Technology and stages of production of fermented milk products. General technology of dietary fermented milk products

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1. Milk

Cow's milk is the secretion product of the cow's mammary gland. It is a white liquid with a yellowish tint and a specific slightly sweet taste. Milk is produced in the mammary gland as a result of profound changes components feed in the animal's body. The mammary gland of a cow consists of cells penetrated by nerves, a network of blood and lymphatic vessels that deliver substances necessary for the synthesis of milk. The cells form small bubbles - alveoli, which contain the resulting milk. The alveoli are united into lobules and communicate with each other using thin tubules leading into a special cavity called a cistern, where milk accumulates.

The physiological process of milk formation is very complex, and many of its phenomena have not yet been sufficiently studied. It has been established that the main components of milk are synthesized in the mammary gland from substances brought in by the blood. Only a small part of the substances (mineral elements, vitamins, enzymes, hormones, immune bodies) pass into milk from the blood without changes.

Mostly cow's milk is used directly for food and for processing, and less often milk from mares, goats, sheep and deer.

Milk and dairy products occupy an important place in human nutrition. They provide the body with favorably balanced and easily digestible proteins, fats, carbohydrates, minerals and vitamins.

The main indicators of milk as an object of technological processing are: composition, degree of purity, organoleptic, biochemical, physical and mechanical properties, as well as the presence of toxic and neutralizing substances in it. When using high-performance equipment, it is very important to preserve the properties of milk and its components. This is why dairy technology must have extensive knowledge of the chemical, biochemical and physical properties of milk constituents.

1.1 Composition of milk

Milk consists of water and nutrients distributed in it - fats, proteins, carbohydrates, enzymes, vitamins, minerals, gases These substances, after removing water and gases, are called milk solids. The content of dry matter and its individual components is not constant during the lactation period. The amount of fat varies the most, followed by protein. The content of lactose and salts, on the contrary, remains almost unchanged throughout the entire lactation period. The range of vibrations is closely related to the particle size of the individual components.

Water. Water is an essential part of milk and determines its physical state. Milk contains on average 87% water.

Milk fat. The basis of milk fat is triglycerides, which are esters of trihydric alcohol glycerol and fatty acids. Milk fat is of greatest importance for milk processing compared to its other components.

More than 60 fatty acids have been identified in milk fat. The most important of them are: palmitic, myristic, oleic and stearic. The content of fatty acids in milk fat is different in winter and summer. In winter, milk fat is characterized by more high level myristic, lauric and palmitic acids, and in summer - linoleic acid. A feature of milk fat is the presence of a large number of low-molecular volatile, water-soluble acids.

The mass fraction of fat in cow's milk averages 3.6-3.9%. It is found in milk in the form of small balls: in chilled milk - in the form of a suspension, and in uncooled milk - an emulsion.

Proteins are complex high-molecular nitrogen compounds.

The basis of protein molecules is amino acids. IN milk protein 18 amino acids were discovered, 8 of them are classified as essential. Milk contains 3.2% protein (casein, lactalbumin, lactoglobulin, etc.), and it is absorbed much better than meat protein. Milk proteins combined with plant products(for example, potatoes, legumes and cereals) create food combinations that are especially valuable for the body; their content in milk varies depending on the breed of livestock, lactation period, type of feed and other factors.

Milk sugar (lactose) makes up approximately 4.9% of the total volume of milk. He creates best conditions for healthy intestinal flora, calcium absorption, and in general has an extremely beneficial effect on the condition of the gastrointestinal tract. However, in most cases, it is lactose and the lack of an enzyme in humans that breaks it down that is responsible for the so-called “milk intolerance.” This disease manifests itself as dysfunction of the gastrointestinal tract.

Milk is rich in all known vitamins and enzymes, especially vitamins B2 and B12. A glass of milk satisfies 1/5 of the daily requirement for riboflavin. I would especially like to say about vitamin D, which is very important for the formation of bones and teeth.

Extremely varied mineral composition milk, in addition to vitamins and enzymes, it includes: potassium, calcium, phosphorus, iron, iodine. Calcium occupies an important place among them. It belongs to substances vital for the body; it is found in bone and dental tissues, ensuring their strength. Playing a critical role in the complex cellular processes that result in muscle function, calcium also regulates heart rhythm. With insufficient consumption of this mineral, especially in the first 30 years of life, the risk of various bone injuries increases sharply, ranging from fractures to postural disorders.

The composition of milk is not constant. The absence of one of the substances or a slight deviation in its quantity from the norm indicates a painful condition of the animal or an inadequate diet.

The properties of milk as an object of technological processing depend not only on its composition. But to a greater extent, it depends on biological and chemical indicators: bactericidal activity and acidity. Bactericidal activity is the property of freshly milked milk to suppress the development of microorganisms associated with the presence of immune bodies produced by the animal’s body and coming from the blood to the mammary gland.

The acidity of milk is due to the presence of acidic salts and proteins in it. It can be titrated or active. The unit of acidity measurement is Turner degree, (?T). 1 Turner degree is equal to the number of milliliters of 0.1 sodium hydroxide solution (potassium), which is spent on neutralizing acidic compounds in 100 ml of milk. Diluted twice with distilled water. The acidity of freshly milked milk is 16 -18?T. It is caused by acidic salts - dehydrogen phosphates and dehydrogen citrates, proteins - casein and whey proteins, carbon dioxide, acids.

Milk minerals play a significant role in the plastic processes of the formation of new tissue cells, enzymes, vitamins, hormones, as well as mineral metabolism body substances.

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

One liter of milk satisfies an adult’s daily need for animal fat, calcium, and phosphorus; 53% in animal protein; 35% - biologically active essential fatty acids and vitamins A, C, thiamine; by 12.6% in phospholipids and 26% in energy. The energy value of milk is 2720*10 J/kg.

The presence of all components in an optimal combination and easily digestible form makes milk extremely valuable, an indispensable product for dietary and therapeutic nutrition, especially for gastrointestinal diseases, heart disease and blood vessels, liver, kidneys, diabetes mellitus, obesity, acute gastritis. It should be consumed daily as part of a balanced diet to maintain tone and as a factor in increasing longevity.

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

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

Therefore, milk and dairy products are also widely used as remedy in case of intoxication of the body with toxic products of putrefactive microflora. Daily norm Milk consumption for an adult is 0.5 liters; for a child, 1 liter.

Fermented milk products are made from milk. It has long been believed that fermented milk products improve the health of the body. With the development of microbiology, the dietary, and with the discovery of antibiotics, the medicinal properties of these products were scientifically substantiated. Enormous credit for this belongs to the great Russian physiologist and microbiologist I.I. Mechnikov. While studying the problems of longevity, at the beginning of the twentieth century, the scientist came to the conclusion that one of the reasons for premature aging is the constant poisoning of the body with food breakdown products. “This is the only conclusion,” wrote I.I. Mechnikov, “the more the intestine abounds in microbes, the more it becomes a source of evil, shortening existence.”

2. History of fermented milk products

Our distant ancestors were able to process milk and consume it not only in its natural form. Herodotus in the 5th century BC reported that the most favorite drink of the Scythians was mare's milk prepared in a special way - kumiss. Kumis and curdled milk are mentioned in 17th-century medical books as a medicine against tuberculosis, typhoid and fever.

Man has long known the healing power of milk. Hippocrates, for example, prescribed milk to patients with tuberculosis. He also believed that it was extremely useful for nervous disorders. Aristotle recognized the most valuable milk from mares, then donkey, cow and, finally, goat. Pliny the Elder secreted cow's milk. However, he also argued that medicinal purposes You can also use pork milk.

Avicenna actively treated various diseases with milk. He considered it useful for children and people “advanced in age.” According to Avicenna, the most healing is the milk of those animals that bear the fetus for about the same amount of time as humans. In this regard, he believed that cow's milk is most suitable for humans.

Outstanding Russian scientist S.P. Botkin called milk a “precious remedy” for treating the heart and kidneys. Healing properties The author of the “Russian method” of treating tuberculosis patients with kumis, G.A., also highly valued milk. Zakharyin. Everyone and always, wrote I.P. Pavlov, - milk is considered the easiest food and is given for weak and sick stomachs and for a lot of severe general diseases.

At the end of the 19th century, the St. Petersburg doctor Karell used milk to treat diseases of the stomach, intestines, liver and other diseases. Moreover, he used skim milk for the first time, gradually increasing the dose from 3 to 12 glasses per day and not giving the patient other food for several days. This method of treatment fully justified itself and was approved by Botkin.

Almost everywhere, milk was actively used in folk cosmetics. Thus, in ancient Rome, donkey milk was considered the most suitable means against wrinkles. Pompeia, Nero's second wife, took baths from donkeys' milk, and during her travels she was usually accompanied by a herd of 500 of these animals. Avicenna claimed that milk eliminates ugly spots on the skin, and if you drink it, it greatly improves your complexion. Especially if you drink it with sugar. Curd serum, when rubbed into the skin, destroys freckles.

