is a white liquid with a bluish tint, with a sweet taste; it differs from cow's liquid in its increased lactose content, less fat, salts and proteins. When soured, mare's milk does not form a clot; casein precipitates in the form of small, delicate flakes. Mares' milk has high bactericidal properties; in composition and properties it differs little from women's milk. It is used to prepare kumiss.

.2 Classification, characteristics of milk assortment

Cow's milkDepending on the heat treatment, it goes on sale pasteurized and sterilized.

-pasteurized fat content 1.5; 2.5; 3.2 and 6%;

-protein 1.0 and 2.5%;

-fortified (with vitamin C) - low-fat and fat content of 2.5 and 3.2%;

-milk with cocoa or coffee with fat content of 1.0 and 3.2%;

-low-fat;

-baked milk with fat content of 4 and 6%.

The following range of milk goes on sale: Volkovysk, Minskoe; cow pasteurized Berestye, pasteurized Lung; pasteurized cow's milk, enriched with bifidoflora, Rosinka; pasteurized Lugovoe; sterilized with lactulose; iodized Jodis; pasteurized, enriched with iodized protein; pasteurized Green Valley; fortified Vita; pasteurized Poleskoe, Molodetskoe, Vitalakt, etc.

Ionite milk and Vitalakt-DM are produced for feeding infants.

Ionic milkobtained by treating milk with cation exchange resin, which removes 20-25% of calcium, which is replaced by an equal amount of sodium and potassium; produced without additives, with vitamins B and C.

Vitalakt-DMproduced from a homogenized mixture consisting of normalized cow's milk, cream, refined sunflower oil, sugar and other additives.

Sterilized milkThey are produced in paper bags with a plastic coating inside. Fat content - 3.2 and 3.5%.

For direct consumption, pasteurized or sterilized milk is used.

Wholecalled normalized or reconstituted milk with a certain fat content - 3.2% and 2.5%.

Restoredrefers to milk prepared in whole or in part from canned milk. To obtain reconstituted milk, whole milk powder is dissolved in warm water and kept for at least 3-4 hours to maximize the swelling of the proteins, eliminate the watery taste, and also to achieve normal density and viscosity. The mixture is then purified, homogenized, pasteurized, cooled and bottled.

High fat milkprepared from normalized milk containing 6% fat, subjected to homogenization.

Meltedcalled milk containing 6% fat, subjected to homogenization, pasteurization at a temperature of at least 95 degrees and aged for 3-4 hours.

Protein milkcontains an increased amount of dry fat-free substances. It is produced from milk, normalized for fat content, with the addition of dry or condensed milk.

Fortified milkprepared from whole or low-fat milk, enriched with vitamins A, C, D2.

Low-fat milk- this is the pasteurized part of milk, obtained by separation and containing no more than 0.05% fat.

Heat treatment of milk is necessary to kill microorganisms and destroy enzymes in order to obtain products that are hygienically safe and have a longer shelf life. For this purpose, pasteurization and sterilization of milk are used.

Pasteurization can be long-term (milk is kept at a temperature of 63°C for 30 minutes), short-term (at a temperature of 72°C - for 15-30 s) and instant (high temperature at 85°C and above without holding). Heat treatment should preserve the nutritional and biological value of milk as much as possible and not lead to undesirable changes in the physicochemical properties of milk. During the heating process, whey proteins denature (structural changes in molecules), and the milk acquires the taste of a boiled product or the taste of pasteurization. As a result of pasteurization and sterilization, the amount of calcium in milk decreases due to the formation of poorly soluble calcium phosphate (precipitates in the form of milk stone or burnt along with denatured proteins). This impairs the milk's ability to rennet; When producing cottage cheese and cheese, calcium chloride is added to pasteurized milk.

As a result of pasteurization and sterilization, the physicochemical and technological properties of milk change: viscosity, surface tension, acidity, the ability of milk to settle cream, the ability of casein to coagulate rennet. Milk acquires a specific taste, smell and color. The components of milk change. Milk is sent to the distribution network at a temperature not exceeding 8°C.

According to the standard, milk is classified as follows:

GOST 37-91. Cow butter. Specifications

GOST 1349-85. Canned milk.

GOST 3622-68. Milk and dairy products.

GOST 3623-73. Milk and dairy products. Methods for determining pasteurization

GOST 3624-92. Milk and dairy products. Titrimetric methods for determining acidity

GOST 3625-84. Milk and dairy products. Methods for determining density

GOST 4495-87. Whole milk powder.

GOST 5867-90. Milk and dairy products. Fat determination methods

GOST 8218-89. Milk. Method for determining purity

GOST 10970-87. Skimmed milk powder. Specifications

GOST 23327-98. Milk and dairy products.

GOST R 51917-2002. Dairy and milk-containing products.

GOST R 52054-2003. Natural cow's milk is a raw material.

milk food range quality

1.3 Quality requirements, defects

The quality of milk is assessed by organoleptic, physico-chemical and bacteriological indicators.

Milk must comply, in terms of organoleptic properties, with GOST No. 28283-89 “Drinking milk. Method for organoleptic evaluation of smell and taste, color and consistency."

By appearanceAnd consistencymilk is a homogeneous liquid without sediment. Cream sediment is not allowed in high-fat and baked milk.

Colormilk should be white with a slightly yellowish tint, baked milk should have a creamy tint, low-fat milk should have a slightly bluish tint.

Vkuwith and smellmilk must be clean, without any extraneous taste or smell that is not characteristic of fresh milk.

From physical and chemical parametersFor milk, fat content, density, acidity, degree of purity, temperature, and the presence of phosphatase are standardized. An indicator of freshness is acidity. The acidity of pasteurized milk should be no more than 21°T, with the exception of high-fat milk (6%) - no more than 20°T and protein milk - no more than 25°T. The acidity of sterilized milk is no higher than 20°T, milk for baby food is no more than 19°T.

Density

The density of milk should be at least 1.024-1.030 g/cm 3depending on fat content.

From microbiological indicatorsThe total number of bacteria in 1 ml, the titer of Escherichia coli, and pathogenic microorganisms are determined.

Milk defects

More Only defects in taste and smell reduce the quality of milk.

Feed taste, silage, barnyard smelland other odors more often arise due to the adsorption of feed odors by milk.

Sour tasteoccurs when lactic acid bacteria develop in milk.

Bitter tasteappears in milk during long-term storage in a refrigerated state as a result of the development of putrefactive microflora. Under these same conditions, a rancid taste may appear when, under the action of lipase, fat glycerides are broken down into glycerol and fatty acids.

Metallic tasteOccurs in milk during storage when metals in containers with disturbed half-milk dissolve.

Foreign tastes and odorsmilk is acquired when transported along with odorous products (onions, petroleum products, chemicals).

Salty and rancid tasteshas old milk due to changes in the mineral composition and increased lipase content.

1.4 Packaging, labeling, storage of milk sold in the Rublevsky store (produced by suppliers)

For packaging milk, they mainly use paper bags with a polymer coating (tetra-pak, tetra-brick, pure-pak), plastic bags, flasks and other types of containers. A lot depends on the shape of the package: ease of purchase for the buyer, type of transport container, stability of the packaging during production and distribution. The sharper the corners in the bags (tetra-pack), the faster they are damaged and leak, which entails certain losses. For stacking tetra-packs, special containers have been developed and used - hexagonal boxes made of low-density polyethylene. Milk in pure-pack and tetra-brick packages in blocks of 10-12 pieces is covered with shrink film and placed in container equipment. Fin-pack - a soft polymer bag is also convenient for the distribution of milk. The use of these packages eliminates the need to use returnable glass containers. However, we must remember that all polymer containers are not yet recycled and pollute the environment. The following designations must be embossed or indelibly painted on the packaging of the container: name or number of the manufacturer or trademark; type of milk; volume in liters (on bags); date or day of the deadline for implementation; designation of the standard.

When bottling milk into flasks or tanks, a label is affixed to the container or a label with the same designations is hung. Additional information for buyers is to print on the packages information about the composition of the product and calorie content. Drawings and instructions for opening containers, storage conditions and periods. Package labeling must be clear and colorful.

Keepmilk should be kept in clean and ventilated areas without access to light. Pasteurized cow's milk should be stored at a temperature of 4+-2 for no more than 5 days from the end of the technological process, sterilized milk at a temperature from 0 to 10°C - 6 months, at a temperature from 0 to 20°C - no more than 4 months .

Relative humidity should not be higher than 80%. Higher humidity may cause mold to grow in the room.

It is prohibited to store milk together with meat and fish products, vegetables, fruits and spices to avoid the appearance of foreign odors and contamination.

In refrigeration chambers and utility rooms, milk is stored on shelves and shelving. Packaged dairy products are stored in the container in which they were delivered to the store.

At the seller's workplace, milk is placed in refrigerated cabinets or refrigerated counters. In the absence of cooling means, the supply of milk taken to the sales floor should be designed for a two- to three-hour sales period.

2. Practical part

.1 Assortment of milk sold by the Rublevsky store (produced by suppliers)

I work in the Rublevsky store, located at 69 Kosmonavtov Avenue, owned by the Rublevsky open joint-stock trade company.

The type of this store is combined, since the forms of service in it are traditional, that is, through the counter, and self-service. The specialty of this store is food products, but it also has a “corner” with industrial goods.

The store operates on the basis of a license (Appendix A). The number of employees of this store is 56 people.

The total area of ​​the store is 1024.1 m 2, and the sales area is 379.2 m 2

Trade turnover for the month is 605,000,000 million rubles, for the quarter - 1,815,000,000 million rubles, for the year - 7,260,000,000 million rubles.

The assortment of milk in this store is quite large, since the store works with many suppliers of dairy products. Milk is delivered to the store on time; it is very rare that suppliers delay delivery, and if this happens, it is only for a good reason. This also applies to the quality of the milk supplied.

Range and suppliers of dairy products in the Republic of Belarus:

Table 2.1.1

Babushkina Krynka OJSC Mogilev, st. Pavlova, 3.

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Drinking milk. paste 2.4% 11210 film 2 Drinking milk paste 3% 11370 film 3 Drinking milk paste 1.5% 1940 film 4 Drinking milk paste 3.2% 11680 lin-pack 5 Drinking milk paste 2.5% 11460 lin-pack 6 Drinking milk fuel 4% 0.51010 lin-pak 7 Children's milk 3.2% 0.2620 tetra-brik

Table 2.1.2

TD Rumyantsevsky, Gomel, st. Br. Lizyukov, 1.

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Drinking milk. paste 1.5% 1950 film 2 Drinking milk paste 2.7% 11300 film 3 Drinking milk paste 3.6% 0.5820 film 4 Drinking milk paste 3.6% 11560 film

Table 2.1.4

SOZH JSC State Farm-Kombinat

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Drinking milk. paste 3.5% 11540 film

Table 2.1.5

Savushkin Product OJSC, Brest, st. Ya. Kupala, 108.

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Drinking milk. paste 3.1% 12730 puree pack 2 Milk drink. paste 2.6% 12030 film 3 Drinking milk paste 1.8% 11790 film

Table 2.1.6

TD Milk Lace, Gomel, st. Br. Lizyukov, 1a

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Drinking milk. paste 2.8% 11330 film 2 Drinking milk paste 1.5% 1950 film 3 Drinking milk paste 3.2% 11450 film 4 Drinking milk paste 3.6% 11560 film 5 Drinking milk paste 2.8% 0.5760 film 6 Drinking milk paste 3.2% 0.5830 puree pack 7 Drinking milk paste 3.2% 11590 puree pack 8 Drinking milk paste 3.2% 11460 film 9 Drinking milk paste 1.5% 11010 pure pack

Table 2.1.7

Gormolzavod No. 1, Minsk, st. Soltysa, 185

No. Name of product Fat content Volume, l Retail price, rub. Packaging 1 Children's milk 3.2% 250 g 830 tetra-brik 2 Petit milk. paste 1.8% 11370 tetra-brik 3 Drinking milk paste 3.2% 11450 film 4 Drinking milk fuel 2.5% 0.51030 film 5 Drinking milk paste 1.5% 1940 film

Based on a social survey, the milk from the Gomel supplier was recognized as the best milk. The reason for this is the taste and price of milk. The most commonly purchased milk among older people is milk with a fat content of 1.5% in a film bag, since it is cheaper. And younger people pay less attention to price and prefer milk with higher fat content. Therefore, milk from this supplier is ordered in larger quantities than milk from others.

