Veterinary and sanitary control of milk quality. Veterinary rules for conducting veterinary and sanitary examination of milk and dairy products

Ural State Academy of Veterinary Medicine

Department: Veterinary sanitary examination

Course work

Veterinary and sanitary examination of milk

Troitsk, 2009

Introduction. 3

Veterinary and sanitary rules for milk production technology. General provisions. 4

Construction and equipment of premises and territory of dairy farms.. 6

Veterinary and sanitary requirements for milking cows. eleven

Primary processing, storage and transportation of milk. 12

Personal hygiene rules for farm workers.. 15

Veterinary and sanitary control of milk quality in complexes and farms. physico-chemical methods for determining the quality of milk. 17

Organoleptic examination of milk. 18

Determination of the percentage of fat in milk. 21

Determination of milk acidity. 22

Determination of milk purity. 24

Checking the quality of milk pasteurization. 25

Determination of the class of milk. 26

Microbiological analysis of milk. 28

Express methods for detecting E. coli and salmonella bacteria in milk and equipment. 29

Indication of staphylococci in milk. 31

Sanitary assessment of milk for animal diseases. 32

Prevention of cow mastitis in dairy complexes and farms 34

List of used literature... 41

Introduction

The importance of milk in human nutrition.

Milk is one of the most valuable food products. It contains about 200 substances vital for humans and young animals. The main ones are proteins, fat, milk sugar and mineral salts. Milk proteins contain 20 amino acids, including tryptophan, lysine, methionine, lecithin and others, which are essential. Milk contains 25 fatty acids, most of which are unsaturated and therefore easily absorbed by the human body. Milk sugar (lactose) is only slightly fermented in the intestines and is almost completely absorbed. Mineral salts are widely represented in milk: calcium, potassium, sodium, magnesium, phosphorus, sulfur and others, necessary for the normal flow of basic life processes in the body,

In total, milk contains 45 mineral salts and trace elements. Milk contains both fat-soluble vitamins - A, D. E, and water-soluble vitamins - C, P, B1, B2, B6, B12 and others that regulate metabolism. It is very important that the numerous components of milk are in a strictly interconnected relationship, which is important in the life of the body. Pure fresh milk from a healthy cow has bacteriostatic properties. If freshly milked pure milk is cooled to 3-4°, then it retains these properties for up to 1.5 days, and at a temperature of 10° - 24 hours. Lactic acid products made from milk (yogurt, kefir, cottage cheese, etc.) are antagonists of putrefactive intestinal microflora and are irreplaceable as dietary products.

Meanwhile, milk, if the sanitary conditions of milking, primary processing, storage and transportation are violated, as well as if cows are sick, can become contaminated with pathogenic and toxicogenic microflora, which poses a danger to people and young animals.

Veterinary and sanitary rules for milk production technology. General provisions

The entire herd of dairy cows (buffaloes, camels, mares) must be under the constant supervision of a veterinarian or paramedic and be examined for brucellosis, tuberculosis, and, if necessary, for other diseases at the optimal time using methods provided for by the relevant regulatory documents of the Ministry of Agriculture of the Russian Federation.

In order to prevent infectious animal diseases, farm managers are obliged to ensure compliance with zootechnical and veterinary rules and timely implementation of other measures provided for by the Veterinary Legislation of the Russian Federation.

To supply children's institutions (pioneer camps, children's dairy kitchens) directly from the farm, it is allowed to use milk obtained only from healthy animals. For this purpose, farms that are free from infectious animal diseases are identified, which are located within a radius of no more than 25-30 km from the place of consumption of this milk, near highways and highways. Milk supplies through other direct connections are decided on site in agreement with the veterinary and sanitary-epidemiological services. All cows allocated to supply milk to children's institutions are subject to mandatory veterinary examination twice a month and testing for brucellosis and tuberculosis at least twice a year, and for mastitis once a month. The results and measures taken are recorded in a log. A certificate on the welfare of animals on the farm is submitted to the chief veterinarian of the district on a monthly basis.

In farms affected by infectious diseases of cattle, measures are taken to ensure complete recovery of the herd from these diseases in a short time. Before eliminating the disease, when deciding on the use of milk for food and its release from the farm, one should be guided by the instructions set out in paragraphs 1.5-1.10 of these Rules and the corresponding instructions for the fight against infectious diseases.

If a disease is suspected in livestock, the farm manager or foreman is obliged to immediately isolate the sick animals and notify the veterinary specialist serving the farm.

Milk from sick cows must be poured into a separate container. It is prohibited to use this milk for food or animal feed and donate it to milk processing plants until a diagnosis of the disease has been established.

In case of livestock illness with contagious diseases transmitted from animals to humans, veterinary workers are obliged to prohibit the export of milk from the farm, its use within the farm until the diagnosis is clarified and require the implementation of measures in accordance with existing instructions to combat these diseases, at the same time inform the territorial sanitary and epidemiological service about this .

It is prohibited to use or feed milk to animals from cows suffering from anthrax, emphysematous carbuncle, rabies, malignant edema, leptospirosis, plague, general pneumonia, Q fever, as well as when the udder is affected by actinomycosis, necrobacteriosis, and in other cases provided for instructions. After boiling for 30 minutes, such milk must be destroyed.

Milk from cows sick or suspected of having tuberculosis, brucellosis and leukemia is used in accordance with current instructions on measures for the prevention and elimination of animal tuberculosis, on measures for the prevention and elimination of animal brucellosis, on measures to combat leukemia in cattle.

Milk from the affected quarters of the udder of animals with mastitis must be destroyed after boiling. Milk from the unaffected quarters of the udder of the same animals is subjected to thermal disinfection (boiling or pasteurization for 20 s at 76 °C) and used for feeding young farm animals.

Milk from cows treated with antibiotics should be used in accordance with current guidelines for the control of bovine mastitis.

To identify animals with mastitis, all cows on the farm must be clinically examined daily during milking and, once a month, milk samples from each lobe of the udder must be examined in accordance with current recommendations for the control of cow mastitis or from the milk yield of each cow in accordance with current instructions for the use of a 10% solution of mastidine. The results are presented to the chief veterinarian of the district on a monthly basis.

Cow's milk supplied by farms in all respects must meet the requirements of GOST 13264-70 "Cow's milk. Requirements for procurement."

It is prohibited to donate milk obtained from cows during the first 7 days after calving and for the same period until the end of lactation. It is used for fattening young animals.

Milk, dairy products, containers of individual farms must meet the requirements set out in the current rules for veterinary and sanitary examination of milk and dairy products in markets.

Construction and equipment of premises and territory of dairy farms

The construction of new and reconstruction (re-equipment) of existing cowsheds, dairy, milking, maternity wards, calf barns and other premises of a dairy farm must be carried out in accordance with all-Union standards for the technological design of cattle enterprises (ONTP 1-77) (M. 1979) and all-Union standards technological design of veterinary facilities for livestock, fur and poultry enterprises (ONTP 8-85) (M., 1986) in compliance with the sanitary requirements provided for therein. Dairy containers must be made from materials approved by the Ministry of Health of the Russian Federation for these purposes.

A mandatory facility on every livestock farm is a sanitary passage built according to a standard design.

To receive and store milk on the farm, it is planned to build a dairy (an isolated room in a barn or a separate building) with rooms for primary processing and temporary storage of milk, for sanitizing milking equipment, storing and preparing detergents and disinfectants. A separate room for milk research (laboratory) is provided in the dairy.

To ensure the proper sanitary condition of livestock and milking premises, it is necessary to constantly monitor their cleanliness, landscaping of the territory of farms, walking areas, entrances to barns, calf barns, milking rooms and dairy.

The farm should be surrounded by a fence and a strip of green space. The territory free from buildings is also landscaped and landscaped.

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Introduction

. Literature review

1. Composition of milk

2. Sampling

4. Determination of fat in milk

6. Determination of milk purity

9. Rapid methods for detecting E. coli and salmonella bacteria in milk and equipment

10. Indication of staphylococci in milk

.Own research

1. Purpose of the work

2. Objectives

3. Material for research

4. Methods

5. Research results

6. Conclusions

Introduction

Milk is one of the most valuable food products. It contains about 200 substances vital for humans and young animals. The main ones are proteins, fat, milk sugar and mineral salts. Milk proteins contain 20 amino acids, including tryptophan, lysine, methionine, lecithin and others, which are essential. Milk contains 25 fatty acids, most of which are unsaturated and, therefore, easily absorbed by the human body. Milk sugar (lactose) is only slightly fermented in the intestines and is almost completely absorbed. Mineral salts are widely represented in milk: calcium, potassium, sodium, magnesium, phosphorus, sulfur and others, necessary for the normal flow of basic life processes in the body.

In total, milk contains 45 mineral salts and trace elements. Milk contains both fat-soluble vitamins - A, D, E, and water-soluble vitamins - C, P, B1, B2, B6, B12 and others that regulate metabolism. It is very important that the numerous components of milk are in a strictly interconnected relationship, which is important in the life of the body. Pure fresh milk from a healthy cow has bacteriostatic properties. If freshly milked pure milk is cooled to 3-4°, then it retains these properties for up to 1.5 days, and at a temperature of 10° - 24 hours. Lactic acid products made from milk (yogurt, kefir, cottage cheese, etc.) are antagonists of putrefactive intestinal microflora and are irreplaceable as dietary products.

Meanwhile, milk, if the sanitary conditions of milking, primary processing, storage and transportation are violated, as well as if cows are sick, can become contaminated with pathogenic and toxicogenic microflora, which poses a danger to people and young animals.