And yet, at all times, milk has been valued mainly for its amazing properties. nutritional properties. In the apt expression of I.P. Pavlova, “milk is an amazing food prepared by nature itself.”

3. Fermented milk products

One of the remarkable properties of milk is its ability to ferment. After some time, a seemingly spoiled product suddenly acquires a completely new taste and pleasant aroma. People have long noticed this property of milk and used it for their own benefit.

The taste and consistency of these products depend on many factors - the properties of milk, types of starter cultures, fermentation methods, etc. Fermented milk products are prepared from the milk of almost all types of domestic animals. In our country, milk from cows, mares and sheep is mainly used for this purpose.

Used as starter cultures pure cultures lactic acid bacteria with or without the addition of lactic yeast cultures: lactic acid streptococci, Bulgarian stick, acidophilus bacillus, aroma-producing bacteria, etc.

As a rule, two groups of fermented milk products are distinguished. The first of them consists of products obtained as a result of lactic acid fermentation (yogurt, acidophilus milk, cottage cheese, etc.), the second - products obtained as a result of mixed (lactic and alcoholic fermentation 9 kefir, kumis, etc.). Products of the first group are distinguished by a delicate taste and have a dense and homogeneous curd. In contrast, mixed fermentation products have a sharper, slightly pungent taste due to the presence of ethyl alcohol and carbon dioxide, and a delicate clot. Permeated with tiny bubbles of carbon dioxide, the result of fermentation is also sour cream.

Milk is the optimal substrate for the growth of many representatives of beneficial microflora: lactic acid bacteria, bifidobacteria, E. coli, and yeast. The introduction of specially selected strains of lactic acid bacteria and bifidobacteria into fermented milk products promotes better absorption of calcium in adults and children. Reduces blood cholesterol levels and provides the body with physiological needs for vitamins and amino acids. Antioxidants, activates the formation of microbial lactase.

Recently, a new generation of probiotics has emerged. Based on genetically modified strains of microorganisms with specified properties. For example, the probiotic subalin: to obtain it, the authors used one of the strains included in the probiotic biosporin, into which an antiviral gene responsible for the production of the universal antiviral agent interferon was inserted. Recombinant probiotics are also produced with the erythromycin resistance gene.

There are other criteria for selecting strains introduced into the product. This is, first of all, safety for the human body, resistance to antibiotics most often used in medicine today, the ability to actively absorb wide range vitamins and microelements. Have an immunostimulating effect. Some researchers attribute this effect of probiotic cultures to the stimulation or production of interferon produced by the human body. In addition, today scientists are actively looking for strains in which these properties are maximally expressed. In the West, similar studies were carried out with representatives of the genera: Lactococcus, Enterocrocus, Streptococcus. The number of living cells of these microorganisms in a test tube is billions of colony-forming units per gram. Bifidobacteria and lactobacilli, known to many today, also have the properties of increasing non-specific resistance of the body.

4. Technology for the production of fermented milk products

In production fermented milk drinks Two methods are used: thermostatic and reservoir. With the thermostatic method of producing fermented milk drinks, the fermentation of milk and the maturation of the drinks are carried out in bottles in thermostatic and refrigeration chambers.

With the tank production method, fermentation, souring of milk and ripening of drinks occur in one container.

Fermented milk drinks produced tank method, after ripening and mixing, they are poured into glass or paper containers, so their curd is disturbed compared to the thermostatic method - it has a homogeneous creamy consistency.

To obtain a product with a dense, uniform consistency, it is necessary to maintain the fermentation temperature optimal for of this product. The duration of milk fermentation depends on the type of fermented milk products obtained and ranges from 4 to 16 hours. The end of ripening is determined by the nature of the curd and the acidity, which should be slightly lower than the acidity of the finished product.

Cooling and maturation is carried out at a temperature not exceeding 6 for several hours (6-8). During this time, milk proteins swell, which leads to the formation of a denser clot, and the lactic acid process weakens or completely stops.

In the production of mixed fermentation products, during cooling and ripening, the development of lactic acid microorganisms is suspended, but yeast develops, as a result of which alcohol and carbon dioxide accumulate in these fermented milk drinks.

Finished products are monitored for the presence of coliform bacteria and microscopic samples from one or two batches at least once every 5 days.

Equipment that comes into direct contact with the product during the production process requires special attention. Before starting the technological process, such equipment should be thoroughly sanitized. If the sanitary indicators of the finished product deteriorate, a thorough analysis and additional monitoring of the technological process is carried out to establish the causes of secondary contamination of the product, the quality of the starter is checked, as well as the sanitary and hygienic condition of the workshop.

Fermented milk products are also produced with fruit and berry fillings and fortified. Control finished products carried out according to the methods adopted for fermented milk drinks with fruit and berry fillings. When producing fermented milk drinks with fillers, you need to be especially careful to avoid producing products of unguaranteed quality.

Tank method for the production of fermented milk products

Description of the general operations of the technological process.

Milk acceptance is carried out in accordance with GOST R 52054-2003. Milk is cooled to 4 °C in order to prevent the development of microflora and milk spoilage. Reserving milk should not last more than 12 hours. Before cleaning, the milk is heated to 40...45 °C. Normalization of milk according to mass fraction fat is carried out in a stream or by mixing. Normalized milk is homogenized to eliminate fat sediment and to obtain a product with a uniform consistency. Pasteurization is carried out at a temperature of 90...95 °C with holding time from 2 to 8 minutes. The pasteurized normalized mixture is cooled to fermentation temperature. Fermentation is carried out with specially selected starter cultures from thermophilic or mesophilic lactic acid bacteria and bifidobacteria. Depending on the type of product and starter, the duration of ripening is 4...12 hours, the ripening temperature is 20...43 °C.

Kefir, which contains yeast, requires additional maturation for 12-14 hours, during which the specific taste of the product is formed. Finished product cooled and sent for bottling.

Production of fermented milk dietary products- kefir, acidophilus, acidophilus milk, acidophilus-yeast milk, drinks “Snezhok”, “Yuzhny”, yogurt and others - increased tenfold.

Kefir is the most popular among the population, so it has taken a dominant position in the production of fermented milk drinks produced in Kazakhstan. The birthplace of kefir is the North Caucasus, where for a long time it was produced in wineskins or wooden tubs. The technology for its production in villages is simple - kefir grains pour in fresh milk, cooled to 18-20" C; during the process of ripening and ripening, the product is periodically shaken. When kefir matures, due to increased aeration, yeast actively develops, which affects the taste and consistency of the product: the consistency becomes liquid, creamy, the taste becomes specific, sour, and acquires a pungency.

In Russia, kefir was produced back in 1866-1867. using artisanal methods using fungi brought from the Caucasus in dry form. Kefir grains were revived in boiled, cooled skim milk and used to prepare starter cultures. Milk for kefir was heated to 16-23° C and fermented with starter directly drained from fungi. After obtaining a clot, the bottles were shaken to speed up the process of forming the drink and kept in a room at a temperature of 14 - 16 ° C for 24 hours, and sometimes for a longer time.

Kefir was produced using the same technology at city dairies, using pasteurization of milk and bottling the drink in bottles with hermetically sealed closures. As a result of the length of the technological process and the labor intensity of many operations, the production of kefir was limited and the population's demand for it was not satisfied, so the technology of kefir was changed: it began to be produced in an accelerated way, which was later called thermostatic.

Milk used for the production of kefir was fermented at high temperatures in thermostats without shaking and the corresponding accumulation of yeast fermentation products. As a result of changes in technology, instead of a soft but semi-liquid drink with a characteristic refreshing taste, factories began to produce a product with a dense curd, similar in taste to yogurt.

As a result of a series of research works, VNIMI has developed a tank method for the production of kefir, which is currently a generally recognized progressive method that is widely being introduced into the dairy industry.

The main stages of the technological process are the following:

Heat treatment and homogenization of milk used for the production of kefir;

Fermentation of milk, cooling and ripening of kefir in tanks;

Bottling a high-viscosity drink into paper bags and glass bottles.

When producing kefir using the tank method, milk is pasteurized at 85C and aged. As the pasteurization temperature increases, the holding time decreases. A mandatory operation is homogenization of milk: it prevents whey from settling in the finished product and gives it a uniform, creamy consistency. Milk is homogenized under a pressure of at least 125 atm, the optimal homogenization pressure is 175 atm. Milk is fermented at a temperature of 20-25°C in double-walled tanks-reservoirs, specially designed for the production of fermented milk drinks. The starter is introduced in a stream or in any other way with continuous mixing of the milk in the tank. The end of ripening is determined when the acidity of the curd reaches 85-90 ° T. Water at a temperature of 1-3 ° C is supplied to the interwall space of the tank to cool the curd to the ripening temperature, and then a mixer is turned on to stir it and left alone for ripening.

During the ripening process, kefir acquires a specific taste, different from the taste inherent in yogurt.