Update of the assortment of drinking milk for April 2011

Table 2.1.6

Product name Number of items Renewability % Drinking milk all including new items 4251

Conclusion: in April 2011, the assortment of milk in the store was updated by 4%.

Labeling analysis

Consumer labeling of products must contain the following information:

product name: “Mozyrskoe pasteurized milk”;

mass fraction of fat: 2.7%;

name and location of the manufacturer: Private Unitary Enterprise "Mozyr Dairy Products", Belarus, 247760, Mozyr, st. Proletarskaya, 114;

trademark - in stock;

volume: 1000 l;

product composition: no, because not recombined;

nutritional value: proteins, fats, carbohydrates;

storage conditions: store at a temperature of 4±2 C;

-storage conditions and period of use of the sterilized product after opening the package: 2 days at a temperature of 4±2;

date of manufacture: 06/16/2011 at 16.06

designation of this standard: STB 1746-2007;

designation of a technological document if there are expiration dates different from those established by this standard:

information on confirmation of conformity (if available) is missing, because milk that cannot be stored for a long time;

barcode identification - in stock;

Appendix E

Conclusion: The milk meets the requirements of the STB 1746-2007 standard.

The quality and safety certificate indicates:

certificate number and date of issue;

name and address of the supplier;

name and type of product;

batch number;

date and time (h, min) of shipment;

batch volume, l;

test results data (mass fraction of fat, density, acidity, purity, shipping temperature);

number and date of issue of the accompanying veterinary certificate (certificate) and the name of the organization of the state veterinary service that issued it;

designation of this standard.

The labels of milk-based baby food products must include the following statement: “For baby food.” The font size of such an inscription cannot be smaller than the main font used.

The packaging of adapted milk formulas and subsequent formulas must bear the warning message “Breastfeeding is preferable for the nutrition of young children.”

2.2 Quality of milk sold by a trading enterprise

Before milk reaches the refrigerator shelves in the sales area, it undergoes a quality check. Each batch of milk is accompanied by a copy of its quality certificate (Appendix B). At the same time as checking the documents, they inspect the transport in which the milk was delivered. If milk is delivered to the store on dirty transport, it will not be accepted. Transport delivering milk has a sanitary passport.

They also check the condition of the container and labeling during an external inspection of the entire batch of milk. After inspecting the container and checking the correctness of labeling, a batch of milk is accepted by quantity and its uniformity is established. In case of mixing of batches, the products are sorted into homogeneous batches.

When inspecting the container, pay attention to the presence or absence of leakage, and determine by eye how completely the milk has been filled.

If milk is found to have hidden defects, an act of “Acceptance of goods by quality and quantity” is drawn up. Issued in 2 copies. One copy remains in the store, and the second is given to the supplier. In the future, the milk is subject to exchange. Suppliers never refuse this and conscientiously fulfill all the terms of the contract.

The drinking milk sold by this store complies in terms of quality with GOST No. 28283-89 “Drinking milk. Method for organoleptic evaluation of smell and taste, color and consistency."

2.3 Packaging, storage, ensuring milk quality, labeling

Milk arrives at this store already packaged and packaged. The packaging of milk is different and since the assortment is large, the milk comes to the store in different packages.

Milk sold by this store comes in paper bags with a polymer coating (tetra-pak, tetra-brick, pure-pak, lean-pak), plastic bags, flasks and other types of packaging. A lot depends on the shape of the package: ease of purchase for the buyer, type of transport container, stability of the packaging during production and distribution.

Milk supplied to this store has the following designations printed on the packaging with embossing or indelible paint:

1)mass fraction;

2)fat content;

)manufacturer, address;

)date of manufacture;

)expiration date;

)nutritional and energy value;

)compound;

)volume and barcode;

The store provides all conditions for storing milk. It is stored in a special chamber where there is no light and there is constant ventilation of the room. The rules of commodity neighborhood are also observed. Boxes of milk are placed on pallets. Store pasteurized at a temperature of 4+-2°C for 5 days, sterilized from 0 to 10°C - 6 months, from 0 to 20°C - 4 months.

Conclusions and offers

Milk -biological fluid that is synthesized in the mammary glands of mammals from blood components. Milk contains physiologically valuable nutrients that are well balanced and easily and completely absorbed by the human body.

The chemical composition of milk depends on the species and animals, time of year, livestock feeding conditions and other factors.

Having analyzed the quality of milk sold by this store and having studied the suppliers and the range of milk, we can note the following: that when accepting milk, they evaluate not only the product, but also the container and the vehicle in which this product was delivered. Transport must have sanitary transport, be clean, and have all the conditions for transporting milk. Also, the supplier’s representative must have accompanying documents about the availability and quality of the product.

When comparing two samples of drinking milk, it turned out that the milk, both upon receipt and during storage in the sales area, did not change its organoleptic properties and complies with the requirements of the regulatory and technical document GOST No. 28283-89 “Drinking milk. Method for organoleptic evaluation of smell and taste, color and consistency."

When buying milk, each person makes a choice based on different indicators: price, taste, packaging, volume. Therefore, the range must be wide enough to satisfy different segments of the population.

Offers:

My suggestions for improving customer service: add a “new products” section to the sales floor, that is, post new products received in this section. And also improve control over the trading floor with the help of security officers.

Literature

1)Directory of food products merchandising - T.1 M.: Economics, 1987.

2)Mikulovich L.S. et al. “Commodity research of food products” - Mn.: BSEU, 1998.

)Mikulovich L.S. et al. “Commodity research of food products” - Mn.: Vysh. Shk, 2007.

)Kastornykh M.S., ed., Commodity research and examination of edible fats, milk and dairy products, M.: 2003.

)Shalygina E.A., General technology of milk and dairy products, M.: Kolos, 2001.

)Shepelev A.F. Commodity research and examination of milk and dairy products, Rostov, 2001.

Applications

Shelf life: 5 days

Date of the study: 05/18/2011

Table 2.2.1

Name Indicators of the standardResults of the studyConclusionAppearancehomogeneous liquid without sedimenthomogeneous liquid without sediment meets the requirements of the standardColorwhite with a slightly yellowish tintwhite, slightly with a yellowish tint meets the requirements of the standardSmell and tasteclean, without foreign tastes and smells not characteristic of fresh milk.clean, without foreign odors and tastes meets the requirements of the standardCon homogeneous consistency, liquid without sediment .homogeneous, sediment-free liquid. meets the requirements of the standard

Conclusion: pasteurized milk with 1.5% fat content, at the time of acceptance, meets the requirements of STB 1746-2007 “Drinking milk”.

Organoleptic assessment of the quality of drinking milk 1.5% fat

Product name: Pasteurized milk 1.5% fat

Date of manufacture: 05/18/2011

Shelf life: 5 days

Date of the study: 05/18/2011

Table 2.2.2

Name Standard indicators Research results Conclusion Appearance homogeneous liquid without sediment homogeneous liquid without sediment meets the requirements of the standard Color white with a slightly yellowish tint white, slightly with a yellowish tint meets the requirements of the standard Consistency homogeneous, liquid without sediment. homogeneous, liquid without sediment. meets the requirements of the standard Smell and taste are clean, without foreign substances not characteristic of fresh milk taste and smell .clean, without foreign odors and tastes, meets standard requirements

Conclusion: Drinking milk with 1.5% fat content did not change its organoleptic properties during storage. Complies with the requirements of STB 1746-2007 “Drinking milk”.

Milk is a biological fluid secreted by the mammary gland of female mammals. Milk serves as a complete and irreplaceable food for newborn animals and is used as the main food product for humans. Milk is not a mechanical mixture of individual parts, but a complex dispersed system consisting of a dispersed medium and a dispersed phase of the milk components. The main components of milk are well digestible: protein - 96%, fat - 95%, milk sugar (lactose) - 98%. The energy value of milk is 1 kg - 660 kcal or 2740 kJ. In terms of nutritional value, milk can replace any product, but no product can replace milk. Milk and dairy products are widely used in the treatment and prevention of various human diseases. Milk protein binds pairs of acids and alkalis, neutralizes toxic metals and other substances harmful to health that enter the gastrointestinal tract. Milk proteins are proteins of high biological value, containing all the amino acids necessary for the human and animal body. Milk proteins are used in meat and dairy, baking, in the production of processed cheese, sour cream and others. The nutritional value of milk, along with proteins and milk fat, is determined by lactose. Lactose can improve calcium absorption by the human intestine. The role of the alkaline derivative of lactose, lactulose, recognized in the world as the main probiotic used for nutritional function, is important. The nutritional value of milk and dairy products lies largely in their high calcium content (cottage cheese - 150 mg%; in milk - 120 mg%). Milk contains all the vitamins: fat-soluble and water-soluble.

12. Organization of milking of cows. Preparing cows for milking, rules for machine milking.The machine can milk all cows, with the exception of animals with abnormalities in the structure of the udder or nipples (very thin and short, too long or thick), open wounds on the nipples, clinical forms of mastitis, inflammation of the integument of the nipple opening. Cows with cup- or bath-shaped udders with evenly developed quarters are selected for the group; attention is paid to the shape of the nipples, the distance from the tip of the nipple to the ground (at least 45 cm). Before milking, operators wash their hands with soap, put on clean gowns and headscarves, wash the udders of the cows, perform a preparatory massage and milk the first streams of milk into a separate container. Wash the udder with clean (40-45C) water and disinfectants, then wipe with a clean towel. Inspect the udder, paying attention to the presence of redness, thickening and damage. Washing the cow's udder not only helps clean it from dust and dirt, but also stimulates the milk letdown reflex. In our country, three-stroke and two-stroke milking machines are produced. In three-stroke milking machines, there are 3 strokes in the cycle: so sucking - milk flows out of the nipple; so compression - the nipple is compressed and massaged; so rest - during this period the nipple “rests” and blood circulation is restored in it. All three beats together make up the pulsation. The longest cycle of sucking is 60%, compression is 10%, and rest is 10%. Milking cows with a push-pull milking machine is carried out in two strokes. During the sucking stroke, a vacuum is formed under the nipple and the interstitial chamber and milk flows out of the nipple. For two-stroke devices, the suction stroke is 66%, and the compression stroke is 34%; so there is no rest.

13. Sources of bacterial contamination of milk. Measures to prevent bacterial contamination of milk. Main sources of bacterial contamination: The cow's udder is the main source of bacterial contamination of milk. If the udder is not washed and wiped dry before milking, a large number of microbes get into the milk. Washing the udder with disinfectants reduces on average more than 30 times the number of microbes in milk ke. After wiping the udders of 4-5 cows, the towel must be changed. The water in the bucket is changed after washing 2-3 cows. At milking machines, as well as when milking in stalls, the washed udder is wiped with disinfected wipes. Before wiping the udder, wring out the napkin removed from the vessel. First, take napkins from one vessel, and when the solution becomes dirty, use napkins from another vessel, and replace the solution in the first one. At the inlet of the nipple a bacterial plug is formed, so the first streams of milk contain 40 times more bacteria than the last ones. Thus, 1 ml of milk in the first portions contains 16,000 bacteria, in the middle portions - 480, and in the last portions - 360. In this regard, the first streams of milk must be poured into a separate container and used as feed for young animals after pasteurization. Sick cows are milked last; their milk should not be mixed with the total milk yield. Skin and hair animals, contaminated with particles of manure, dust, which contain billions of bacteria, are serious sources of contamination of milk with microflora. Moreover, this microflora is mainly represented by butyric acid bacteria and a group of Escherichia coli, which cause spoilage of milk and dairy products. In order to avoid contamination of milk with microflora, it is necessary to regularly clean animals. In the barnyard air After cleaning the premises or distributing food, there is a lot of dust, on the particles of which microorganisms concentrate. Microorganisms enter the milk along with the settling dust. Therefore, cows must be milked after distributing heavily dusty feed and cleaning the premises, or 1-1.5 hours after that. The room must have good ventilation and ventilation. Dairy utensils, filter materials and equipment- all of these can be a source of milk contamination if they are not thoroughly washed and disinfected. Particular care must be taken to monitor the cleanliness of flasks, milk meters, metal equipment, and inventory. There should be no rinsing water left in milk containers, in which micrococci, spore and non-spore bacteria, and fluorescent bacteria that decompose milk fat can develop. Feed can be a direct source of milk contamination if sanitary and hygienic rules for its preparation and distribution are not observed. In addition, when cows are fed excessive amounts of feed such as pulp, stillage and some others, gastrointestinal disorders are observed, feces become more liquid, resulting in the possibility of milk contamination by microorganisms. The most common insects in the barnyard are flies. To combat them, they use chemicals and install metal mesh on the windows. Litter can become a source of milk contamination with butyric acid and putrefactive bacteria. Therefore, dirty litter must be promptly removed from the barnyard and replaced with fresh litter: litter particles must not be allowed to get into the milk.

