"Sour-milk products. Features of production."
Fermented milk products (lactic acid products), a group of food products produced from milk or its derivatives (cream, whey, etc.) by fermentation (fermentation) using starter cultures. For the manufacture of fermented milk products, cow's milk is most widely used, less often the milk of sheep, goats, mares and other animals. The tradition of making fermented milk products has long been developed among the pastoral peoples of Eurasia, who almost did not consume fresh milk. Traditional fermented milk products include curdled milk, kefir, fermented baked milk, sour cream, cottage cheese and products derived from it (kurut, syuzme, etc.), yogurt, koumiss, katyk, ayran, shubat, etc. The impetus for the widespread industrial production of fermented milk products in the world was studies by I. I. Mechnikov, which revealed the positive effect of lactic acid bacteria contained in them on human health. In the production of fermented milk products, milk is first pasteurized or sterilized to destroy the pathogenic microflora in it, and then fermented. The range of fermented milk products is extremely diverse. Fermented milk products differ in the composition of microflora and manufacturing technology, consistency, mass fraction of fat and protein; various fruit and vegetable fillers, flavorings, vitamins, food additives can be added to them. Some fermented milk products (for example, ayran) can be produced in carbonated form. Sometimes fermented milk products are produced in dry form (mainly abroad). The diversity of the range of fermented milk products is also associated with national traditions.
Fermented milk products are divided into products of lactic acid (cottage cheese, curdled milk, fermented baked milk, sour cream, yogurt, etc.) and mixed (lactic acid and alcohol) fermentation (kefir, acidophilus, koumiss, etc.).
In fermented milk products of lactic fermentation, the vital activity of lactic acid bacteria contained in starter cultures leads to the breakdown of lactose with the formation of lactic acid, under the influence of which milk proteins coagulate, which increases the digestibility of fermented milk products compared to milk. Cottage cheese is part of diets prescribed for liver diseases, obesity, etc. In Russia, the industrial production of cottage cheese was organized at the end of the 18th century at the first dairy enterprises. The modern volume of industrial production of cottage cheese in the Russian Federation is more than 300 thousand tons per year. Prostokvasha is a widespread traditional fermented milk product for Russia; its industrial production began in the 1st half of the 20th century. Fermented milk products such as curdled milk produced in other countries have traditional local names: matsoni (in Georgia), matsun (in Armenia), etc. Ryazhenka is made by fermenting baked milk. Sour cream is produced by fermenting cream; the most common fermented milk product with high fat content, in Russia it is also a traditional product. Yoghurt is a fermented milk product with a high content of non-fat milk solids. The composition of the sourdough includes thermophilic lactic streptococci and the so-called Bulgarian lactic acid bacillus (Lactobacillus bulgaricus). Yoghurt is the most common fermented milk product abroad. Its production in the Russian Federation is developing at the fastest pace and in 2006 amounted to 679 thousand tons.
In fermented milk products of mixed fermentation, as a result of the vital activity of microorganisms contained in starter cultures (lactic acid bacteria, yeast, etc.), along with lactic acid, alcohol, carbon dioxide and volatile fatty acids are formed, which also increase the digestibility of fermented milk products. Kefir by the beginning of the 21st century is the most common fermented milk product in the Russian Federation. From the 2nd half of the 19th century, kefir became the subject of study, and in the 1930s, its widespread industrial production began. In 2006, the production of kefir in the Russian Federation amounted to 835 thousand tons. For its production, a natural, microbiologically complex symbiotic leaven, the so-called kefir fungus, is used. Kefir is a probiotic product (see Probiotics), its consumption leads to an increase in the activity of leukocytes, an increase in immunity. Kefir contains the polysaccharide kefiran, which has an antitumor effect. Acidophilus is also a probiotic fermented milk product, it is prepared using a starter consisting of acidophilic lactic acid bacteria isolated from the human intestine (Lactobacillus acidophilus), bacteria of the genus Lactococcus and kefir fungus. Feature used acidophilic lactic acid bacteria - high acid-forming and antagonistic activity against pathogenic and opportunistic microorganisms. In Buryatia, Tataria, Bashkiria and other republics of the Russian Federation, local traditional fermented milk products of mixed fermentation (kurunga, tarag, etc.) are produced.
At the beginning of the 21st century, the production of probiotic fermented milk products began to actively develop using bifidobacteria, propionic acid bacteria, etc. The production of synbiotic fermented milk products, in addition to probiotics, was also enriched with prebiotics (indigestible components that stimulate the growth and / or activity of the protective intestinal microflora). The production of fermented milk products in the Russian Federation is growing by approximately 10% per year, in 2006 its volume exceeded 3 million tons.
Some fermented milk products, as well as by-products of their production, are used to feed farm and other animals.
Lit .: Bannikova L. A., Koroleva N. S., Semenikhina V. F. Microbiological foundations of dairy production. M., 1987; Stepanenko P. P. Microbiology of milk and dairy products. M., 1996; Tverdokhleb G. V., Sazhinov G. Yu., Ramanauskas R. I. Technology of milk and dairy products. 3rd ed. M., 2006.
V. D. Kharitonov, V. F. Semenikhina, I. V. Rozhkova.
At present, more than 300 species are produced. All of them are produced by fermenting raw materials with pure bacterial starters. Under certain conditions, the microflora turns into so-called. secondary microflora. It gives the products a specific taste and smell. Use: Mesophilic streptococci, thermophilic streptococci and coli, yeast. Their use in various combinations makes it possible to obtain a large amount of sour mol. products.
