Production and sale of fermented milk products. Topic: Production of fermented milk products

General technology of dietary fermented milk products

Common in the production of all fermented milk drinks is the fermentation of prepared milk with sourdough cultures and, if necessary, ripening. The specificity of the production of individual products differs only in the temperature conditions of some operations, the use of starter cultures of different compositions and the addition of fillers.

For a long time, all fermented milk drinks were produced by the thermostatic method, in which fermented milk is poured into small containers and fermented at the optimum temperatures for each product in a thermostatic chamber. After the formation of a clot, the product is sent to the refrigerating chamber, where it is cooled and, if necessary, kept for some time for maturation.

In accordance with the reservoir method (M.G.Demurov), fermentation and maturation of the product is carried out in tanks with stirring. This reduces production space and labor costs.

For the production of dietary fermented milk drinks, milk is used not lower than the second grade, acidity not higher than 19 ° T, and cream - plasma acidity not higher than 24 ° T.

Normalized milk is pasteurized at temperatures of 85-87 ° C with an exposure of 5-10 minutes or 90-92 ° C with an exposure of 2-3 s for a more complete destruction of microflora, destruction of enzymes, activation of the development of microflora of the starter culture, and improvement of the consistency of the product. Under these conditions, denaturation of whey proteins occurs, as a result of which the hydration properties of casein increase and its ability to form a denser clot that holds well

serum. This is facilitated by the participation of denatured whey proteins in the formation of the structure of the milk clot.

Heat treatment is usually combined with milk homogenization at a temperature of 60-70 ° C and a pressure of 12.5-17.5 MPa, which provides a more uniform and dense consistency, and in a stirred state - more viscous, prevents cream sludge with better retention of whey. In the production of fermented milk drinks, homogenization is mandatory, since cream sludge is inevitable during long-term fermentation and cooling processes.

Then the milk is cooled to the optimum fermentation temperature and the starter is immediately added to it to prevent the development of extraneous microflora. The starter culture is usually added to the mixer using a dispenser.

In the production of fermented milk products, lactic acid streptococci are used: mesophilic (Lc. Lactis) with an optimal development temperature of 30-35 ° C and thermophilic (Str. Termophilus) with an optimal development temperature of 40-45 ° C.

To give the curd a creamy consistency, creamy streptococcus (Lc. Cremoris) is introduced into the starter, the optimum temperature of development of which is 30 ° C. Some starter cultures include aromatic streptococci (Str. Citrovorus, Str. Paracitrovorus, Lc. Diacetilactis, Lc. Lactis subsp. Acetoinicus, Lc. Lactis subsp. Diacetilactisf. Enterococci. In the course of their vital activity, in addition to lactic acid, they form volatile acids carbon dioxide, alcohols, ethers, diacetyl, imparting a specific odor to the product, imparting certain properties to the consistency These microorganisms are capable of 1 biosynthesis of vitamins, amino acids, carbon-containing polymers.

The combination of starter cultures gives certain qualities to the fermented milk product. The optimum temperature for their development is 25-30 ° C. Microorganisms can increase the acidity in the drink up to 80-120 ° T.

Lactic acid sticks are more powerful acid-forming agents. Of these, in the production of starter cultures, the Bulgarian bacillus (L. bulgaricum) and acidophilic (L. acidophilum) and others are widely used with an optimum temperature of development of 40-45 ° C and a maximum acidity of milk fermentation up to 200-300 ° T.

The composition of the starter cultures of some fermented milk drinks includes milk yeast, which provides alcoholic fermentation, as a result of which the drinks acquire a slightly spicy, tingling taste and a foamy consistency.
The quality of fermented milk drinks largely depends on the quality of the starter culture used. It should have a dense homogeneous clot, pleasant taste and smell, optimal acidity (streptococcal - no higher than 80 ° T, rod-shaped - no higher than 100 ° T). With increased acidity, the activity of the sourdough decreases, which increases the duration of milk coagulation and worsens the quality of the finished product. Sourdough is added depending on its activity in an amount from 1 to 5%.

Milk is fermented at the fermentation temperature until a tender, sufficiently dense curd is formed, without signs of whey separation, and slightly lower to acidity than in the finished product.

At the end of the fermentation, the product is immediately cooled. With the thermostatic method, it is sent to the refrigerator, where it is cooled to a temperature of 6-8 ° C. The product should be moved carefully to avoid breaking the delicate curd. The curd obtained by the reservoir method is cooled with gentle stirring in the same container by supplying ice water to the jacket of the reservoir. In this case, the properties of the formed clot change somewhat.

The lactic acid process weakens with decreasing temperature, proceeds slowly, and gradually the optimal acidity for this type of product is achieved, and at 8-10 ° C acid formation practically stops. Swelling of proteins also occurs, which leads to binding and a decrease in free moisture and a thickening of the clot.

Mixed fermentation products (kefir, kumis, acidophilic yeast milk) after cooling are ripened in refrigerating chambers (with a thermostatic method) or tanks. At the same time, the lactic acid process dies out, yeast is activated in an acidic environment, alcoholic fermentation occurs with the accumulation of alcohol, carbon dioxide, etc., giving these drinks specific properties. Ripening of the product in tanks lasts, depending on the type of product, from 12 hours to 3 days at a temperature of 8-10 ° C. After ripening, it is poured and sent to storage in refrigerators.

In order to better use production areas in some countries (Bulgaria, Hungary, etc.), fermentation and cooling of fermented milk drinks are carried out in one chamber by changing the air temperature in it.

Storage until the sale of dietary fermented milk drinks is carried out in refrigerators at temperatures from 0 to 6 ° C and humidity 85-90% in a strict sanitary and hygienic regime. They are released from enterprises at a temperature not higher than 8 ° C after checking the physical, chemical and organoleptic characteristics of each batch of the product.

MINISTRY OF YOUTH EDUCATION AND SPORT

TECHNICAL UNIVERSITY OF MOLDOVA

Department of Technology and Organization of Public Catering

Course work

Milk processing technology on the topic:

"Technology of liquid fermented milk products and drinks"

Performed:

Student gr. TL - 052

Checked:

Senior Lecturer Popescu L.

Chisinau 2009

Introduction

1. Assortment of liquid fermented milk products.

Terms and definitions ………………………………… ..3

2. Quality indicators of the finished product ………… .5

3. General technology ………………………………………… .8

4. Theoretical foundations of production ……………… 10

5. Influence of various factors on the production process ... 14

6. Vices ……………………………………………………… 17

List of references.

Introduction

The national fermented milk product is a fermented milk product that has a historically established name in the country, depending on the type of starter culture and specific technology.

Fermented milk products include liquid fermented milk products and drinks, as well as cottage cheese and curd products and sour cream. Liquid fermented milk products and drinks include the following products.

1. Assortment of liquid fermented milk products .

Curdled milk - a national fermented milk product made by fermenting milk with pure cultures of lactococci and / or thermophilic lactic acid streptococci, the total content of which in the finished product at the end of the shelf life is at least 107 CFU per 1 g of the product, without adding non-dairy components.

Mechnikovskaya simple milk - a national fermented milk product made by fermenting milk with pure cultures of thermophilic lactic acid streptococci and lactic acid Bulgarian bacillus, the total content of which in the finished product at the end of the shelf life is at least 107 CFU per 1 g of the product, without adding non-dairy components.

Ryazhenka - a national fermented milk product made by fermenting baked milk with pure cultures of thermophilic lactic acid streptococci, the total content of which in the finished product at the end of the shelf life is at least 107 CFU per 1 g of the product, without adding non-dairy components.

Varenets - a national fermented milk product made by fermenting sterilized or heat-treated milk at a temperature of (97 ± 2) ° C for 40 to 80 minutes by pure cultures of thermophilic lactic acid streptococci, the total content of which in the finished product at the end of the shelf life is at least 107 CFU in 1 g of product, without the addition of non-dairy components.