14. Milk proteins and milk sugar, their physiological technological significance.The average mass fraction of proteins in milk is 3.5%. If cows' diets are insufficient in terms of overall nutritional value and digestible protein, the amount of protein in milk can drop to 2%. This indicator fluctuates throughout the lactation period. Proteins are high molecular weight compounds, including hydrocarbons, hydrogen, oxygen, nitrogen, sulfur, and sometimes phosphorus. All these elements are included in the structural particles of amino acid proteins, which are connected to each other by peptide bonds. Protein molecules contain from 100 to several thousand amino acids. The molecule contains a number of proteins: casein, albumin, globulin, etc. Casein is easily isolated by coagulation with weak acids or rennet. Albumin dissolves in a semi-saturated solution of ammonium sulfate. Whey proteins are used in the production of dry baby and dietary products and in the pharmaceutical industry in the manufacture of protein preparations. When casein is coagulated by rennet, it produces a dense, sweet curd and sweet whey. The production of cheese, cottage cheese, food and technical casein is based on this property. Casein has amphoteric properties: when adding a small amount of weak acid or alkali, it neutralizes them without changing the solution. Albumin and globulin are found in milk in a state close to the true solution; protein therapeutic and dietary preparations are prepared from them. Non-protein nitrogenous substances include creatine, uric acid, hippuric acid and orotic acid, creatinine, urea, and free α-amino acids. Amino acids are of great importance for the dairy industry, as they serve as a source of nitrogenous nutrition for lactic acid bacteria used in the production of fermented milk products and cheeses. Milk sugar (lactose) found only in milk and dairy products. In cow's milk, the average mass fraction is from 4.5 to 5.3%. Milk sugar is a carbohydrate necessary for the nutrition of newborns in the first days of life. It is part of the enzymes involved in the synthesis of fats and proteins; it is needed for normal metabolism, heart function, kidneys and liver. In the gastrointestinal tract, under the action of the lactose enzyme, milk sugar breaks down into glucose and galactose, which are necessary to nourish the main brain of the nervous system. Lactose is a source of carbon for lactic acid bacteria; it is fermented under the action of their enzymes, on which the production of fermented milk products, cheese, and fermented butter is based. When milk is heated above 100°C, lactose reacts with amino acids and proteins, and melanoidins are formed. Depending on the final decomposition products, the following types of fermentation are distinguished: 1) lactic acid fermentation, lactic acid is formed. 2) alcoholic fermentation, 2 hexoses and ethyl alcohol are formed. 3) butyric acid fermentation, 2 hexoses and an butyric acid are formed, hydrogen is released. Lactose is used to produce lactulose (this probiotic creates a normal environment for probiotics)

15. Composition and properties of milk fat. Its difference from other fats Milk fat is formed from fats, proteins, and carbohydrates in feed. As a result of fermentation, a significant amount of volatile fatty acids (acetic, propionic, butyric) are formed in the rumen, which are “precursors” of milk fat. “precursors” of milk fat are absorbed first into the lymph and then into the blood, which transports them to the mammary gland, where fat synthesis occurs in the secretory cells of the alveoli. In fresh or heated milk, the fat is liquid (in the form of drops) and forms an emulsion with the water part (plasma). In cold milk, the fat is solid, in the form of globules and in a state of suspension. The size of fat globules is 3-5 microns. Their size is of great technological importance in oil production. The larger the fat globules, the easier they are separated when separating milk, and the better the cream is churned. Milk fat is a mixture of glycerides, which are esters of alcohol and monocarboxylic acids. Milk fat consists of saturated (50-74%) and unsaturated fatty acids (25-50%). Milk fat is high in monounsaturated fatty acids. Unlike other fats, milk fat is easier to digest and absorb, contains essential fatty acids and large amounts of fat-soluble vitamins and volatile fatty acids. No type of fat has such a pleasant taste and aroma as milk. Cow's milk fat differs from animal fats and vegetable oils in its high saponification number and Reichert-Meisl number due to the high content of low molecular weight acids. Physical properties of fat: 1) melting point 27-30C 2) freezing point (solidification) of fat 18-23 3) fat density 0.91-0.93 g/cm 3 4) refractive index 1.453-1.455.

16. Factors affecting the density of milk. The importance of density in establishing the naturalness and accounting of milk A. Density of milk - the ratio of its mass at 20 ̊ C to the mass of H 2 O dist at 4 ̊ C in the same volume. This indicator is used when converting milk expressed in kg into liters and vice versa, to establish the naturalness of milk, to calculate the mass fraction of dry matter and dry skim residue and other components of milk when using special coefficients. ρ of normal milk should be at least 1.027 g/cm 3 (fluctuations 1.027-1.032). Determine ρ in accordance with GOST R 52054-2003 using a hydrometer. It is necessary to determine at t=20 0 C or (15-25 ̊ C), bringing the hydrometer readings to 20 ̊ C, using the correction (0.2 ̊ A). If t milk ↓ 20 ̊ C, the amendment is subtracted from ρ milk, expressed in ̊ A, if t milk 20 ̊ C, then the amendment is added. When skimming or adding skim milk to milk, ρ milk, and when adding water ↓. Adding 3% water ↓ ρ milk per 1̊ A. Fat ↓, and the dry fat-free residue ρ milk. ρ is determined no earlier than 2 hours after milking, and for skim milk 2 hours after separation, since ρ of fresh milk is slightly lower. An increase in ρ occurs as a result of a decrease in gases dissolved in milk, cooling and partly hardening of fat. Lactation affects the ρ of milk - in the first 7 days after calving, milk is called colostrum, its ρ is significantly higher than the norm (1.040 g/cm3). Milk is adulterated with water ↓ ρ; when adulterated with skimming or skimming, ρ occurs.

17. Non-dairy raw materials: vegetable proteins and fats, food additives . Plant proteins are found in significant quantities in grains and legumes. The most valuable crops are soybean seeds (up to 40% protein). Soybean seeds contain undesirable and toxic substances, which precludes the use of soybeans not only in food products, but also in feed, without pre-treatment. Soy-based food proteins are produced in the form of the following products: defatted soy flour (54% protein); soy concentrate -70% protein; soy protein isolate -92% protein. They differ from others in the mass fraction of protein and the degree of purification from carbohydrates and dietary fiber. The proteins of soy products only in terms of the content of cystine, triamine and the total amount of sulfur-containing acids, especially methionine, do not satisfy the ideal protein. In terms of the mass fraction of methionine, soy proteins are inferior to casein, however, combining them with other proteins can compensate for the methionine deficiency. Vegetable fats. In order to reduce the resource capacity of dairy products, fats of vegetable origin are used to replace milk fat or part of it. They are used in the form of analogues, which are obtained by special processing - these are: refining; hydrogenation; transesterification grows fats. The purpose of processing is to obtain solid fats of plastic consistency by changing the fatty acid composition of the original growing fats. The following types of oil are used on the Russian market: soybean; sunflower; rapeseed; corn and palm; coconut, etc. Grows oils: liquid (soybean, sunflower, rapeseed, olive); solid (cocoa butter, coconut, palm). Food additives are a group of natural or synthetic substances that are specially introduced into semi-finished raw materials or finished foods in order to improve their technology or give them the necessary properties. The number of food additives used in different countries is approximately 500, not counting individual fragrant substances and flavorings. The European Council has developed a digital codification system for food additives with the letter (E), each additive is assigned its own 3 or 4 digit code. Has the use of nutritional supplements caused an acute problem? about their toxicity. The decisive element is the dose, route of administration, and duration of administration. Based on the purpose of food, additives are divided into: those that improve the appearance of food (dyes); giving the product a certain taste and aroma; changing the structure of the product (thickeners and gelling agents); increasing the shelf life of food (preservatives); regulating saints of food. Classification of additives: E-182 - dyes; E-200-300 - preservatives; E-400 consistency stabilizers; E-450 - emulsifiers; E-500-disintegrants; E-600 – flavor and aroma enhancers, etc. Food dyes: β-carotene (natural) provides coloring to fats, fruits, vegetables, etc.; eno dye - obtained from the marc of dark grape varieties and elderberries, intensely red in color; Sugar color is a dark-colored product obtained by heating various types of sugars. Aqueous solutions of saz kohlera are a dark brown liquid (used for decorating confectionery products, drinks and in cooking). Thickeners, gelling agents - bind water (natural ingredients with such action: gelatin, pectin, agaroids, gums). Ingredients regulating the properties of the product (surfactants) - mono and diglycerides, phospholipids, esters, sorbitols. They have an emulsifying effect in the production of margarine, mayonnaise, etc. Flavoring and aromatic additives: malt extract, lactose, sorbitol and xylitol, aspartame, etc. Ingredients that increase food safety: antioxidants (natural - tocopherols; synthetic - butyl- oxytoluene), preservatives – sulfur dioxide, nisin, etc.

18. Conditions for obtaining high-quality milk for the farm. Personal hygiene rules for dairy farm workers. To obtain high milk yields and good quality milk, the nutritional value of the cow's diet, the level of protein, carbohydrate, fat, mineral and vitamin nutrition, the use of a variety of feeds and their most appropriate combination are of great importance. At the same time, the ratio of nutrients in the diet should be optimal. The influence of green feed on animal milk yield, composition, technological properties of milk and the quality of dairy products depends on the nutritional value of this feed. Natural pastures generally do not provide the nutritional needs of cows, therefore, when keeping animals on such pastures, it is necessary to feed them, as well as to use cultivated artificial pastures. Housing conditions: Certain conditions are created so that the cow’s milk yield is maximum, and the milk contains an increased amount of dry matter, fat, protein and other components. The conditions of detention primarily mean the microclimate of the premises. The main parameters of the microclimate are t, air humidity, illumination. With excessive increases in temperature and air humidity, the productivity of cows decreases. Exercise is of great importance for dairy cows at all times of the year. This contributes to an increase in fat in milk (by 0.2-0.3%). The positive effect of exercise appears only during the period when animals receive it. When you stop exercising, milk yield and fat content decrease. Persons working on farms, especially those in contact with milk, must follow certain rules: have personal health records, which indicate a monthly medical examination; do not smoke or eat while working; have special clothing and keep it clean, cut your nails short, and keep your hands clean. If skin and infectious diseases occur in a worker or members of his family, he is obliged to immediately notify the foreman, farm manager or medical personnel. Farm managers and foremen must systematically monitor the observance of personal hygiene rules by operators, provide them with overalls, clean towels, soap, and workers involved in washing dairy utensils, equipment and equipment with rubber gloves, boots and rubberized aprons. For farm workers, classes are organized on the sanitary minimum, and a journal is kept to record instructions and suggestions from employees of the sanitary and anti-epidemic health service and veterinary supervision.