The cooling method depends on the technological process scheme adopted at a given enterprise.

In the production of kefir great importance has mixing and cooling when feeding it for bottling. The mixer should not shake or cut it into layers and cubes, but should smoothly and evenly mix the entire mass of kefir. Partial stirring or cutting of the curd leads to the separation of whey (syneresis), just as shaking kefir with a stirrer leads to foaming, which entails the formation of whey sediment. To preserve the quality of kefir, you should not use pumps that foam the kefir and break the product. Chilled kefir is packaged in small containers (bottles and paper bags). Before release into the retail chain, the finished product is cooled in a chamber to 6-8° C.

Below is the basic technological scheme for the production of fermented milk drinks using the tank method (in two versions - with cooling in tanks and in-flow cooling on a plate heat exchanger), developed by VNPLSH and providing for mechanization and automation of main and auxiliary operations.

According to this scheme, milk is supplied by pumps through pipes, and the packaged finished product is supplied by in-plant transport (chain and belt conveyors, etc.).

In heat exchangers, milk and drinks are subjected to heat treatment (heating and cooling) to a predetermined temperature. Milk is purified from mechanical impurities in in-line separator-cleaners and processed in homogenizers to obtain appropriate fat dispersion and improve the viscosity of the drink.

The drink in the tank is mixed with a power mixer. The drink is packaged in bottles or paper bags using filling machines and automatic machines. Labor-intensive equipment washing processes are carried out using irrigation and reactive devices.

Process control and management are automated.

The peculiarity of this scheme is that kefir, after fermentation and reaching the specified acidity, is mixed and cooled in the same tank, after which it is bottled and fed into the chamber for additional cooling.

The cooling process of a fermented fermented milk drink in a double-walled tank lasts 3.5 - 6 hours. When producing fermented milk products using thermophilic cultures, acidity increases very quickly. To stop the rapid increase in acidity after reaching 85-90° T, the product is supplied from the reservoir to a plate cooler using a low-speed pump, where the duration of the cooling process is reduced to 1 hour.

Another version of the basic flow diagram for the production of fermented milk drinks using the tank method with in-flow cooling is shown in Fig. 2.

The peculiarity of this technological mode is that the milk is fermented in a double-walled tank or in a conventional milk storage tank 13, equipped with driven tubular mixers, and when the acidity reaches 85-90 ° T, the drink is supplied from tank 13 to cooler 15 using a low-speed pump 14. cools in a thin layer very quickly. Next, it enters the intermediate tank 16, and then is sent by gravity to machines of the Yudek, OR-6U, I2-ORK-6, I2-ORK-3 types for packaging in glass bottles or to an automatic machine of the AP-1N, AP-2N type for packaging in paper bags. The packaged drink is transported to the storage chamber for further cooling.

The advantages of producing fermented milk drinks using the tank method are as follows:

Manual labor is almost completely eliminated as a result of mechanization and automation of the technological process;

The qualifications of workers servicing the line are increased; labor costs are reduced and productivity is increased:

The cost of 1 ton of product is reduced by 4 rubles. 46 k.; production space is reduced, since the finished product is matured and cooled in the same tanks in which it is prepared, and not in thermostatic rooms; the consumption of heat and cold is reduced.

The practice of operating equipment for the tank method of producing drinks has shown that lines equipped with machines and apparatus specially designed for the tank method of producing fermented milk drinks are cost-effective in operation and ensure the production of high-quality products.

If production lines for fermented milk drinks using the tank method use equipment for the production drinking milk, then it works intermittently.

Currently, all the main machines and devices for completing a standard line are mass-produced (heat exchangers type OPL-5 and OPL-10, homogenizers A1-OGM, automatic machines AP-1N, AP-2N, double-walled tanks and bottling lines I2-OL2- 6 and I2-OL2-3. The production line for fermented milk drinks, equipped with double-walled tanks, is universal, since it can produce drinks in two ways technological scheme after adding a pump and a plate pasteurizer.

5. Kefir production technology

5.1 Raw materials

Kefir is produced using the tank method from whole natural normalized milk of at least second grade, with an acidity of no more than 19 0 T, a density of at least 1.0278 kg/m 3, with a different mass fraction of fat, so the original milk is normalized to the required mass fraction of fat. When normalizing whole milk by fat, there can be two options: there is more fat in whole milk than required in production, and there is less fat in whole milk than required. In the first option, the fat is partially selected by separation or skimmed milk is added to the original milk. In the second option, to increase the fat content of the original milk, cream is added to it. One of the simplest methods of normalization for fat is normalization by mixing in a container calculated quantities of milk to be normalized and a normalizing component (cream or skim milk) with thorough mixing of the mixture.

5.2 Heat treatment and homogenization

Pasteurization of milk is carried out with the aim of destroying vegetative forms of microflora, including pathogenic ones. The most common method in the production of fermented milk products is short-term pasteurization at a temperature of 85-87 0 C with holding for 5-10 minutes. or at 90-92 0 C with a holding time of 2-3 minutes. followed by cooling to fermentation temperature. The pasteurization regime must ensure that the desired properties of the finished product are obtained, in particular organoleptic characteristics (taste, desired viscosity and density of the curd). High pasteurization temperatures cause denaturation of whey proteins, while the hydration properties of casein increase. This promotes the formation of a denser curd, which retains moisture well, which prevents the whey from separating during storage.

Homogenization is the crushing (dispersing) of fat globules by subjecting milk to significant external forces. During the treatment, the size of fat globules and the floating speed are reduced. The fat globule shell substance is redistributed, the fat emulsion is stabilized, and the homogenized milk does not settle. Currently, two-stage homogenization is used, which eliminates the sticking of particles of fat globules at the exit from the valve slit of the homogenizing head. Homogenization is carried out at a temperature of 60-65 0 C and a pressure of 15-17.5 MPa (125-175 atm). After pasteurization and homogenization, the mixture is cooled to fermentation temperature.

5.3 Fermentation and fermentation of milk

In the production of kefir, a starter prepared with kefir grains is usually used. Their main representatives are lactic acid rods, lactic acid streptococci, including flavor-forming and lactic yeasts of the Torula type. The random microflora of grains consists of spore sticks, acetic acid bacteria, milk molds, filmy yeasts, bacteria of the Coli group, etc.

To prepare kefir starter, dry kefir grains are kept in warm water (25-30 0 C) for 24 hours, changing it 2-3 times during this time. After this, the water is drained and the swollen grains are poured with warm milk, taken in ten times the volume of the fungi.

To produce kefir with a characteristic taste and strong consistency, it is necessary to use a production starter, kept after ripening at a temperature of 10-12 0 C for 12-24 hours. The starter, the mass of which is usually 5% of the mass of the fermented mixture, is added to the mixture, cooled to the fermentation temperature. The mixture is fermented at a temperature of 23-25 0 C until a milk-protein clot with an acidity of 80-100 0 T (pH 4.5-4.65) is formed. During ripening, the microflora of the starter multiplies, acidity increases, casein coagulates and a clot forms. After fermentation is completed, the product is immediately cooled.

5.4 Stirring and cooling the curd

After ripening, kefir is stirred and cooled to ripening temperature. Mixing of the product begins after 60-90 minutes. after the start of its cooling time and is carried out for 10-30 minutes. The clot, mixed and cooled to a temperature of 20 0 C, is left alone.

Maturation of kefir. The duration of kefir ripening is 6-10 hours. During ripening, yeast is activated, alcoholic fermentation occurs, as a result of which alcohol, carbon dioxide and other substances are formed in the product, giving this product specific properties.

Mixing and pouring. After the ripening time has expired, the kefir is stirred in the tank for 2-10 minutes before bottling.

Packaging and labeling are carried out in accordance with the requirements of the standard for this product. In order to improve the consistency of the finished product, it is recommended to keep packaged kefir in a refrigerator before sale. When kefir reaches the required conditional viscosity and temperature of 6 0 C, the technological process is considered complete and the product is ready for sale. The taste and smell are clean, sour milk, refreshing. The consistency of kefir should be homogeneous, reminiscent of liquid sour cream. Gas formation caused by yeast or flavor-producing streptococci is allowed.

Conclusion

Fermented milk products are products produced by fermenting milk or cream with pure cultures of lactic acid bacteria, with or without the addition of yeast and acetic acid bacteria. Fermented milk products are classified as biotechnology products.

Fermented milk products are grouped into three main groups: fermented milk drinks; sour cream; cottage cheese and curd products. These products play a special role in human nutrition, since in addition to their high nutritional value, they have great therapeutic and preventive value.

The consistency and character of the curd of fermented milk drinks depend on the raw materials and technology, as well as on the production method.

The most common technological falsification of fermented milk drinks occurs. It consists of a violation of the qualitative and quantitative composition of microflora (for example, the absence of bifid flora in bifido products), as well as a discrepancy between the mass fraction of milk fat and SOMO and regulatory and technical documentation.