In the production of fermented milk products, milk is used, in which the protein content is not less than 3%, lactose is not less than 4.5%. In addition, during the production of cottage cheese by the rennet method, the rennet coagulability of milk is determined, it should be 1 or 2 classes. Production of sour milk. products is carried out in 2 ways. 1) reservoir 2) thermostatic. The tank method uses large production areas, but it is a relatively cheap method. The thermostatic method requires additional, equipment costs, but requires less manufacturing. areas. Scheme of the production of fermented milk products by the thermostatic method.
Acceptance and quality assessment of raw materials, reservation, heating and cleaning, normalization by fat, pasteurization, cooling to 1 fermentation (for mesof. 30-32°C, for thermofil. 40-42°C, for kefir fungus 20 °C), packaging , introduction of starter (in each container), hermetic sealing, fermentation and maturation in a thermostatic chamber, cooling (up to t 6-8), storage and sale. (72 hours) The shelf life of sour cream is 5 days. Cottage cheese is produced in 2 ways: Traditional and separate. In addition, depending on the method of fermentation of milk, cottage cheese is produced: Acid method (only leaven is added) Rennet method (in addition to leaven, rennet and calcium chloride are added). Defects of fermented milk products: Defects of taste and smell. Excessively sour taste and smell. Violated modes of fermentation and fermentation, as well as transportation and storage. Feed taste and smell. Mild taste and smell. Due to the violation of the technological regimes of fermentation. Rancid taste and smell. For high fat foods. Color defects: uneven. Consistency defects: heterogeneous with whey separation - violation of transportation and storage regimes.
55. Butter production technology.
For the production of butter, milk of at least grade 2, cream of grade 1 or 2 is used. In cream of the 1st grade, the presence of mechanical impurities, protein flakes, signs of freezing is not allowed. For cream of the 2nd grade, a slightly pronounced fodder taste and smell, individual protein flakes are allowed. The temperature of incoming cream of grade 1 should not be higher than 10°C, grade 2 should not exceed 15°C. It is most preferable to use raw materials with a high fat content.
The production of butter is carried out in 2 ways: 1) Churning; 2) Conversion of high fat cream
Technological scheme for the production of butter by the churning method. Acceptance and quality assessment of raw materials, cooling (up to 14-6°C), reservation, heating (30-35°C), cleaning, separation (obtaining cream (32-35% fat), heat treatment of cream (pasteurization), physical maturation cream (low-temperature processing), cream churning, butter grain processing, buttermilk separation, butter washing, butter mechanical treatment, packaging, storage and sale.
Cleaning, separation is carried out: in separators of open or closed type. The fat content of the resulting cream depends on the type of butter produced.
Heat treatment is carried out in order to destroy all harmful microflora, as well as inactivate enzymes that accelerate oil deterioration. Pasteurization below 85 °C is not carried out. For cream I grade I pasteurized in summer 85-90, in winter 92-95. For butter produced from cream of the 2nd grade t, regardless of the time of year 95, with preliminarily. Cream deodorization. Cream must go through a stage of physical maturation. When churning cream that has not passed this stage, a soft product with a smearing consistency with a large waste of fat into buttermilk is obtained.
Cream churning is carried out in continuous or batch butter makers. The temperature at which the cream is churned depends on the time of year, the fat content of the cream and the degree of solidification of the fat in the cream. For summer it is 7-12°C, winter 8-14. The churning process can be divided into 3 stages: I) Beginning of churning (the viewing window of the churn is covered with a film of cream). 2) The formation of individual oil grains (the window brightens 3) Finish, the formation of oil grains (the window is transparent and oil grains are visible). The duration of churning of a periodic butter churn is 20-30 minutes. Butter grains separated from buttermilk are washed 2 times with drinking water, t which is 2 ° C lower than the churning t, to remove lactose, protein residues from butter grains, min. substances. The volume of wash water is 50% of the initial volume of cream. The washed grain is pressed and molded. To do this, the churn is transferred to the deboning mode, lasting 5 minutes.
Packaging is carried out at the exit of the churn, both in cardboard boxes and in small containers of 180-200 gr. Be sure to indicate on the packaging: product labeling, name, GOST, manufacturer, conditions and shelf life, composition and value.
Store at 14-6 °C for no more than 20 days. Frozen, at t -20, -25 ° C can be stored for up to 3 months.
Butter defects: defects of taste and smell, consistency, color. Taste and smell: bitter, rancid, empty, fodder smell. Consistency; crumbly, too soft, too wet. Colour: uneven, top layer yellow and separate pieces of fat are visible).
Fermented milk products are produced in two ways: thermostatic and reservoir.
Scheme: milk acceptance - normalization - pasteurization - cooling - 1 (reservoir) fermentation in the tank - fermentation - cooling - maturation - packaging - storage - sale. 2 (thermostatic) fermentation in a thermostat and bottling in consumer packaging - fermentation in a thermostatic chamber - cooling in a refrigerator - maturation - storage - sale.
Acceptance and evaluation of milk: the mass fraction of fat, density, acidity, temperature, organoleptic indicators are determined. Raw materials are used: at least 2 grades with an acidity of less than 20 degrees T, a reductase test of at least 1 class, fur. pollution not more than 1 group, density not lower than 1.027g/cm3. Skimmed milk: acidity less than 20°T, density not less than 1.030g/cm3
Milk purification: carried out at 43°C. Homogenization: at R-15MPa, 45-48 degrees C. Pasteurization: 85-87 degrees C - 10-15 minutes, 92 degrees C - 2-8 minutes. Cooling? to fermentation temperature. Fermentation: sourdough 3-5% of the total volume, mixing 15 min. Fermentation: 10-12 hours, the end of fermentation is determined by acidity (65-90 degT) and clot density. Cooling: with ice water with stirring (30-60 min), until a homogeneous mass is obtained. Adding fillers: add fillers to a partially cooled clot, mix, serve for bottling. Storage: no more than 36 hours at 6 degrees C from the end of those. percent
Technology for the preparation of liquid fermented milk products.