19. Indicators included in GOST R 52054-2003 for determining the type of milk. Methods for determining these indicators When accepting milk, its quality indicators and grade are established in accordance with GOST R 52054-2003 “Natural cow's milk - raw material. Technical conditions" and SaNPiN 2.3.2.1078-01. In accordance with the standard, the raw milk produced is divided into grades: highest, first, second and non-grade. GOST R 52054-2003 Natural raw cow milk (date of introduction 2004-01-01)(further insert GOST table) Methods for determining these indicators. Determine the color of milk in a glass cylinder in reflective daylight. The smell of milk is detected when it is poured from the milking bucket into the milk meter or when the vessel in which the milk is delivered is opened. The taste is assessed as follows: take a sip of milk, trying to moisten the entire oral cavity with it to the root of the tongue. You need to take in more air with your mouth and exhale slowly through your nose. During testing, milk should be at room temperature. Consistency is determined by slowly pouring milk from one vessel to another according to the width of the strip (stack) left by the milk on the wall of the cylinder; the thicker the milk, the wider the strip, and vice versa. The density of milk should be determined no earlier than 2 hours after milking, and skim milk 2 hours after separation, as the density of fresh and warm milk is slightly lower. To determine this, milk hydrometers are used. Determine the density of milk required at 20°C or at a temperature within 15-25°C, bringing the hydrometer readings to 20°C, using a correction of ±0.2°A for each temperature degree deviating from 20. Mechanical contamination of milk is determined by filtering 250 ml of milk and comparing the contamination of the filter with the standard. To determine the purity of milk, a special device is used, in which the milk is filtered using a cotton or flannel circle (filter). Cold milk is preheated to 35-40°C. Next we compare with the standard: 1 g - there are no particles of fur impurities on the filter; 2 grams of individual particles of fur impurities; 3g - noticeable sediment of particles of fur pollution (sand, hay, etc.). Determination of bacterial contamination of milk. Reductase test with methylene blue. Pour 1 ml of methylene blue solution and 20 ml of milk into a test tube, close the tube with a stopper, mix the milk with methylene blue solution. Place the test tube in a thermostat preheated to 37°C. The color is monitored for 40 minutes, 2.5 hours and 3.5 hours. The end of the analysis is considered to be the moment of methylene blue discoloration. Depending on the duration of discoloration, milk is classified into one of 4 classes. Reductase test with resazurin. Pour 10 ml of milk and 1 ml of resazurin solution into a test tube, close it with a stopper and slowly turn it over 3 times, then place it in a thermostat and note the start time of the analysis. We note the color change after 1 hour. Leave the test tubes with a gray-lilac color for another 30 minutes. The class is determined by color. Determination of acidity. To determine the titrated brush, measure 10 ml of milk into the flask, add 20 ml of distilled water and 2-3 drops of 1% phenolphthalein alcohol solution. Then, while slowly shaking the contents of the flask, decinormal alkali solution is poured from the burette until a faint pink color does not disappear within 1 minute. The amount of alkali used for titration multiplied by 10 will express the acidity of the milk in °T. Determination of somatic cells in milk using a viscometer. On the Somatos analyzer, the number of somatic cells in milk is determined depending on the duration of flow of the mixture of milk and the drug Mastoprim from the viscometer. The flow time of the mixture is 0.1-99.9 s. the range of measurement of the number of somatic cells is 90-500 thousand/cm3.

20. What is the heat stability of milk. What methods are used to determine the heat resistance of milk and how it is divided according to this indicator. Thermal stability of milk refers to the ability of milk to withstand exposure to high temperatures without visible coagulation of proteins. It is expressed in various units - the thermal stability group, the time required for protein coagulation at t = 120-140 ̊ C, the number of Ca ions, etc. Thermal stability is related to the degree of casein dispersion and the lower it is, the easier protein coagulation occurs. The degree of dispersion of casein is influenced by the acidity of milk, its salt and protein composition, the content of SOMO and other factors that depend on the time of year, stage of lactation, physiological state and individual characteristics of the living creature. Thus, an increase in the acidity of milk leads to a decrease in the negative charge of casein micelles, the degree of their hydration and the transition of colloidal Ca salts to the ionic-molecular state. A decrease in elstatic repulsion forces and an increase in the amount of ionized Ca contributes to the aggregation of protein particles and a decrease in their dispersity. With a slight increase in acidity, the decrease in the charge of protein particles is small, and the degree of demineralization is moderate. As a result, coagulation of cold milk does not occur, because the protein particles are hydrated. The thermal stability of milk also depends on the salt balance of milk, in particular on the ratio of the sums of Ca and Mg cations and citrate and phosphate anions. An excess of one or another can lead to protein coagulation. The protein composition, namely the ratio of casein and whey proteins, plays a great role in the heat stability of milk. In milk that has not been subjected to heat treatment, proteins form a stable colloidal system. Heating milk causes denaturation of whey proteins, which are adsorbed onto the surface of casein particles, so their transition to an insoluble composition is imperceptible. If the content of whey proteins is excessive (more than 0.9%), for example, in colostrum and milk obtained at the end of lactation, as well as in the milk of cows with mastitis, casein is not able to take on denatured whey proteins; if there is an excess of them, it falls out into sediment. There are a number of methods for determining the heat resistance of milk: alcohol and heat tests. The essence of the alcohol test is that ethanol acts on proteins similar to heating, that is, it promotes hydration and partial denaturation of proteins, causing their coagulation. The thermal stability of milk is determined using an aqueous solution of ethyl alcohol with the Vth alcohol content of 68,70,72,75 and 80%. Depending on which ethyl alcohol solution does not cause sedimentation of flakes in the milk being tested, milk is divided into five groups according to heat resistance: alcohol content 80% - I; 75% - II; 72% - III; 70% - IV; 68% - V. When establishing the grade of milk upon acceptance, premium milk must pass an alcohol test with 75% alcohol, and standard milk with 72% alcohol. The thermal test is carried out using the Termol-1 device or a glycerin bath and is based on the thermal effect on milk.

21. Milk sugar (lactose) found only in milk and dairy products. In cow's milk, its average mass fraction is 4.7% (variations from 4.5 to 5.3%). Milk sugar is a carbohydrate necessary for the nutrition of newborns in the first days of life. It is part of the enzymes involved in the synthesis of fats and proteins and is needed for normal metabolism, heart, kidney and liver function. In the gastrointestinal tract, under the action of the lactose enzyme, milk sugar breaks down into glucose and galactose, which are necessary to nourish the brain and nervous system. Calorie content of 1 g of lactose is 3.8 kcal (15.909 kJ). Milk sugar is also used as a raw material in the pharmaceutical industry. Lactose is a source of carbon for lactic acid bacteria; it is fermented under the action of their enzymes, on which the production of fermented milk products, cheese, and cultured butter is based. Together with other substances, it determines the properties and taste of milk and dairy products. In milk, milk sugar is in a molecular state and is a disaccharide consisting of glucose and galactose, which differ in the spatial arrangement of hydrogen and hydroxyl groups. Lactose is formed in the glandular tissue of the udder when glucose combines with galactose and splits off a water molecule. In its pure form, milk sugar is a white crystalline powder, the crystals of which have a characteristic shape with a length of 10-20 nm or more. Saturation of the solution with lactose and its precipitation in crystalline form are observed during condensation of milk and subsequent cooling of condensed milk with sugar, as well as during condensation of whey in the production of milk sugar. To obtain high quality sweetened condensed milk, it is necessary that the size of lactose crystals does not exceed 10 microns. With crystal sizes of 12-20 microns, the consistency of the product becomes mealy, with larger crystals it becomes sandy. Prolonged heating of milk at a temperature of 100°C and above leads to a change in its color. This is due to the formation of melanoidins due to the reaction between lactose and proteins, as well as between lactose and some free amino acids. Melanoidins are brown substances with a distinct caramelized taste. This reaction occurs when producing baked milk, fermented baked milk and canned milk. Carbohydrates play an important role in the processes of lactic acid fermentation. They are based on the fermentation of lactose under the action of enzymes secreted by microorganisms to lactic acid. The product acquires a specific fermented milk taste and viscoplastic consistency, as well as medicinal properties. Compared to cane and beet sugar, milk sugar is less sweet and less soluble in water. Under the action of microbial enzymes (lactase), it is fermented, resulting in the formation of low molecular weight compounds.

22. BASIC SANITARY AND HYGIENIC REQUIREMENTS FOR RECEIVING MILK AND ITS PRESERVATION

The sanitary and hygienic condition of milk is judged by its contamination with mechanical impurities (purity group), the content of bacteria and somatic cells, the nature of the microflora, acidity, the presence of pathogens, heavy metals, pesticides, nitrates and nitrites, antibiotics, radionuclides and other harmful substances. Sources of milk contamination with mechanical impurities and undesirable (harmful) microflora can be: the udder, skin and hair of the animal, barnyard air, milk utensils and equipment, feed, bedding, and service personnel. To obtain high-quality milk, it is necessary to comply with sanitary and veterinary rules for dairy farms. Mechanical impurities in milk (hair, particles of hay, sand, manure) indicate unsanitary conditions for obtaining, storing or transporting milk. Along with mechanical impurities, microorganisms enter the milk and cause spoilage. Microorganisms of raw milk can be conditionally divided into three groups: beneficial to human health (lactic acid, widely used in the dairy industry), harmful to human and animal health (pathogens), worsening the hygienic properties of milk (butyric acid, putrefactive). Bacteria content in milk is determined by the reductase test. Bacteria that get into milk secrete enzymes, in particular psductase and other waste products. There is no reductase in freshly milked milk. Therefore, the general bacterial contamination of milk can be judged by the presence of this enzyme. If the sanitary and hygienic rules for obtaining and storing milk are violated, the number of bacteria in it increases, and therefore the content of enzymes increases. Reductase decolorizes weak organic dyes added to milk - H1P1 solution of methylene blue or resazurin. If a solution of methylene blue is added to the mixture, the mixture will turn into a grayish-lilac color; when resazurin is added, the mixture will become discolored under the action of reductase. Coloring is achieved the faster the more reductase in milk, and therefore , bacteria. Having established the duration of discoloration of tmethylene blue or resazurin, the class of milk and the number of bacteria in it are determined using special tables. In Denmark, the Voss Electric company has developed an automatic counter for direct counting of microbes in milk. With a high content of microflora, milk becomes unsuitable for the production of complete products, since the acidity of the milk increases and the microflora destroys its biological properties. When there is a large accumulation of psychrotrophic bacteria, fat and protein undergo changes, which causes defects in the taste, smell and consistency of dairy products. Character of microflora determined by fermentation test. The essence of this test is that different types of microorganisms form different enzymes. Under the influence of enzymes, milk sugar decomposes and the acidity of milk increases, its coagulability and the formation of a clot. The nature of the curd during natural souring of milk depends on the predominance of one or another type of bacteria. Based on the quality of the curd, milk is classified into one class or another. Drinking milk from cows with mastitis (inflammation of the udder) can cause serious illness in humans. When cows have mastitis, they do not receive a significant amount (up to 15%) of milk during lactation. The content of somatic cells increases in mastitis milk. Somatic cells (from the Greek soma - body) are represented mainly by leukocytes, the epithelium of the milk alveoli and milk ducts and are common elements of normal milk. When an animal gets mastitis, the migration of leukocytes to the site of inflammation increases, which leads to an increase in the number of somatic cells in the milk. Collected milk arriving at dairies often contains an admixture of mastitis milk. This milk contains more than 500 thousand somatic cells per 1 cm3. Milk with a large number of somatic cells has a high bacterial contamination. An admixture of abnormal (mastitis) milk can distort the results of the reductase test. A change in the chemical composition of collected milk with an admixture of mastitis causes disruption of biochemical and microbiological processes during its processing. Such milk is less heat-resistant, does not coagulate well with rennet, and lactic acid bacteria slowly develop in it. In this regard, workers at dairy farms and factories need to carefully monitor the milk they produce for the presence of mastitis. There are various methods to control mastitis. In production conditions, a method is used based on the indirect determination of the number of somatic cells in milk using the surfactant “Mastoprim” using milk control plates PMK-1, devices “ISKM-1”, “Somatos”, etc. To identify milk In cows with mastitis, the following tests are also used: leukocyte, dimastine, mastidine and chlorine-sugar number. A ring test is used to determine the milk of cows with brucellosis. The benzidine test for ketone bodies is an indicator of the health status of cows. Using a test with resazurin, methylene blue and express methods, the presence of antibiotics in milk is detected. The methods used to detect antibiotics when they are present in milk are based on suppressing the proliferation of bacterial cells, and consequently, less release of enzymes that discolor the indicator added to milk. Antibiotic-sensitive thermophilic streptococcus is used as a test microbe. Pesticides are detected using bioassays or chromatographic analysis.