Kefir - national fermented milk product of mixed lactic acid and alcoholic fermentation, made by fermenting milk with a ferment prepared on kefir fungi without adding pure cultures of lactic acid bacteria and yeast, the content of lactic acid microorganisms in the finished product at the end of the shelf life is at least 107 CFU in 1 g of the product, and yeast not less than 104 CFU in I g of the product, without the addition of non-dairy components.

Acidophilus - a national fermented milk product made by fermenting milk with pure cultures of lactic acidophilus bacillus, lactococci and starter culture prepared on kefir fungi in equal proportions, the total content of lactic acid microorganisms in the finished product at the end of the shelf life is at least 107 CFU in 1 g of product, without adding non-dairy components.

Ayran - national fermented milk product of mixed lactic acid and alcoholic fermentation, made by fermenting milk with pure cultures of thermophilic lactic acid streptococci, lactic acid Bulgarian bacillus and yeast, the content of lactic acid microorganisms in the finished product at the end of the shelf life is at least 107 CFU in 1 g of product, and CFU in 1 g of product, no added non-dairy ingredients.

Koumiss - a national fermented milk product of mixed lactic acid and alcoholic fermentation, made by fermenting mare's milk with pure cultures of Bulgarian and acidophilic lactic acid sticks and yeast, the content of lactic acid microorganisms in the finished product at the end of the shelf life is at least 107 CFU in 1 g of the product, and yeast is not less than 105 CFU in 1 g of product, without the addition of non-dairy components.

Yogurt - fermented milk product with a high content of dry fat-free milk substances, made by fermentation with a protosymbiotic mixture of pure cultures of thermophilic lactic acid streptococci and lactic acid Bulgarian bacillus, the content of which in the finished product at the end of the shelf life is at least 10 7 CFU in 1 g of the product (it is allowed to add food additives , fruits, vegetables and products of their processing).

1.1. Classification of liquid fermented milk products and drinks

Fermented milk drinks, depending on the raw milk from which they are produced, are divided into products :

From natural milk;

From standardized milk;

From reconstituted milk;

From recombined milk;

From their mixtures.

Sour milk drinks, depending on the mass fraction of fat, are divided into products :

Low fat (ppm,%, 0.1);

Low-fat (ppm,%, 0.3; 0.5; 1.0);

Low fat (ppm,%, 1.2; 1.5; 2.0; 2.5);

Classic (m.d. f.,% 2.7; 3.0; 3.2; 3.5; 4.0; 4.5);

Fatty (ppm,%, 4.7; 5.0; 5.5; 6.0; 6.5; 7.0);

High fat (m.f.,%, 7.2; 7.5; 8.0; 8.5; 9.0; 9.5).

2.Finished product quality indicators .

In terms of organoleptic characteristics, fermented milk drinks must meet the requirements given in Table 1

Table 1

Organoleptic characteristics of fermented milk drinks

In terms of physical and chemical characteristics, fermented milk drinks must meet the requirements specified in table. 2

table 2

Physicochemical indicators of fermented milk products

Phosphatase is not allowed in the product.

Table 3

Microbiological indicators of fermented milk drinks are shown in table. four

Table 4.

Microbiological indicators of fermented milk drinks

For the manufacture of fermented milk drinks, the following raw materials are used :

raw cow milk not lower than the second grade in accordance with GOST E52054; whole milk powder of the highest grade according to GOST 4495; skimmed milk powder according to GOST 10970; dry cream according to GOST 1349; unsalted butter in accordance with GOST 37; starter cultures on pure cultures of lactic acid microorganisms, produced according to TU 9229-369-0019785-04 “Starter cultures, bacterial concentrates, yeast and test cultures”; drinking water according to SanPiN 2.1.4.1074 (for recombined or reconstituted milk).

3.General technology of fermented milk products .

Milk and other raw materials are accepted according to the weight and quality established by the quality control department (laboratory) of the enterprise, as well as on the basis of the certification documents of the supplier companies.

Immediately after receiving milk

1.heat to a temperature of 35 ... 40 ° C and cleaned on centrifugal milk purifiers or other equipment without heating. For cleaning raw milk, it is also recommended to use a bacteriofuge with a specially built-in hermetic separator to remove bacteria from milk.

2. After this milk is sent for processing or cooled to a temperature of (4 ± 2) ° С and stored in intermediate storage tanks. Storage of milk chilled to a temperature of 4 ° C before processing should not exceed 12 hours, cooled to a temperature of 6 ° C-6 hours.

3. Quality selected milk normalize by mass fractions of fat and protein so that they in the finished product are not less than that provided for by the standard.

Normalization, as well as the preparation of butter, recovery of dry milk products is carried out in the same way as it was shown in the technology of drinking milk.

4. Normalized mixture warmed up to a temperature of (43 ± 2) ° С and cleaned on centrifugal milk purifiers or filters.

5. Clarified milk homogenize at a pressure of (15.0 ± 2.5) MPa at a temperature of 45 to 85 ° C. If necessary, it is allowed to homogenize milk at pasteurization temperature.

Instead of full homogenization, it is allowed to use separate homogenization of milk. When using separate homogenization, the milk normalized by fat and heated in the second regeneration section of the plate pasteurizer to a temperature of 55 ... 65 ° C is separated. In this case, the mass fraction of fat in the resulting cream is from 16 to 20%. The resulting cream is homogenized on a two-stage homogenizer at a pressure: in the first stage from 8 to 10 MPa, in the second - from 2 to 2.5 MPa. The homogenized cream is in-line mixed with skim milk leaving the cream separator and sent to the pasteurization section.

In order to improve the taste of fermented milk drinks, it is also recommended to homogenize the milk intended for their production with a mass fraction of fat less than 2.5%.

6. Purified and homogenized mixture pasteurize at a temperature of (92 ± 2) ° С with exposure from 2 to 8 minutes or (87 ± 2) ° С with exposure from 10 to 15 minutes. Milk can be kept at these temperatures for 30 to 40 minutes. In the production of fermented baked milk, milk is pasteurized at temperatures from 95 to 99 ° C with exposure from 3 to 4 hours until a pronounced light cream color, and varenets - at the same temperatures with exposure from 60 to 80 minutes.

In the production of fermented baked milk, it is necessary to take into account the degree of bacterial contamination, composition, heat resistance of raw materials, etc. Pre-pasteurization of the normalized mixture at a temperature of (76 ± 2) ° C is allowed, followed by heating to a temperature of 95 ... 99 ° C with an exposure of 3 to 4 hours to a pronounced light cream color. Moreover, during heating, the mixture is stirred 1-2 times per hour to prevent the formation of foams.

7. After pasteurization and aging, milk cooled to fermentation temperature : (40 ± 2) ° С or (30 ± 2) ° С in the production of yogurt; (42 ± 2) ° С in the production of Mechnikovskaya curdled milk, yoghurt, fermented baked milk, varenets, etc .; (37 ± 2) ° С in the production of acidophilic fermented milk drinks; from 18 to 25 ° C in the production of kefir, etc., that is, to a temperature that is optimal for the development of microflora used in the production of one or another fermented milk drink. Storage of unleavened mixture at the fermentation temperature is not allowed.

With the reservoir method of production, milk is fermented and fermented in tanks for fermented milk drinks with a cooling jacket, equipped with special stirrers that ensure uniform and thorough mixing of milk with starter culture and fermented milk curd. In order to avoid foaming, which affects the separation of whey during storage of fermented milk drinks, milk is fed into the tank through the lower fitting.

The starter culture is prepared in accordance with the current technological instruction for the preparation and use of starter cultures and bacterial concentrates for fermented milk products at the dairy industry, approved in the prescribed manner.