Fermented milk drinks TU 46.073-2003
Developed by the National Association of Dairymen of Ukraine. It applies to sour-milk drinks that are fermented with a special starter with or without sugar, stabilizers, milk powder, natural fruit fillers, with further heat treatment.
Assortment: drink "Jubilee" (1, 2.5%); drink "Jubilee" with fruit filling (1, 2.5%); drink "Snowball" (1.0, 2.5, 3.2, 3.5%); drink "Snowball fruit and berry" (1%); low-fat yogurt (1.5, 2.5, 3.2, 3.5%); fruit and berry yogurt (1, 3.5%).
Organoleptic indicators. Appearance and consistency: homogeneous, moderately viscous. With the reservoir method - with a broken clot; at thermostatic - with undisturbed. With the presence of soft particles of fruits and berries, whey separation is allowed no more than 2-3%. The drink "Snowball" has a slight flouriness.
Taste and smell. Pure fermented milk, moderately sweet, with a taste and smell of the added filler.
Color. Depends on the filler or milky white.
Acidity. Anniversary - 80-110 degrees T (pH - 4.6-4.0); "Snowball" - 80-120 degrees T (pH - 4.6-3.9); yogurt - 80-140 degrees T (pH - 4.4-3.8)
Sucrose is added more than 7%, jam - more than 4%.
Microbiological indicators. Bacteria of the Escherichia coli group are not allowed in 0.1 g of the product. Salmonella is not allowed in 25 g of the product. Staphylococcus aureus is not allowed in 0.1 g of the product. The number of lactic acid microorganisms is not less than 1 million per cm3.
Storage. At a temperature of 4+-2gardS. If the product is without stabilizers and leaking, no more than 36 hours. Without stabilizers, but in sealed packaging - no more than 3 days. With a stabilizer and in sealed packaging up to 14 days.
This is a fermented milk drink obtained by fermenting milk with sourdough on kefir fungi.
Range: low fat, 1%, 2.5%, 3.2%.
Acidity 850120grad.
Appearance and texture. Homogeneous, with a broken clot in the tank method of production and undisturbed in the thermostatic method. Gas formation is allowed, in the form of separate bubbles.
Taste and smell. Pure fermented milk, refreshing, slightly spicy.
A slight separation of whey is allowed - no more than 2%. Microbiological indicators. Bacteria of the Escherichia coli group - not allowed in 0.01 g prod. Pathogenic microorganisms are not allowed in 1 g of the product.
Shelf life, as in dairy products.
Scheme of directions for processing milk into kefir.
Milk 3.4% - normalized mixture - (sourdough 5%): 1 - kefir 1%; 2 - kefir 2.5%; 3 - kefir 3.2%.
A fermented milk drink made from baked milk fermented with pure cultures of thermophilic lactic streptococci, with or without the addition of Bulgarian sticks.
Range: 1%, 2.5%, 4%.
Acidity 70-110grad.
Appearance and texture. Homogeneous, the presence of foam is allowed.
Taste and smell. Clean, fermented milk, with a pronounced aftertaste of pasteurization.
Color. Light cream, due to the presence of melonoidins, due to the languor of milk.
Technological features. Pasteurization temperature - 95-98 degrees C with an exposure of 3-5 hours, in order to obtain a light-cream color and a specific taste.
Storage. In the presence of stabilizers no more than 14 days.
The requirement for raw materials is the heat resistance of milk.
Yogurt.
A fermented milk product produced from milk by fermenting it with pure cultures of lactic acid bacteria.
Ordinary yogurt.
Cooked only in a thermostatic way. The sourdough contains thermophilic lactic streptococcus and Bulgarian stick. The starter temperature is 40°C. The duration of fermentation is 3-4 hours. A dense clot is formed without gas formation. Taste and smell - pure sour milk. Color - milky white. Acidity 80-130grad. Storage: at a temperature not higher than 8 degrees C - 36 hours.
Southern curd.
thermostatic method. The sourdough is the same and + lactic yeast. Fermentation 6-8 hours. Color - milky white. Taste - pure sour-milk, alcoholic aftertaste. The clot is dense. In the presence of mucous strains, there may be a viscous consistency. Acidity - 90-140 degrees T.
Acidophilic yogurt.
Sourdough - acidophilus bacillus, lactic acid streptococcus. The taste is sour milk. The consistency is tender, in the presence of mucous strains - viscous. Acidity - up to 140grad
Taste and smell: pure sour milk, with a pronounced taste and aroma of pasteurized cream (during pasteurization of cream, diaceyl, acetoin is formed). All types of sour cream are allowed to have a slightly fodder aftertaste (especially in the winter-spring period), and a slight bitterness.
Color: white with a cream shade.
Physical and chemical indicators.
Acidity: 10.15.30% - 60-90grad; 20.25% - 60-100 degrees T. Phosphatase is absent. The temperature of release from the factory is less than 6 degrees C. For sour cream produced using dry dairy products, an increase in the upper limit of acidity by 10 degrees T is allowed.
Microbiological indicators.