Nutritional value and chemical composition

Milk - biological fluid formed in the mammary gland of mammals and intended for feeding a newborn baby. This is a complete and healthy food product, containing all the necessary elements for building the body. It contains over 200 different components: 20 fatty acid glycerides, more than 20 amino acids, 30 macro- and microelements, 23 vitamins, 4 sugars, etc. The composition of the milk of various mammals depends on the environmental conditions in which the young organism grows, and can change as a result of animal diseases, microbiological and other processes occurring in it.

Water. Milk consists of 85...89% water, which takes part in various reactions occurring in the body of animals: hydrolysis, oxidation, etc. Its main source is blood, and only part is formed during the synthesis of triglycerides, while three water molecules are released.

Water in milk is in a free and bound state. There is significantly more free water (83...86%) than bound water (3.0...3.5%). It takes part in biochemical reactions and is a solution of various organic and inorganic substances. Milk sugar, water-soluble vitamins, minerals, acids, etc. dissolve in free water. It can be easily removed when condensing and drying the milk. Free water freezes at 0°C.

Bound water (adsorption-bound water) is held near the surface of colloidal particles (proteins, phospholipids, polysaccharides) by molecular forces. The hydration of protein molecules is due to the presence of polymer groups (hydrophilic centers) on their surface. These include carboxyl, hydroxyl, amine and other groups. As a result, dense hydration (water) shells are formed around the particles, preventing their connection (aggregation). Bound water has different properties from free water in milk. It freezes at temperatures below 0 °C, does not dissolve sugar, salts and other substances, and is difficult to remove when dried.

A special form of bound water is chemically bound water. This is crystalline and crystallized water. It is associated with crystals of milk sugar C 12 H 22 O m H 2 0 (lactose).

Dry substances. Dry substances (DS) in milk contain an average of 12.5%; they are obtained by drying milk at

102... 105 °C. The solids contain all the components of milk except water. The nutritional value of milk is determined by its dry matter content. Consumption of raw materials per 1 kg of finished product when processing milk into cottage cheese, cheese, canned food, etc. also depends on the amount of dry matter.

The productivity and breeding quality of animals is assessed not only by the fat content in milk and milk yield, but also by the content of dry matter in it.

Milk proteins. Protein is the most valuable component of milk. It contains a variety of proteins that differ in structure, properties and play a strictly defined role. The mass fraction of proteins in milk is 2.1 ... 5%.

From a chemical point of view, proteins are high-molecular compounds that are part of all living structures of cells, tissues and the body as a whole. Proteins are building energy materials that perform various functions: transport, protective, regulatory. They are built according to the same principle and consist of four main elements: carbon, oxygen, hydrogen and nitrogen. All proteins contain a small amount of sulfur, and some contain iron, calcium, phosphorus, zinc, etc. The structural blocks of proteins are amino acid residues arranged in a certain order and interconnected in a chain. A protein molecule consists of more than 20 amino acids.

The acids contain amine (NH 2) and carboxyl (COOH) groups. The amine group is in the ^-position relative to the carboxide. Amino acids can contain an equal number of carboxyl and amine groups (serine, alanine, cysteine, glycine, phenylalanine, etc.) - they are neutral, and there are amino acids containing two carboxyl groups (glutamic acid) or two amino groups (lysine); their aqueous solutions show an acidic or alkaline reaction, respectively.

A protein is a long chain of different amino acid residues. The combination of amino acids into a protein polymer occurs as follows: the amino group of one amino acid reacts with the carboxyl group of another amino acid, and water molecules are released and a peptide bond -CO-NH- is formed.

Amino acids, when combined in different combinations, form long polypeptide chains with R groups in the form of branches. The sequence of the polypeptide chain of amino acid residues is specific for each protein. Protein molecules have a certain flexibility. In water, hydrophobic regions are in contact with each other, and hydrophilic regions are in contact with water and the molecule. When bending, the molecule folds in such a way that all hydrophobic side chains end up inside the globule, and hydrophilic ones on its surface, closer to the water.

The primary structure is an elongated thread, the secondary is a spiral, the tertiary is a globule; when globules are combined into one, a quaternary structure is formed. In proteids (complex proteins), unlike proteins (simple proteins), in addition to the protein part, there is also an additional component of a non-protein nature (phosphoric acid residues in phosphoproteins, fats, carbohydrates, etc.), which affects the properties of the protein. In water, the protein forms a stable colloidal solution.

Milk contains more than 20 different proteins, but the main ones are casein and whey proteins: albumin, globulin, etc. The nutritional value of whey proteins is higher than casein.

Casein is the main protein of milk, its content ranges from 2 to 4.5%. Casein is present in milk in the form of colloidal particles (micelles).

The structure of casein. On the surface of the micelles there are charged groups (negative sign) and a hydration shell; therefore, they do not stick together or coagulate when approaching each other. Casein particles in fresh milk are quite stable. Like other animal proteins, casein contains free amino groups (NH 2) and carboxyl groups (COOH): the former are 83, the latter are 144, therefore it has acidic properties and has an isoelectric point at pH 4.6...4, 7. In addition, casein contains -OH groups of phosphoric acid, being not a simple, but a complex phosphoprotein protein. In milk, casein is combined with calcium salts and forms a caseinate calcium phosphate complex, which in freshly milked milk forms micelles that can bind a significant amount of water. Casein Formula:

Casein isolated from milk consists of the following fractions: a, b, c, p. They differ in physicochemical properties, sensitivity to calcium ions and solubility. So, A- and β-casein are sensitive to calcium ions and, under their influence, precipitate, are unstable and are located inside micelles; c-casein is insensitive to calcium ions and is located on the surface. Under the action of rennet, all three fractions of casein are precipitated; the fourth fraction - p-casein - is not part of the micelles and is not precipitated by the rennet enzyme, therefore, when producing cottage cheese and cottage cheese using the rennet method, it is lost with whey.

Properties of casein. Casein, isolated from milk and treated with alcohol, is an amorphous white powder, tasteless and odorless, with a density of 1.2...1.3 g/cm 3 . It dissolves well in some salt solutions, less well in water; It is completely insoluble in ether and alcohol.

Thanks to casein, the color of milk is also white. Casein does not precipitate when heated, but coagulates under the action of rennet, acids and salts. These properties are used in the production of fermented milk products and cheese. The concentration of casein and the size of its particles determine the rate of sedimentation and the strength of protein clots. The thermal stability of milk depends on the size of the particles: the larger they are, the less thermally stable it is. Hydrophilic properties of casein, i.e. its ability to bind and retain moisture determines the quality of the resulting acid and rennet curds, as well as the consistency of finished fermented milk products and cheese. The nature of the interaction of casein with water depends on its amino acid composition, the reaction of the medium and the concentration of salts in it.

When proteins are deposited with acid, rennet, after mechanical and heat treatment, the hydrophilic properties of casein change as a result of changes in the structure of protein particles and the redistribution of hydrophobic and hydrophilic groups on their surface. The hydrophilic properties of casein are greatly influenced by the whey proteins of milk, since during heat treatment they interact with its particles. Whey proteins bind water more actively than casein; at the same time its hydrophilic properties increase. These properties are taken into account when choosing milk pasteurization modes. Under the influence of acids, rennet, calcium chloride, casein precipitates, and the colloidal solution of protein turns into a clot or gel; Protein particles are connected to each other in chains and form spatial networks.

Whey proteins (albumin and globulin). Their milk contains significantly less than casein (0.2...0.7%), i.e.

15...22% of the mass of all proteins. Albumin and globulin contain more sulfur than casein, they are soluble in water and do not coagulate under the influence of acids and rennet, but precipitate when heated, and together with salts they form a “milkstone”.

Albumin and globulin are of great importance for a newborn animal. Immunoglobulins that pass from the animal’s blood into milk are antibodies that neutralize foreign cells, i.e. play a protective role in the body. There are especially many of these proteins in colostrum. Thus, the albumin content can reach 10...12%, globulin - up to 8...15%.

Whey proteins are contained in milk in the form of small particles compared to casein, on the surface of which there is a total negative charge. The particles are surrounded by a strong hydration shell, so they do not coagulate even at the isoelectric point. When milk is heated to 70...75 °C, albumin precipitates, and globulin is precipitated by heating to 80 °C. By heating milk to 90...95 °C, albumins and globulins can be isolated from whey. Whey proteins can be isolated by combined heat, calcium or acid treatment. The resulting protein mass is used in the production of protein products, processed cheeses, baby food and dietary foods. The shell protein makes up about 70% of its mass. This complex protein is a mixture of protein and phospholipids. The protein shell fat globules contain a fat-like substance called lecithin. Unlike other milk proteins, whey proteins contain less nitrogen and no phosphorus, calcium, or magnesium.

Milk fat. It is a combination of esters of glycerol and fatty acids. Glycerol, which is part of triglycerides, is a trihydric alcohol.

Fatty acids contain a carboxyl group (COOH) and a radical at the end of which there is a methyl group (CH 3) and an unequal number of carbon atoms (from 0 to 24), forming carbon chains of different lengths. Carbon may be present in the form of saturated methylene (-CH 2 -) compounds - in this case, the fatty acids will be saturated (saturated) - or unsaturated ethylenic compounds (-CH =) - the acids will be unsaturated (unsaturated).

The mass fraction of fat in milk averages 3.8%. Fat is synthesized from feed, which consists of proteins, carbohydrates and fats. These substances, entering the gastrointestinal tract of an animal, undergo complex changes. In the stomachs of ruminants (in the rumen), during fermentation, acetic acid and other volatile fatty acids (propionic, butyric, etc.) are formed, which are precursors of fat: the more acetic acid is formed, the fattier the milk. If the amount of propionic acid increases, the fat content decreases and the amount of protein in milk increases. The listed volatile fatty acids are absorbed first into the lymph, then into the blood, which transfers them to the mammary gland, where fat synthesis occurs. The source of milk fat can also be neutral blood fat formed in the liver.

The mass fraction of fat in milk depends on the breed, productivity, age and diet of the animal. In fresh milk, fat is present in a liquid state and forms an emulsion in the water part. In cold milk, the fat is solid and in the form of a suspension. The fat in milk has the shape of balls (Fig. 1) with a strong elastic shell, so they do not stick together. The diameter of the ball is 3...4 microns (sizes range from 0.1 to 10 microns, in some cases up to 20 microns). 1 ml of milk contains from 1 billion to 12 billion, on average from 3 billion to 5 billion fat globules. The content of fat globules in milk changes during the lactation period: at the beginning of lactation they are larger and there are fewer of them, and by the end of lactation it is the other way around. Small fat globules float up faster as they stick together into lumps.

The physical stability of fat globules in milk and dairy products depends mainly on the composition and properties of their shells. The shell of the fat globule consists of two layers: the outer layer is loose (diffuse), easily desorbs during technological processing of milk; the inner one is thin, tightly adjacent to the crystalline layer of high-melting triglycerides of the fat globule (see Fig. 1).

The composition of the shell substance includes proteins, phospholipids, sterols, 6-carotene, vitamins A, D, E, minerals Cu, Fe, Mo, Mg, Se, Na, K, etc.

Rice. 1.

1 - fat globule: 2 - inner layer; 3 - outer layer

Rice. 2.

1 - hydrophilic shell: 2 - lipophilic shell: 3 - fat: 4 - water

The inner layer includes lecithin and in small amounts cephalin and sphingomyelin. Phospholipids are good emulsifiers; their molecule consists of two parts: lipophilic, similar to fat, and hydrophilic, which attaches water of hydration.

The protein components of the shell include two fractions: soluble in water and poorly soluble in water. The water-soluble protein fraction contains a glycoprotein with a high carbohydrate content and enzymes: phosphatase, cholinesterase, xanthine oxidase, etc.

The fraction that is poorly soluble in water contains 14% nitrogen, more arginine than in milk, and less leucine, valine, lysine, ascorbic and glutamic acids. It also contains significant quantities of glycoproteins containing hexoses, hexosamines and sialic acid. The outer layer of the fat globule shell consists of phosphatides, envelope protein and water of hydration. The composition and structure of the fat globule membranes change after cooling, storage and homogenization of milk and cream.

The protein shell of the balls is also destroyed by mechanical and chemical influence. In this case, the fat is released from the shell and forms a solid mass. These properties are used in the production of butter and in determining the fat content of milk.