Starter culture is introduced into milk in a stream using a dosing pump simultaneously with milk, or after some time from the beginning of filling the reservoir, or after filling the reservoir. The volume fraction of the starter culture in relation to the volume of the fermented mixture prepared in sterilized or pasteurized milk is 3 ... 5%. During the addition of the starter culture, the milk must be stirred to evenly distribute the starter culture in the volume of the product and prevent the formation of protein flakes. The milk with the added starter culture is mixed for 10 ... 15 minutes.

In the case of the tank production method, after mixing, the fermented milk is left alone to ferment. It is allowed to re-mix in 1 ... 1.5 hours after fermentation.

With the thermostatic method of production, milk is fermented in tanks for fermented milk drinks with a cooling jacket, equipped with special stirrers that ensure uniform and thorough mixing of milk with the ferment. Fermented milk is immediately poured into consumer containers with continuous stirring. The filling from each tank should be completed within 45 ... 60 minutes in order to avoid the formation of flakes of curdled protein. The mixture is fermented in a thermostatic chamber at the temperature indicated below.

The temperature and duration of fermentation in the production of fermented milk drinks are different depending on the microflora of the starter used. The modes are the same in the production of the same type of fermented milk drink using reservoir or thermostatic production methods. The end of fermentation is determined by the nature of the curd and its acidity. The curd should be smooth, firm enough and not release serum. Fermentation temperature and duration:

In the production of curdled milk - within 5 to 7 hours at a temperature of (30 ± 2) ° С and from 3 to 4 hours at a temperature of (40 ± 2) ° С

when using dry bacterial concentrate of lactococci, milk is fermented at a temperature of (30 ± 2) ° С from 8 to 10 hours, when using dry bacterial concentrate of thermophilic lactococcus - at a temperature of (40 ± 2) ° С from 6 to 8 hours; I in the production of fermented baked milk, yoghurt, Mechnikovskaya yogurt, varenets, etc. - for 4 to 6 hours at a temperature of (40 ± 2) ° С or when using dry bacterial concentrate - within 8 ... 10 hours at a temperature ( 40 ± 2) ° C;

in the production of acidophilic fermented milk drinks - within 7 ... 9 hours at a temperature of (37 ± 2) ° С;

in the production of kefir - within 8 to 12 hours at a temperature of 18 to 25 ° C. In addition, in the production of kefir, the fermented mixture is ripened for 9 to 13 hours at a temperature of (14 ± 2) ° C.

Fermented mixtures are fermented to form a milk-protein clot and acidity: from 75 to 80 ° T in the production of sour milk; from 65 to 70 ° T - in the production of fermented baked milk; from 85 to 100 T - in the production of kefir, etc.

8. At the end of the fermentation in the tank production method, the supply of ice water with a temperature of (2 ± 2) ° С to the inter-wall space of the tank for partial cooling of the curd to a temperature: in the production of curdled milk - 25 ... 35 ° С, in the production of fermented baked milk - (22 ± 5 ) ° C; in the production of kefir - (14 ± 2) ° С

In the case of a tank production method, after a period of time from 60 to 90 minutes after the water supply, the stirrer is turned on and the curd is stirred for 10 to 30 minutes, depending on the design of the mixer and the viscosity of the curd, to obtain a uniform curd consistency. When storing fermented milk drinks with a heterogeneous, lumpy consistency, whey may be released. Further mixing, if necessary, is carried out periodically, turning on the mixer for 5 ... 15 minutes.

In the production of kefir, the milk curd, mixed and cooled to a temperature of (14 ± 2) ° C, is left alone for maturation for a period of 9 to 13 hours. It is allowed to send a mixed and partially cooled curd for bottling, followed by maturation and cooling of the packed kefir in the refrigerating chamber. From the moment of fermentation to the end of ripening, at least 24 hours must pass.

2 to 5 minutes - in the production of kefir or within 5 to 15 minutes - in the production of fermented baked milk and curdled milk.

When stirring, pumping and pouring a fermented milk curd, it is recommended to avoid intense mechanical stress (long narrow pipelines, pumps that lead to significant damage to the clot, etc.), air leaks, which negatively affect the quality of the finished product. It is desirable to pour the fermented curd by gravity with a minimum level difference in height.

The mixed curd is fed into a consumer container by means of a pump designed for viscous liquids. In the presence of plate coolers, the curd can be cooled to a temperature of (4 ± 2) ° C before filling.

9. Fermented milk drinks are packaged and labeled in accordance with the requirements of the current standard for this product. The duration of pouring the fermented product from one container should not exceed 2 hours.

The packaged fermented milk drink, if necessary, is additionally cooled in a refrigerating chamber to a temperature of (4 ± 2) ° С, after which the technological process is considered complete and the product is ready for sale.

With a thermostatic production method, at the end of fermentation, the packaged product is placed in a refrigerator and cooled to a temperature of (4 ± 2) ° C. In the case of production of kefir in the refrigerating chamber, the milk-protein clot matures within 8 ... 13 hours. After that, the technological process is considered complete and the product is ready for implementation.

4. Theoretical foundations of production

The production of fermented milk products is a complex biochemical process, as a result of which the taste and smell, texture and appearance characteristic only of this fermented milk product are formed. Fermented milk products are obtained by fermenting thermally processed milk, cream, buttermilk, whey or mixtures thereof.

According to GOST 51917, a fermented milk product is a dairy product made by fermenting milk or cream with kefir fungi and / or pure cultures of lactic acid, propionic acid, acetic acid microorganisms and / or yeast and / or their mixtures. The total content of lactic acid microorganisms in the finished product at the end of the shelf life is at least 107 CFU per 1 g of the product. After ripening, the use of food additives, fruits, vegetables and their processed products is allowed. Bifidoproduct is a product containing bifidobacteria, the number of which at the end of the shelf life is at least 106 CFU per 1 g of the product.

The technological process for obtaining fermented milk products includes the following general operations:

• normalization of dairy raw materials for fat, in the production of kefir - additionally for protein, yogurt - for the mass fraction of milk solids;
• heat treatment,
• homogenization,
• fermentation and fermentation,
• cooling
• packaging.

In the production of fermented milk products, both biochemical and physicochemical processes are carried out

• fermentation of milk sugar,
• casein coagulation
• gelation.

BIOCHEMICAL AND PHYSICO-CHEMICAL PROCESSES IN THE PRODUCTION OF SOUR MILK PRODUCTS

Fermented milk products play an important role in the nutrition of people, especially children, the elderly and the sick. The dietary properties of fermented milk products are primarily in the fact that they improve metabolism, stimulate the secretion of gastric juice and stimulate appetite. The presence of microorganisms in their composition that can take root in the intestine and suppress the putrefactive microflora leads to inhibition of putrefactive processes and the cessation of the formation of toxic products of protein breakdown entering the human blood

FERMENTATION OF MILK SUGAR

The most important biochemical process in the production of fermented milk products is the fermentation of milk sugar caused by microorganisms of bacterial starter cultures. Its speed and direction determine the consistency, taste and smell of finished products. By the nature of milk sugar fermentation, fermented milk products can be divided into two groups. The first group includes products, the preparation of which is mainly based on lactic acid fermentation (curdled milk, yogurt, acidophilus, cottage cheese, sour cream), the second group includes products with mixed fermentation, in the manufacture of which lactic acid and alcoholic fermentation occurs (kefir, koumiss, acidophilic - yeast milk).

During lactic acid fermentation, each pyruvic acid molecule formed from a glucose molecule is reduced with the participation of the redox enzyme lactate dehydrogen-1 to lactic acid:

By increasing the acidity of milk during lactic acid fermentation, it is possible to calculate how much milk sugar has been fermented. For example, the acidity of milk increased by 60T (the acidity of fresh milk was 17 ° T, after fermentation of milk sugar - 77T). 1˚T corresponds to I cm3 0.1 N. alkali solution or 1 cm 30.1 N. lactic acid solution, which is 90 / (10 1000) \u003d 0.009 g of lactic acid. Therefore, 60T will correspond to 600.009 - 0.54 g of lactic acid.