Therefore, one of the most important tasks of the veterinary service is proper organization veterinary and sanitary examination of milk, in order to control their quality and safety at all stages (receipt, transportation, processing, storage and sale).

Literature review

1. Composition of milk

milk pasteurization bacteria

The complex chemical composition and the reciprocity of individual components determine specific properties, high nutritional and biological value milk.

Milk from farm animals is valuable food product. Most widespread cow's milk and its processed products are included in people's diets, as they contain all necessary substances in a form that is easily absorbed by the body.

It contains proteins, milk fat, milk sugar, salts, microelements, and vitamins. In total, milk contains more than 90 different substances: 20 amino acids, 20 fatty acids, 25 mineral salts, 12 vitamins, 20 enzymes, milk sugar, etc.

The components of milk are formed from those substances that enter the mammary gland with the blood in the form of precursors: milk sugar - from glucose and galactose; protein from amino acids; fat - from glycerol and fatty acids found in feed.

The composition of the main components of cow's milk ranges from: protein - 2.7 - 3.7%, fat - 2.7-6.0%, milk sugar - 4.0 - 5.6%, minerals - 0.6 - 0.85%

Milk proteins: casein (2.7%), lactalbumins (0.4%), lactoglobulins (0.1%), enzymes, low molecular weight proteins, proteases and peptones. Milk fat, a mixture of various triglycerides in which substances with high biological activity (fat-soluble vitamins, etc.) are dissolved, contains more than 40 fatty acids. The main carbohydrate in milk is lactose (milk sugar), which is easily fermented by lactic acid microflora. Fresh milk contains all the vitamins and microelements necessary for the normal functioning of the body.

Milk is a high-calorie product, per 100 g whole milk contains 58 kcal.

The production of milk and dairy products is one of the most important sectors of human activity in all developed countries of the world, since this product is an important component nutrition for people of all ages. Milk proteins are especially valuable because they contain all the essential amino acids.

Milk water is presented in the form of free, bound and crystallization. Water is an important component of milk (81.4 - 89.7%). Lactose, acids, minerals, and water-soluble vitamins are dissolved in water.

Table 1

Chemical composition cow's milk

Name of components
	average	Oscillation limits

Solids

Phosphatides


Including:

Albumen
Globulin
Other proteins

Milk sugar (lactose)
Minerals
Including:
Salts of inorganic acids
Salts of organic acids
Vitamins (A, B1, B2, C, D, E, PP), µ/kg
Enzymes
Pigments

Milk fat serves as a source of energy for humans and animals. It's a mixture esters glycerol and fatty acids (neutral fat), in which fat-like substances, vitamins and other important organic compounds are dissolved. In milk, fat is presented in the form of fat globules - coated fat particles consisting of proteins and phospholipids. In 1 ml of whole cow's milk, the number of fat globules ranges from 1 to 12 billion (on average 3-5). Their number changes sharply during the lactation period. With prolonged shaking, the fat globules are knocked together into a homogeneous mass, forming butter. When milk is stored, the fat globules gradually float to the surface, resulting in a layer of cream forming at the top of the container.

Fatty acids determine the physical and chemical properties of milk fat, based on which the nutritional value and quality of the product are judged.

Minerals (about 0.7%) are necessary to maintain balance in tissues between alkalis and acids. They are needed for the formation of blood elements, growth of bones, cartilage, synthesis of enzymes and hormones.

The total amount of minerals in milk is determined by the size of the ash residue. On average, the amount of ash residue is 0.7%. The macroelements Ca, Mg, Ka, Fe, K, P, S, and C1 were found in significant quantities in the milk ash residue. Cu, Mn, Co, I, Zn, Rb, Al, Cr, Li, N1 and other elements were found in small quantities.

On average, cow's milk contains about 1% minerals, which include more than 50 macro- and microelements. Minerals are found in milk, mainly in the form of salts of inorganic and organic acids (lactic, phosphoric, citric, etc.). Minerals participate in the formation of nutritional and biological value, the thermal stability of milk, its technological properties, and stabilize the colloidal state of proteins. They are part of enzymes and vitamins.

Milk vitamins

Of the fat-soluble vitamins, milk contains vitamins A, D, E and K.

Milk is the most important source of vitamins. A person’s need for B complex vitamins (B2 or B12) is fully satisfied, and vitamins A, B1, D, folic and pantothenic acid can be satisfied to a large extent through milk and dairy products. Properties and composition of milk, and therefore its nutritional value- are fickle. They depend on the type of animal, its breed, age, conditions of detention, period and stage of lactation, nature of feeding, etc.

Properties of milk

Physical properties:

They are characterized by organoleptic indicators of milk (color, consistency, smell, taste), density, viscosity, osmotic pressure, freezing point, etc. When examining milk, they are of particular importance organoleptic indicators and density.

Whole fresh milk - homogeneous liquid white or yellowish-white in color, with a pleasant, slightly sweetish taste and a specific smell. When defatted, the color becomes bluish-white and the taste deteriorates. A decrease in protein content leads to a watery taste. Old milk has a specific salty taste.

Density is a value that shows how much the mass of milk at a temperature of 20°C is greater than the mass of distilled water at a temperature of 4°C. it is determined by a set of density indicators components milk, g/cm: water-1, fat-0.92, lactose-1.6, proteins-1.3, salts-2.8. When the ratio of milk components changes, its density also changes.

It ranges from 1.027 to 1.033 g/cm. For an objective assessment, density should be measured periodically natural milk. With an increase in the fat content in milk, the density decreases; on the contrary, with an increase in the amount of dry fat-free substances, it increases.

The density of fresh milk is slightly lower (by 0.001 - 0.002 g/cm) than that of cooled milk, which is associated with the transition of fat from a liquid to a solid state and, to some extent, with a decrease in the gas content in milk.

Milk whose density is below 1.027 g/cm3 is considered abnormal; it is either diluted with water or obtained from sick cows. The naturalness of milk is determined by the density indicator. When water is added, the density of milk decreases, and when fat is removed or added skim milk- increases. Since if 3% water is added to milk, its density decreases by 0.001 g/cm. In addition, the density indicator is used to recalculate the volume of milk by weight (to do this, the number of liters is multiplied by the density, and vice versa). When assessing the quality of milk, indicators of other physical properties, so when water is added to milk, the value of osmotic pressure, viscosity, and boiling point decreases. In milk obtained from sick animals, electrical conductivity increases, osmotic pressure, viscosity, etc. change.

Chemical properties:

Characterized by general and active acidity, and each has its own significance in assessing the quality of the product.

Total (titratable) acidity is mainly used as an indicator of milk freshness. It is expressed in degrees Turner (T) - number ml 0.1 n. sodium hydroxide solution required to neutralize 100 ml of milk diluted with twice the amount of water. One ml of 0.1 N used. sodium hydroxide solution corresponds to one Turner degree of milk acidity.

The acidity of freshly milked milk is 16-18 T. It is caused by acidic salts, casein and carbon dioxin. The more of these components it contains, the higher the acidity of freshly milked milk. Total acidity depends on the feed used, the lactation period, etc. Thus, the presence of sour herbs, sour pulp, and an increased amount of concentrates in the diet leads to an increase in the acidity of milk.

Milk with acidity below 15T is considered abnormal and is not used for food. It is believed to be obtained from diseased animals or adulterated by the addition of water. During storage, the acidity of milk increases due to the accumulation of lactic acid as a result of lactose fermentation.

According to GOST 3624-92, dairy industry enterprises accept milk with an acidity of no more than 20T. if the acidity is below 16T. milk is not allowed to be sold until the reason for its decrease is clarified. If the decrease is due to feed factors, then, as an exception, the sale of milk with an acidity of 14T is allowed.

Active acidity (pH indicator) is determined by the degree of dissociation of acids and their salts. A decrease in total acidity does not affect the pH value, which is associated with the buffering properties of milk. It has great importance in the dairy industry, since lactic acid bacteria remain viable even with a significant increase in total acidity, but a change in pH causes their death.

With a slightly acidic reaction, characteristic of fresh milk (pH 6.4 -6.8), the development of putrefactive and pathogenic microflora is delayed. Therefore, adding soda to milk in order to reduce overall acidity is considered gross falsification, since the pH increases and conditions for the development of pathogenic bacteria are created.

In case of some diseases (mastitis, foot-and-mouth disease, tuberculosis, etc.), freshly milked milk has not an acidic, but a neutral or slightly alkaline reaction (pH 7-7.4), using this pH indicator it can be determined whether the milk was obtained from a sick or healthy animal.

Biological properties

Manifested in the ability to delay the development of microflora for a certain time (bactericidal phase). It is believed that the effect of bactericidal substances ends if the acidity of the milk increases by 1T. Bactericidal substances are contained only in

freshly milked milk, they are destroyed when heated. The duration of the bactericidal phase depends on the speed and depth of milk cooling, the health of the animal, the amount of microflora, and compliance with veterinary and sanitary standards for milk production.

The bactericidal phase, when the vital activity of microorganisms in milk is suppressed. Microbes in this phase, as a rule, do not multiply, sometimes their number even decreases as a result of the bactericidal effect of lactein I and II, lysozyme and leukocytes. The duration of the bactericidal phase depends on the number of bacteria present in the milk, storage temperature and the individual properties of the animal’s body. The duration of the bactericidal phase is of great importance, since milk is considered more reliable only during this phase, and after it ends, microorganisms begin to develop and the milk spoils faster.