Bibliography

1 Bogdanova A. T., “Production of whole milk products.” - M.: “Light and food industry”, 1982.

2 Bogdanova G.I., “Production of whole milk products. - M.: “Light Industry”, 1982.

3 Bredikhin S. I, Kosmodemyansky Yu. K, Yurin Yu.N. Technology and technology of milk processing. - M.: “Kolos”, 2001. - 400 p.

4 Guseva L.B. Chemistry and physics of milk. Vladivostok 2004.

5 Krus G.N., Tinyakov V.G., “Milk technology and equipment of dairy industry enterprises” - M.: Agroprmizdat, 1986.

6 Kunizhev S.M., Shuvaev V.A. New technologies in the production of dairy products. - M.: DeLi print, 2004.

7 Puchkova Yu.S., Kristafovich V.I. “Methodological instructions for laboratory exercises.” - M.: 1999.

8 Belyaev A.N. Mechanization of the production of fermented milk drinks using the tank method - M.: Publishing house " Food industry", 1964

9 Bogdanova G.I., Novoselova L.F. Experience in producing kefir using the tank method. - M.: Tsentipischprom, 1965

10 Glazachev V.V. Production of fermented milk products. - M.: Pishchepromizdat, 1960

11 Krus G.N. and others. Technology of milk and dairy products / G.N. Krus, A.G. Khramtsov, Z.V. Volokitina, S.V. Karpychev; Ed. A.M. Shalygina. - M.: Kolos, 2006. - 455 p.

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Introduction

Fermented milk products are products that are produced from pasteurized milk or cream by fermenting them with starter cultures prepared with pure cultures of lactic acid bacteria with or without the addition of lactic yeast cultures.

Used in the production of fermented milk products different kinds lactic acid bacteria and yeast: lactic acid streptococci, Bulgarian bacillus, acidophilus bacillus, aroma-forming bacteria, lactic yeast. Each product is made using specific cultures of microorganisms. Moreover, some lactic acid bacteria secrete enzymes that partially break down proteins into simple compounds, which contributes to better absorption of products. This occurs to a greater extent in kefir and kumis, and to a lesser extent in yogurt. And some flavor-forming bacteria decompose lactose to form aromatic substances (diacetyl, etc.), which determine the aroma of fermented milk products. As a result of the vital activity of a number of microorganisms in fermented milk products, vitamins B1, B2, B12 and C are synthesized, which increases their dietary properties.

Some lactic acid bacteria produce antibiotics (nisin, streptomycin, etc.), which suppress the causative agents of typhoid, tuberculosis and other diseases. Therefore, fermented milk products can be used in the treatment of tuberculosis, diseases of the gastrointestinal tract, anemia and other diseases.

It has long been believed that fermented milk products have a positive effect on the body, so various types of sour milk were widely consumed. Only much later were the dietary and medicinal properties of these products scientifically substantiated. This was first done by the Russian physiologist and microbiologist I. I. Mechnikov.

All fermented milk products are divided into two groups: products obtained as a result of lactic acid fermentation (yogurt, acidophilus milk, etc.), and products obtained as a result of mixed (lactic acid and alcohol) fermentation (kefir, kumis, etc.). In some products, alcoholic fermentation is weak; only traces of alcohol (acidophilus) accumulate in them.

1. Types of fermented milk products

sanitary fermented milk curd curdled milk

Curdled milk is a fermented milk product, the basis of which is the fermentation of milk with a special starter with lactic acid bacteria. It is produced from milk with or without the addition of flavoring and aromatic substances. Sugar, honey, vanillin, cinnamon, fruit and berry creams or jam are used as flavoring and aromatic substances.

Ordinary yogurt - produced by fermenting pasteurized milk with or without the addition of Bulgarian stick.

Mechnikovskaya curdled milk is made by fermenting pasteurized milk and Bulgarian stick. The finished product has a more pronounced fermented milk taste compared to ordinary yogurt.

Acidophilus yogurt - obtained by fermenting milk and acidophilus bacillus.

Ryazhenka, or Ukrainian curdled milk, is produced by fermenting a baked mixture of milk and cream with or without the addition of a Bulgarian stick.

Varenets - made by fermenting sterilized or baked milk with or without the addition of Bulgarian stick.

Snowball is a fermented, low-fat sweet product made from milk with sugar by fermentation with a special starter. Snowball is considered one of the healthiest dairy products due to the fact that it has dietary and health properties, is enriched with vitamins, minerals, microelements, has a beneficial effect on intestinal microflora and improves metabolism.

Yogurt is a fermented milk product with increased content skimmed milk solids produced using a mixture of starter microorganisms - thermophilic lactic acid streptococci and Bulgarian lactic acid bacillus.

Depending on the raw materials used, yogurt and bio-yogurt are divided into:

· yoghurt from natural milk;

· yoghurt made from normalized milk or normalized cream;

· yoghurt made from reconstituted (or partially reconstituted) milk;

· yogurt made from recombined (or partially recombined) milk.

Depending on the normalized mass fraction of fat, the following types of yogurt are distinguished:

§ low-fat milk;

§ semi-fat milk;

§ milk classic;

§ milky and creamy;

§ creamy milky;

§ creamy.

Yogurt is produced in 1.5%, 3.2% and 6% fat content.

Depending on the flavors and aromatic substances used, unsweetened, sweet, with vanillin and fruit yogurt are produced, the color of which depends on the color of the added syrup.

Acidophilus dairy products are fermented milk products prepared from pasteurized whole or skim cow's milk by fermenting it with a starter culture of pure cultures of lactic acid streptococci and acidophilus bacillus, as well as kefir grains and milk yeast. Such products include the following:

Acidophilus milk is produced from whole or skim milk, with or without added sugar, which is fermented with pure cultures of acidophilus bacillus.

Acidophilus is prepared from whole or skim milk with or without added sugar, fermented with pure cultures of acidophilus bacillus and kefir starter. Acidophilus can be fatty or nonfat.

Acidophilus-yeast milk is prepared from whole or skim milk with or without added sugar, fermented with pure cultures of acidophilus and yeast.

Kefir is a fermented milk drink made from whole or skim cow's milk by fermented milk and alcohol fermentation using kefir grains - a symbiosis of several types of microorganisms: lactic acid streptococci and rods, acetic acid bacteria and yeast.

Kumis is a fermented milk drink made from mare's milk, obtained as a result of lactic and alcoholic fermentation using Bulgarian and acidophilus lactic acid rods and yeast.

Cottage cheese is a fermented milk product obtained by fermenting cow's milk and partially removing the whey. The starter is prepared using pure cultures of lactic acid streptococci, and sometimes rennet is added. Cottage cheese is rich in calcium, phosphorus, iron, magnesium.

Curd products are made from cottage cheese that has been crushed and ground with the addition of flavoring and aromatic substances.

Curd masses can be unpackaged and packaged in 250 and 500 grams, depending on the fillings they are divided into sweet and salty, without additives and with additives.

Curd cheeses are packaged in 50-125 grams. They are divided into sweet and salty, with and without additives, with a high fat content, fatty, semi-fat and low-fat.

Curd cakes are products made from fatty cottage cheese with the addition of butter, flavoring and aromatic substances, decorated with designs from buttercream, jelly or covered with chocolate glaze.

Curd spreads are made from fatty cottage cheese with the addition of cream, flavoring and aromatic substances, as well as from a mixture of gelatin and cream. They produce curd pasta, sweet and salty. This group also includes pastes prepared on a protein basis. They contain a small amount of fat, but rich in valuable milk protein.

Sour cream is a fermented milk product obtained from normalized pasteurized cream by fermenting it with sourdough prepared with pure cultures of lactic acid bacteria and ripening at low temperatures. Sour cream differs from other fermented milk products in its high fat content.

2. Fundamentals of technology for the production of fermented milk products

There are two ways to produce fermented milk products: tank and thermostatic.

Production of fermented milk products using the tank method

1. Acceptance of raw materials.

3. Heating.

4. Cleaning, normalization.

5. Heating.

6. Homogenization.

7. Pasteurization.

8. Cooling to fermentation temperature.

9. Fermentation.

10. Fermentation.

11. Cooling.

12. Ripening (or without ripening).

13. Cooling.

14. Bottling.

15. Storage until sale.

Description of the technological process.

Reception of milk is carried out in accordance with GOST-1326488. Milk is cooled to 4? C in order to prevent the development of microflora and spoilage of milk. Reserving milk should not last more than 8 hours. Before cleaning, the milk is heated to 40-45? C. Normalization of milk by mass fraction of fat is carried out in a stream or by mixing. Normalized milk is homogenized to eliminate fat sediment and obtain a product with a uniform consistency. Pasteurization is carried out at a temperature of 90-95? C for 300 seconds. The pasteurized mixture is cooled to fermentation temperature. Fermentation is carried out with specially selected starter cultures from thermophilic or mesophilic lactic acid bacteria and bifidobacteria. Depending on the type of product and starter, the duration of ripening is 3-12 hours, the ripening temperature is 20-43? C. Kefir, which contains yeast, requires ripening for 10-12 hours, during which the specific taste of the product is formed. The finished product is cooled and sent for bottling.