Bacteria of the Escherichia coli group are not allowed in 0.001 g of the product. Pathogenic microorganisms are not allowed in 25 g of the product. Staphylococcus aureus is not allowed in 1 g of the product.
Scheme of milk processing directions for sour cream.
Milk 3.4% (for separation) - : 1 - skimmed milk residue; 2 - cream (for normalization) -: 1 - sour cream 10%; 2 = (adding fillers) dessert sour cream.
The technological scheme for the manufacture of fermented milk products consists of the following operations: preparation of raw materials (milk or cream), normalization for fat, heat treatment, homogenization, cooling to the fermentation temperature, fermentation, fermentation, cooling (to a temperature not higher than 8 ° C).
The production of kefir and sour cream has its own characteristics.
Depending on the conditions of fermentation, there are thermostatic and reservoir methods of production. With the thermostatic method, fermented milk or cream is poured into bottles or jars, which are then placed in thermostatic chambers, where the fermentation process takes place. The next operations are cooling in a cold chamber and ripening of kefir and sour cream, i.e. keeping the products at a low positive temperature.
With the tank method of production, fermentation, cooling and maturation are carried out in large containers (double-walled tanks), and then ready-to-sell kefir is bottled or packaged, sour cream is placed in large containers (bidong, barrels).
Features of the manufacture of cottage cheese are that the fermentation process can proceed not only as a result of the vital activity of the starter microorganisms, but also under the action of rennet (a powder obtained from the mucous membrane of the fourth compartment of the stomach - the abomasum of dairy calves and lambs) introduced into milk. In addition, after fermentation, whey is separated from the clot.
The quality of fermented milk products depends on the composition and properties of raw materials, the type and activity of starter cultures, and technological modes.
So, with a reduced content of vitamins in milk, free
amino acids and trace elements that are necessary for reproduction
lactic acid bacteria, the process of fermentation of milk proceeds slowly. In the spring, milk lacks these elements.
Lactic acid bacteria develop poorly, and the ability of rennet to coagulate in old milk, in milk obtained from cows with mastitis, is reduced. Milk coagulates poorly with rennet if the content of proteins and calcium salts in it is lowered. Defects in milk in terms of organoleptic characteristics will also appear in fermented milk products.
The taste, smell and texture of fermented milk products depend on the composition of the starter culture. Vigorous acid-forming agents (mesophilic and thermophilic lactic streptococcus, Bulgarian bacillus) cause significant accumulation of lactic acid and obtaining a dense clot with intensive whey separation, weak acid-forming agents (aroma-forming streptococci) - a delicate clot with a pleasant taste and aroma. Creamy streptococcus, acidophilus bacillus contribute to an increase in the viscosity and elasticity of the product, and prevent the separation of whey. Yeast, aroma-forming and acetic acid bacteria, releasing carbon dioxide in the process of their development, destroy the clot.
The heat treatment of raw materials, which is necessary to destroy foreign microflora and inactivate enzymes, affects the strength of the clot and the intensity of whey separation. With an increase in the pasteurization temperature of milk, the strength of the clot increases and the intensity of whey separation decreases.
In the production of fermented milk drinks and sour cream, high pasteurization temperatures are recommended for milk (85-87 ° C with an exposure of 5-10 minutes or 90-92 ° C with an exposure of 2-3 minutes) and cream (85-95 ° C with an exposure of 15- 20 s).
In the production of cottage cheese, in order to better separate whey and reduce protein losses, it is advisable to pasteurize milk at 78-80 ° C with or without holding for 20-30 seconds.
Homogenization of milk and cream (in the production of kefir, curdled milk, sour cream) accelerates the formation of a clot, increases its viscosity and plasticity, and reduces the release of whey. In the production of cottage cheese, it is impractical to homogenize milk, since the clot is flabby, poorly releasing whey.
In milk or cream having a temperature favorable for the development of microorganisms, leaven is added in the amount of 3-5%.
The temperature regime and the duration of fermentation depend on the microflora that is part of the starter cultures. When using mesophilic types of lactic acid bacteria, the fermentation temperature is 28-32 ° C and the duration is 5-7 hours, thermophilic - 40-45 ° C for 2.5-4 hours, kefir culture - at a temperature of 20-25 ° C for 8- 12 noon
The end of fermentation is determined by the strength of the clot and titratable acidity. For drinks, it should be 75-85 °T, for sour cream - 65-70, cottage cheese of various fat content - 60-85 °T. The consistency, taste and smell of products are formed during this technological process.
To stop lactic fermentation, fermented milk products are cooled and stored at a temperature not exceeding 8°C.
Kefir, koumiss and other products of mixed fermentation before cooling are subjected to maturation for the development of yeast and aroma-forming bacteria (kefir is kept at a temperature of 14-16°C for 6-12 hours, koumiss - at 16-18°C).
Sour cream is also ripened. At the same time, the structure and consistency of the product are finally formed. Sour cream is cooled to a temperature of 1-6°C and kept. Cooling and ripening lasts 6--48 hours depending on; sour cream packages. In the process of maturation, crystallization and hardening of milk fat occurs, which increases the strength of the structure and viscosity of sour cream, as well as the absorption of moisture by casein and whey proteins, which also improves the consistency of the product.
When curd is produced, the separation of whey from the clot begins at an acidity corresponding to the isoelectric point of casein (i.e., pH 4.6-4.7) for an acid clot and at a pH of 4.7-5.0 for acid-rennet. The process of syneresis is accelerated by cutting the clot and heating it to a temperature of 30-36 °C.