From the total reaction of lactic acid fermentation, it follows that 4 moles of lactic acid are formed from 1 mole of lactic sugar, i.e. 4-90 \u003d 360 g of lactic acid is formed from 342 g of lactic sugar. Therefore, to obtain 0.54 g of lactic acid, milk sugar was required

When fermenting sugar, many lactic acid bacteria, in addition to lactic acid, form a number of other chemicals that give fermented milk products a specific taste and aroma. These include volatile acids (acetic, propionic, etc.), carbonyl compounds (diacetyl, acetoin, acetaldehyde), alcohol and carbon dioxide.

Depending on the products accumulated during fermentation, all lactic acid bacteria are subdivided into homofermentative and heteroenzymatic. Lactic acid bacteria (lac. Lactis, Lac. Cremoris, Lac. Diacetilactis, Str. Thermophilus, L. bulgaricus, L. acidophilus), which form lactic acid as the main fermentation product, are referred to as homo-enzymatic; bacteria (Leuc. cremoris, Leuc. dextranicum, etc.), which, in addition to lactic acid in significant quantities, form other fermentation products, are heterofermentative.

By a certain combination of various types of lactic acid bacteria and regulation of the fermentation temperature, it is possible to obtain a product with the desired taste, aroma, texture and dietary properties.

In fermented milk products with mixed fermentation (kefir, koumiss, etc.), along with lactic acid, a large amount of ethyl alcohol and carbon dioxide is formed. The causative agent of alcoholic fermentation in these products is yeast. During alcoholic fermentation, pyruvic acid, under the action of the enzyme pyruvate decarboxylase, which catalyzes the elimination of carbon dioxide, is split into acetaldehyde and carbon dioxide:

Acetic aldehyde with the participation of the redox enzyme alcohol dehydrogenase is reduced to ethyl alcohol:

The ability of yeast to produce alcohol and carbon dioxide depends on many factors: the type of yeast used, the amount of milk sugar in the feedstock, temperature, pH of the medium, etc.

CASEIN COAGULATION AND GEL FORMATION

The accumulation of lactic acid during lactic acid fermentation of lactose is essential for the formation of a protein clot, which determines the consistency of fermented milk products. The essence of acid coagulation is as follows. The resulting (or added) lactic acid reduces the negative charge of casein micelles, since H-ions inhibit the dissociation of the carboxyl groups of casein, as well as the hydroxyl groups of phosphoric acid. As a result, the equality of positive and negative charges and isoelectric point of casein (pH 4.6-4.7) is achieved.

With acid coagulation, in addition to reducing the negative charges of casein, the structure of the calcium-caseinate complex is disturbed (calcium phosphate and structure-forming and calcium are split off). Since calcium and calcium phosphate are important structural elements of the complex, their transition to solution further destabilizes casein micelles.

In the production of cottage cheese by the acid-rennet method, lactic acid and introduced rennet act on casein.

Under the action of rennet, casein is converted into paracasein, which has an isoelectric point in a less acidic environment (pH 5-5.2).

At the isoelectric point, casein or vapor casein particles collide to form chains or threads, and then a spatial network, in the cells or loops of which a dispersion medium with fat balls and other constituents of milk is captured. Gelation occurs. In the production of fermented milk products and cheese, the gelation process can be conditionally divided into four stages: the stage of latent coagulation (induction period), the stage of mass coagulation, the stage of structure formation (clot thickening) and the stage of syneresis.

In colloidal systems, gelation is influenced by the concentration of the dispersed phase, size, shape of particles, temperature, etc. The resulting clot (gel) has certain mechanical properties: viscosity, plasticity, elasticity and strength. These properties are associated with the structure of the system, therefore they are called structural-mechanical or rheological.

Structural and mechanical properties of clots are determined by the nature of the bonds that arise between protein particles during the formation of the structure. Relationships can be reversible and irreversible. Reversible (thixotropic-reversible) bonds are restored after disruption of the clot structure. They determine the phenomenon of thixotropy (Fig. 1a) ((Greek thixis - touch + trope - change) - the ability of structures after their destruction as a result of some mechanical action to spontaneously recover in time.

Irreversible (irreversibly destroyed) bonds do not have the property of being restored after mechanical action on the clot. The phenomenon of syneresis is associated with them. Syneresis (Fig. 1b) - compaction, tightening of the clot with shortening of casein filaments and displacement of the liquid contained between them. Fig 2. The rate of syneresis is determined by the water-holding capacity of casein and depends on the concentration of dry substances in the raw material, the composition of bacterial starter cultures, heat treatment modes for homogenization, the method of milk coagulation and other factors.

For fermented milk drinks and sour cream, syneresis is an undesirable phenomenon. Therefore, during their production, bacterial starter cultures of the desired composition are used and the technological process is carried out under conditions that prevent the occurrence of syneresis. In the production of curd, on the contrary, it is required to remove the excess whey from the curd. Therefore, such modes of milk processing are chosen that would contribute to obtaining a dense, but easily giving off whey curd. To enhance syneresis, grinding, heating of the clot, etc. is also used.

The nature of bonds in the structure of the clot (product) can be determined by measuring the so-called effective viscosity - the viscosity due to the formation of internal structures in the product. At the same time, the effective viscosity of the intact η n, destroyed ηp and restored ηp structures is determined and compared with each other (Table 5)

As can be seen from Table 5, during the formation of curdled milk and fermented milk beverages, irreversibly destroyed (nonthixotropic bonds) are mainly formed. There are few thixotropic bonds characterized by spontaneous recovery after mechanical action. Sour cream is characterized by a lower loss of viscosity during structure destruction and a large number of thixotropic bonds in comparison with fermented milk drinks.

Table 5

BIOCHEMICAL BASIS OF PRODUCTION SEPARATE TYPES OF SOUR MILK PRODUCTS

The quality of the fermented milk products produced depends on the nature of the formed clots, as well as the degree of accumulation of flavoring and aromatic substances. The nature of clots is determined by the level of accumulation of lactic acid, the ability of proteins to form spatial structures, retain moisture, etc. The formation of flavoring and aromatic substances depends on the composition of bacterial starter cultures, conditions of fermentation, ripening and cooling of products.

SOFT MILK DRINKS

The main process that determines the consistency of all fermented milk drinks is gelation. The clots of these products are different: in some cases the clot is dense (prickly), in others it is even and tender (creamy) or flaky, etc.

During the formation of the structure of product clots, irreversibly destructible bonds are generally formed, there are few thixotropic-reversible bonds in them, therefore it is so important to conduct the technological process under such modes that would ensure minimal separation from the whey clot. This primarily refers to the modes of pasteurization, homogenization and fermentation of milk.

It is known that the synergistic properties of the curd depend on the temperature of milk pasteurization. To increase the strength of the curds and prevent the release of whey when storing curdled milk and other fermented milk drinks, it is recommended to use high pasteurization temperatures of milk (85-87 ° C with exposure for 5-10 minutes or 90-94 ° C with exposure for 2-8 minutes).

The duration of milk fermentation during the production of products is determined by the type of bacterial starter culture and the fermentation temperature. The end of the fermentation is usually set to obtain a sufficiently strong curd and a titratable acidity of 75-85 ° T. In the production of fermented milk drinks by the reservoir method, it is necessary to obtain a clot with the maximum amount of thixotropic-reversible bonds, therefore, before mixing and cooling the clot, the pH value should be monitored: it should be 4.5-4.4 for kefir, and 4.7 for acidophilus. 4.55, fermented baked milk - 4.45-4.35. Additionally, the viscosity of the clot is checked by the duration of the flow from a pipette with a capacity of 100 cm 3 at 20 ° C or using a capillary viscometer.

The specific fermented milk taste and smell of products are formed mainly during the period of their fermentation and ripening. The taste and smell of products are complemented by compounds formed during heat treatment of milk (they play a major role in the production of varenets and fermented baked milk).