Process flow diagram

1. Acceptance of raw materials.

2. Cooling, redundancy.

3. Heating.

4. Cleaning, normalization.

5. Heating.

6. Pasteurization.

7. Cooling to fermentation temperature.

8. Fermentation.

9. Stirring.

10. Filling into consumer containers.

11. Fermentation in a thermostatic chamber.

12. Cooling.

13. Ripening (or without ripening).

14. Storage until sale.

Description of the technological process

After pasteurization, milk is cooled to fermentation temperature and enters the tank along with the starter. The mixture is thoroughly mixed with a stirrer for 15-20 minutes. and enters the bottling line. The filling time of one tank should not exceed 30 minutes. The poured and sealed fermented mixture enters a thermostatic chamber, the air temperature in which is maintained at the level of the fermentation temperature of a certain fermented milk product. The end of ripening is determined by the acidity and density of the curd. The packaged product enters the refrigeration chamber at a temperature of 6-8? C, where it is cooled at this temperature. If necessary, the product is matured here.

Figure 1 Diagram technological line production of fermented milk drinks by thermostatic method: 1- container for raw milk; 2- pump; 3- balloon 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- machine for packing milk; 12- thermostat chamber; 13 - refrigeration chamber; 14 - storage chamber for finished products.

Figure 2 Scheme of the technological line for the production of fermented milk drinks using the tank method

3. Technology for the production of curdled milk, fermented baked milk, Varents

Curdled milk, fermented baked milk and Varenets are produced by tank and thermostatic methods from pasteurized milk, sterilized, baked milk fermented with pure cultures of lactic acid bacteria.

Operation	Characteristic
Heat treatment of the normalized mixture	for yogurt: 85-870°C 10 min
	for fermented baked milk 95-99°C 3-5 hours
	for Varents 95-99°C 40-80 min
Cooling to fermentation temperature	cooling the mixture to 41-45°C
Fermentation	fermentation with sourdough in quantity 1-3%
	sourdough acidity 90-110°T
	for curdled milk, fermented baked milk: pure cultures of Bulgarian bacillus and thermophilic streptococcus
	for Varenets: pure cultures of thermophilic streptococcus
Fermentation	ripening duration 3-6 hours until clot formation 75-80°T
Stirring, cooling, maturing	stirring 30-40 minutes, cooling to 4±20°C, ripening duration 9-13 hours.

4. Technology production kefir

It is produced by tank and thermostatic methods from pasteurized milk fermented with kefir grains.

Pasteurized milk is cooled to the fermentation temperature and at this temperature pure cultures of lactic acid bacteria are added to it in the form of a production starter in an amount of 3-5%.

With the thermostatic production method (see Fig. 1), after mixing, milk with starter is poured into bottles and sealed with aluminum pots, on which the plant number, product name, GOST number and the deadline for the sale of the product are embossed. Sealed bottles with fermented milk are sent to special warm chambers - thermostats, where the temperature necessary for the development of lactic acid bacteria is maintained. ripening lasts about 6 hours and ends with an acidity of about 75-850? T and the formation of a weak clot, slightly swaying in the center.

After ripening is completed, the product is not yet ready for release, since

has an insufficiently strong, easily destroyed clot and insufficient

pronounced aroma. To complete the technological process, products

placed in cool chambers where it cools and ripens.

With the tank production method (see Figure No. 2), milk after pasteurization enters large metal reservoirs - tanks equipped with a mixer, into which the starter is first added. The milk is left to ferment to an acidity of 850?T. Then cold water is supplied to the interwall space of the tank and a stirrer is turned on to stir the curd. You cannot start stirring when the acidity of the curd is lower, as whey may be released. Stirring is continued periodically until the curd acquires a homogeneous, creamy consistency. In the same tanks, kefir is cooled and left to mature.

5. Technology production acidophilus

Acidophilus is a fermented milk drink produced from pasteurized milk fermented with starter cultures. It is prepared using Bacillus acidophilus, kefir grains and lactic acid streptococcus.

When producing acidophilus, milk is fermented at 30...33°C. Depending on the fermentation temperature, acidophilus is obtained with a more pronounced taste of kefir, curdled milk or acidophilus milk. It is produced both by tank and thermostatic methods.

Tank production method.

For acidophilus, each type of starter is prepared separately in starter containers and added to the milk in equal quantities when fermenting it. The total volume of the starter must be at least 5% of the amount of fermented milk. The starter is thoroughly mixed until liquid and poured into the milk while stirring. Mixing the milk with the starter is completed 20 minutes after introducing the last portions of the starter. Then the mixer is turned off and the milk is left alone until the end of ripening, which is determined by the acidity and density of the curd. Fermentation of milk cannot be stopped until the acidity reaches 85°T. The finished product can be cooled in a container or in a stream. The product is bottled at a temperature of 20°C and further cooled in the refrigeration chamber.

6. Technology for the production of cottage cheese and curd products

The main physico-chemical and biological processes, occurring during the production of cottage cheese, are the coagulation of proteins during ripening of milk and dehydration of the curd. When making cottage cheese, it is important to easily and quickly separate the whey from the curd, that is, dehydrate the curd obtained from skim milk. When whole milk is fermented, the separation of whey deteriorates, so in order to intensify this process, milk-clotting (rennet) enzyme and calcium chloride are added. Thus, the formation of a clot can be a result of acidic (for skim milk) and acid-rennet (for whole, normalized, skim milk) coagulation of proteins.

Acid coagulation of proteins occurs under the influence of lactic acid formed as a result of the vital activity of the starter microflora. Acid-rennet coagulation of proteins is carried out not only under the influence of lactic acid, but also milk-clotting enzymes, which contribute to the formation of a more durable clot that easily releases whey.

Methods for producing cottage cheese depend not only on protein coagulation processes, but also on the equipment used. In this regard, there are two main methods of cottage cheese production: traditional (using the TO-2.5 set, TI-4000 curd maker, Ya9-OPT lines) and separate (using mechanized lines OLPT or Alfa Laval, as well as equipment used in the traditional method).

General technology production cottage cheese.

The technological process for producing cottage cheese in the traditional way includes milk cleaning, obtaining raw materials of the required composition, pasteurization, cooling to fermentation temperature, fermentation, ripening, crushing the curd, separating the whey, cooling the cottage cheese, and packaging. The production process using a separate method includes heating and separating milk, pasteurization and cooling of cream, pasteurization and cooling of skim milk, fermentation and fermentation of skim milk, skim curd, cooling low-fat cottage cheese, mixing low-fat cottage cheese with cream, packaging.

7. Sour cream production technology

Sour cream is obtained from normalized pasteurized cream by fermenting it with a starter prepared with pure cultures of lactic acid bacteria and ripening it at low temperatures.

Sour cream is produced by tank and thermostatic methods. The general scheme for sour cream production looks like this.

1. Reception of milk. Milk must comply with GOST 1326488.

2. Cooling milk to 4°C. Carried out to prevent the development of microflora and spoilage of milk.

3. Reserve milk for no more than 8 hours. Necessary for the continuous operation of the enterprise.

4. Heating to 40-45 °C. It is carried out to reduce the viscosity of milk, as well as to convert the refractory fat fraction into a liquid state, which subsequently improves the process of purification and separation of cream.

5. Milk purification.

6. Milk separation. Whole milk is divided into skim milk (skimmed milk) and cream with a given proportion of fat.

7. Normalization of cream. Carried out if necessary to adjust the fat content in the finished product.

8. Heating the cream to 60-65 °C. It is necessary to reduce viscosity and increase the plasticity of the membranes of fat globules.

8. Homogenization. It is produced to crush fat globules, thereby forming a homogeneous mixture, which helps improve consistency and prevents sedimentation of fractions.

9. Pasteurization 90-95 °C. Pursues several goals:

a) destruction of vegetative forms of microorganisms;

b) inactivation of enzymes in their native state;

c) providing conditions for the formation of the required consistency of the finished product.

10. Cooling to 2-6 °C

11. Physical maturation 1-2 hours. The operation is optional and is carried out to prepare milk fat for hardening, which additionally contributes to the formation of the structure of the finished product.

12. Heating the cream to 20-26 °C.

13. Fermentation with specially selected starters.

Thermostatic method.

15. Filling into consumer containers.

16. Fermentation 7-12 hours.

17. Cooling 6-8°C.

18. Ripening and storing sour cream for 14-48 hours.

Sour cream produced by this method has a denser consistency and a solid curd.

Reservoir method.

15. Fermentation in a tank at 22-28 °C. During ripening, a clot is formed, as well as the accumulation of flavoring and aromatic substances. The product must be stirred from time to time. Duration 7-12 hours.