Whey is easier to separate with the acid-rennet method of manufacture. This method is used in the production of fatty cottage cheese. At the same time, the clot is not heated and the loss of fat with whey is insignificant. Milk fat makes it difficult to release moisture from the clot, so whey separation is easier to control in a fat-free clot. The acid method is more often used in the production of low-fat cottage cheese.
Thus, summing up all of the above, it can be noted that the technological processes for the production of fermented milk products are very diverse, but all of them must comply with production standards so that buyers receive a quality product, and, accordingly, its producers receive high profits.
Industrial technologies for the production of milk, cream, fermented milk products, ice cream, canned milk, as well as dairy products for baby and medical nutrition are presented. Particular attention is paid to the compliance of the described technologies with the current regulatory and technical documentation. Designed for university students and technologists of dairy production.
* * *
The following excerpt from the book Industrial technologies for the production of dairy products (N. G. Dogareva, 2013) provided by our book partner - the company LitRes.
TECHNOLOGY OF FERROUS MILK PRODUCTS
A fermented milk product is a dairy product or a dairy compound product that is produced by reducing indicator of active acidity (pH) and coagulation of the fermentation protein milk and (or) dairy products, and (or) their mixtures using starter microorganisms and subsequent addition not for the purpose of replacing components of milk of non-dairy components or without the addition of such components, and contain live starter microorganisms in the amount established by the Technical Regulations for milk and dairy products.
Fermented milk products include: liquid fermented milk products, sour cream, cottage cheese and cottage cheese products.
Normative and technical documentation:
– GOST R 51331–99 Dairy products. Yoghurts. General specifications
– GOST R 52092–2003 Sour cream. Specifications
– GOST R 52093–2003 Kefir. Specifications
– GOST R 52094–2003 Ryazhenka. Specifications
– GOST R 52095–2003 Prostokvash. Specifications
– GOST R 52096–2003 Cottage cheese. Specifications
– GOST R 52687–2006 Fermented milk products enriched with bifidobacteria bifidum. Specifications
– GOST R 52790–2007 Glazed curd curds. General specifications
– GOST R 52974–2008 Kumis. Specifications
– GOST R 53504–2009 Grained cottage cheese. Specifications
– GOST R 53505–2009 Mechnikovskaya yogurt. Specifications
– GOST R 53506–2009 Acidophilus. Specifications
– GOST R 53508–2009 Varenets. Specifications
– GOST R 53668–2009 Airan. Specifications
2.1. Dietary and medicinal properties of fermented milk products
These properties have been known since ancient times. The Russian physiologist I. I. Mechnikov explained the longevity of the Bulgarians by the consumption of yogurt. From it, he isolated a lactic acid stick, which he called Bulgarian. It ferments milk sugar into lactic acid and, with the systematic consumption of yogurt, inhibits putrefactive processes in the intestines, being an antagonist of putrefactive microflora. Later, Podgaetsky isolated from the intestines of an infant more resistant to alkalis and hydrochloric acid, similar in properties to Bulgarian and called acidophilus, a bacillus. It is easier to digest in the human intestine, ferments not only milk, but also other sugars, has stronger antibiotic properties, and produces the antibiotic nisin. Milk yeast also possesses this property to some extent. In the production of fermented milk products, lactic acid, cream, and aroma-forming streptococci, kefir fungi, koumiss yeast, lactic acid bacillus, and bifidobacteria are also used. Under the action of enzymes secreted by lactic acid microflora, milk sugar is fermented with the formation of lactic acid, sometimes other acids, alcohol, carbon dioxide, dicetyl. During fermentation, partial hydrolysis of proteins occurs with the formation of free amino acids and glycolysis of glucose, metabolites appear that significantly change the biophysical structure of micelles of caseinate-calcium phosphate complex (CCPC) and the bioactivity of mineral salts. Lactic acid streptococcus also secretes the antibiotic nisin, creamy - diplococcin, aroma-forming - an antibiotic close to dysplococcin, lactic acid bacillus-lactonin. Produced antibiotics with great destructive power act on decay microorganisms.
Dairy products are probiotics.
Probiotics are preparations and food products containing substances of microbial origin that, when administered naturally, have beneficial effects on the physiological functions and biochemical reactions of the host organism through optimization of its microecological status..
The great Russian scientist I.I. Mechnikov first expressed and scientifically substantiated the idea of the possibility of using lactic acid bacteria to combat unwanted microflora of the human gastrointestinal tract. I. I. Mechnikov suggested using lactic acid bacteria that can take root in the intestines.
There is a close relationship between the state of human health, the functioning of his immune system and the composition of the microflora of his gastrointestinal tract. The alimentary canal is a natural habitat for microflora, which is involved in the formation of the immunobiological reactivity of the organism. Bifidobacteria and lactobacilli have the greatest positive effect on the human body. In the small intestine, these are mainly lactobacilli, among which acidophilus bacillus predominates, and in the large intestine - bifidobacteria.
Under the influence of adverse factors, first of all, the number of beneficial microorganisms decreases and the amount of flora that has a negative effect on the human body increases. It has been established that the normal composition of the microflora changes with the occurrence of various diseases, and some diseases are caused by changes in the microflora, i.e. these are interdependent factors that directly affect human health. All this confirms the need for widespread use of agents that help restore the normal composition of beneficial microflora in the intestine. One of these products is dairy products.
The probiotic effect of the products is primarily due to the properties of the microorganisms used, in particular bifidobacteria, lactobacilli and other lactic acid bacteria. Therefore, the principles of selecting bacterial strains play an important role in obtaining products with specified quality and safety indicators.