The main flavoring and aromatic substances of fermented milk products are lactic and acetic acids, diacetyl, acetaldehyde (its high concentration is typical for yogurt), etc. Ethyl alcohol and carbon dioxide give a refreshing, slightly spicy taste to kumis and kefir. The alcohol retention in beverages is determined by the type of yeast, temperature and duration of maturation. In kumis it is 1 - H "6, in kefir - 0.01-0.03%. They are also characterized by the breakdown of proteins (proteolysis), so the released amino acids and peptides can take part in the formation of the taste of these products.

5 ... INFLUENCE OF MILK COMPOSITION, BACTERIAL STEAMS AND OTHER FACTORS ON FERMENTATION LACTOSE AND COAGULATION OF CASEIN

The quality of fermented milk products, mainly their consistency, depends on the composition and properties of milk, the type and activity of bacterial starters, modes of pasteurization, homogenization, fermentation, ripening and other factors.

Composition and properties of raw materials determine the rate of coagulation of milk proteins and the strength of the resulting clots. The development of microorganisms of bacterial starter cultures that ferment milk sugar also depends on them.

The composition and properties of milk change during the year, the stage of lactation, with diseases of animals, etc. It is known from the practice of dairy factories that in the fall and especially in the spring there is a slow fermentation of milk. This may be due to a decrease in its biological value. For example, in spring, the content of vitamins (biotin, niacin, B 6, etc.), free amino acids (valine, leucine, phenylalanine, etc.) and trace elements (Mn, Co, Fe, etc.), which are necessary for the reproduction of lactic acid bacteria. In addition, antibiotics and other substances that inhibit the development of lactic acid bacteria may be the reason for non-fermentation of milk at this time of the year. Lactic acid bacteria develop poorly in old milk and milk obtained from cows with mastitis.

In spring, the technological properties of milk also deteriorate - the rate of formation and density of the acid curd decrease. This is due to a decrease in the content of dry substances in milk, casein, the size of casein micelles, and an increase in milk acidity.

· Individual characteristics and breeds of animals

The ability of milk to rennet is determined by the concentration of proteins, calcium salts and depends on the individual characteristics and breed of animals, feed, stage of lactation and other factors. Milk coagulates poorly at the beginning and end of lactation, as well as when animals are sick.

· Storage time

The properties of milk (and the properties of the curd obtained from it) change during storage. So, after long-term storage of milk (raw and pasteurized) at low temperatures, the viscosity and strength of the acid curd increase, the syneresis slows down. Therefore, milk stored at low temperatures should be sent to the production of fermented milk drinks and should not be used. for the production of curd

· The composition of the starter cultures.

Not only the taste of fermented milk products, but also their consistency depends on the composition of the starter cultures. The main component of the microflora of the starter cultures of all fermented milk products, which ensures the formation of a clot, is milk lactococcus (Lac. Lactis). The inclusion of energetic acid-formers in the starter cultures results in a dense prickly curd with an intensive separation of whey, and low-energy acid-formers - a more delicate curd. The introduction of the starter culture Str. thermophilus, Lac. cremoris and thermophilic sticks increases the viscosity of the product, gives the clot elastic properties, prevents the release of serum.

Therefore, by selecting the composition of the starter cultures, it is possible to regulate the properties of the curd and ensure the optimal consistency and taste of fermented milk products.

· Heat treatment

Heat treatment of milk affects the rate of clot formation, structural and mechanical properties and syneresis.

According to VNIMI and VNIIMS, with an increase in the pasteurization temperature, the strength of acid and acid-rennet clots increases (Table 6).

Table 6.

When the temperature of milk pasteurization rises (from 63 to 90" C ) the intensity of the separation of whey from the curd is reduced.Increase in the strength of the curd and the deterioration in the release of whey from them after high heat treatment temperatures can be explained by an increase in the content of denatured whey proteins in the curd, which increase the rigidity of the spatial structure and water-holding capacity of casein

Thus, by regulating the modes of heat treatment of milk, it is possible to obtain a curd with the desired rheological properties, i.e. to improve the consistency of the fermented milk product

· Milk homogenization

When making fermented milk drinks, it is recommended to homogenize milk before fermentation (for kefir and yogurt obtained by the reservoir method, it is mandatory). As a result of homogenization, the dispersion of the fat increases, the crushed fat in the clots is distributed more evenly, the strength of the clot increases, while the viscosity of the products slightly increases and the release of whey decreases.

At the same time, homogenization of milk with increased (above 10%) fat content and cream contributes to a significant increase in the viscosity of the clots and a decrease in their ability to separate whey. In this case, the increase in the viscosity of the formed clots depends on the pressure and the method of homogenization of the raw material.

Structural-mechanical and synergetic properties of clots significantly depend on the method of protein coagulation

· Coagulation type

Clots formed during acidic coagulation of proteins are less stable than acid-rennet ones (the spatial structure of acid clots is supported by weak bonds, the structure of acid-rennet ones is additionally stabilized and strengthened by calcium bridges formed between the parts of paracasein); they are made up of smaller protein particles and less serum. However, along with an increase in the strength of acid-rennet clots, their fragility, degree of dispersion and the ability to separate whey during processing increase.

· Clotting duration and temperature

The duration and temperature of clotting (fermentation) of milk are important factors affecting the consistency of fermented milk products. The duration of milk fermentation is usually determined by the increase in acidity, viscosity or strength of the resulting curd. It is especially important to determine the moment when the curd is ready for the production of drinks by the reservoir method. Sometimes there is a liquid consistency of products and whey sludge. This is caused by the wrong choice of the moment for mixing the bunch. Whey is released by stirring the curd in the case when it has a minimum viscosity and exhibits insignificant thixotropic properties.

In addition, the temperature and duration of milk fermentation determines the accumulation of substances in the products that give them a certain taste and aroma (volatile acids, diacetyl, acetaldehyde, etc.).

To stop lactic acid fermentation and strengthen the structure of the formed clot, fermented milk products are cooled to 8 ° C and stored at this temperature. The products of mixed fermentation are subjected to maturation before cooling, for the development of yeast and aroma-forming bacteria. In the process of maturation and aging in the refrigerator, aromatic substances, alcohol and carbon dioxide accumulate in the products, and partial decomposition of proteins also occurs under the influence of proteolytic enzymes of lactic acid bacteria and yeast. In this case, various soluble polypeptides and free amino acids are formed, which affect the consistency, taste and smell of products.

In the production of sour cream, the additional purpose of cooling and ripening is the hardening of the fat, which improves the structure and consistency of the product.

5.VINCES OF SOUR MILK PRODUCTS .

Bibliography

1 TO. K. Gorbatova "BIOCHEMISTRY OF MILK AND DAIRY PRODUCTS" St. Petersburg GIORD 2004

2.H. A. Tikhomirova "Technology and organization of milk and dairy products production" 2007 Moscow DeLi print

Fermented milk products are produced by thermostatic and reservoir methods. (Tverdokhleb G.V., 1991)

Tank method. The technological process for the production of drinks by the reservoir method consists of the following technological operations: acceptance and preparation of raw materials, qualitative assessment, normalization, homogenization, pasteurization and cooling, fermentation, fermentation in special containers, cooling the curd, maturation of the curd (kefir, kumis), packaging.

For the production of fermented milk drinks, milk is used not lower than second grade, acidity not more than 19 ° T, density not less than 1027 kg / m 3. Powdered milk is pre-reconstituted. Skimmed milk, buttermilk, cream, condensed and powdered milk, sodium caseinate, fruit and berry and vegetable fillers must be sound, without foreign tastes and odors and consistency defects.

Fermented milk drinks are produced with different mass fraction of fat, therefore the original milk is normalized to the required mass fraction of fat. Milk standardization is carried out in the flow on standardizing separators or by mixing. Some foods are made from skim milk. When normalizing raw materials by mixing, the mass of products for mixing is calculated using the material balance formulas or determined by the recipe.