The temperature of milk storage has a great influence on the duration of the bactericidal phase. So, at a temperature of 37°C it is only 2 hours; at 10° - up to 36 hours, at 5° - up to 48 hours, and at 0° - up to 72 hours. With an increase in the number of microbes in milk by several thousand per ml at the same storage temperature, the duration of the bactericidal phase is reduced by approximately 2 times.

2. Sampling

When collecting samples for research, it is very important that a proportional amount of milk is taken from each milk yield (average sample). Selection is carried out using a metal tube with a diameter of 8 - 10 mm after thoroughly mixing the milk in each flask. Before taking a sample, milk in tanks is mixed with a whorl for 3-4 minutes, and samples are taken from each compartment of the tank. The layer of cream adhering to the walls of the flask is cleaned and mixed with milk. Before taking a sample, the tube is rinsed with the same milk from the flask being tested. The collected samples are poured into a flask.

A full production analysis requires 250 ml of milk. If necessary, milk samples for some studies can be preserved by adding 1 ml of a 10% solution of potassium dichromate for every 100 ml of milk. Canned milk samples can be stored at a temperature of 4-6°C for up to 10 days. Samples are stored in clean bottles, sealed with stoppers.

The quality of milk is determined in a complex of organoleptic, physico-chemical, and, if there is suspicion of milk contamination with pathogenic microflora, and bacteriological studies. Freshly milked milk is characterized by the following organoleptic and physical properties.

3. Organoleptic examination of milk

Appearance: A homogeneous white liquid with a slightly yellowish tint. The color of milk is determined in a glass cylinder by viewing it in reflected light. Colostrum is yellow or yellow-brown in color. Changes in the color of milk are observed in some diseases of cows. For example, with leptospirosis and some forms of mastitis, the milk has a yellow color. The yellow color of milk is observed when cows are fed large amounts of carrots and corn. Milk becomes reddish when cows are sick with piroplasmosis or pasteurellosis. anthrax and hemorrhagic mastitis, as well as in case of violation of the rules of machine milking, when after the end of milk flow the milking cups are kept on the teats. Feeding cows large quantities of certain plants from the ranunculaceae, spurge and horsetail families will also give the milk a reddish color. Red or pink milk occurs when pigment bacteria, miraculous bacteria, etc. develop in it. Therefore, in each case of a change in the color of milk, it is necessary to establish its causes.

The smell of milk is specific. When determining the smell, cold milk is heated in a flask or test tube to a temperature of 25-30°. In cold milk the smell is less recognizable. Good-quality milk has a pleasant, specific smell. Milk acquires foreign odors when stored with odorous substances (kerosene, fish, sauerkraut, creolin, etc.). Milk acquires a manure (barn) smell when it is filtered not to the dairy, but in a dirty barn, and also when particles of manure get into the milk. A musty smell appears when freshly milked milk is stored in a tightly sealed container. In such cases, putrefactive microorganisms multiply abundantly, hydrolyzing milk proteins. Milk has a silage smell when feeding poor-quality silage to cows, as well as when storing silage in a barnyard.

The taste of milk is pleasant, slightly sweet. To determine the taste, the milk is slightly heated. Then take a sip of milk into your mouth and rinse it oral cavity to the root of the tongue. Some foods can have a negative effect on the taste of milk. For example, radish, turnip, rutabaga, rapeseed, field mustard, fed in large quantities. Milk has a salty taste at the end of lactation, when mixed with colostrum, with udder tuberculosis and mastitis.

The bitter taste is caused by cows eating a large number of bitter plants: wormwood, lupine, buttercups, burdock, beet tops, turnips, because of the mold of spring straw and rancid cakes. At long-term storage milk or dairy products when low temperatures cold-resistant microorganisms develop in them, giving milk, cream, sour cream and butter a rancid taste. In this case, the decomposition of milk fat occurs with the formation of butyric acid, aldehydes, ketones and other substances that determine this taste. Milk acquires a soapy (alkaline) taste when it is contaminated with putrefactive bacteria.

The consistency of the milk is homogeneous. It is determined by slowly pouring milk from one container (cylinder, beaker, etc.) to another. An admixture of flakes or clots in the milk indicates a breast disease. Slimy (sticky) milk is caused by certain races of lactic acid streptococci, lactobacilli, etc.

Density. The density of milk is the ratio of its mass at a temperature of 20° to the mass of water of the same volume at 4°. The density of milk characterizes to a certain extent its naturalness. The density of whole milk ranges from 1.027 to 1.033, the average is 1.030. The density of skim milk is within 1.038, with an average of 1.035. When skim milk is added to whole milk, the density of the latter increases, and when water is added, it decreases. Every 10% of water added to milk reduces its density by three divisions of the hydrometer scale, or by 3°. When skim milk is added or fat is removed, the density of the milk increases accordingly. However, if you skim the milk and then add the same amount of water, its density will not change. This type of falsification is called double falsification. To identify it, it is necessary to determine not only the density of the milk, but also the fat content in it.

The density of milk is determined no earlier than 2 hours after milking and at a temperature not lower than 10° and not higher than 25°. The density of milk is determined with a special milk hydrometer (lactodensimeter) at a temperature of 20°.

Method for determining density: 200 ml of the milk being tested is poured into a glass cylinder and a milk hydrometer (lactodensimeter) is lowered. The reading is made on the scale of a thermometer and a hydrometer. If the temperature of the milk is 20°, then the readings on the hydrometer scale correspond to the actual density. Otherwise, an adjustment is made for temperature. Each degree of deviation from normal temperature (20°) corresponds to an amendment equal to +-0.2 degrees of the hydrometer. At a milk temperature above 20°, the density will be less and the correction is made with a plus sign. When the milk temperature is below 20° - with a minus sign.

Research method: 1 ml of the milk being tested is poured into a test tube, 2 drops of a 10% solution of potassium chromate and 1 ml of a 0.5% solution of silver nitrate are added. The test tube with the contents is shaken. Conditioned milk turns lemon yellow, and milk diluted with water turns brick red.

Determination of ketone bodies in milk. To 5 ml of the milk being tested in a test tube add 2.5 g of ammonium sulfate, 2 drops of a 5% aqueous solution of sodium nitropruside and one ml of a 25% aqueous solution of ammonia. Shake the test tube and read the reaction after 5 minutes.

4. Determination of fat in milk

Determination of fat in milk is carried out using the sulfuric acid method. It is based on the dissolution of milk proteins with sulfuric acid, as a result of which fat is released into pure form. Used as a solvent sulfuric acid density 1.81-1.82 and isoamyl alcohol with density 0.811-0.812.

Research method: 10 ml of sulfuric acid is poured into a milk butyrometer using an automatic pipette, then 10.77 ml of milk and 1 ml of isoamyl alcohol are carefully added (along the wall). The butyrometer is closed with a rubber stopper, wrapped in a towel and gently stirred until the contents are completely dissolved. The butyrometers are then placed with the plug down and water bath at a temperature of 65-70° for 5 minutes. The butyrometer removed from the bath is subjected to centrifugation for 5 minutes. After centrifugation, the sheaf is placed in a water bath for 5 minutes, after which the amount of fat is measured on the butyrometer scale. Each large division corresponds to 1% fat, and each small division corresponds to 0.1%. In accordance with the standard (GOST 5867-90), whole milk must contain at least 3.2% fat.

Determination in skim milk. It is produced in the same way as in whole milk, using the sulfuric acid method but in special butyrometers with a scale divided into tenths and hundredths of a percent. All components included in the analysis of whole milk are poured into such butyrometers in double quantities: 20 ml of sulfuric acid, 21.54 ml of skim milk and 2 ml of isoamyl alcohol. The exposure in a water bath before and after centrifugation is the same, but threefold centrifugation is used.

5. Determination of milk acidity

Freshly milked milk has an amphoteric reaction. An increase in the acidity of milk is caused by the breakdown of milk sugar into lactic acid, caused by the development of lactic acid and other bacteria. The longer milk is stored unrefrigerated, the more lactic acid accumulates in it.

Freshly milked milk from a healthy cow has 16-18° acidity. Increased acidity can be observed in the milk of cows grazing in summer in areas with acidic grains or in wet meadows. The acidity of colostrum reaches 50° Turner, and at the end of lactation it drops to 12-14°. With mastitis, the acidity of milk decreases to 7-15° Turner. Cow's milk procured for state and cooperative purchases on collective farms, state farms and other farms should not have an acidity higher than 20°. The acidity of first-grade milk is usually 16-18°, second-grade milk is 19-20°, and non-high-grade milk is 21°.

Determination of titratable acidity of milk. Titratable acidity is indicated in titration degrees - Turner T°. The degree of acidity is the number of ml of decinormal alkali solution used to neutralize 100 ml of milk.

Research method: 10 ml of the test milk, 20 ml of distilled water and 3 drops of 1% phenolphthalein are poured into a conical flask and titrated with a 0.1 alkali solution until a faint pink color appears, which does not disappear within one minute. The number of milliliters of alkali used for titration, multiplied by 10, shows the degree of acidity of the milk being tested. During mass acceptance of milk in markets, the maximum acidity is determined.

Extreme acidity. Maximum acidity is the degree of acidity of milk, above which milk is not allowed for sale. When selling milk on markets, the maximum acidity should not be higher than 20° and lower than 16°.

Research method: 10 ml of 0.01 N alkali solution is poured into a row of test tubes placed in a stand, which is prepared as follows: 100 ml of 0.1 N alkali solution and 10 ml of 1% phenolphthalein solution are measured into a liter flask, add distilled water to a volume of 1 liter. 5 ml of milk is poured into a test tube with 10 ml of indicator. If the acidity of the milk is below 20°, then an excess of alkali remains in the test tube and the pink color remains; if the acidity is higher than the limit, then there is not enough alkali to centralize it and the liquid in the test tube becomes discolored. An increase in the acidity of milk can occur when cows are fed spoiled silage or pulp containing oxalic acid, as well as when cows are fed concentrated feed in excess of norms. An increase in acidity, as well as milk density, is observed in the initial stage of cows' disease with mastitis.