As a result of technological processing of milk, the outer layer of the shell first of all changes due to an uneven, rough, loose surface and a rather large thickness after mixing, shaking and storage. The shells of fat globules become smoother and thinner as a result of desorption of lipoprotein micelles from the shells into the plasma. Simultaneously with the desorption of micelles, sorption of proteins and other components of milk plasma occurs on the surface of the membrane of fat globules. These two phenomena - desorption and sorption - cause a change in the composition and surface properties of the shells, which leads to a decrease in their strength and partial rupture.

Already during the heat treatment of milk, partial denaturation of membrane proteins occurs, which further reduces the strength of the shells of fat globules. They can collapse quite quickly and as a result of special mechanical stress: during oil production, as well as under the influence of concentrated acids, alkalis, and amyl alcohol.

The stability of the fat emulsion is primarily due to the appearance of an electrical charge on the surface of the fat droplets due to the content of polar groups on the surface of the fat globule shell - phospholipids, COOH, NH 2 (Fig. 2). Thus, a net negative charge is formed on the surface (isoelectric point at pH 4.5). Calcium, magnesium, etc. cations are added to the negatively charged groups. As a result, a second electrical layer is formed, the repulsive forces of which exceed the attractive forces, so separation of the emulsion does not occur. In addition, the fat emulsion is further stabilized by the hydration shell that forms around the polar groups of the membrane components.

The second factor in the stability of a fat emulsion is the formation of a structural-mechanical barrier at the interface, due to the fact that the shells of fat globules have increased viscosity, mechanical strength and elasticity, i.e. properties that prevent the balls from merging. Thus, to ensure the stability of the milk and cream fat emulsion during the production of dairy products, it is necessary to strive to preserve the shells of the fat globules intact and not reduce the degree of their hydration. To do this, it is necessary to reduce to a minimum the mechanical effects on the dispersed phase of milk during transportation, storage and processing, to avoid foaming, and to properly conduct heat treatment, since prolonged exposure at high temperatures can cause significant denaturation of the structural proteins of the shell and a violation of its integrity.

Additional fat dispersion by homogenization stabilizes the fat emulsion. If, when producing some dairy products, the process engineer is faced with the task of preventing the aggregation and opalescence of fat globules, then when producing butter, on the contrary, it is necessary to destroy (demulsify) the stable fat emulsion and separate the dispersed phase from it.

Milk fat differs from other types of fat in that it is easier to digest and absorb. It contains more than 147 fatty acids. Fats of animal and vegetable origin contain

5...7 low molecular weight fatty acids with the number of carbon atoms from 4 to 14.

Milk fat has a pleasant taste and aroma, but under the influence of light, high temperature, oxygen, enzymes, solutions of alkalis and acids, it can acquire an unpleasant odor, rancid taste, and a taste of lard. Such changes occur during hydrolysis, oxidation and rancidity of fat.

Fat hydrolysis is the process of water acting on triglycerides at elevated temperatures, as a result of which triglycerides are broken down into glycerol and fatty acids. Hydrolysis increases the acidity of the fat. The origin and method of obtaining milk fat can influence the rate of hydrolysis. If milk fat is obtained by rendering at 65 °C, then hydrolysis proceeds faster than at 85 °C. Hydrolysis proceeds more slowly at low temperatures (4 °C) and in sealed packaging.

Fat oxidation occurs under the influence of sunlight, elevated temperature or catalysts, as a result of which hydrogen and oxygen are added at the site of double bonds. During the oxidation of milk fat, the fat becomes discolored as a result of the decolorization of carotenoids, and the smell and taste also change. Fat oxidation occurs as a result of the transition of liquid unsaturated acids to solid saturated ones. Rancidity of fat leads to the appearance of a bitter taste and specific odor in milk fat due to the formation of peroxide, aldehydes, etc. The process of rancidity occurs under the influence of enzymes, oxygen, heavy metals, and microorganisms.

All of the listed changes that occur in fat are difficult to differentiate, since they occur together and are accompanied by side processes, therefore, under production conditions, the physicochemical constants of fat are determined, which depend on its quantitative and qualitative composition. These include acid number, Reichert-Meissl number, iodine number (Gübl number), saponification number (Kettstorfer), pour point and boiling point.

Carbohydrates. In milk they are represented by lactose - milk sugar - and consist of carbon, hydrogen and oxygen. Lactose is a disaccharide (C | 2 H 22 O p) and includes residues of two simple sugars - galactose and glucose. The average mass fraction of lactose is 4.7%.

Carbohydrates are necessary for metabolism, heart, liver, and kidney function; are part of enzymes.

Lactose is formed in the glandular tissue of the mammary gland by combining galactose, glucose and water molecules. Lactic sugar is found only in milk. Pure lactose is a white crystalline powder, 5...6 times less sweet than sugar (sucrose). Lactose is less soluble in water than sucrose.

Lactose is present in milk in two forms: ai b, which differ in physical and chemical properties and can transform into one another at a rate that depends on temperature. In a supersaturated solution, lactose forms crystals of more or less regular shape.

Crystalline lactose is obtained from whey. Crystallization of lactose also occurs during the production of sweetened condensed milk.

When milk is heated to temperatures above 150 °C, a reaction occurs between lactose and proteins or some free amino acids. As a result, melanoidins are formed - substances of a dark color, with a pronounced smell and taste. When heated to 110...130°C, lactose loses its water of crystallization, and when heated to 185°C, it caramelizes. The decomposition of milk sugar in solutions begins at temperatures above 100 ° C, and lactic and formic acids are formed.

Under the action of the lactase enzyme, secreted by lactic acid and other bacteria, lactose is broken down into simple sugars. The process of lactose breakdown under the influence of microorganisms is called fermentation. Until the stage of formation of pyruvic acid (C 3 H 4 0 2), all types of fermentation proceed in the same way. Further transformation of the acid occurs in different directions. As a result, various products are formed: acids (lactic, acetic, propionic, butyric, etc.); alcohols (ethyl, butyl, etc.); carbon dioxide, etc.

The following types of fermentation are distinguished: lactic acid, alcoholic, propionic acid, butyric acid.

Lactic acid fermentation is caused by lactic acid bacteria (streptococci and rods). During fermentation, pyruvic acid is reduced to lactic acid. From one sugar molecule four molecules of lactic acid are formed:

After a certain amount of lactic acid accumulates during fermentation, the lactic acid bacteria die. For rods, the limit of lactic acid accumulation is higher than for coccal forms. Lactic acid formed during the fermentation process is of great importance for the coagulation of casein in the production of most fermented milk products - it gives the product a sour taste. The yield of lactic acid depends on the type of lactic acid bacteria included in the starter.

Along with lactic acid, lactic acid fermentation produces volatile acids (formic, propionic, acetic, etc.), alcohols, acetaldehyde, acetone, acetoin, diacetyl, carbon dioxide, etc. Many of them give the finished product a specific fermented milk taste and smell. To improve these properties, in addition to lactic acid bacteria, aroma-forming microorganisms are also used, which form aromatic substances from pyruvic acid - acetoin, acetaldehyde, diacetyl. To accumulate diacetyl, the presence of citric acid is necessary, which is added to milk, which improves the taste and aroma of the product. In the production of fermented milk products, different combinations of lactic acid bacteria, as well as flavoring and aromatic substances, are used.

Alcoholic fermentation is caused by yeast contained in bacterial starter cultures (kefir grains). Under the influence of these starters, pyruvic acid is broken down into acetaldehyde and carbon dioxide. Acetaldehyde is then reduced to ethyl alcohol. As a result, four molecules of alcohol and carbon dioxide are formed from one molecule of lactose:

The resulting products, in which 0.2...3% alcohol accumulates, give fermented milk products (kefir, kumiss, ayran) a sharp, refreshing taste.

Propionic acid fermentation occurs in ripening cheeses under the action of enzymes secreted by propionic acid bacteria. This fermentation begins after the formation of lactic acid in the presence of lactic acid bacteria. The products of propionic acid fermentation include propionic and acetic acids, carbon dioxide, water:

Butyric acid fermentation. This process is caused by spore-forming butyric acid bacteria that secrete enzymes. This type of fermentation is undesirable in the production of fermented milk products. Cheeses acquire an unpleasant taste, smell and swell.

Butyric acid bacteria enter milk from soil, manure, dust and withstand pasteurization. Their presence is the result of non-compliance with sanitary rules for obtaining raw materials.

Minerals. Milk is a constant source of minerals for the body. Depending on their content, they are divided into macro- and microelements. On average, milk contains 0.7% in the form of salts of inorganic and organic acids.

Macroelements. Of this group, calcium, phosphorus, potassium, sodium, magnesium, sulfur and chlorine are important. In milk they are present in the form of inorganic and organic salts (medium and acidic) and in a free state. Acidic salts, along with other substances, determine the acidity of freshly milked milk. The main part of the salts is in milk in the ionic and molecular state, and phosphoric acid salts form colloidal solutions. Average content of macroelements in milk: sodium - 50 mg%, potassium -145, calcium -120, magnesium -13, phosphorus -95, chlorine - 100, sulfate - 10, carbonate -20, citrate (in the form of citric acid residue) - 175 mg%.

The salt composition of milk can be judged by the content and ratio of macroelements. Mostly milk contains potassium, calcium and sodium salts, as well as inorganic and organic acids: phosphoric acids (phosphates), citric acids (citrates), chlorides (chlorides). Calcium ions strengthen the hydration shell, as they are adsorbed on the surface of casein micelles and thereby increase their stability. Phosphates, citrates and carbonates take part in the buffer system of milk.

Calcium is of great importance for milk processing processes. Its content in milk ranges from 112 to 128 mg%. About 22% of all calcium is bound to casein, and the rest is represented by phosphate salts and citrates. The low calcium content in milk causes slow rennet coagulation of casein during the production of cheese and cottage cheese, and its excess causes the coagulation of milk proteins during sterilization. When milk sours, almost all the calcium goes into whey, since under the influence of lactic acid it is split off from the casein complex. The properties and quality of dairy products depend on the calcium content in milk. Calcium plays an important role in the production of processed cheeses. It binds melting salts and passes from calcium caseinate to plastic sodium caseinate. In the latter, the fat emulsifies better, and the characteristic consistency of the cheese is formed. The quality of the resulting condensed milk and the solubility of milk powder in the production of reconstituted milk also depend on the calcium content.

Phosphorus in milk is part of the caseinate calcium phosphate complex. Protein resistance to proteolytic enzymes depends on the phosphorus content. Phosphorus gives stability to the membrane of fat globules. The development of microorganisms in milk in the production of fermented milk products is associated with phosphorus.

Microelements. 19 microelements were found in milk. 1 kg of milk contains approximately (mg): copper -0.067...0.205; manganese-0.1 16...0.365; molybdenum - 0.015...0.090; cobalt-0.001...0.009; zinc - 0.082...2.493; magnesium -84.05... 140; iron - 2.55...77.10; aluminum - 1.27...22.00; nickel-0.017...0.323; lead - 0.017...0.091; tin - 0.004...0.071; silver - 0.0002...0.11; silicon - 1.73...4.85; iodine-0.012...0.020; titanium, chromium, vanadium, antimony and strontium - decimals and traces. The content of microelements in milk depends on the diet, stage of lactation of animals and other factors. Colostrum contains significantly more microelements, such as iron, copper, iodine, cobalt, and zinc, than milk. Microelements are part of vitamins and enzymes.

Microelements play an important role in the human body. Thus, manganese acts as a catalyst in oxidative processes and is necessary for the synthesis of vitamin C, as well as B vitamins! and D. Cobalt is part of vitamin B 12. Iodine stimulates the activity of the thyroid gland. Some trace elements contribute to the formation of defects in milk, as they catalyze chemical reactions. Excessive amounts of copper cause fat to oxidize, giving milk an oxidized taste; its deficiency slows down the process of lactic acid fermentation.

Vitamins. Almost all of the vitamins contained in milk are transferred into it from the feed eaten by animals, and are also synthesized by the rumen microflora. Their number depends on the time of year, breed, and individual characteristics of the animals. Lack or absence of vitamins leads to metabolic disorders and the occurrence of diseases such as rickets, scurvy, vitamin deficiency, etc.

Vitamins serve as regulators of metabolism, since many of them are part of various organic compounds: acids, alcohols, amines, etc. The sensitivity of vitamins to high temperature, acids, oxygen and light has been noted. Most vitamins are soluble in water, some are soluble in fats, ether, chloroform, etc. In this regard, vitamins are divided into water-soluble and fat-soluble.