The scheme of the technological line for the production of fermented milk drinks by the reservoir method is shown in Figure 1.

Figure: one. 1 -- installation for dissolving milk powder; 2 -- container for the normalized mixture; 3 -- centrifugal pump; 4 - balancing tank; 5 - pasteurization and cooling unit; 6-- centrifugal milk purifier; 7 - homogenizer; 8-- aging; 9, 14 -- containers for fermented milk drinks; 10-- sourdough; 11 - dosing pump; 12 -- screw pump; 13-- plate cooler. (Bredikhin S.A., 2001)

The normalized mixture is heat treated. As a result of pasteurization, microorganisms in milk are destroyed and conditions favorable for the development of the microflora of the starter culture are created. The normalized mixture is pasteurized at a temperature of 92 ± 2 ° C with an exposure of 2 ... 8 minutes or at a temperature of 85 ... 87 ° C with an exposure of 10 ... 15 minutes; UHT treatment is possible at 102 ± 2 ° C without holding. For the production of fermented baked milk, the mixture is pasteurized at 95 ... 98 ° C with exposure for 2 ... 3 hours. High pasteurization temperatures cause denaturation of whey proteins, while the hydration properties of casein increase. This contributes to the formation of a denser curd, which retains moisture well, which, in turn, prevents whey from separating during storage of fermented milk drinks.

Heat treatment of the mixture is usually combined with homogenization at a temperature of 60 ... 65 ° C and a pressure of 15 ... 17.5 MPa.

After pasteurization and homogenization, the mixture is cooled to the fermentation temperature, after which it enters the fermentation tank. Sourdough is added to the cooled mixture, the mass of which is usually 5% the mass of the fermented mixture. Direct addition starter cultures are used.

The mixture is fermented at the fermentation temperature. During fermentation, the microflora of the starter culture multiplies, acidity increases, casein coagulates and a clot is formed. The end of fermentation is judged by the formation of a sufficiently dense clot and the achievement of a certain acidity.

After the end of fermentation, the product is immediately cooled.

Kefir, produced with ripening, after fermentation is cooled to 14 ... 16 ° C and ripens at this temperature. The duration of the maturation of kefir is not less than 10 ... 12 hours. During maturation, yeast is activated, alcoholic fermentation occurs, as a result of which alcohol, carbon dioxide and other substances are formed in the product, which give this product specific properties. In the production of fruit kefir, fillers are added after ripening before packing.

Fermented milk drinks are packed in heat sealable bags, boxes, cups, etc.

Thermostatic way. The technological process for the production of fermented milk drinks by the thermostatic method consists of the same technological operations as in the production of the reservoir method, carried out in the following sequence: preparation of raw materials, normalization, pasteurization, homogenization, cooling to the fermentation temperature, fermentation, filling, fermentation in thermostatic chambers, cooling clot, clot ripening (kefir, kumis).

The scheme of the technological line for the production of fermented milk drinks by the thermostatic method is shown in Figure 2.

Figure: 2. 1 -- container for raw milk; 2 -- pump; 3 -- balancing tank; 4 - pasteurization and cooling unit; 5 - control panel; 6-- return valve; 7 - separator-normalizer; 8 -- homogenizer; 9 -- container for keeping milk; 10-- container for fermenting milk; 11 - car for packing milk; 12 -- thermostatic chamber; 13 - refrigerating chamber; 14 -- storage room for finished products. (Bredikhin S.A., 2001)

Acceptance and preparation of raw materials, normalization, heat treatment, homogenization of the normalized mixture and its cooling to the fermentation temperature are performed in the same way as in the tank production method. Next, the normalized mixture is fermented in a container. After fermentation, the mixture is packed into consumer containers and sent to a thermostatic chamber, where a temperature is maintained that is favorable for the development of the ferment microflora. The end of fermentation is judged by the acidity and density of the curd. After the end of fermentation, the product is sent to the refrigerating chamber for cooling, and kefir - for maturation.

The tank method for the production of fermented milk drinks in comparison with the thermostat has a number of advantages. First, this method allows you to reduce production space by eliminating bulky thermostatic chambers. At the same time, the removal of products from 1 m 2 of the production area increases and the consumption of heat and cold decreases. Secondly, it allows for more complete mechanization and automation of the technological process, reducing the cost of manual labor by 25% and increasing labor productivity by 35%.

Defects of fermented milk products

Defects of fermented milk products occur as a result of the use of poor-quality raw materials, the action of bacterial starter cultures in violation of technological production regimes or non-observance of the conditions for cooling and storing finished products.

Defects of taste and smell. Indistinct (insipid) taste - due to low acidity, weak aroma and insufficient curd density. Such a defect appears when using a poor-quality starter culture (weak acidity) or at too low fermentation temperatures.

Fodder flavors that have passed from milk to fermented milk products (wormwood, silage). Ammonia and bready flavors appear when milk is kept in a poorly ventilated barnyard for a long time.

A bitter taste can appear as a result of the development of peptonizing bacteria in the case of prolonged (up to two days) storage of raw milk at low temperatures, as well as in cottage cheese with the addition of excessive doses of pepsin.

A metallic taste appears in food when stored for a long time in poorly tinned dishes.

An excessively sour taste is detected as a result of delayed cooling after fermentation or due to a long fermentation time itself, as well as when stored under conditions of unacceptably high temperatures.

Acetic acid and butyric acid taste depend on the activity of the corresponding extraneous microflora that has entered the milk or sourdough.

A greasy aftertaste in sour cream can appear as a result of oxidative processes of fat during prolonged storage or direct sunlight on the surface of sour cream. (Kastornykh M.S., 2003)

Consistency defects

A flabby curd is the result of using starter cultures with weakened cultures or keeping the product at low temperatures, as well as violations of the pasteurization temperature regime (at low temperatures and without aging).

A viscous consistency is formed with a significant predominance of mucous races of lactic acid bacteria in the leaven.

Isolation of whey - the main defect of fermented milk products produced by the reservoir method - is a consequence of the unsatisfactory quality of raw materials (low solids content), deviations from the normal mode of homogenization and pasteurization of milk when the product is fermented.

The swollen consistency is caused by contamination of the starter culture by gas-forming bacteria species, and also appears at low fermentation temperatures. (Shepelev A.F., 2001)

In accordance with GOST R 52090-2003 “Drinking milk. Technical conditions " drinking milksubdivided depending on the raw milk used:from natural milk, from normalized milk, from reconstituted milk, from recombined milk, from mixtures thereof; depending on the heat treatment mode:pasteurized, melted, sterilized, UHT (ultra high temperature) -processed, UHT-processed sterilized; depending on the fat content:low fat (0.1%), low fat (0.3; 0.5; 1.0% fat), low fat (1.2; 1.5; 2.0; 2.5% fat), classic (2, 7; 3.0; 3.2; 3.5; 4.0; 4.5% fat), fatty (4.7; 5.0; 5.5; 6.0; 6.5; 7.0 % fat), high fat (7.2; 7.5; 8.0; 8.5; 9.0; 9.5% fat).

Pasteurized milk. Milk heat treated at certain temperature conditions (up to 100 0 C) and then chilled. The technological process for the production of drinking milk at the factories is carried out according to the following scheme: purification, normalization, homogenization, cooling, filling with packaging and storage.

Milk homogenization(homogeneous - homogeneous). In the process of homogenization, large fat globules with an average diameter of about 1 micron are obtained and uniform in size. From one fat globule with a diameter of 6 microns, more than 200 small ones, with a diameter of 1 micron, are formed. In homogenized milk, there is practically no cream settling.