6. Determination of milk purity

One of the main indicators characterizing the quality of milk is the degree of its purity. Filtering dirty milk. no matter how carefully it is carried out, it does not improve its quality, but on the contrary, it deteriorates faster, because dirt inactivates the bactericidal and bacteriostatic substances contained in it (lysozyme, lactenins, bacterilysins, etc.).

Determination of the degree of purity of milk. The purity of milk is determined using the Record device. 250 ml of milk is passed through the device, the filter is dried and compared with special standards, on the basis of which I establish the milk purity group.

Based on the degree of contamination, milk is divided into 3 groups. The first group includes milk, during filtration of which the sediment is almost invisible. The second group includes milk that has traces of contamination on the filter (in the form of small dots). Milk from the third group clearly shows contamination. A mechanical suspension in the form of larger dots is noticeable on the filter; the color of the filter is gray.

According to GOST 8218-89, first-grade milk must have purity group I, second-grade milk must have group II purity, and non-grade milk must have a purity of at least group III.

Determining the presence of soda in milk. Sometimes, in order to protect milk from curdling due to high acidity, soda is added to it. However, soda does not increase its resistance, but on the contrary, favorable conditions are created for the development of putrefactive microflora. To determine soda in milk, indicators are used: rosolic acid, bromothymol blau. phenolrot.

Research technique: 1 ml of the milk being tested is stuck into a test tube and the same amount of 0.2% roseolic acid solution is added. Milk that does not have an admixture of soda with roseolic acid acquires an orange color, and milk containing soda becomes raspberry-red.

7. Checking the quality of pasteurization

On farms that are vulnerable to infectious diseases in cattle, milk is pasteurized. In this regard, there is a need to control the quality of pasteurization. To check the quality of pasteurization, a peroxidase test is used on farms, and a phosphatase test is used at dairy industry enterprises.

Reaction to peroxidase: if you add a few drops of potassium iodide starch solution and one drop of hydrogen peroxide solution to raw milk, the following reaction will occur: peroxidase + H2O2 + 2KOH + starch == 2KOH + J2 + starch, i.e. a blue color appears. In milk heated to 80-85°, a color change will not occur, since peroxidase is destroyed when heated.

Research method: To 3-5 ml of the milk being tested in a test tube, add 5 drops of potassium iodide starch (3 g of potassium iodide and 3 g of starch per 100 ml of water) and 5 drops of a 1% solution of hydrogen peroxide. The appearance of an intense blue color indicates the presence of peroxidase in milk. Therefore, this milk has not been pasteurized. The appearance of a pale blue color indicates partial destruction of the enzyme when the milk is exposed to a temperature of 65 - 70°, i.e. the milk is not pasteurized enough.

Phosphatase reaction. The enzyme phosphatase is less resistant to heat compared to peroxidase. Consequently, this reaction can establish the correctness of compliance with the low pasteurization regime, which is used in dairies.

Research methodology; 2 ml of the test milk and 1 ml of sodium phenolphthalein phosphate solution are poured into the test tube, closed with a stopper and after thorough mixing, the test tube is placed in a water bath at 1 40-45 °. The reaction is read after 10 minutes. In a test tube with properly pasteurized milk, no changes are observed. If the pasteurization regime is violated and the phosphatase remains active, the contents of the test tube take on a bright pink color.

8. Determination of milk class

Milk classification is a chemical method for determining the degree of microflora contamination of milk. It is established by a reductase test.

When determining the class of milk, we tentatively establish that the microflora, multiplying in milk, releases the products of its vital activity - reductase, which has the ability to discolor some paints, in particular methylene blue or change the color of resazurin. Consequently, the more microflora the milk contains, the more reductase is released and the faster the methylene blue discolors or the color of resazurin changes.

The reductase test with methylene blue is carried out as follows; 1 ml of methylene blue solution (5 ml of a saturated solution and 195 ml of distilled water) is poured into a test tube and 20 ml of the milk being tested is added. If there are no test tubes big size, you can use regular ones, but the amount of milk and reagent is halved. After stirring, place in a water bath at 38-40°C and observe the discoloration of the contents of the test tube every 15-20 minutes.

Based on the time of onset of discoloration, the good quality of the milk is determined, as can be seen from the data in the table: good quality of milk and class.

table 2

Good quality of milk and class

The disadvantage of the reductase test with methylene blue is that it poorly detects milk contamination in winter. If during milking (in unsanitary conditions) bacteria get into the milk and it is immediately cooled to 4°C or lower, then the biochemical activity of microorganisms is delayed. In addition, milk for streptococcal mastitis can be of the first class according to the reductase test with megillenope blue.

Reductase test with resazurin. Due to the fact that the methylene blue test has disadvantages, the resazurin test is used.

Method: 10 ml of test milk is poured into a test tube and 1 ml of 0.05% resazurin solution is added. The test tubes are closed with sterile stoppers, placed in a water bath at 42 - 43° and the time is noted. Observation is carried out after 10 minutes and 1 hour. Resazurin is reduced by reductase to refurin (pink).

This test makes it possible, comparatively faster than with methylene blue, to obtain results for assessing milk according to the degree of bacterial contamination. It is very important that this sample is the milk of cows with mastitis.

To increase the effectiveness of the resasurium test, I.S. Zagaevsky proposed adding 0.5% formaldehyde to a 0.05% solution of resazurin; as a result, the photosensitivity of the indicator in milk decreases and the accuracy of analyzes increases.

The results of this test are taken into account according to the following indicators:

first class - blue-blue color in vitro,

second class - blue-violet,

third class - pink.

It should be noted that the reductase test with resazurin. Compared to methylene blue, it speeds up analysis by more than five times. Constant monitoring of the reaction progress is not required. Reveals the reductase of all microorganisms that contaminate milk and is more demonstrative when reading the reaction to the quality of milk.

9. Rapid methods for detecting E. coli and salmonella bacteria in milk and equipment

To determine the quality of milk and dairy products, it is important to establish not only the total number of microbes they contain, some of which have useful qualities, but also to identify Escherichia coli bacteria (Escherichia), which are sanitary indicator microorganisms. The detection of these bacteria in milk, dairy products and objects in contact with milk indicates unsatisfactory conditions for milking crowns, violations of the rules for processing milk on farms, contamination with manure, bedding, poor preparation for milking of the udder, milking equipment, non-compliance with the rules of personal hygiene of milkers or dairy industry workers,

However, the complexity and multi-stage nature of testing milk and equipment for coli bacteria contamination makes it difficult to systematically monitor the sanitary quality of milk and products made from it. Therefore, we proposed the PZh-65 medium for this purpose, which allows us to quickly give an answer about the degree of contamination of milk, dairy products and milking equipment with coli bacteria.

PZh-65 medium is intended for the isolation of Escherichia coli and Salmonella bacteria from milk, cream, sour cream, cottage cheese, butter and cheeses. The medium is prepared according to the following instructions (in g): lactose 20.0. potassium phosphate (disubstituted) - 3.0, nutrient agar (powder) - 50.0, sterilized cattle bile - 100 ml, 1% alcohol solution of brilliant green - 2 ml. These components are dissolved by heating and stirring in 900 ml of distilled water, pH is set to 7.2-7.3, poured into 5 ml test tubes, heated with flowing steam at 100° for 15 minutes, cooled to 45-46° and added into test tubes with milk dilution medium or dairy product, previously ground in a sterile mortar with physiological sodium chloride solution. Inoculations from milk and products are done in dilutions of 1: 5, 1: 10, 1: 100, 1: 1000, etc. Incubate in a thermostat at a temperature of 43-44°C.

If there are Escherichia in the product, even in dilutions up to 10"9, after 16-18 hours of incubation, the column of the medium breaks, but its original green color does not change. With the growth of Salmonella, the medium acquires an olive color, without breaking its mass. Gram-positive microorganisms on The PZh-65 environment is not being developed. Production testing of this environment is being carried out in ten regional centers. veterinary laboratories Ukraine has shown that it significantly reduces the analysis time when E. coli bacteria are detected in milk and dairy products.

10. Indication of staphylococci in milk

There is a connection between the occurrence of staphylococcal diseases and the consumption of milk from animals with mastitis. In primary cultures on meat-pentone agar, staphylococcal cultures form golden, orange, brown, white or gray pigment. When reseeding staphylococci, the shades of pigment and the intensity of its formation change. Hemolysis rates (alpha or beta) in individual cultures are also not constant; they fluctuate depending on the freshness of the blood, the concentration of red blood cells in the agar, the thickness of the medium layer on Petri dishes, temperature, duration of incubation and other conditions. Often, the same culture of pathogenic staphylococcus, depending on the growing conditions, will give different types of hemolysis. When the epithelium of the teat canals in cows is injured by faulty milking machines, causing inflammation of the mammary gland or when the milk tank is damaged, staphylococci are sown from milk in almost 100% of cases.