Water-soluble vitamins include vitamins B, B2, B6, B12, PP, choline and folic acid.

Vitamin B /(thiamine) in its pure form is a white crystalline powder. 1 kg of milk contains about 500 mg of thiamine and its amount depends on the season of the year, as well as on the microflora of the gastrointestinal tract. The vitamin decomposes in alkaline solutions, but is stable in acidic solutions. When drying, up to 10% of thiamine is destroyed, and when thickening, up to 14%.

Vitamin B stimulates the growth of microorganisms, including lactic acid bacteria, as it is a coenzyme of dicarboxylase. In this regard, the amount of this vitamin in fermented milk products increases by 30%. In skim milk, the content of vitamin B increases and reaches 340 mg/kg, in whey - 270, in buttermilk - 350 mg/kg. The daily human need for thiamine is 1...3 mg.

Vitamin B 2(riboflavin) is synthesized in the gastrointestinal tract of the animal. Milk contains 1.6 mg/kg; in colostrum -6; in cheese -3.07 mg/kg; There are traces in the oil. Riboflavin is resistant to high temperatures and pasteurization, in fermented milk products its amount increases to 5% compared to the original milk, and only when dried it becomes less by 10... 15%. Vitamin B2 is part of enzymes and takes part in carbohydrate and protein metabolism; the redox potential of milk depends on it.

Riboflavin gives the greenish-yellow color to whey and the yellow color to raw sugar. With a lack of vitamin B 2, growth retardation, eye diseases, etc. are observed. The daily requirement for vitamin B 2 for adults is 1.2...2 mg.

Vitamin B 3(pantothenic acid) stimulates the development of lactic acid bacteria, is part of coenzyme A, which takes part in the synthesis of fatty acids, styrene and other components. Milk contains 2.7 mg/kg; in whey - 4.4; in buttermilk -4.6; in skim milk -3.6 mg/kg. Vitamin B 3 is destroyed during sterilization.

Vitamin B 6(pyridoxine) is found in milk in a free and protein-bound state. In the free state, its amount in milk is 1.8 mg/kg; in bound - 0.5; in oil -2.6; in condensed milk with sugar -0.33...0.4 mg/kg. Pyridoxine stimulates the growth of microorganisms and is resistant to high temperatures. A lack of vitamin B6 in the body leads to diseases of the nervous system and intestines.

Vitamin B /2(cobalomin) is synthesized by the microflora of the gastrointestinal tract. Content in milk - 3.9 mg/kg. In the spring and summer, milk contains significantly less vitamin B12 than in the autumn. A decrease in the vitamin content also occurs when milk is processed at high temperatures (sterilization); losses can reach 90%. During the production of kefir, the amount of cobalomin is reduced by 10...35% due to the fact that it is used by lactic acid bacteria.

Cobalomin takes part in metabolic processes and catalyzes circulatory reactions.

Vitamin C(ascorbic acid) is a crystalline compound, easily soluble in water to form acidic solutions. Content: in raw milk -3...35 mg/kg; in serum -4.7; in milk powder -2.2; in condensed -3.9; in cheese -1.25 mg/kg.

The vitamin is synthesized in the body, participates in redox processes, inactivates toxins, and improves the absorption of hormones. The lack of vitamin causes gum disease; with a deficiency, the body becomes less resistant to infectious diseases. When raw milk is stored, the vitamin C content decreases significantly. Long-term pasteurization, as well as thickening, reduce the vitamin C content by up to 30%.

Vitamin PP(nicotinic acid, or inacin) is synthesized by intestinal microflora. Raw milk contains 1.51 mg/kg (fluctuations 1.82...1.93 mg/kg). There is a lot of vitamin PP in milk powder - 4.8 mg/kg; in cottage cheese -1.5; in cream -1.0; in sour cream -0.9; in cheese - 0.37 mg/kg. In yogurt it is 27...73% less, and in the production of condensed milk the inacin content decreases by 10%.

Vitamin H(biotin) is resistant to high temperatures during both pasteurization and sterilization. Content in milk is 0.047 mg/kg. In summer, the amount of biotin in milk doubles. When drying and condensing milk, the vitamin content decreases by 10...15%. Biotin has a beneficial effect on the growth of microorganisms (yeast, etc.).

Kholin is part of the lecithin-protein shell of the fat globule. Contents: in milk - 60...480 mg/kg, in colostrum - 2.5 times more, in dry milk - 1500, in cheese - 500 mg/kg. Choline is unstable to high temperatures; during pasteurization, losses reach 15%. During the production of fermented milk products, the choline content in yogurt increases by 37%, in kefir - by 2 times.

Folic acid contained in raw milk in an amount of 0.5...2.6 mg/kg. It is synthesized by lactic acid bacteria, so the content of folic acid in fermented milk products increases by 50%. Pasteurized milk contains 6...7% more folic acid than raw milk (due to the release of bound forms of the vitamin).

Fat-soluble vitamins include vitamins A, D, K, E and F.

Vitamin A(retinol) is formed in the liver of animals from provitamin (L-carotene) supplied with feed under the action of carotinase. When one molecule of carotene is broken down, two molecules of vitamin A are formed, which enters first into the blood and then into milk. Thus, the vitamin A content in milk depends entirely on the carotene content in feed.

In the spring-summer period, more carotene is supplied with feed than in the autumn-winter period.

Raw milk contains 0.15 mg/kg of vitamin A, colostrum contains 5...10 times more, and butter contains 4 mg/kg. In pasteurized powdered milk, spray-dried and during storage, the vitamin A content is reduced to 15%, and in fermented milk products it increases to 33%.

Lack of the vitamin causes eye damage (“night blindness”) and dry cornea. The presence of vitamin A in the diet increases the body's resistance to infectious diseases, promotes the growth of young animals, etc. The daily human need for vitamin A is 1.5...2.5 mg.

Vitamin D(calciferol) is formed under the influence of ultraviolet rays. Milk contains an average of 0.5 mg/kg; in colostrum - 2.125 mg/kg on the first day and 1.2 mg/kg on the second; in ghee - 2.0...8.5; in sweet cream butter (summer) - up to 2.5 mg/kg. Keeping cows on pasture increases the amount of vitamin D.

The vitamin takes part in mineral metabolism, i.e. in the exchange of calcium salts. With a prolonged lack of vitamin D, bones become soft, brittle, and rickets occurs.

Vitamin E(tocopherol) is an antioxidant in milk fat and promotes better absorption of vitamin A. The content in milk depends on its content in the feed. In milk it is 0.6...1.23 mg/kg; in oil -3.4...4.1; in milk powder - 6.2; in colostrum - 4.5; in sour cream -3.0; in yogurt -0.6 mg/kg. When cows are kept on pasture, the amount of vitamin E increases, and when cows are kept in stalls, it decreases. By the end of lactation, the tocopherol content in milk reaches 3.0 mg/kg. Long-term storage of milk at temperatures below 10 °C leads to a decrease in vitamin content.

Vitamin K synthesized by green plants and some microorganisms, its biological activity is similar to vitamin E.

Vitamin F normalizes fat and water metabolism, prevents liver diseases and dermatitis. Milk contains approximately 1.6...2.0 mg/kg.

Enzymes. Milk contains various biological catalysts - enzymes that accelerate chemical reactions and help break down large molecules of nutrients into simpler ones. The action of enzymes is strictly specific. They are sensitive to temperature changes and environmental reactions. Milk contains more than 20 true, or native, enzymes, as well as enzymes that are produced by microorganisms that enter the milk. One part of native enzymes is formed in the cells of the mammary gland (phosphatase, etc.), the other passes from the blood into milk (peroxidase, catalase, etc.) The content of native enzymes in milk is constant, but their increase indicates a violation of secretion. The amount of enzymes produced by bacteria depends on the degree of contamination of the milk.

Enzymes are divided into groups depending on their specific action on various substrates: hydrolases and phosphorylases; digestion enzymes; redox.

Among hydrolases and phosphorylases, lipase, phosphatase, protease, carbohydrase, etc. are of greatest interest for dairy production.

Lipase catalyzes the hydrolysis of milk fat triglycerides, releasing fatty acids. Milk contains native and bacterial lipases. There is more bacterial lipase, less native lipase.

Native lipase is associated with casein, and a small part of it is adsorbed on the surface of the membranes of fat globules. The milk fat of fresh milk is usually not spontaneously affected by lipase.

The hydrolysis of fat by lipase is called lipolysis. Lipolysis of milk occurs under mechanical influence (homogenization, pumping milk, strong stirring, as well as freezing and thawing, rapid temperature changes).

A highly active bacterial lipase produced by molds and bacteria that can cause milk, butter and other foods to taste rancid.

Native lipase is inactivated at a pasteurization temperature of 80 °C, while bacterial lipase is more resistant to high temperatures.

Protease- the result of the vital activity of lactic acid bacteria. This enzyme is active at 37...42 °C, destroyed at 70 °C for 10 minutes or at 90 °C for 5 minutes. There is a lot of protease in cheeses, which is formed in them during the ripening process. It gives cheeses a characteristic taste and smell, but in milk and butter it can cause taste defects.

Carbohydrases include amylase and lactase. Amylase is produced by glandular tissue cells and from them enters the milk. There is a lot of it in the first portions of colostrum, and the amount of amylase increases during inflammation of the mammary gland. The enzyme is not resistant to high temperatures. At a temperature of 65 ° C it is destroyed within 30 minutes. It is believed that glycogen is converted into lactase in the mammary gland.

Phosphotase synthesized by secretory cells of the udder and some milk microorganisms. It catalyzes the elimination of phosphoric acid residues from phosphorus esters. Milk contains acid and alkaline phosphatases. There is more of the latter, and it enters the milk from the mammary gland cells. Alkaline phosphatase is sensitive to heat; it is completely destroyed when milk is heated to 74 ° C and with an exposure of 15...20 s. This property of phosphatase underlies the method for monitoring the effectiveness of milk pasteurization. Acid phosphatase is resistant to heat and is destroyed when milk is heated above 100 °C.

Of the digestion enzymes, the one of greatest interest for the dairy industry is catalase. In milk it is formed from the secretory cells of the mammary gland and as a result of the activity of putrefactive bacteria. Lactic acid bacteria do not produce catalase. When hydrogen peroxide is added, it is decomposed by catalase into molecular oxygen and water.

Catalase is identified by adding hydrogen peroxide to milk.

Redox enzymes include reductase and peroxidase. With their help, the quality of milk and the results of pasteurization are determined.

Reductase unlike other enzymes, it is secreted only by microorganisms and is a product of their vital activity. The mammary gland does not synthesize reductase. Aseptic milk does not contain reductase, so its presence indicates bacterial contamination of the product.

The quality of milk is assessed using the reductase test. There are very few microbes in freshly milked milk. As they accumulate, the reductase content increases. When a redox dye (methylene blue or resazurin) is added to milk, it is reduced: the more enzyme there is in the milk, the faster it becomes discolored.

Peroxidase is produced by the mammary gland and is used to determine the pasteurization of milk.

Hormones. They are necessary for the normal functioning of the body, as well as for regulating the formation and secretion of milk, into which they enter from the blood.

Prolactin stimulates milk secretion and is produced by the anterior pituitary gland.

Luteosterone inhibits the action of prolactin and milk secretion, is a hormone of the corpus luteum, and is activated during deep pregnancy of lactating animals.

Folliculin stimulates the development of glandular tissue of the udder in first-calf heifers and dry cows, and is formed in the ovarian tissue.

Thyroxine is a thyroid hormone. Regulates fat, protein and carbohydrate metabolism in the body, contains iodine. Milk also contains other hormones: insulin (pancreatic hormone), adrenaline (adrenal hormone), etc.

Pigments. These include carotenoids, which provide the creamy color of milk. Their content in milk depends on the season of the year, feed, and breed of cows.

Immune bodies. Immune bodies include agglutinins, antitoxins, oxonins, precipitins, etc. Colostrum contains much more of them than milk. The bacterial and bactericidal properties of milk depend to some extent on immune bodies. The milk of animals that have suffered from any disease contains more immune bodies than the milk of healthy ones. The content of immune bodies in colostrum provides the calf with immunity.