Sterilized milk. The production of sterilized milk at factories can be carried out according to two schemes: with a one-stage and two-stage sterilization mode. In a one-stage scheme, milk is sterilized once before or after filling at a temperature of 130-150 ° C with an exposure of 2-3 seconds. This regime is accompanied by the smallest changes in the native properties of milk. Such milk can be stored for up to 2 months from the date of release from the factory at temperatures from 1 to 20 0 C. In a two-stage mode, milk is sterilized with exposure for 20 s, and then in bottles with steam at a temperature of 116-118 0 C for 12-15 min. Double sterilization causes deeper changes in the constituent parts of milk, but at the same time ensures its high stability - it can be stored in uncooled rooms for more than a year.

Reconstituted milk is produced by complete or partial dissolution in drinking water at a temperature of 38-42 ° C of dry whole or skim milk, followed by its purification, homogenization and normalization in terms of fat.

Protein milk contains an increased amount of non-fat milk solids. It is produced from milk, normalized in terms of fat content, with the addition of dry or condensed whole or skim milk.

Baked milk - a specific product with definite taste properties and a pronounced color shade. It is produced from normalized and homogenized ordinary milk, which is heated to a temperature of 96-98 ° C with keeping at this temperature for 3-4 hours. As a result of prolonged exposure to high temperatures, physicochemical changes in milk proteins and lactose occur, therefore the finished product has a pronounced taste boiled milk and becomes creamy with a brown tint.

Dairy productsare produced by fermentation of milk and cream with pure cultures of lactic acid bacteria (starter culture). Most of the fermented milk products have not only high nutritional, dietary, but also medicinal properties. Acidophilus bacilli, as well as yeast used in the production of fermented milk products, are capable of producing significant amounts of antibiotics such as nisin, lactolin, lactomin, etc. Scientifically grounded human nutritional standards provide that 40-50% of all milk intended for consumption, it is desirable to use it in the form of fermented milk products, which are absorbed by the body much easier and faster than milk.

Fermented milk products are produced:

1) liquid and semi-liquid consistency (curdled milk, kefir, etc.);

2) high in fat (sour cream);

3) with a high protein content (cottage cheese, curd mass, curd products).

Depending on the type of fermentation, fermented milk products are distinguished, obtained only using lactic acid fermentationand the accumulation of lactic acid (curdled milk of all types, yoghurt, acidophilus and acidophilus milk, the "Snowball" drink, and products obtained with joint lactic acid and alcoholic fermentation,when lactic acid, ethyl alcohol and carbon dioxide accumulate (kefir, kumis, acidophilic yeast milk, etc.). In the manufacture of fermented milk products, starters are used, which are prepared on pure cultures of the corresponding types of microorganisms. In the process of fermentation, biochemical and physicochemical changes occur in almost all components of milk.

The use of lactic acid microorganisms in various combinations makes it possible to obtain a large number of types of fermented milk products. The dairy industry produces various fermented milk products: all kinds of yogurt, yoghurt, kefir, acidophilic products, kumis, sour cream, cottage cheese, etc.

The production of fermented milk products consists of the following processes: reception and sorting of milk, normalization, pasteurization, homogenization, cooling, fermentation, fermentation, cooling, maturation, storage, sale.

Liquid fermented milk products are prepared by thermostatic and reservoir methods. Thermostatic and reservoir methods have the same initial technological operations, including fermentation.

Thermostat methodthe production of fermented milk drinks is a method in which the fermentation of milk and the maturation of drinks is carried out in bottles in thermostatic and refrigerated chambers.

Tank methodproduction of liquid fermented milk drinks - a method in which fermentation, fermentation of milk and ripening of drinks are carried out in one container.

Butter and cheese making

Butter -high-calorie food product, which is a concentrate of milk fat. The raw material for the preparation of butter is cream, which undergoes a whipping process. It consists mainly of a fatty part and water. The quality of the butter and its stability during long-term storage largely depend on the quality of milk and cream. Particular attention should be paid to the defects of milk fat, as they intensify in butter (20-25 kg of milk is used to produce 1 kg of butter). The best is milk with a high fat content, which has large fat globules, obtained from cows whose rations were complete in terms of total nutritional value, protein, and minerals. As the fat content of milk increases, its costs for butter production decrease and relatively less fat remains in the by-products - skim milk and buttermilk.

There are two ways to make butter:

1) whipping cream;

2) conversion of high fat cream.

Method of whipping creamprovides for the production of butter grains from cream of medium fat content (30-35%) and its subsequent mechanical processing. Oil by this method can be produced in batch-type (roller and non-roller) and continuous oil makers.

Method for converting high fat cream(82% fat and more) consists in thermomechanical action on high-fat cream in special devices.

Carrying out individual operations when obtaining butter by whipping cream. Normalization of cream.For sweet butter, the optimum fat content of cream is 32-37%.

Pasteurization.Normalized cream of grade I is pasteurized at a temperature of 85-90 0 С without aging, grade II - at 92-95 0 С, to destroy microflora and lipase enzyme.

Cooling and physical maturation of the cream.After pasteurization, the cream is quickly cooled to 4-6 0 C. At this temperature (physical maturation), mass crystallization of milk fat glycerides occurs: it passes from a liquid to a solid state, which makes it possible to form an oil grain with subsequent churning.

When physical maturationthe fat globules become more elastic, their protein shell becomes thinner, the viscosity of the cream increases, and the fat globules are more capable of forming lumps. The lower the temperature, the shorter the maturation time of the cream. With deep cooling (0-1 0 C) and intensive stirring, the ripening period of the cream is reduced to several minutes, which makes it possible to create continuous technological lines for the production of butter.

Biochemical maturationused in the manufacture of sour cream butter. Its essence lies in the fermentation of cream with sourdoughs (the same as when making sour cream). Biochemical maturation contributes to a greater thinning of the membrane of the fat globules and the release of fat from them.

Filling the buttermaker.The buttermaker is filled with cream to about 35-40% of its volume. The temperature of the cream in the spring-summer period should be 7-12 0 С, in the autumn-winter period 8-14 0 С.

Whipping cream.When cream is churned into butter, the shell of the fat globules is destroyed and they are combined into an oil grain. The essence of the process of churning butter is the flotation theory, which is that when churning cream, air bubbles (foam) are formed. Fat globules accumulate (float) on the surface of the air bubbles. Under the influence of mechanical shocks, air bubbles burst and fat globules are interconnected by bare areas into conglomerates.

Removing the buttermilk and washing the oil grain.When the grain is ready, remove the buttermilk by filtering it through a sieve to retain the small grains. Then the grains (oil) are washed 2 times. Water takes 50-60% of the amount of cream. The temperature of the first wash water is equal to the temperature of the cream, the second is lower by 1-2 0 C. When making sour cream butter, it is washed less intensively, using only 15-20% of water by weight of the cream, in order to maintain a specific taste and smell.

Oil processing.The goal is to combine the oil grain and obtain a layer of uniform consistency, give the oil a certain structure, presentation, evenly distribute salt and moisture throughout the mass, and disperse water droplets to a minimum size. Processing is carried out by passing oil between the rollers of the oil maker. Its rotation speed is 3-5 rpm. Duration of processing in summer 20-30 minutes, in winter 30-50 minutes. In the finished oil on the cut and on the surface, there should be no noticeable drops of moisture.

Butter production by means of converting high-fat cream. This method allows you to create in-line production. Its essence lies in the fact that first the milk is separated on a conventional separator, cream is obtained with 35-40% fat content, then they are pasteurized at a temperature of 85-90 0 C. Pro-pasteurized cream at high temperature is separated on a special separator in order to obtain high-fat cream (84- 85%), normalize them to the required fat content and send them to the butter maker, where they are cooled and converted into oil.

Oil classification. In accordance with the requirements of the standard, butter is divided into the following types: unsalted, salted, Vologda, amateur, peasant, ghee, etc.

Unsaltedand saltybutter is made from pasteurized cream with or without the use of pure cultures of lactic acid bacteria (sweet cream or sour cream). When making salted butter, table salt is added.

Vologdaunsalted butter is made from sweet cream that has been pasteurized at high temperatures and has a nutty flavor and smell.