Traditional fermented milk products such as cottage cheese, sour cream, fermented baked milk, curdled milk, etc. are produced using mesophilic lactic acid bacteria and thermophilic lactic acid streptococci. These products have dietary properties and mainly act as suppliers of nutrients that are well absorbed by the human body. Among fermented milk products produced for a long time, products containing thermophilic lactic acid bacilli (acidophilic, Bulgarian) have the most pronounced probiotic effect. In our country, a wide range of fermented milk products is produced using acidophilus bacteria. These are products such as acidophilus, acidophilic milk, acidophilic paste, etc. But during storage, titratable acidity increases very quickly in them, and organoleptic indicators change. Bulgarian stick also has a high limit of acid formation. The ability for intense acid formation in acidophilus and Bulgarian sticks is a deterrent to the industrial production of fermented milk products based on these cultures. The beneficial properties of cultures of acidophilus bacteria and Bulgarian bacterium have become an incentive to obtain products that use combinations of lactobacilli with thermophilic lactic streptococcus, the so-called symbiotic starter cultures. Thermophilic lactic streptococcus has a low limit of acid formation and its use in the production of fermented milk products does not lead to a large increase in acidity in the product. The most popular among the population among this group of products is Mechnikovskaya yogurt and classic yogurt, for the production of which sourdoughs are used, consisting of cultures of Bulgarian bacillus and thermophilic streptococcus.
Bifidobacteria are the dominant representatives of the beneficial human intestinal microflora, therefore, more and more attention is paid to the development and production of fermented milk products with bifidobacteria. The use of bifidobacteria as starter cultures in the biotechnology of fermented milk products has opened up great prospects for increasing the biological value of dairy products. In milk fermented with bifidobacteria, the share of essential amino acids accounts for 40%.
The effect of fermented milk products on the human body has been studied in sufficient detail. Fermented milk products contribute to a higher absorption of calcium, increase the secretion of digestive juices and bile secretion, increase gastric secretion and the secretion of pancreatic juice, increase the excretion of urea and other products of nitrogen metabolism, inhibit the growth of unwanted microflora due to the bactericidal action of lactic acid and antibiotic substances, and have a beneficial effect on motility intestines, help reduce serum cholesterol, tone up the nervous system. Fermented milk products with probiotic properties have a stimulating effect on the immune system, reduce the risk of malignant neoplasms, in particular colon and breast cancer, and remove toxic substances from the body.
Thus, the systematic use of fermented milk products and preparations with probiotic properties, which have a regulatory effect on the body or certain organs and systems, provides a healing effect without the use of drugs.
2.2. Starter cultures for fermented milk products
Starter cultures are microorganisms and/or associations of microorganisms, predominantly lactic acid, specially selected and used for the production of milk processing products..
The starter introduced into milk is the primary microflora of fermented milk products, from which the secondary one develops.
Currently, pure cultures of bacteria for the production of various dairy products are produced mainly in the form of dry starter cultures. The starter cultures are dried by spraying or sublimation. The most progressive method is sublimation, which consists in drying pure cultures in a frozen state under high vacuum. Under these conditions, the persistence of living cells reaches 90% for many months and even years. Drying liquid cultures by spraying, as in the production of powdered milk, retains their activity for 3 months. In order to increase the number of bacterial cells in starter cultures, preliminary centrifugation of the liquid starter culture is used. The resulting biomass is diluted in sterile skimmed milk and then dried in a spray dryer. In dry sourdough prepared by this method, after storage in the cold for 6 months. there are billions of cells in 1 g. Dry cultures are distributed in test tubes containing 1 g of powder. There are a number of ways to increase the potential viability of cells, the most effective of which is microencapsulation. Microencapsulation is understood as the creation of various polymer systems in the form of hydrogel nano- and microparticles, nano- and microcapsules or polymer films with biomaterial. Ionic cross-linking of multivalent cation- and anion-containing polymers, in particular polysaccharides of marine origin, such as chitosan, alginates, carrageenans during encapsulation leads to the formation of gel structures, inside which bacteria are placed.
In addition to increasing the survival of starter cultures in fermented milk products and in the gastrointestinal tract, microencapsulation provides cell protection from bacteriophages, increases survival during drying and freezing, and stability during storage.
Preparation of industrial starter cultures
For the preparation of industrial starter, milk is taken from obviously healthy cows, fresh, with an acidity in the range of 17–19 ° T, clean, with minimal contamination, with a clean pleasant taste, without foreign aftertastes. The sourdough is prepared with whole or skimmed milk. Milk is pasteurized at 95 °C for 30 minutes or sterilized in an autoclave at 120 °C for 20 minutes.
A special VNIIMS starter for the preparation of industrial starter consists of two isolated sections: one contains three tubs with a capacity of 25 liters each and two of 5 liters, in the other section - one for 25 liters and two for 5 liters.
In the starter, you can simultaneously prepare two types of starter cultures according to a given regime, including production, transfer and mother starter cultures for each type.
Industrial starter is also prepared in long-term pasteurization baths (LTP).
To revive a dry culture and obtain an active industrial starter, several successive transplants are made, first preparing the mother (laboratory), then the transfer and finally the production (working) starter. The mother sourdough is prepared in the laboratory. For laboratory starter, it is better to use skimmed milk with an acidity of no more than 19 °T. Milk bottled in 1 liter bottles is sealed with cotton or special caps (in the manufacture of large quantities of laboratory starter, aluminum flasks with a capacity of 5–10 liters are used) and sterilized at 120 ° C for 15–20 minutes, then cooled in the same containers and fermented in strictly aseptic conditions. Fermented milk is kept at a temperature that is optimal for the development of microorganisms included in the starter culture. Then, from the laboratory starter, a transfer starter is prepared, and then a production starter. Sourdough for transplantation is taken in the amount of 3-5%. In production, it is desirable to use the starter only after the third transplant. The finished starter is stored at 4–8 °C (Fig. 2.1).