Gases. Freshly milked milk contains gases, including carbon dioxide, which are present in the blood of animals. They are easily adsorbed during milking, processing and storage. Oxygen in milk - 5.. L 0%, nitrogen - 20...30, carbon dioxide - 55...70%. The latter dissolves in plasma and is one of the components that ensure its acidity. At the moment of filtering milk through filters, the oxygen content increases to 25%, nitrogen - up to 50%, carbon dioxide - decreases to 25%. When heated, the amount of gases in milk decreases.

The nutritional value of milk and products prepared on its basis determines its importance in children's and dietary nutrition. By including such food in your diet, you will saturate your body with calcium and other valuable substances. Milk makes a person healthier and more beautiful.

What is the nutritional value?

If you are interested in certain characteristics of products, you should know for sure what they mean. Thus, nutritional value is a complete list of properties that satisfy the physiological needs of the body. Most often, this concept refers to the content of proteins, fats and carbohydrates in every 100 grams of product.

It is also worth noting the importance of such an indicator as biological value. It characterizes the compliance of amino acids with the needs of the human body. Speaking about energy value, it is worth noting that this is the number of calories that are released during the processing of the product by the body.

Milk: chemical composition and nutritional value

Milk is the first human food, which provides the body with everything it needs from birth. Thanks to its rich chemical composition, it is possible to maintain the active functioning of the body. So, milk contains the following substances:

• proteins;
• fats;
• milk sugar;
• mineral salts;
• water.

It is worth noting that this is a basic set of components that cannot fully characterize milk. The chemical composition and nutritional value can vary greatly depending on the origin of the product and how it is processed.

If we take a closer look at the proteins contained in milk, they are represented by albumin, globulin and casein. The latter is involved in the formation of glycopolymacropeptide, which increases the digestibility of other components. All proteins are easy to absorb and contain all the amino acids necessary for the body.

Fats in milk are contained in the form of tiny particles. They form everyone's favorite cream. Milk fat is 96% absorbed by the body, which is due to its high dispersion. Its content in the product depends on the season (in summer this indicator decreases), as well as the quality of care for the animal.

Considering such an indicator as the nutritional and energy value of milk, one cannot help but mention the carbohydrate component. It is represented by lactose. It is the presence of this component that makes it possible to prepare fermented milk products.

The nutritional value of milk is determined by the increased content of vitamins. The main ones are A and B. Ascorbic acid, nicotinic acid, riboflavin and thiamine are present in small quantities. The highest concentration of vitamins in milk is observed in the summer. This indicator may also be affected by the processing method and storage conditions.

More about vitamins

As already mentioned, the nutritional value of milk and dairy products is largely due to the high content of vitamins in them. So, if we take a closer look at the chemical composition, we can note the presence of the following useful components in it:

Vitamin	Benefit	Where is it contained?
IN 1	Takes part in metabolism, normalizes the functioning of the nervous system and heart muscle, improves the condition of the skin and hair.
AT 2	Takes part in protein and carbohydrate metabolism.	Milk, dairy products, cheeses, whey and cream
AT 3	Regulates fat metabolism and also activates the synthesis of amino acids.
AT 6	Promotes lipid and protein metabolism.	Milk
AT 12	Strengthens the immune system, reduces the risk of tumor formation, and increases the body's resistance to radiation.	Milk and cheeses
A	Improves the functional state of tissues.	Milk and dairy products

Different types of milk

The nutritional value of milk is largely determined by its origin. Thus, deer is considered the most nutritious. The concentration of proteins and fats reaches 11% and 20%, respectively. As for the vitamin component, it is three times more saturated than in the case of cow's milk.

The nutritional value of milk is largely determined by the nature of the proteins it contains. Thus, most farm animals (including cows and goats) produce casein milk. And, for example, mare and donkey are albuminous. Since its composition is most similar to mother's milk, such milk is an ideal substitute for feeding infants. Albumin particles are several times smaller than casein, and therefore we can talk about its good digestibility.

Whole milk

Despite the fact that milk is one of the most common products that is familiar from childhood, not everyone thinks that there are several types that are characterized by certain indicators. So, first you should pay attention to whole milk. The nutritional value, in this case, will be the highest, because the product has not been subjected to any processing. An exception may be the straining process, which is carried out immediately after milking.

Whole milk contains the largest amount of vitamins and microelements. There is also a high concentration of calcium, which is almost completely absorbed by the body. This product is credited with strengthening the immune system, normalizing the functioning of the nervous system, eliminating heartburn, and accelerating metabolism.

However, there are a number of skepticisms regarding whole milk. Given its high fat content, it is not suitable for feeding children. And even in adulthood, not everyone tolerates this product well. Thus, according to the latest data, a sixth of the world's population suffers from lactose intolerance. Whole milk is an allergen and can also cause dangerous infections.

Skimmed milk

The desire to be slim makes people buy products labeled “0% fat.” This trend has also affected milk. The amount of fat in it does not exceed 0.1%. In fact, this is the so-called skim milk, which is obtained by separating cream from milk. It may be of interest to consumers that most of this milk is not sent to store shelves, but back to farms to feed animals.

You should not place high hopes on a product such as skim milk. Its nutritional value is negligible. Carbohydrates and proteins, respectively, 5% and 3%. Calorie content is characterized by 35 kcal. Moreover, such milk is characterized by a rich vitamin and mineral composition. However, doctors do not recommend using it on an ongoing basis.

It is worth paying attention to the manufacturing process. The nutritional value of dry, skim milk is significantly reduced during processing. When the fat component is removed, vitamins A and D are almost completely removed from the product. Thus, the proteins and calcium that remain in the milk are not absorbed by the body. With frequent consumption of skim and powdered milk, the body's own resources are depleted.

Powdered milk: nutritional value

In a big city it is not always possible to find a natural product. In addition, people strive to give known substances a more convenient form, for example, a powder. A good example is powdered milk. The nutritional value of this product is the same as the original. But for this you need to prepare the so-called reconstituted milk. To do this, the powder is diluted in water (1:7). At the same time, it is quite possible to make homemade kefir, cottage cheese and other healthy products from such milk.

The nutritional and biological value of milk is preserved thanks to a special manufacturing technology. Drying is quick and the temperature does not exceed 40 degrees. Thus, all useful substances are preserved. And thanks to the low moisture content (no more than 6%), long-term storage of the product is ensured.

Nutritional value of condensed milk

It is worth admitting that few people are interested in such a question as nutritional value. For most people, this is a favorite delicacy. Nevertheless, condensed milk is not only tasty, but also a very healthy product. To begin with, it is worth noting the high protein content in this product. Its concentration can reach 35%.

Essentially, condensed milk is evaporated cow's milk. The nutritional value of the final product is slightly lower, but overall it is no less healthy. Condensed milk is completely absorbed by the body, saturating it with calcium and phosphorus. Thus, by regularly consuming this product, you can strengthen the health of your bones, eyes and enhance mental activity.

However, condensed milk should not be overused. The fact is that it contains a significant amount of sugar, which results in a high calorie content (328 kcal) and a significant carbohydrate component (55.5 g). A large amount of the product contributes to the development of obesity, diabetes and caries.

Dairy products

The composition and nutritional value of milk make this product one of the most popular. Nevertheless, few people like it in its pure form. Most people prefer fermented milk products. They not only preserve the benefits of milk, but also have a beneficial effect on the functioning of the digestive system. So, you should especially pay attention to the following products:

• Kefir is prepared from pasteurized milk. A special starter is added to it, after which the fermentation process begins. The nutritional value of this product depends entirely on the quality of the milk. If a whole product is used, then the protein component accounts for almost 3%, the concentration of fats is 3%, and carbohydrates are 4%.
• prepared from a pasteurized product using bacterial cultures. It will contain approximately equal amounts of fat and carbohydrates (about 3%) and 10% carbohydrates. Given the low acidity of the product, it is actively used in artificial feeding of children.
• "Belact" is also a fermented milk product produced using bacteria. It is characterized by a high content of enzymes. Another feature of the product is the presence of substances that resemble antibiotics in their properties.
• "Narine" is a fermented milk product that came to us from Armenia. There it is actively used for feeding infants. Thanks to the special bacteria contained in the sourdough, the acidity level is quite low. And when it enters the body, “Narine” activates the production of a substance that suppresses pathogenic microbes. Proteins and fats in the product account for 3% and 4%, respectively, and carbohydrates - just over 6%.
• Kumis is traditionally made from mare's milk. Nevertheless, there are recipes adapted for cow's milk. A starter culture that contains bacteria and yeast is added to the milk. The nutritional value largely depends on the quality of the base and the degree of ripeness. It can contain up to 3% proteins, up to 1% fats and 6% carbohydrates. The product is good for digestion and also has a general strengthening effect.
• Yogurt is not just a popular fermented milk product, but also a favorite delicacy. In ancient times, it was prepared exclusively from To obtain yogurt, you need to add the so-called Bulgarian stick to the base. On average, the calorie content of the finished product is 57 kcal. It contains 4%, 2% and 6% of proteins, fats and carbohydrates, respectively. These indicators may vary depending on the type of milk and processing method. It is worth noting that only pure yogurt, which does not contain dyes or flavoring additives, has exceptional benefits.

Other Popular Products

Since ancient times, people have been interested in such a question as the nutritional value of milk. A great variety of dairy products are prepared on its basis. However, there are a number of popular ones that are almost always present on the table, namely:

• Cottage cheese is one of the most valuable food products, which is characterized by a high protein content (about 14%). Its preparation is based on the processes Cottage cheese is characterized by high acidity. But this indicator decreases with increasing fat content of the product.
• The cheese making process is based on the precipitation of casein. Depending on how the milk is processed, the product can be hard, soft, brine or processed. The protein component can reach 30% (as well as fat).
• Sour cream is a product made from pasteurized cream. It is quite fatty (this figure can reach 40%).

Milk quality

The high nutritional value of milk proteins determines the popularity of this product. Nevertheless, only what is of high quality is useful for the body. The characteristics of milk largely depend on how the processing was carried out.

The milk that arrives at the plant is first checked for organoleptic indicators. If it turns out to meet the standards, it is carefully filtered to remove foreign impurities. Next, the fat content is normalized by adding skim milk or cream.

The most important stages are pasteurization and sterilization. These processes are necessary to destroy pathogens, as well as a number of enzymes. Thus, it is possible to obtain a safe product that is characterized by long-term storage.

Pasteurization is carried out by prolonged heating. As a result, the milk changes its natural taste. It is also worth noting the decrease in calcium concentration in the product.

Is milk dangerous for humans?

The nutritional and biological value of milk makes this product one of the most useful. However, it is worth mentioning the danger it poses. Milk can serve as a source of dangerous infectious diseases. In this case, viruses can enter the product from an animal and during processing.

Viruses can be contained not only in milk, but also in products prepared from it. At the same time, the incubation period of bacteria increases. Thus, the most dangerous diseases transmitted through milk are the following:

• Foot and mouth disease is a viral disease that affects the mucous membrane and respiratory tract. It appears in the form of blisters and ulcers. The virus of this disease is resistant to heat. To get rid of it, you need to boil the milk for at least 5 minutes.
• Brucellosis is a disease that affects almost all body systems. Its danger lies in the fact that at the initial stage it is practically asymptomatic. Milk from animals infected with brucellosis is subjected to prolonged boiling followed by pasteurization.
• Tuberculosis primarily affects the respiratory system. If such an infection is detected in an animal, then milk is strictly prohibited from being consumed.
• Other dangerous infections are anthrax, rabies, hepatitis, plague and others. Animals with such diseases are subject to destruction with the obligatory presence of a sanitary doctor.

Conclusion

From the very first days of a person’s life, it is milk that supplies the body with all the necessary nutrients and vitamins. Thus, the benefits of this product are undeniable. To maintain bones, digestive, nervous and other systems of the body in optimal condition, milk simply must be present in the diet. It is important to choose a quality product, and treat whole or low-fat products with caution.

At the moment, there is a wide range of dairy products on the market, which are also characterized by high nutritional value. Among them you can often find many copies marked “Farm” or “Rustic”. Contrary to fashion trends, such products should be treated with special caution, because milk that has not been subjected to heat treatment and pasteurization may contain viruses that are dangerous to humans.