To isolate staphylococci from milk I.S. Zagajewski proposed the P-3 environment. To prepare it, 30.0 g of sodium chloride, 30.0 nutrient agar (powder), 10.0 g of glucose, 0.8 g of sodium carbonate, 0.25 I sodium sorbinate are dissolved in 500 ml of liver broth. The mixture is heated at 100 °C for 30 minutes. The pH is adjusted to 7.3-7.4 and before pouring into Petri dishes (at an ambient temperature of 47-48° C), 40 ml of fresh defibrinated cattle blood is added. At the same time, there is no advantage of rabbit blood in the hemolysis reaction by pathogenic staphylococci in comparison with the blood of cattle. A sodium chloride content of over 6.5% in the medium slows down the hemolysis of erythrocytes by staphylococci. Agar clearing (zone of hemolysis of red blood cells) forms around colonies of pathogenic staphylococci.

One of the most important criteria for differentiating pathogenic staphylococci from saprophytic ones is the plasma coagulation reaction. It has been established that when adding 2 drops of a broth culture of pathogenic staphylococcus or 5 drops of milk from udder lobes affected by staphylococcal mastitis to 2 ml of pig blood plasma, plasma coagulation occurs at a temperature of 38-40° for 1 1/2 hours, at a temperature of 25-30° for 3-12 hours, at a temperature of 20-22°C for 6-18 hours. The plasma coagulation reaction with whole plasma is more demonstrative than with diluted plasma. The optimal temperature for plasma coagulation is 38° C. Blood clotting in rabbits and pigs occurs at almost the same time. Pathogenic staphylococci do not coagulate the blood plasma of sick animals treated with antibiotics, as well as not fresh plasma.

11. Sanitary assessment of milk for animal diseases

Tuberculosis. The greatest danger is posed by the milk of animals with tuberculosis lesions in the udder, which always contains a large number of tuberculosis bacilli. In the pulmonary form of animal tuberculosis, the pathogen is initially detected in saliva, which can enter manure through the digestive tract, and then from animal skin or bedding into milk.

Tuberculous mycobacteria are very heat-resistant compared to other pathogenic non-spore bacteria. According to our research, bovine tuberculosis bacilli are inactivated only when they are heated to 85" for 30 minutes, in cottage cheese and butter they survive up to 3 months, and in hard cheeses - about 8 months (observation period).

The increased resistance of tuberculous mycobacteria is associated with the presence of a waxy, dense shell. Therefore, temperature and time in the accepted milk pasteurization regimes do not always ensure the death of these bacteria.

In accordance with current rules, milk obtained from animals with tuberculosis lesions of the udder is subject to destruction under the supervision of veterinary supervision. Milk obtained from animals that react positively to tuberculin and do not have clinical signs of the disease must be boiled and used on the farm. This milk can be processed into melted butter, and the skim milk obtained from processing this oil, after boiling, is used as animal feed. Milk from animals from health-improving farms that do not respond to tuberculin is pasteurized at 85° for 30 minutes or 90° for 5 minutes.

Brucellosis. Brucella multiply slowly in milk, and at temperatures below 20° their development stops. Their survival rate in dairy products is quite high. Thus, in fermented milk products they remain viable for up to 2 weeks, in feta cheese - 1.5 months.

The presence of Brucella in milk is determined using a ring test, which is based on the presence of corresponding antibodies in the milk of animals with brucellosis. A suspension of killed Brucella stained with hematoxylin or other paint is used as an antigen. As a result of the addition of colored antigen 13 to the milk of a cow with brucellosis, the antibodies present there bond with the antigen. The resulting antibody + antigen complex has the property of being adsorbed on the surface of fat globules, which at 37-38° rise upward, carrying along with them the glued bacteria. Therefore, with a positive reaction, a blue ring of colored Brucella cells forms in the upper layer of cream. If the test results are negative, the top layer of cream is not colored, and the milk takes on the color of the dye that was used to stain the antigen. According to the instructions for combating brucellosis, milk from cows. having clinical signs of brucellosis and reacting to brucellisate are boiled on the farm for 5 minutes and used on the farm. Milk from cows from a health-improving farm that do not respond to brucellosis is pasteurized at a temperature of 80° for 30 minutes. In sheep farms unaffected by brucellosis, sheep are not milked.

Foot and mouth disease. When cows become ill with foot-and-mouth disease, there is a decrease in milk yield, an increase in leukocytes, fat, as well as albumin, globulin and calcium in the milk. Along with this, the amount of vitamin A and riboflavin in the milk of sick cows decreases. The resistance of the foot-and-mouth disease virus is as follows: fresh milk at 37° it lasts 12 hours, at 5° - 12 days, in milk cooled to 4° - 15 days. When milk sours, the virus in it is inactivated when exposed to increased acidity.

According to the instructions for combating foot-and-mouth disease, when quarantine is imposed on a farm unaffected by foot-and-mouth disease, the export and use of milk and dairy products in non-dehydrated form is prohibited. Milk obtained from animals quarantined for foot-and-mouth disease can be used for food after pasteurization at 85° for 30 minutes or boiling for 5 minutes. When foot and mouth disease is complicated by purulent mastitis, the milk is boiled and destroyed.

.Own research

1. Purpose of the work

The purpose of the work is to conduct a veterinary and sanitary examination of milk selected from the private sector.

2. Objectives

Conduct a physical and chemical assessment of the quality of milk selected in the private sector;

Compare the obtained indicators with standard indicators;

Draw appropriate conclusions about the quality of the studied samples;

Offer a practical solution to improve the quality of milk obtained.

3. Material for research

Milk for the study was collected from seven cows of the red steppe breed. Sampling was carried out in the private sector of the Saki district, in the village of Izvestkovoe, on 40 Let Pobedy Street, 9, the owner of the cows is Tkach Maria Petrovna. The work was carried out in October 2013 at the Department of Microbiology, Epizootology and Veterinary and Sanitary Expertise. The work was carried out in October 2013 at the Department of Microbiology, Epizootology and Vet-San Expertise.

4. Methods

Quality:

Determination of milk purity. (GOST 8218-89)

To determine the degree of purity of milk, 250 ml of well-mixed milk is taken with a measuring cup and passed through a filter vessel of the Record device, which has a cotton or flannel filter. To speed up filtering, it is recommended to heat the milk to a temperature of 35-40°C. After filtering the milk, the filter is placed on a sheet of paper, preferably parchment, and dried in air, protecting it from dust. Depending on the amount of mechanical impurities on the filter, milk is divided into three groups according to the GOST standard 8218-56.

First group: there are no particles of mechanical impurities on the filter.

Second group: individual particles of mechanical impurities on the filter.

Third group: there is a noticeable sediment on the filter of small or large particles of mechanical impurities (hairs, particles of hay, sand). [Rice. 1, Fig. 2].

Bacteriological examination of milk.

For bacteriological research, test for reductase. Take 10 ml of milk, heat it in a water bath to 37-38°C and add 1 ml of methylene blue working solution. The test tubes are closed with sterile rubber stoppers, mixed thoroughly and placed again in a water bath at a temperature of 37-38°C (the water level in the bath should be higher than the level of the contents of the test tube). Based on the time of onset of milk discoloration, bacterial contamination and the class of milk are determined according to the table.

For control, the same milk sample is placed in a test tube, but without the addition of methylene blue, which is examined 10 minutes and 1 hour after the sample is taken. [Rice. 3, Fig. 4, Fig. 5, Fig. 6].

Discoloration rate Number of bacteria Class and rating of milk in 1 ml of milk

Less than 10 minutes More than 20 million IV, very poor

From 10 minutes to 1 hour Up to 20 million III, poor

From 1 hour to 3 hours Up to 4 million II, satisfactory

More than 3.5 hours Up to 500 thousand I, good

Determining the presence of soda

Progress of determination. To 3-5 ml of milk in a test tube add the same amount of 0.2% solution of rosolic acid in 96% alcohol and mix thoroughly. Milk containing soda turns pink, without it - orange. [Rice. 7].

Determination of ketone bodies

Progress of determination. To 1-2 ml of milk add a couple of Ross reagent granules on a scalpel blade. Milk containing ketone bodies takes on a blue tint, which in turn normal milk does not change its color. [Rice. 8]

Definitions of milk for mastitis

Technique for setting up a reaction. Add 1 ml of milk and 1 ml of dimastin or mastidine to each recess of the plate. The mixture of milk and reagent is stirred with a stick for 30 seconds when working with dimastin and 15-20 seconds when using mastidine. The reaction is taken into account in crosses based on the thickness of the jelly, and the change in color is an orienting and complementary indicator. [Rice. 9, Fig. 10].

Accounting for the reaction based on jelly thickness:

1) negative reaction - homogeneous liquid;

2) questionable reaction - traces of jelly formation;

3) positive reaction - a clearly visible clot (from weak to dense), which is half or entirely thrown out of the well of the plate with a stick when stirring.

Color of the mixture when working with dimastin:

1) orange, orange-red (red-orange) - normal slightly acidic reaction of milk;

2) yellow -- increased acidity milk;

3) red - shift towards increasing alkalinity;

4) scarlet, crimson, raspberry - increased alkalinity

Quantitative:

Determination of pH (GOST 26781-85)

The method is based on determining the activity of hydrogen ions using cyometric analyzers and pH meters.

The potentiometric analyzer is prepared for use in accordance with the instructions that come with the device.

Preparing for the study. Buffer solutions for pH measurements are prepared from fixonals and stored at a temperature of 20±3°C for no more than two months. The device is calibrated using buffer solutions with a pH value of 6.88 and 4.00 at a temperature of 20±1°C. The device is calibrated each time before starting work.

In a glass with a capacity of 50-100 cm3, pour 40±5 cm3 of milk at a temperature of 20±2ºC and lower the electrodes of the device into it. The electrodes should not touch the walls or bottom of the cup. After 10-15 seconds, read the readings on the instrument scale.