Rice. 2.1. Characteristics of the types of starter cultures
In the production of starter cultures, significant difficulties sometimes arise due to bacteriophage. Bacteriophages infect the cells of microorganisms used as starter, as a result of which the latter die. The most characteristic sign of the development of a bacteriophage in starter cultures is the cessation of the increase in acidity 2–4 hours after fermentation, during which the normal development of microflora was observed and the acidity increased to 28–30 °T; in this case, partial or complete disappearance of bacterial cells occurs. In the case of a weak infection with a bacteriophage, the fermentation of milk slows down. Among lactic acid cultures there are strains with greater or lesser resistance to phage. As a rule, the bacteriophage is more resistant to high temperatures than the lactic acid bacteria that it infects. The bacteriophage dies when milk is briefly heated to 100 °C; at 90 °C a holding time of 30 minutes is required. An effective way to destroy the bacteriophage is to irradiate the room with ultraviolet lamps. The quality of starter cultures is checked systematically by determining the acid-forming activity by the duration of milk fermentation and by the increase in acidity. The quality of the finished product largely depends on the quality of the starter used. The starter should have a dense homogeneous clot, a pleasant taste and smell, optimal acidity (streptococcal - no more than 80 °T, rod-shaped no more than 100 °T). With increased acidity, the activity of the starter decreases, which increases the duration of milk coagulation and worsens the quality of the finished product. When viewing a microscopic preparation of a starter, only the microbes that make up this starter should be found in it. The presence of foreign microbes in the field of view is not allowed. The contamination of the sourdough with BGKP is most probable.
Starter cultures
Increasingly, fermented milk producers are opting for the concept of direct application cultures ( DVS), recognized throughout the world and widely used due to its significant advantages over the traditional transfer method of preparing industrial sourdough. The expediency of using cultures of direct application is confirmed by many factors, the main of which are simplicity and ease of use, the stability of the ratio between the types and strains of the microorganisms used, the exclusion of the possibility of introducing foreign microflora with starter, the guarantee of the number of active cells, compliance with international standards, the possibility of flexible expansion of the range of products. An important advantage of using DVS-cultures is a lower possibility of phage contamination. Direct application makes it possible to eliminate the stage of preparation of the production starter and the reproduction of bacteriophages in it, as well as significantly reduce the duration of the production cycle and “push back” the adaptation of bacteriophages to starter cultures, which ensures greater safety.
In Russia, in conditions of low quality of raw materials, direct application of crops is of particular relevance.
2.3. Liquid dairy products
Common in the production of all liquid fermented milk products is the fermentation of prepared milk with starters and, if necessary, maturation. The specifics of the production of individual products differ only in the temperature regimes of some operations, the use of starters of different composition and the introduction of fillers. Currently, the range of liquid fermented milk products is very wide and includes more than 200 items.
The list of the main types of fermented milk drinks is presented in Table. 2.1.
Table 2.1
Assortment of fermented milk drinks
According to organoleptic, physicochemical and microbiological indicators, fermented milk drinks must meet certain requirements (Tables 2.2–2.6).
Table 2.2 Physical and chemical parameters of fermented milk drinks
1 Phosphatase is absent.
2 For products formulated with vitamin C.
3 For products formulated with vitamin A.
4 For products manufactured with a multivitamin premix.
5 For products manufactured with cyclocar.
Table 2.3 Physical and chemical parameters of kefir
1 Phosphatase is absent.
2 For kefir produced with vitamin C.
3 For kefir produced with multivitamin premix.
4 For kefir produced with vitamin A.
5 For kefir produced with cyclocar.
Table 2.4 Physical and chemical parameters of yogurt
1 Phosphatase is absent.
2 For drinks made with sugar.
3 For drinks made with aspartame sweetener
Table 2.5
Physical and chemical indicators of fermented milk drinks
Table 2.6
Microbiological indicators of fermented milk drinks
Organoleptic characteristics of liquid fermented milk products
Appearance and texture. Homogeneous consistency with an undisturbed clot with a thermostatic method of production, with a disturbed clot - with a reservoir method. For kefir, gas formation is allowed in the form of separate eyes caused by normal microflora. For drinks prepared on acidophilic cultures, a viscous consistency is characteristic. Koumiss is characterized by a carbonated, foamy consistency with small protein particles, while “Citrus” curdled milk has a slight flouriness. For fruit and berry yogurt - the presence of small particles of fruits and berries. Fruit and berry yogurt, produced by a thermostatic method, should consist of two layers: a filler located at the bottom of the package, and a milk base. For curdled milk produced in a tank method using a stabilizer, it is slightly gelled. For creamy curdled milk produced by a reservoir method, it is a disturbed clot of a homogeneous consistency.
A slight separation of whey on the surface of the clot is allowed: for kefir - no more than 2% of the volume of the product, yogurt and yogurt - 3% of the volume of the product, koumiss - 5%; for ryazhenka - the presence of foam.