Amateurbutter is made from pasteurized cream with or without the use of pure cultures of starter cultures (sweet cream or sour cream), with or without the addition of table salt (salted or unsalted).

Peasantunsalted butter is made from pasteurized cream with or without the use of pure cultures of lactic acid bacteria (sweet cream or sour cream), and peasant sweet cream salted - from fresh pasteurized cream.

Meltedbutter is melted milk fat with a specific taste and aroma inherent in it. Each type of oil is characterized by a specific chemical composition.

When establishing the quality of the oil, its chemical composition and organoleptic data are taken into account, which is carried out on a 100-point scale. The results of the assessment for taste, smell, consistency, color, salting, packaging and labeling are summed up and the grade of oil is established according to the overall score: the highest (over 88 points) and the first (over 80 points).

Cheese making. Cheese- a high-value food product obtained from milk by enzymatic coagulation of proteins, extraction of cheese mass with its subsequent processing and maturation. According to the International Dairy Federation, more than 500 names of cheese are produced in the countries with developed dairy farming that are part of the Federation.

Classifycheeses in a number of ways, primarily in terms of technology. Cheeses are mainly divided into rennet and fermented milk. Processed or processed cheeses are also produced.

Each type of cheese is characterized by a certain shape, organoleptic properties, chemical composition, which must comply with the standard.

Cheese technology consists of a number of operations that can be performed in different ways, which determines the characteristics of a particular type of cheese or a group of cheeses. In general, the process of production of natural rennet cheeses is carried out according to the following scheme: 1) Determination of the quality of milk and its sorting; 2) Preparation of milk for processing; 3) Coagulation of milk; 4) Processing curd and curd; 5) Shaping the cheese; 6) Salting cheese; 7) Maturation of cheese; 8) Preparation of cheese for sale; 9) Storage and transportation.

Requirements for milk for cheese production.Milk with organoleptic flaws is not suitable for cheese production. The flavors of taste and smell are more pronounced in the finished cheese than in milk. The yield of cheese depends on the content of fat and casein in milk. For the production of cheese, milk is used only 7-10 days after calving and 7-10 days before the start of the cows, since an admixture of colostrum or old-milk milk to normal milk reduces the quality of the cheese. Milk of cows with mastitis is unsuitable for cheese making. Milk must contain sufficient amounts of calcium and phosphorus, especially calcium in a soluble state. For cheese-making, milk with an acidity of not higher than 20 0 T is used, since high-quality cheese cannot be obtained from milk with high acidity.

Cheese suitability of milk is assessed by the duration of its coagulation by rennet. Milk that slowly curdles by rennet is considered non-chewable or rennet. To improve cheese suitability, calcium chloride, an increased dose of bacterial starter culture, and also increase the temperature of milk clotting are added to milk. For the production of cheese, the so-called "mature" milk is used. Freshly milked milk cannot be processed into cheese, as it does not coagulate well with rennet. Exposure (maturation) of good-quality milk for 10-15 hours at 8-10 0 C leads to the development and accumulation of lactic acid microflora, the enlargement of casein micelles, an increase in acidity by 1-2 ° T. Changes (ripening) that take place have a positive effect on the quality of the cheese.

Pasteurization.In cheese-making, milk is pasteurized at 71-72 0 C, higher pasteurization temperatures lead to a loss of curdling ability of milk.

Curdling milk.For coagulation of milk, an enzyme preparation is used - rennet powder, obtained in special factories from the mucous membrane of the rennet of suckling calves of lambs. For coagulation of milk, pepsin is also used, obtained from the gastric mucosa of adult animals. Before curdling, a bacterial starter culture, calcium chloride, chemically pure potassium or sodium nitrate (to suppress the development of Escherichia coli), paint are added to the cooled milk. After that, the required amount of rennet is set for milk coagulation.

Clot processing.The curd is processed in order to partially remove whey from the curd and curd, as well as to create optimal conditions for microbiological and biochemical processes in the curd, grain and cheese during the first period of its maturation. To accelerate and more complete release of whey, the curd is subjected to cutting, kneading the resulting curd, and the second heating. Cut the curd with cheese lire and knives. Cutting the curd and crushing it to the required size is called curd setting.

Plasma curd- carried out in order to combine the curd into a solid monolith.

Cheese shaping.To give the cheese an appropriate shape, characteristic of a particular type, the cheese mass is molded. To do this, the cheese layer is cut into pieces corresponding to the molds (45x10 cm) and placed in these molds.

Cheese pressing.The cheeses are pressed to give them shape, firmness and to remove residual whey. The duration of pressing is 2-3 hours at a press pressure of 30-40 kg per 1 kg of cheese mass, the air temperature should be 15-18 ° C.

Salting cheese.The salting gives the cheese certain taste, with the help of salting the development of microbiological processes is regulated, it affects the changes in the physicochemical properties of the cheese crust, cheese dough and the cheese yield.

Maturation of cheese.This is a complex of consistently occurring complex biochemical changes in the substances of the cheese mass. Maturation gives the cheese pronounced organoleptic properties characteristic of this type, primarily taste and smell, as well as color, consistency, pattern, distinguishing mature cheese from fresh cheese mass. The ripening period is up to 2.5 months or more (depending on the type of cheese).

Cheese waxing and packaging.Ripe cheeses are thoroughly washed, rinsed in a lime solution, dried, stamped with a factory stamp and waxed to prevent shrinkage during long-term storage. To protect the cheese from shrinkage and the development of aerobic microflora on the surface of the cheese head, some types of polymer films are also used.

Storage and transportation of hard cheese.When transporting cheeses, they must be protected from high and extremely low temperatures. They do not undergo changes at temperatures from plus 10 to minus 6 0 C. If cheeses are transported at high temperatures, the cheese dough softens, fat is released, resulting in a deterioration in taste and consistency. When the cheese freezes after thawing, it becomes crumbly, and its taste is empty, unexpressed. On refrigerators for long-term storage of cheese, the air temperature should be from 0 to 2 ° C, with short storage - 2-8 ° C. Hard rennet cheeses can be stored for up to 8 months, soft cheeses - up to 4 months, Swiss - up to a year or more. Each type of finished cheese is characterized by a specific shape, chemical composition, organoleptic properties. The organoleptic assessment of hard cheese is made on a 100-point scale. Depending on the overall assessment and assessment for taste and smell, cheese is classified as the highest (over 87 points) and first (over 75 points) grade. Cheeses that do not meet the requirements of the standard in composition or have received an assessment of less than 75 points are subject to processing into processed cheeses.

Processed cheese production. Both non-standard cheeses and cheeses of various degrees of maturity and grade are used as raw materials. In addition, “specific” processed cheeses are produced from natural high-quality cheeses of the same type. These cheeses are named after the cheese from which they are produced (Kostroma processed, Russian processed, etc.).

The technological scheme for the production of processed cheese includes the following operations: 1) selection, cleaning and crushing of cheese; 2) preparation of a mixture for melting and adding melting salts; 3) ripening of the mixture; 4) melting cheese; 5) packaging; 6) Processed cheese cooling and storage.

An important process in the production of processed cheese is the addition of melting salts (dibasic sodium phosphate, sodium metaphosphate, tartaric salt, etc.) to the crushed cheese mass. The introduction of melting salts into the cheese mass significantly reduces the release of moisture from the cheese mass when it is melted (heated to 95 ° C), the mass turns out to be plastic, viscous, with increased swelling. Upon cooling, a gel forms, the properties of which largely depend on the selection of the melting salt.

Processed cheeses are packaged in a molten state in aluminum foil, plastic molds. The shelf life of processed cheeses is 3-6 months at 5-8 0 С. The assortment of processed cheeses is very diverse. They produce smoked processed cheese, sterilized processed cheese, pasteurized processed cheese, processed sweet cheeses, plastic (chocolate, coffee, fruit, nuts) cheeses, powdered processed cheeses, etc.