16. Stirring and cooling to 6-8°C.

17. Maturing and stirring before bottling.

18. Packaging in consumer containers.

19. Storage until sale for no more than 48 hours.

During the production of different assortments of sour cream, the components are added as follows:

A) protein supplements, powdered milk, casein, cottage cheese, copricipitate are added until fat is normalized.

B) rennet, pepsin - with sourdough.

IN) flavorings, vitamins - into the finished product before mixing.

8. Packaging and transportation of fermented milk products

They are packaged in large and small containers. As large containers for sour cream, metal wide-necked flasks with a net weight of 10, 30 and 35 kg are used, and wooden tanks - no more than 50 kg. Used as small containers glass jars, polymer and cardboard cups.

Amateur sour cream is packaged in 100 grams. in foil, as well as in paper and cardboard boxes. Packaged sour cream is placed in cardboard boxes or wooden boxes no more than three rows high. The boxes are sealed.

Cottage cheese is packaged in cardboard boxes or parchment bags,

polyethylene films of polymer-coated paper or other packaging materials. Each box or package is marked accordingly. Cottage cheese is also packaged in wooden barrels of no more than 50 kg, metal flasks or cardboard boxes with a plastic film liner. Curd products are usually packaged using automatic machines. They should be wrapped in clean parchment, clear cellophane or plastic film. Wrapped products are placed in paper boxes or other containers.

Cakes are packaged in paper boxes, the bottom of which is pre-lined with parchment.

Cream and spreadable cheese curds are packaged in glass jars.

Fermented milk products are transported by specialized transport that has cooling facilities and a sanitary passport. Products are delivered to the store centrally.

9. Veterinary and sanitary examination of fermented milk products

Taking an average sample

The fermented milk product is thoroughly mixed. For all products, an average sample of 50 ml is taken. The exceptions are sour cream (15 g) and cottage cheese (20 g). In all cases, fermented milk products are examined organoleptically and the fat content and acidity are selectively determined. If necessary, examine for falsification and control the pasteurization or boiling regime.

Products are examined no later than 4 hours after taking average samples. If the product contains a lot of carbon dioxide and has a pronounced ability to foam (kumys, kefir, etc.), then it is examined after removing carbon dioxide by heating at 40-45 °C for 10 minutes and then cooling to 18-20 °C .

Organoleptic studies

The color of the product is determined in a clean glass made of colorless glass. It depends on the type of fermented milk product.

The consistency should be uniform, moderately thick, stable, without disturbing the surface and without pores of gas formation. There may be a slight separation of whey on the surface (no more than 5% of whey to the total volume of the product is allowed). Matsoni and fermented baked milk should have a slightly viscous curd. For Varents, the presence of milk films is allowed. The taste and smell of benign products is fermented milk, without any foreign tastes or odors. Fermented milk products that are unleavened, swollen, excessively sour, with gas formation, with a pronounced foreign odor or taste, with a sour (bitter) taste, unusual color, friable, with mold on the surface and with the release of whey of more than 5% of the total are not allowed for sale. volume of product. Mild defects are allowed in first-grade sour cream and cottage cheese: tastes of feed origin, wooden containers or slight bitterness.

Determination of fat content in fermented milk products.

In two milk butyrometers (types 1 - 6 or 1 - 7), weigh out (counting to 0.005 g) 11.00 g of fermented milk product, 5.00 g of sour cream or cottage cheese. Carefully pour 10 cm3 of sulfuric acid (density from 1810 to 1820 kg/m3). Using a dispenser, add 1 cm3 of isoamyl alcohol to the butyrometers.

The level of the mixture in the butyrometer is set to 1-2 mm (when determining fat in sour cream 4-5 mm) below the base of the butyrometer neck, for which it is allowed to add a few drops of distilled water.

Butyrometers are closed with dry stoppers and shaken until the protein substances are completely dissolved, turning at least 5 times. Install the butyrometers with the plug down for 5 minutes. water bath at a temperature of 65±2°C. After removing from the bath, the butyrometers are centrifuged for 5 minutes. Then the butyrometers are immersed with their plugs down in a water bath for 5 minutes at a temperature of 65±2°C, while the water level in the bath should be slightly higher than the level of fat in the butyrometer.

Butyrometers are removed one at a time from the water bath and the fat is quickly measured. When counting, the butyrometer is held vertically, the fat border should be at eye level. By moving the plug, the lower limit of the fat column is set at zero or a whole division of the butyrometer scale. From it the number of divisions is counted to the lower point of the meniscus of the fat column with an accuracy of the smallest division of the butyrometer scale.

The interface between fat and acid should be sharp and the fat column transparent. If there is a “ring” (plug) of a brownish or dark yellow color, various impurities in the fat column or a blurred lower boundary, the measurement is repeated.

The measurement result is taken as the arithmetic mean of the results of two parallel observations, the discrepancy between which (convergence) does not exceed 0.1 for fermented milk products and 0.5 for sour cream and cottage cheese.

The butyrometer readings during measurements correspond to the mass fraction of fat in these products as a percentage.

Determination of acidity of fermented milk products.

Distilled water and fermented milk product in volumes of 10 and 20 cm3, respectively, and three drops of phenolphthalein are measured into a flask with a capacity of 100 or 250 cm3. The remaining fermented milk product is transferred from the pipette to the flask by washing the pipette with the resulting mixture 3 - 4 times. The mixture is thoroughly mixed and titrated with 0.1 N sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.

In sour cream, acidity is determined in the following way: in a flask with a capacity of 100 or 250 cm3, weigh out 5 g of the product, add 30 cm3 of water and three drops of phenolphthalein. The mixture is thoroughly mixed and titrated with sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.

To study cottage cheese, add 5 g of the product to a porcelain mortar. Mix thoroughly and grind the product with a pestle. Then add in small portions 50 cm3 of water heated to a temperature of 35 - 40 ° C and three drops of phenolphthalein. The mixture is stirred and titrated with sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.

Acidity, in degrees Turner (°T), is found by multiplying the volume, cm3, of sodium hydroxide solution spent on neutralizing the acids contained in a certain volume of the product by the following factors: 10 - for fermented milk products, 20 - for sour cream, cottage cheese and curd products.

The permissible error of the analysis result with the accepted confidence probability P = 0.95 is: ±1.9°T - for fermented milk products; ±2.3°T - for sour cream; ±3.6°T - for cottage cheese and curd products.

The discrepancy between two parallel determinations should not exceed: 2.6°T - for fermented milk products; 3.2°T - for sour cream; 5.0°T - for cottage cheese and curd products.

Control of pasteurization of fermented milk products

The analyzed product and distilled water are measured or weighed into a test tube. When studying fermented milk drinks, the product should be 5 cm3, and no water should be added. When studying sour cream and cottage cheese, the product should be 2-3 g, and water - 2-3 cm3.

Fermented milk drinks with fruit and berry fillings are filtered through a paper filter.

Pasteurization is determined by the reaction of the filtrate with potassium iodide starch.

2.5 cm3 of the buffer mixture is poured into a test tube with the specified amount of product and water, mixed thoroughly with a glass rod and placed in a water bath with a water temperature of 35±2°C, where it is kept for 3-5 minutes so that the contents of the test tube reach this temperature. Then add 6 drops of 0.5% hydrogen peroxide solution and 3 drops of paraphenylenediamine hydrochloride solution, mix the contents of the test tube with rotational movements after adding each reagent. After this, place the test tube in a water bath again and observe the change in color of the liquid.

In the absence of the peroxidase enzyme, the color of the contents of the tube does not change. Consequently, dairy products were pasteurized at a temperature of at least 80°C.

In the presence of peroxidase in fermented milk products, the contents of the test tubes acquire a gray-violet color, gradually turning into a dark blue color. Therefore, the dairy products were not pasteurized or were pasteurized at temperatures below 80°C, or were mixed with unpasteurized products. The sensitivity of the method allows you to detect the addition of at least 5% of unpasteurized dairy products to pasteurized ones.

Method for determining the number of Staphylococcus aureus

Method definitions With preliminary enrichment.

A series of tenfold dilutions are prepared from a sample of the product in accordance with GOST 9225 so that it is possible to determine the presence or absence of Staphylococcus aureus in a certain mass (volume) specified in the regulatory document for a specific product.

A 1 cm3 sample of the product or its dilution is inoculated into test tubes or flasks with saline broth. The ratio between the amount of product sown or its equivalent dilution and the nutrient medium is 1:10. Test tubes and flasks with inoculations are kept in a thermostat at a temperature of 37±1°C for 24 hours.

To confirm that microorganisms grown in salt broth belong to Staphylococcus aureus, subculture with a loop from the broth is done to obtain isolated colonies on Petri dishes with dried media such as Baird-Parker, yolk-salt agar or milk-salt agar. Cups with crops are kept in a thermostat at a temperature of 37±1°C for 24-48 hours.