After each measurement, I wash the electrodes of the device with distilled water. When measuring the pH of milk on a mass scale, the residues of the previous sample are removed from the electrodes with the next sample. [Rice. 11, Fig. 12, Fig, 13].

Determination of acidity. (GOST 3624-92)

Acidity is determined by the titrimetric method and calculated in degrees Turner. The degree of acidity is the number of milliliters of a decinormal solution of sodium hydroxide (potassium) used to neutralize 100 ml of milk or 100 g of product. To determine acidity, pour 10 ml of milk, 20 ml of distilled water (freshly boiled and cooled to room temperature) and 3 drops of a 1% alcohol solution of phenolphthalein. The contents of the flask are thoroughly mixed, and then a decinormal alkali solution is added dropwise from the burette into the flask until a faint pink color appears, which does not disappear within one minute (compare with the standard).

The number of milliliters of decimormal alkali solution used for titration, multiplied by 10, will indicate the degree of titratable acidity of the milk. In some cases, it is allowed to check the acidity of milk without adding distilled water, but the resulting acidity must be reduced by 2 degrees.

To prepare a control standard for coloring, pipet 10 ml of milk, 20 ml of water and 1 ml of a 2.5% solution of cobalt sulfate into a flask with a capacity of 150-200 ml (2.5 g of cobalt sulfate is added to a volumetric flask with a capacity of 100 ml and topped up with distilled water up to the mark). The shelf life of cobalt sulfate solution is 6 months.

The reference standard is suitable for use for one day. To increase the shelf life of the standard, it is necessary to add one drop of formaldehyde to it. [Rice. 14, Fig. 15].

Determination of density. (GOST 3625-84)

Density is determined by lowering a milk lactodensimeter into a glass cylinder filled with the test milk, previously thoroughly mixed (without foam), in an amount of up to 250 ml at a milk temperature of 20±5°C. When determining density, the lactodensimeter should not touch the walls of the cylinder. 1-2 minutes after placing the lactodensimeter in a stationary state, the readings of the lactodensimeter scale are counted.

The density of milk is measured using a lactodensimeter to a whole division, and the temperature is measured with an accuracy of 0.5°C. Based on the readings of the milk lactodensimeter, the density of the milk is determined according to the table. [Rice. 16RRRP].

Determination of fat content. (GOST 5867-90)

Pour 10 ml of sulfuric acid (density 1.81-1.82) into a clean milk butyrometer, without wetting the neck, and carefully, so that the liquids do not mix, add 10.77 ml of milk with a pipette, placing its tip against the wall of the butyrometer neck at an angle ( The level of milk in the pipette is set according to the lower level of the meniscus). Blowing a master from a pipette is not allowed. Then 1 ml of isoamyl alcohol (density 0.810-0.813) is added to the butyrometer. The butyrometer is closed with a dry rubber stopper, inserting it a little more than halfway into the neck, turning it over 4-5 times until the protein substances are completely dissolved and uniform mixing, after which it is placed with the stopper down for 5 minutes in a water bath with a temperature of 65±2ºC.

Having been removed from the bath, the butyrometers are inserted into the cartridges (glasses) of the centrifuge with the working part towards the center, placing them symmetrically one against the other. If there is an odd number of butyrometers, a butyrometer filled with water is placed in the centrifuge. After closing the centrifuge lid, the butyrometers are centrifuged for 5 minutes at a speed of at least 1000 rpm. Then each butyrometer is removed from the centrifuge and by moving the rubber stopper the fat column in the butyrometer is adjusted so that it is in the tube with the scale. Then the butyrometers are re-immersed with their plugs down in a water bath at a temperature of 65±2°C. After 5 minutes, the butyrometers are removed from the water bath and the fat is quickly read. To do this, the butyrometer is held vertically, the fat border should be at eye level. By moving the plug up and down, the lower limit of the fat column is set on a whole division of the butyrometer scale and the number of divisions is counted from it to the lower level of the meniscus of the fat column. The interface between fat and acid should be sharp and the fat column transparent. If there is a brownish or dark yellow ring (plug), as well as various impurities in the fat column, the analysis is repeated.

...

1. Organoleptic examination of milk

Appearance and the color of the milk is assessed by inspection in a transparent cylinder (milk volume 50-60 ml). Homogeneity and the presence of sediment and impurities are noted. Natural whole milk should be white color with a yellowish tint. Skimmed milk or milk diluted with water may have a blue tint. The pink tint can be determined by the admixture of blood, colored bacteria, or depend on the animal’s food (beets, carrots, rhubarb).

Consistency milk is determined by the trace remaining on the walls of a transparent vessel after shaking. At normal consistency, a white mark should remain. If milk is diluted with water, no trace remains. If the milk has a viscous consistency (in the case of the proliferation of mucous bacteria in the milk or the presence of starch), then the trace is slimy and viscous.

Smell determined after shaking the milk in a conical flask covered with a watch glass. Natural fresh milk has a pleasant milky smell; a sour smell indicates milk has soured; the smell of ammonia or hydrogen sulfide indicates the development of putrefactive bacteria. Other odors (oil, kerosene, fish, perfume) may appear in milk if storage rules are violated.

Taste milk is determined by rinsing your mouth with a small amount of milk (5-10 ml). The taste of whole benign milk is pleasant and sweet. A salty, bitter, astringent taste may indicate an animal’s illness. The composition of a dairy animal's feed (for example, wormwood) can also change the taste of the milk.

2. Physico-chemical study of milk

1). Reductase test . A positive reductase test is an indirect method for detecting microbial contamination. The test for reductase is carried out using an aqueous solution of the redox indicator methylene blue (the color of the oxidized form is blue, the reduced form is colorless) at a temperature of 37°C (in a thermostat). The stock solution of methylene blue has Blue colour. In the presence of reductase in milk, milk becomes discolored.

Place 20 ml of the test milk and 2-3 drops of a 1% aqueous solution of methylene blue into a sterile test tube (flask), mix thoroughly, layer 0.5 ml of sterile petroleum jelly on top of the mixture and place it in a thermostat. The rate of discoloration of methylene blue indicates the degree of microbial contamination of milk (Table 16). On this basis, the quality of milk is assessed, indicating the quality class.

Table 16. Sanitary assessment of the degree of microbial contamination of milk depending on the time of decolorization with methylene blue reductase

2). Determination of the specific gravity of milk using a lactodensimeter . Milk (150 ml) is poured into a large glass cylinder, the lactodensimeter is carefully lowered into it to the 1.030 mark on the lower scale so that it does not touch the walls and bottom of the cylinder, and left for 5 minutes. According to the readings on the lower scale, specific gravity is measured, and on the upper scale, temperature. Specific gravity milk (d) can be expressed in absolute units (g/cm2) or conventional units (degrees Keven). Each degree of Keven is equal to one thousandth of g/cm 2, for example, d = 1.027 g/cm 3 = 27K.

Since the specific gravity of milk depends on temperature, for an adequate comparison with the norm (at 20°C), the scale readings should be “reduced” to 20°C. At T>20С, a correction equal to 0.2 Keven for each degree of temperature difference should be added to the value established by lactodensimeter; at N<20С - следует вычесть эту поправку.

Example. Milk has a specific gravity d 10 = 1.028 g/cm 2, temperature t = + 10С. Then the density of milk, expressed in degrees Keven and “reduced” to 20C, is equal to: d 20 = 28 - (0.2 x 10) = 26K, which is lower than the normal specific gravity of whole milk ( 1.028-1.034 g/cm 2 =28-34  Kevena) by 2 Keven.

3a). Determination of milk fat content Gerber's way . The essence of the method is to separate the fat phase from milk using sulfuric acid and isoamyl alcohol and measure the volume of fat in a Gerbera 14 butyrometer after centrifugation in a milk centrifuge for 5 minutes. When centrifuging a mixture of milk, sulfuric acid and isoamyl alcohol, phase separation occurs, fat is collected in the narrowed upper end of the vessel, along the length of which divisions from 0 to 6 are applied, each division corresponds to 1% fat (measurement accuracy 0.1%).

3b) Determination of milk fat content using an acid-free method . 5 ml of a 10% soda solution, 10 ml of test milk, 3-3.5 ml of an alcohol mixture (amyl alcohol: ethanol = 1:6) and 2-5 drops of phenolphthalein working solution are poured into the Gerber butyrometer. The butyrometer is closed with a stopper, shaken until a homogeneous liquid is formed, placed with the stopper down in a water bath (65-70°C) for 5 minutes, after which it is centrifuged in a milk centrifuge. After it stops, the butyrometer is carefully transferred to a water bath and kept there for 3-4 minutes, after which the fat content is determined on a scale. The noted result is compared with the norm of fat content of whole milk (fat content not less than 3.2%).

4). Calculation of dry residue . The dry matter of milk consists of proteins, fats, carbohydrates and mineral salts. The dry residue can be determined by weight, or use the calculation using the Farington formula: C = [(4.8  F + d 4 20)/ 4] + 0.5, where F is fat content (%); d 4 20 - density (degrees Keven);

5). 4.8; 4 and 0.5 are empirical coefficients. 15 . Determination of milk acidity by titration

6). The acidity of milk is measured in degrees Turner (0 T): 1 0 T corresponds to the volume (ml) of 0.1 N sodium hydroxide solution used to neutralize the acids of 100 ml of milk. To determine the acidity of milk, pour 10 ml of milk, 20 ml of distilled water, and 3-4 drops of a 1% phenolphthalein solution into a conical flask. The mixture is titrated with 0.1 N alkali solution until a stable faint pink color appears. The volume of alkali solution used for titration is multiplied by 10 (to be converted to 100 ml of milk). The acidity of milk should be assessed based on the fact that the acidity of fresh milk = 16-19 T, fairly fresh milk - 20-22 T, and more than 23 T for stale milk.

