The technological properties of milk – are properties that ensure the proper conduct of the process and receive a standard milk product that meets the requirements of regulatory documents. By the technological properties of milk include: acidity (total and active), buffer properties, the number and diameter of the fat globules, heat resistance, rennet coagulation of milk. Currently subject to control only some of them – acidity (total and active), thermal stability and rennet coagulation. Applied technological properties of milk for the assessment of the following characteristics: the receipt of dairy products – milk sour ability of lactic acid bacteria to form clots desired consistency with other specific structural and mechanical properties; for oil production – the ability to produce fat milk fat product specific hardness and ductility; for getting canned milk – milk protein thermal stability; for the production of hard cheese and dairy – the ability to milk rennet coagulation; for the production of ice cream – the ability to infant formula stray and well frozen and others.

The main technological properties of milk is heat resistance, which determines its ability to withstand high-temperature heat treatment. Significant role in this played by proteins such as casein contained in milk as submitsel. The degree of heat stability of milk increases with increasing dispersion of casein micelles and decreases with the increase of globulin protein. Heat-resistant Milk resistant to the action of rennet enzyme. Because milk is high heat resistance effectively direct the production of products which do not require the deposition of proteins.Some authors believe that the main factor affecting the thermal stability of milk is calcium content, depending on the balance between cations (Ca⁺, Mg⁺) and anions (citrate, phosphate). The excess of some leads to coagulation. Milk can also curl up on slight heating in case of there microflora and acidity. In addition, the thermal stability of milk has correlation dependency on pH. The broken salt composition leads to a transition of colloidal calcium phosphate ion-molecular consequently increase the content of calcium and increasing the aggregation of casein micelles. With increasing protein in milk increases calcium and phosphorus, increases volumetric acidity, accelerates rennet coagulation and improves the density and ability to clot to syneresis, the quantity of cheese dust, loss of protein and fat, that is improving all the physical and chemical properties of milk as raw material for production cheese. What fatter milk, the worse the cheese clot provides moisture.

The growing number of somatic cells in the sample average raw whole milk of cow shows the development of subclinical mastitis. With the development of inflammation in the mammary gland of cows changes the quality and safety of milk. Titrated acidity of the milk of healthy cows meet the requirements of the standard and made 16.8±0.12 °T (16.0–17.5 °). Mean values of total acidity second experimental group were reduced and amounted to 16.0±0.5 °T (14.6–16.7 °T), however, meet the requirements of GOST 3662-97. It should be noted that 28.5 % of samples pH values were reduced in 1.1 times and amounted to 14.6 °T. Such milk coagulates slowly rennet and clot badly handled. It should be noted that the level of total acidity is an important indicator, but it is necessary to measure the value of active acidity (pH). Indeed, the pH acidity is true, as caused by the presence of ions of hydrogen. Dissociation of milk available phosphates, amine and carboxyl groups and hydroxyl ions causes hydrogenous buffer capacity of value. The results of our study pH of milk obtained from healthy cows averaged 6.7±0.02, ie values close to neutral. With the development of subclinical mastitis significant changes in pH alkaline side not noted the value and the average for the group was 6.8±0.03.

It should be noted that according to some authors Ohrimenko et al., 2005, the pH of fresh milk should not exceed the value of 6.8. All values that are above indicate subclinical mastitis. However, the results of our studies in several animal milk pH was above 6.9, and the number of somatic cells is normal. In this regard, the diagnosis of subclinical mastitis use only the change in pH in milk cows is not necessary. pH of milk depends on the individual cows, feeding methods, balanced diet and the health of animals. Our data coincide with the data of NV Barabanschikova and V.I. Homenko: pH of milk from healthy animals can reach almost neutral reaction. Due to the hydrogen, proteins, citrate and carbon dioxide milk acts as a buffer integrated. The higher buffer properties of milk, the longer the bacteria are able to ferment lactose – to pH 4.76, after which they begin to die.

Buffer capacity of milk by acid in healthy animals is 2.0±0.02, which is more than a group of cows suffering from subclinical mastitis by 21.5 % (p<0.001). Changes in buffer milk acid, can we explain the fact that the milk of sick cows decreased citrate content, hydrocarbons and other components of milk, which entails a reduction in milk buffer acid. The buffer capacity of milk on the meadow, as well as on acid undergoes changes that occur with the disease of cows subclinical mastitis. Thus, in a group of healthy animals alkali buffer capacity on average for the group was 1.2±0.02, which is more than in cow milk subclinical mastitis 14.2 %. These changes buffer milk on the meadow we can explain the fact that the milk of cows suffering from subclinical mastitis contained less casein, compared with a control group of animals. Mass fraction of casein in the milk of healthy cows were within the range of 2.43 to 2.64 % (2.52±0.02), which is more than milk cows for subclinical mastitis by 10.7 % (p<0.001). Mass frequent total protein in cow milk was similar in both groups (p<0.5). Share of total protein casein in milk cows for subclinical mastitis decreased to 73.5 % versus 81.8 % in the milk of healthy cows, and the ratio between casein and serum proteins is 4.5:1 in the milk of healthy cows and 2.7:1 in the milk of cows suffering from subclinical mastitis. By reducing the mass fraction of the total protein casein worse technological properties of milk, in particular, it is bad rennet coagulates. The most suitable milk in cheese is the second class (15–35 min. Milk clotting time). Table 1 shows that the rennet coagulation of milk of healthy animals was 35.2±2.5 min., Which is significantly less than the milk of cows suffering from subclinical mastitis (P<0.05). Thus, according to the time of coagulation of milk cows in milk first group dominated the second class, the second group – the third class. Such milk curd is sluggish and requires additional calcium chloride introduced solutions that reduce clotting time of milk. We attribute this to the fact that the milk is reduced calcium and violation factions ratio of casein in the milk of cows for subclinical mastitis. It is known that most factions have raw α-, β- and κ-casein in particular, which has the ability to form and stabilize micelles, thus causing the greatest impact on the technological properties of milk, compared with other fractions. Resistant to rennet is γ-fraction, and therefore its share in casein should be least. This is what will be the prospect of our further research.

Key words: somatic cells, acidity of milk (total, active), buffer capacity, casein, rennet coagulation.