After thermostatting, the crops are examined and the growth of characteristic colonies is noted. On yolk-salt agar, Staphylococcus aureus colonies have the shape of flat discs with a diameter of 2-4 mm of white, yellow, cream, lemon, golden color with smooth edges; A rainbow ring and a zone of turbidity of the medium are formed around the colonies. On milk-salt agar, Staphylococcus aureus colonies grow as opaque round colonies, white to orange in color, 2-4 mm in diameter, slightly convex. On Baird-Parker medium, Staphylococcus aureus colonies grow in the form of black, shiny, convex colonies with a diameter of 1-1.5 mm, surrounded by a clearing zone of the medium 1-3 mm wide.

At least five characteristic colonies are selected from each Petri dish and transferred to the surface of a nutrient agar slant without the addition of sodium chloride and yolk emulsion. The crops are kept in a thermostat at a temperature of 37±1°C for 24 hours.

From five isolated colonies characteristic of Staphylococcus aureus, preparations are made, Gram stained and microscopically examined.

To prepare the preparation, a drop of distilled water is applied in a loop to a clean and cooled glass slide after filling, into which a small amount of agar culture is added in a loop without stirring in the water. Then add a drop of reagent 1 in a loop, prepared as follows: 0.5 g of crystal violet is dissolved in 100 cm of ethyl alcohol. The mixture is distributed over an area of approximately 1 cm², dried at a temperature of 20 ± 2 ° C and fixed by slowly passing a glass slide over the burner flame. You can prepare 6-8 strokes on one glass, separating them from one another with lines drawn from the front side of the glass.

The preparation is rinsed with water and thoroughly dried with filter paper. After drying, an excess of reagent 2 is applied to the preparation (to 96 cm3 of an alcohol solution of potassium iodide with a mass concentration of 50 g/dm3 and 2 cm3 of an alcohol solution of iodine with a mass concentration of 50 g/dm3; potassium iodide is dissolved in alcohol in a water bath at a temperature of 45±5 ° With constant stirring), so that the liquid covers the entire surface of the glass. Duration of staining is 0.5-1 min. After staining, the preparation is quickly rinsed with running water, directing the stream at an angle onto glass placed vertically. The preparation is dried with filter paper and viewed under a microscope with an immersion system. Microbes that stain positively on the Gram have a spherical shape and are located in clusters, most often resembling bunches of grapes.

To set up a plasma coagulation reaction, a loop of a 24-hour agar culture is added to a test tube with 0.5 cm3 of diluted rabbit plasma. The introduced culture is thoroughly stirred. One tube with plasma is left uninoculated, and the other is inoculated with a control strain of Staphylococcus aureus (coagulase-positive staphylococcus). The test tubes are placed in a thermostat and kept at a temperature of 37±1 °C for 3-6 hours. If after 6 hours coagulation of the plasma has not occurred, then these test tubes are left for up to 24 hours. If after 24 hours the plasma has not coagulated, then the test staphylococcus culture is classified as to coagulase negative.

When determining coagulase activity, the reaction is considered negative in cases where individual threads or clots do not form in the plasma, or in cases where individual threads appear in the plasma (the plasma coagulation reaction is assessed as one plus).

The reaction is considered positive if:

The clot is dense;

A clot having a small compartment;

A clot in the form of a suspended sac.

If a positive reaction is obtained, it is considered that Staphylococcus aureus was detected in the cultures.

The results are assessed for each sample separately.

Morphological, cultural properties and a positive plasma coagulation reaction indicate the presence of coagulase-positive staphylococci in the inoculated mass of the product.

Method definitions without preliminary enrichment.

1 cm3 of liquid product or its dilution is applied to the surface of the nutrient media in 3 Petri dishes, carefully rubbed with a spatula over the surface of the nutrient medium. The crops are incubated at a temperature of 37±1 °C for 24-48 hours. Petri dishes with the crops are incubated with the bottom up.

After thermostatting, the number of characteristic colonies on each Petri dish is counted. From each Petri dish, at least five characteristic and/or suspicious colonies of Staphylococcus aureus are selected and transferred to the surface of a nutrient agar slant poured into test tubes. Test tubes with inoculations are kept in a thermostat at a temperature of 37±1 °C for 24 hours.

In grown cultures, the relationship to Gram staining and coagulation of rabbit plasma is determined.

The results are assessed for each sample separately. If, when studying characteristic colonies, in 80% of cases, that is, in at least 4 out of 5 colonies, the growth of Staphylococcus aureus is confirmed, then it is considered that all characteristic colonies grown on Petri dishes belong to Staphylococcus aureus. In other cases, the number of Staphylococcus aureus is determined based on the percentage of confirmed colonies to the total number of representative colonies taken for confirmation.

The number of colonies of Staphylococcus aureus in 1 g or 1 cm3 after its determination in a certain sample of the product is calculated by the formula:

Х= (Уn1 Х 10? + Уn2 Х 10?) : 2,

where Уn1; Уn2 is the number of colonies grown on all Petri dishes within one dilution or inoculated volume; n is the number of tenfold dilutions.

Determination of ethyl alcohol in kefir and kumiss

First, prepare a pycnometer, which is thoroughly washed successively with a weak alcohol solution of alkali, water, a chrome mixture and again with water, then dried at a temperature of 100-105 ° C, cooled in a desiccator and weighed.

Weigh 100 g of the product into the distillation flask with an error of no more than 0.1 g, add dropwise a solution of sodium (potassium) hydroxide until a neutral or slightly alkaline reaction (according to litmus paper), place several glass capillaries there and close the flask with a stopper. Then connect the flask to reflux and slowly carry out distillation under moderate heating. A volumetric flask with a capacity of 100 cm3 is used as a receiver. The distillation is stopped after filling the flask to approximately 2/3 of the volume.

When a not very pure solution is obtained, it is quantitatively transferred to a clean distillation flask, in which the volume of the solution is adjusted to approximately 100 cm3 with water and distilled a second time. At the end of the distillation, the volumetric flask with the water-alcohol mixture is filled with water to the mark and mixed thoroughly. A water-alcohol mixture is poured into a pycnometer, previously weighed and prepared (with a pipette or a tube with a drawn capillary) from a volumetric flask to a level slightly above the mark, and the determination is carried out. Just like a solution, water is added to it.

A pycnometer with water is suspended on a thin thread from a glass rod placed on a tripod ring, and lowered into a glass of water, which should be approximately at the same level with the water of the pycnometer. To maintain a constant temperature (30.0±0.2°C), the glass is placed in a thermostat.

After 40 minutes, using filter paper or a tube with a retracted capillary, the meniscus of the pycnometer is set exactly on the mark, after which the pycnometer is closed with a stopper, removed from the glass, thoroughly wiped outside with filter paper and weighed.

The water number of a pycnometer P (the mass of water in the volume of a given pycnometer at 20°C) is calculated using the formula:

where m1 is the mass of an empty pycnometer with a plug, g; m2 - mass of the pycnometer with water and stopper, g.

The relative mass of ethyl alcohol solution d is calculated using the formula:

m3 is the mass of the pycnometer with a water-alcohol mixture, g.

The discrepancy between parallel determinations of the relative mass of the distillation solution should be no more than 0.0002.

The mass fraction of ethyl alcohol in the product is determined by relative mass.

Determination of moisture content in cottage cheese.

A porcelain cup with a glass rod and 20-25 g of sand is placed for 1 hour in a drying cabinet at a temperature of 102-105 ° C, after which, without cooling, it is weighed with an accuracy of 0.01 g. Then 5 g of the product is weighed into the cup and mixed it with sand and placed in a drying oven at a temperature of 160-165°C for 20 minutes. After which the cup is quickly weighed without cooling.

B = (A - B)*100/5,

Determination of cottage cheese or yogurt impurities in sour cream.

Add a tablespoon of sour cream to a glass of hot water. If there is falsification, the fat floats to the surface, and the casein of cottage cheese, curdled milk and other impurities settles to the bottom. Sour cream should not have sediment or, as an exception, only traces of it.

11. Own research

Object of study

Object The research of this work is sour cream, sold by JSC VNIMI with a fat content of 20%.

The Vnimi-Sibir Institute of Dairy Products is a specialized enterprise engaged in the production and sale of dairy and fermented milk products for public catering.

This enterprise is located at the address: 644008 Omsk, Krasny Put street, 163. Tel./fax: 23-26-71 OKPO: 11874082 INN: 5502022536 OKOPF: Representative offices and branches OKATO: 52401380000 OKOGU: Russian Academy of Agricultural Sciences. Founders: State Unitary Enterprise "Vnimi-Sibir" RAAS 38617788 dated 11/30/2006 registration chamber depot.

The Institute of Dairy Products "Vnimi-Sibir" is a unitary enterprise, that is, it is a commercial organization that is not vested with the right of ownership of the property assigned to it by the owner. The property of the State Unitary Enterprise “Vnimi-Sibir” is indivisible and cannot be distributed among deposits (shares, shares), including among employees of the enterprise. The property of an enterprise is state-owned and belongs to such an enterprise on the basis of economic management or operational management. General Director of the Institute of Dairy Products "Vnimi-Sibir" - Anatoly Nikolaevich Batukhtin.