Tests for adulteration of milk 6a). Definition in milk. Baking soda can be added to milk to mask its acidity. By neutralizing lactic acid, soda does not delay the development of microorganisms in milk, which increases the epidemic risk, and contributes to the destruction of vitamin C, which reduces the nutritional value of the product. Milk with the addition of soda is classified as adulterated and unsuitable for consumption. An indicator for detecting soda in milk is rosolic acid.

5 ml of milk is poured into a test tube and 4-5 drops of a 0.2% alcohol solution of rosolic acid are added. In the presence of soda, milk turns crimson; in the absence of soda, a yellow-brown color appears. The limit of measurement is 0.1% soda in milk.

6b). Definition starch in milk. Starch is added to milk for the purpose of adulteration to give it a thicker consistency after dilution with water. An indicator for the presence of starch is Lugol's solution (KI, I 2). Milk with the addition of starch is classified as adulterated and unfit for consumption.

10-15 ml of the milk being tested and 1 ml of Lugol’s solution are poured into a conical flask. In the presence of starch, milk turns blue, without starch it turns brown.

6c) Test for nitrates , which can appear in milk as a result of diluting milk with water containing nitrates. 10 ml of milk and 0.3 ml of 20% CaCO 3 solution are poured into the flask. The mixture is boiled until the milk coagulates, cooled and filtered. 1-2 crystals of diphenylamine are placed in a porcelain cup and 1 ml of concentrated sulfuric acid is poured. Along the edge of the cup, carefully layer a few drops of filtrate onto it. The appearance of a blue color indicates the presence of nitrites and nitrates.

Based on the results of the examination, a conclusion is made about the good quality, freshness and integrity of the milk. At the same time, they are guided by the standards for whole, fresh and high-quality milk.

Obtaining milk of high sanitary quality is possible only if veterinary measures are observed on farms, milking hygiene is improved, milk quality is monitored and cow mastitis is prevented.
Milk after milking must be filtered and cooled (not higher than +10 ° C), no later than 2 hours after milking.
It should not contain inhibitory or neutralizing substances (antibiotics, soda, hydrogen peroxide, formaldehyde, etc.).
Milk intended for the production of baby food products must meet the requirements of the highest and first grade, but with a somatic cell content of no more than 500 thousand/cm3.
When receiving each batch of milk, acidity, purity, density, temperature and fat content are determined.
Bacterial contamination, as well as the mass fraction of protein and the content of somatic cells in milk are determined once every 10 days.
The issue of milk quality is associated with the disease of cows with mastitis, since inflammatory processes occurring in the mammary gland change the composition of milk and its physical and biological properties. It lacks antibacterial substances - lysozymes, and the amount of vitamins is reduced. In milk from cows with mastitis, the amount of casein, lactose, SOMO content, and titrated acidity decrease.
At the same time, the content of chlorine, sodium, enzymes (catalase, reductase), as well as the number of leukocytes and pathogenic microorganisms (streptococci, staphylococci, salmonella, etc.) increase in it. Therefore, milk from cows with mastitis is dangerous to human health.
To identify cows with latent forms of mastitis, the following methods are used, based on determining changes in milk that occur when animals become sick:
1. use of dimastin and mastidine;
2. method of settling;
3. bromothymol test;
4. determination of the number of somatic cells (GOST 23453-794);
5. using devices OSM-70 (identifier of hidden mastitis), PEDM (mastitis express diagnostic device).
Test with mastidine and dimastin
These substances are classified as surfactants. The method is based on the ability of these substances to destroy cells (leukocytes) and release a nuclear substance - deoxyribonucleic acid, which produces a jelly-like clot of varying consistency depending on the number of cells.
Mastidine test
To test milk from a cow, a 2% solution is used, and to detect mastitis milk in the collected milk, a 10% solution is used. For this purpose, 1 ml of milk is milked into the recesses of the milk-control plate from each lobe of the udder and 1 ml of mastidine solution is added. The mixture is stirred with a stick for 10-15 s and the reaction in terms of jelly thickness and color change is taken into account. If the mixture has the consistency of egg white and is dark blue in color, this indicates that the milk comes from cows with mastitis. If there are no clots in the mixture and the color is light lilac, this indicates that the milk came from a healthy cow.
Test with dimastin
For the study, a 5% solution of dimastin is used. The test technique is the same as with mastidine. The presence of red or pink jelly in the mixture indicates inflammation of the udder in cows. If there are no clots in the mixture and the color is yellow-orange, the milk is from a healthy cow.
It should be borne in mind that the number of cells in milk increases not only during inflammation, but also at the beginning and end of lactation, therefore, to confirm the diagnosis, it is necessary to use a sedimentation test and bacteriological examination.
Settling test
In a test tube, 15 ml of milk is milked from each lobe of the udder and left to settle at a temperature of 4-5 °C (in the refrigerator). The tubes are examined after 16-24 hours. If a sediment more than 1 mm high appears at their bottom, this indicates that this is milk from a cow with mastitis.
Bromothymol test
It is based on the fact that in an alkaline environment the reagent acquires a blue color. To do this, pour 1 mm of milk into the recess of the milk plate, add 2-3 drops of a 0.5% alcohol solution of bromothymol and mix. Milk from cows with mastitis is colored from dark green to dark blue, depending on the severity of the disease. Milk from a healthy cow is characterized by a yellow-green color.
To determine the number of somatic cells The drug “mastoprim” is used in milk, which is a mixture of sulfinol 74% and sodium hydroxide 26% calculated on dry matter.
Add 1 ml of milk and 1 ml of an aqueous solution of 2.5% matoprim into the recess of the milk-control plate. The milk and the reagent are intensively mixed with a stick. The resulting mixture is lifted up with a stick and the results of the analysis are evaluated. If a homogeneous liquid or weak clot is formed, which slightly stretches behind a stick in the form of a thread, then in 1 ml of milk there are up to 500 thousand somatic cells.
In the presence of a pronounced clot, when stirred, a notch is clearly visible and the clot is not thrown out of the well, from "500 thousand to 1 million cells. When a dense clot is formed, which is thrown out with a stick from the well of the plate, over 1 million cells are contained in 1 ml milk.
The use of OSM-70 and PEDM devices is based on determining the electrical conductivity of milk. Milk obtained from cows with mastitis has increased electrical conductivity due to an increase in chlorine and sodium ions in it.
Sanitary assessment of milk
Milk from cows with clinical mastitis is boiled and destroyed; with latent mastitis, it is boiled and used for animal feed. The clinical form of mastitis is detected during milking by milking the first streams of milk into a special mug. Cows should be examined for latent forms of mastitis once a month.
In farms affected by tuberculosis milk from cows with clinical symptoms is destroyed after adding creolin, Lysol or other disinfectants. Milk from animals that react positively to tuberculin, but do not have clinical signs, is boiled and used on the farm. Milk from such animals can be used for processing into ghee. From cows that react negatively, milk is pasteurized on-farm at a temperature of 85 °C for 30 minutes or at a temperature of 90 °C for 5 minutes.
In cases of brucellosis, cows with clinical forms of the disease do not receive milk.
From cows that react positively, milk is rendered harmless by boiling and used within the farm. From negatively reacting cows on a dysfunctional farm, milk is pasteurized at a temperature of 70 °C for 30 minutes or at a temperature of 85-90 °C for 20 s.
For foot and mouth disease, milk is processed into ghee, or rendered harmless by boiling for 5 minutes, or pasteurized at a temperature of 80 °C for 30 minutes.
In case of leukemia, milk from cows with the clinical form is destroyed. From animals suspected of having a disease, milk is boiled for 5 minutes or pasteurized at a temperature of 85 ° C for 10 minutes.
It is not allowed to sell milk if falsification is established.

For veterinary and sanitary control of milk, not all studies are of equal importance. For example, analysis of protein and sugar content is certainly important for determining the usefulness of milk, but for sanitary control, the determination of mechanical and bacterial contamination, acidity of milk, the presence of pathogenic microbes, admixtures of milk from mastitis cows, the presence of ketone bodies, dilution of milk with raw water, is of greater importance. i.e. everything that can directly affect human health.

Such control is partially carried out when milk is received by the dairy plant, but it cannot in any way replace veterinary and sanitary control directly on the farm.

With modern vehicles for transporting milk (tankers, flasks), the milk coming from farms to the dairy plant is impersonal. Meanwhile, to improve the sanitary culture on the farm, control is important to determine the quality of the milk received by each milkmaid. Finally, some studies, for example the determination of milk from mastitis animals, in collected milk at a dairy plant are not possible at all.

To control the quality of milk, each farm needs to have a small laboratory where the necessary research can be carried out.

Taking samples for research. To determine the bacterial contamination of milk, a sample is taken into sterile bottles or test tubes. If samples are taken directly from the udder, for example, to determine the causative agents of mastitis, then the following order must be followed: wash your hands and udder, wipe them with a clean towel, wipe your hands and udder teats with 70° alcohol, milk the milk into a milk tray and milk the milk from the last portions of the milk yield into bottle or test tube.

If you need to take a sample of collected milk for bacteriological examination from a milking bucket, flask, etc., then the milk is mixed with a whorl washed with hot water, then it is drawn into a sterile bottle with a sterile pipette (5-10 ml is enough for bacteriological examination, for reductase samples - -20--25 ml).