The main activities of the enterprise are:

purchase and processing of milk;

production and sale of dairy products;

trade and commercial activities;

mediation activities;

wholesale and retail trade in food and consumer goods.

According to the standards, the enterprise belongs to class IV - “production for processing food and flavoring substances.” The sanitary protection zone is 50 m. Cargo flows are provided by vehicles.

The company includes:

whole milk production with a capacity of 100 tons of raw material processing per shift;

a workshop for the production of skimmed milk powder with a capacity of 10 tons per shift, butter - 12 tons, equipped with a set of Czech equipment operating in automatic mode;

control;

boiler room;

compressor room

The range of products of the Institute of Dairy Products “Vnimi-Siberia” is very wide. The markets of Omsk, Omsk region and nearby cities receive such types of products as animal butter, whole milk products, milk, fermented milk products, full-fat kefir, cream, sour cream, full-fat cottage cheese, skimmed milk powder, whole milk powder.

animal butter - goes on sale with a fat content of 80% and is packaged in volumes of 1000, 500 and 250 grams.

whole milk products - the fat content of this product is 4.6% and is sold in 1 liter volumes.

milk - the Institute of Dairy Products produces milk with fat content of 3.2%, 2.5%, 1%. Also available in 1 liter volume.

fermented milk products are sold with a fat content of 3.2% and bottled in 1 liter containers.

full-fat kefir - the fat content of this product is 3.2% and is bottled in 1-liter containers.

cream - this product goes on sale with a fat content of 30% and is produced in volumes of 500, 20 grams.

sour cream - the fat content of this product is 15%, 20%, 30% and is packaged in containers of 450, 200, 100 grams.

fat cottage cheese - goes on sale with a fat content of 9% and is packaged in packages of 250 grams.

Skimmed milk powder - available in 500 grams.

Whole milk powder - goes on sale with a fat content of 4.2% and is packaged in 500 gram packages.

The following research methods were chosen when writing this work:

. Organoleptic.

. Statistical.

Research on sour cream 15%, 20%, 30% fat


Proteins/fats/carbohydrates, g per 100g
Energy value, kcal per 100g
Storage period/conditions	no more than 14 days / at a temperature of 4±20C	no more than 7 days / at a temperature of 1...40C and humidity not more than 80%	7 days / at a temperature of 4±20C
	cream from cow's milk, starter of pure cultures of lactic acid bacteria	cow's milk cream, pure cultures of lactic acid bacteria	milk cream, pure culture of lactic acid bacteria
Appearance	color white-cream, uniform, glossy	color white-cream, uniform	color creamy white, uniform
Consistency		slightly lumpy, no whey separated	slightly lumpy, no whey separated
	pure fermented milk	fermented milk with food flavor	feed, weak fermented milk
	fermented milk with a slight feed flavor	pronounced fermented milk with a food tint	weak fermented milk
physical and chemical indicators
Fat content, declared/actual, %
Antibiotics	not detected	not detected	not detected
microbiological indicators
Escherichia coli, 0.001g is not allowed	not detected	not detected	not detected
Lactic acid bacteria, not less than 1x107 CFU per 1g
Fat identification	no non-dairy fat detected	no non-dairy fat detected	no non-dairy fat detected
Overall rating (100%)

Analysis of the results obtained

Since there were no comments from the laboratory, the overall assessment of the product coincides with the organoleptic assessment. Thus, according to the test results, three brands of sour cream numbered 1, 2, 3 received an “excellent” rating; they were real and tasty, and complied with GOST.

Bibliography

1. Dunchenko N.I., Khramtsov A.G., Makeeva I.A. and others. Examination of milk and dairy products. Quality and safety. - Novosibirsk: Sib. Univ. publishing house, 2007. - 477 p.

2. Krus G.N., Shalygina A.M., Volokitina Z.V. Methods for studying milk and dairy products. - M.: KolosS, 2002. - 368 p.

3. Makarov V.A., Frolov V.P., Shuklin N.F. Veterinary and sanitary examination with the basics of technology and standardization of livestock products. - M.: Agropromizdat, 1991. - 463 p.

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

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

6. GOST 3629-47 Dairy products. Method for determining alcohol (alcohol).

7. GOST 5867-90 Milk and dairy products. Methods for determining fat.

8. GOST 30347-97 Milk and dairy products. Methods for determining Staphylococcus aureus.

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Selection of raw materials and their preparation

The first stage of production is the selection and preparation of raw materials for future fermented milk products. The raw materials are milk, cream and whey. All dairy products are based on these components. Sugar, berries, and various necessary chemical additives are most often used as fillers. In recent years, everyone has been trying like crazy to find chemical-free products. But they forget that any product without chemical additives is potentially dangerous. He can be infected with cholera, tuberculosis, dysentery, foot and mouth disease, after all. The colossally low human life expectancy throughout history is explained precisely by the consumption of contaminated foods. And the endless fight against diseases does not benefit any organism. Be calmer about other people's concerns about your health. So the notorious “chemistry” is vital.

Processing stages

After introduction necessary additives an additional stage of product purification begins. The fat content is deliberately reduced, since dairy products that are too fatty can cause upset. Fat content is considered normal from 1% to 6%. The only exception is sour cream. Regulating fat content is called normalization, which is carried out in separators.

Then comes the stage of pasteurization of liquid dairy products. The technology for the production of fermented milk products requires mandatory pasteurization. This is the primary method of destroying harmful contagious viruses and bacteria living in dairy products prior to processing. The pasteurization temperature reaches 85–90 0 C, the duration is approximately 7–10 minutes. It is wrong to think that they die in this case beneficial bacteria. Nothing like this. It is at this temperature that the most active growth of beneficial microflora begins, which at low temperatures is simply choked by harmful bacteria.

At some enterprises, the processing process also includes a homogenization stage - this helps to give the product a more uniform structure, but this procedure is not of fundamental importance for the quality of the product.

Then the dairy products are cooled, a special starter is introduced, and then either a thermostatic manufacturing method or a tank method is used. There is no fundamental difference between them. Simply, the thermostatic production method involves the use of separate containers (glasses, bottles, bags) for fermentation and subsequent ripening of the product, while the tank method involves ripening the entire volume of the product in one large tank.

The final stage of manufacturing fermented milk products

If the tank method was used for fermentation, the product is sent for packaging and sorting. If the thermostatic method was used, quality control is carried out using random samples. Samples are taken at random from individual tanks and the quality of the product is determined based on a number of criteria.

How fermented milk products are produced, video:

Technology and stages of production of fermented milk products. General technology of dietary fermented milk products

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Object of study

Object The research of this work is sour cream, sold by JSC VNIMI with a fat content of 20%.

The Vnimi-Sibir Institute of Dairy Products is a specialized enterprise engaged in the production and sale of dairy and fermented milk products for public catering.

The main activities of the enterprise are:

purchase and processing of milk;

production and sale of dairy products;

trade and commercial activities;

mediation activities;

wholesale and retail trade in food and consumer goods.

According to the standards, the enterprise belongs to class IV - “production for processing food and flavoring substances.” The sanitary protection zone is 50 m. Cargo flows are provided by vehicles.

The company includes:

whole milk production with a capacity of 100 tons of raw material processing per shift;

a workshop for the production of skimmed milk powder with a capacity of 10 tons per shift, butter - 12 tons, equipped with a set of Czech equipment operating in automatic mode;

control;

boiler room;

compressor room

animal butter - goes on sale with a fat content of 80% and is packaged in volumes of 1000, 500 and 250 grams.

whole milk products - the fat content of this product is 4.6% and is sold in 1 liter volumes.

milk - the Institute of Dairy Products produces milk with fat content of 3.2%, 2.5%, 1%. Also available in 1 liter volume.

fermented milk products are sold with a fat content of 3.2% and bottled in 1 liter containers.

full-fat kefir - the fat content of this product is 3.2% and is bottled in 1-liter containers.

cream - this product goes on sale with a fat content of 30% and is produced in volumes of 500, 20 grams.

sour cream - the fat content of this product is 15%, 20%, 30% and is packaged in containers of 450, 200, 100 grams.

fat cottage cheese - goes on sale with a fat content of 9% and is packaged in packages of 250 grams.

Skimmed milk powder - available in 500 grams.

Whole milk powder - goes on sale with a fat content of 4.2% and is packaged in 500 gram packages.

The following research methods were chosen when writing this work:

. Organoleptic.

. Statistical.

Analysis of the results obtained

Since there were no comments from the laboratory, the overall assessment of the product coincides with the organoleptic assessment. Thus, according to the test results, three brands of sour cream numbered 1, 2, 3 received an “excellent” rating; they were real and tasty, and complied with GOST.

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