Milk samples for bacteriological examination are immediately sent to the laboratory and examined no later than 3 hours from the moment they were taken.

During the hot season, samples are transported in a thermos or in a thermos box with double walls and thermal insulation. Thermoses retain ice well and provide the proper temperature for milk samples, but bottles of milk can easily break the glass cylinder of a thermos, and the capacity of thermoses is insignificant, so a thermos box is more suitable for transporting milk samples.

To determine mechanical contamination, density, and acidity, take at least 250 ml of milk. The milk is first mixed by lowering and raising the whorl at least 8-10 times. The sample is taken with a metal tube with a diameter of 9 mm and such a length that it reaches the bottom of the container in which the milk being tested is located. The tube is slowly lowered to the bottom, and then, holding the hole with a finger, it is quickly removed and the sample is poured into the vial.

In order to accurately determine the average content of fat and protein, sugar, etc., a sample is taken from one cow within two days. From 1 liter of milk for each milk yield, take 5-10 ml in such a way that the total amount of sample over two days is at least 250 ml. In these cases, milk samples must be protected from spoilage by adding a preservative. Hydrogen peroxide (2-3 drops of commercial hydrogen peroxide per 100 ml of milk) or a 10% solution of potassium dichromate (1 ml per 100 ml of milk) can serve as a preservative. Organoleptic analysis includes determining the color, taste, smell and consistency of milk. All these indicators are of great importance for the sanitary assessment of milk.

The color of milk from healthy cows is white or slightly yellowish. The yellowish tint depends on the lipochromes of milk fat and carotene in the feed.

The color of milk is determined in a glass cylinder by viewing it in reflected light.

Giving lactating cows strong-smelling medicinal substances, such as creolin, or disinfecting the premises with phenolic preparations before milking, provided that the milk remains in the barnyard for a long time, can give the milk a medicinal smell.

Milk also easily adsorbs the smell of the stall if the sanitary condition of the barnyard is unsatisfactory, if veterinary and sanitary rules are not followed and the milk is filtered not in the dairy, but directly in the barn.

The consistency of the milk is homogeneous. It is determined by slowly pouring milk from a beaker, beaker and other containers into another container.

The milk of old cows and especially colostrum is somewhat thicker. Heterogeneous consistency, admixture of clots and flakes in the milk indicate a disease of the mammary gland.

According to the rules of veterinary and sanitary examination of milk and dairy products, approved by the Main Veterinary Directorate of the USSR Ministry of Agriculture on November 10, 1989, milk with a sharp change in taste, color, smell and consistency is not allowed to be consumed.

Organoleptic changes associated with feed can be eliminated by changing pastures, removing such feed from the diet of dairy cows, or feeding them after milking. The fodder smell does not disappear from milk soon. It takes at least 7-8 hours for the foreign odor to no longer be felt. Therefore, feeds that cause undesirable changes in the taste and smell of milk, especially easily fermented ones, should not be given before milking. It is necessary that at least 7-8 hours pass between the giving of such food and the next milking.

Changes in milk due to bacterial growth are managed by immediately cooling the milk after milking and by proper cleaning and disinfection of milking equipment and milk utensils. Deviations from the norm associated with the disease of lactating cows require appropriate therapeutic and preventive measures.

There are several methods for determining the amount of mechanical impurities in milk: gravimetric, sedimentation and filtration methods. The most accurate weighing method for determining the amount of mechanical impurity on a filter, by weighing the dried filter before and after filtering milk, requires an analytical balance, a drying cabinet, this method is painstaking and time-consuming, so it is unsuitable for analyzing milk on the farm.

The settling method is also unacceptable for practice due to its duration.

The filtration method serves as our official criterion for the degree of purity of milk (GOST 8218--56). The principle of this method is as follows: a certain amount of milk is passed through a cotton or flannel filter and the purity of the milk is judged by the degree of its contamination.

The milk is thoroughly mixed with a whorl, then 250 ml of it is taken with a measuring scoop and poured into a device to determine the purity of the milk. The device is a metal truncated cone with a filter surface diameter of 27-30 ml. The mesh is attached to the narrow part of the body with a nut or spring. A cotton or flannel filter is placed on the mesh, through which the milk is passed. The amount of sediment on the filter determines the purity of the milk.

GOST (8218--56) provides for three degrees of milk purity, shown on the corresponding standard:

Group I - the filter is clean, the sediment is unnoticeable, the weight of the mechanical impurity does not exceed 3 mg per 1 liter.

Group II - the filter contains individual particles of mechanical impurities (impurity weight from 3 to 6 mg per 1 liter).

Group III - noticeable sediment of mechanical impurities on the filter (weight more than 7 mg per 1 liter). The color of the filter turns from white to grayish and contains hairs, sand particles, etc.

The GOST standard shows all three degrees of purity.

The acidity of fresh milk is affected by the lactation period. Colostrum has the highest acidity. As studies by E.M. Buevich have shown, the acid reaction of colostrum increases with silage feeding.

In the first month of lactation, according to I. S. Zagaevsky (1977), the average acidity of milk is about 20°T, then it decreases and in the tenth month of lactation it reaches 15-13°T. However, in the herd’s collected milk these fluctuations are leveled out. The acidity of collected milk can be increased if cows do not receive enough calcium in their feed (marshy pastures). Lack of calcium in feed causes functional disorders of the body of a lactating cow, which, according to the observations of P. V. Mitenko (1989), changes the reaction of milk due to the formation of acid calcium caseinates.

The high titratable acidity of freshly milked milk from cows may be due to an excess of protein and phosphorus in the diet. According to the observations of M.F. Borovkova (2007), when giving cows up to 700 g of concentrates per 1 liter of milk milk, in the absence of succulent feed, the acidity of milk increased to 23.5 ° T, and in some cows to 25-27 ° T. Reducing concentrates to 150 g per 1 liter of milk and transferring the cows to pasture quickly reduced the acidity to normal.

Inflammatory processes in the mammary gland increase the alkalinity of milk. Finally, acidity can be reduced as a result of adulteration (dilution with water, addition of soda).

During storage, the acidity of milk increases under the influence of bacteria, mainly lactic acid, that multiply in it. During their life, microbes produce saccharolytic enzymes, which break down milk sugar to form lactic acid and other acidic products, which ultimately causes an increase in acidity, so the freshness of milk can be judged by the degree of acidity. At 25--28° T, milk may curdle when boiled. A further increase in acidity to 60-65° T leads to spontaneous coagulation of milk.

Determining the titratable acidity of milk has not only hygienic, but also economic importance. According to the resolution of the Council of Ministers, a premium of 50 kopecks is paid for milk with an acidity of up to 19°T. per centner, and with acidity above 19° T, 50 kopecks are retained. per centner. Milk with acidity below 16° T and above 20° T is considered substandard.

There are several methods for determining the freshness (acidity) of milk.

Determination of titratable acidity in Turner degrees. The Turner method for determining acidity is generally accepted in our country and is included in the State Standard (GOST 3624-47).

To determine Turner acidity, 10 ml of the milk being tested is pipetted into a beaker or conical flask with a capacity of 100-200 ml. Add 20 ml of distilled or boiled and cooled water and 3 drops of a 1% alcohol solution of phenolphthalein. The glass is placed on a tripod stand, on which a burette with a decinormal alkali solution is fixed. From a burette, drop by drop, with constant circular rocking of the glass, add an alkali solution until the milk acquires a slightly pink color that does not disappear within 1 minute (compare with a control glass in which milk, water and phenolphthalein are poured, but no alkali). The amount of decinormal alkali in milliliters used to neutralize 10 ml of milk is multiplied by 10, which will be the degree of titratable acidity according to Turner.

When determining the naturalness of milk on a farm, the following types of adulteration are important: adding water, skimming, adding soda (to reduce acidity).

Veterinary and sanitary control of milk quality. Veterinary rules for conducting veterinary and sanitary examination of milk and dairy products

Introduction

Veterinary and sanitary rules for milk production technology. General provisions

Construction and equipment of premises and territory of dairy farms

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Introduction

. Literature review

1. Composition of milk

2. Sampling

4. Determination of fat in milk

6. Determination of milk purity

9. Rapid methods for detecting E. coli and salmonella bacteria in milk and equipment

10. Indication of staphylococci in milk

.Own research

1. Purpose of the work

2. Objectives

3. Material for research

4. Methods

5. Research results

6. Conclusions

Introduction

Meanwhile, milk, if the sanitary conditions of milking, primary processing, storage and transportation are violated, as well as if cows are sick, can become contaminated with pathogenic and toxicogenic microflora, which poses a danger to people and young animals.

9. Rapid methods for detecting E. coli and salmonella bacteria in milk and equipment

10. Indication of staphylococci in milk

11. Sanitary assessment of milk for animal diseases

The increased resistance of tuberculous mycobacteria is associated with the presence of a waxy, dense shell. Therefore, temperature and time in the accepted milk pasteurization regimes do not always ensure the death of these bacteria.

Brucellosis. Brucella multiply slowly in milk, and at temperatures below 20° their development stops. Their survival rate in dairy products is quite high. Thus, in fermented milk products they remain viable for up to 2 weeks, in feta cheese - 1.5 months.

.Own research

1. Purpose of the work

The purpose of the work is to conduct a veterinary and sanitary examination of milk selected from the private sector.

2. Objectives

Conduct a physical and chemical assessment of the quality of milk selected in the private sector;

Compare the obtained indicators with standard indicators;

Draw appropriate conclusions about the quality of the studied samples;

Offer a practical solution to improve the quality of milk obtained.

3. Material for research

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