Taste and smell. Clean, sour-milk, without foreign tastes and odors. For kefir - a refreshing, slightly spicy taste; for fermented baked milk, Varenets, the drink "Turakh" - a pronounced aftertaste of pasteurization; for koumiss - a yeasty taste. Drinks with fruit and berry fillings are characterized by the taste of the added filler and a sweet taste; for drinks produced with sugar - sweet taste, for ayran - slightly salty taste.
Color. Milky white color. Varents, fermented baked milk, Turakh drink are characterized by a pronounced light cream color, for drinks with fillers - the color of the added filler, uniform throughout the mass. The production of drinking fermented milk products is carried out by tank or thermostatic methods and consists of a number of technological operations that are the same for all types of drinks (Fig. 2.2).
Tank method - a method during which the fermentation of milk and the maturation of fermented milk drinks occurs in tanks with further packaging in consumer containers.
Thermostatic method - a method during which the fermentation of milk and the maturation of drinks is carried out in containers in thermostatic and cold chambers.
In order to reduce production space and reduce labor costs, it is currently mainly used reservoir method .
For the production of fermented milk drinks, milk is suitable not lower than the 2nd grade with an acidity of not more than 19 °T, a density of not less than 1027 kg / m 3;
skimmed milk with an acidity of not more than 20 °T, a density of not less than 1030 kg / m, cream with a mass fraction of fat not more than 30% and an acidity of not more than 16 °T, buttermilk from unsalted sweet cream butter, dry milk and buttermilk. Selected quality milk normalize by mass fraction of fat and solids. If a skim milk starter is used and fermented milk drinks are made with sugar and fat-free fillers, the milk is normalized to a higher fat content. The calculation is carried out according to the formula
Where A- the total amount of added components that do not contain fat.
Rice. 2.2. Technological scheme for the production of fermented milk drinks
When making fortified drinks, vitamins are added to the starter or normalized mixture. cleaning normalized mixture is carried out at a temperature of 43 ± 2 °C. Then her homogenize at a pressure of 15 ± 2.5 MPa and 45–48 °C and pasteurized.
Pasteurization modes depend on the type of drink: temperature 85–87 °C with exposure for 10–15 minutes or at 92 ± 2 °C with exposure for 2–8 minutes; for ryazhenka and varenets, the pasteurization temperature is 95–99 °C with a holding time of 3–5 hours for ryazhenka and 60 ± 20 minutes for varenets. pasteurized mixture cools down to the fermentation temperature characteristic of various types of microorganisms on which fermented milk drinks are prepared and ferments specially selected starter cultures. Sourdough prepared with pasteurized milk is added to the mixture in an amount of 3–5% of the volume of the mixture; sourdough in sterilized milk 1-3%. After fermentation, the mixture is stirred for 15 minutes. The amount of starter can be reduced depending on its activity. Duration ripening, which depends on the type of product and the starter used, is 4–10 hours. The end of fermentation is determined by the formation of a sufficiently strong clot, as well as by acidity, which, depending on the type of product, is 65–90 °T. At the end of fermentation, ice water is first served for 30–60 minutes, and then a clot stir. The duration of mixing depends on the consistency of the clot. When the clot reaches a homogeneous consistency, stop stirring. Further mixing is carried out periodically in order to cool the clot to a predetermined temperature. If necessary, fruit and berry fillers are added to the partially (up to 25–30 °C) or completely (6 °C) chilled curd, the curd is mixed and served on bottling. Before bottling, fermented milk drinks are stirred for 3-5 minutes. Drinks are poured into glass containers, paper bags or plastic film bags. Packaged sour-milk drinks should be produced from the enterprise in a shipping container - wire boxes, plastic boxes, as well as containers or other shipping containers. Sour-milk drinks are transported in refrigerated trucks or cars with an isothermal body. Store drinks at a temperature not exceeding 6 °C.
2.3.1. Kefir
Kefir is a fermented milk product made by mixing(lactic acid and alcohol) fermentation using sourdough prepared on kefir fungi, without the addition of pure cultures of lactic acid microorganisms and yeast.
Kefir is the only fermented milk drink produced in industry on a natural symbiotic sourdough.
Kefir is one of the oldest fermented milk drinks. His homeland is the Caucasus. According to folk legend, kefir was a gift from the prophet Mohammed to the faithful followers of Islam as a drink of luxury, happiness and a symbol of longevity.
At the end of the XIX century. in Russia and neighboring countries began to produce kefir on an industrial scale. Kefir fungi are the basis of kefir production. The substance that maintains the structure of kefir fungi is a branched polysaccharide containing equal amounts of glucose and galactose, commonly called kefiran.
The nutritional and medicinal properties of kefir fungi and kefir have long been known.
These properties are due to:
– rich and diverse microflora of kefir fungi;
- oligo- and polysaccharides synthesized by kefir microflora (prebiotics);
- a large number of metabolites formed during the fermentation of milk by kefir microflora.
The composition of kefir fungi includes several hundred strains of lactic bacteria and yeast (about 30 species) belonging to six different functional groups. Among them there are a number of types of lactic acid bacteria ( L. rhamnosus, L.acidophilus, L.plantarum, L.casei etc.) and yeast, which have generally recognized medicinal properties.
The oligo- and polysaccharides produced by kefir fungi stimulate many of the health-promoting functions of bacteria and yeast in the digestive tract.
The nutritional and medicinal properties of kefir are also due to the huge amount of metabolites formed during fermentation on a quantitative and qualitative scale, which are rarely found in dairy products. Due to the presence of yeast, the main metabolite obtained during the fermentation of milk with the participation of the microflora of kefir fungi is, along with lactic acid, ethyl alcohol. At the same time, lacto-fermenting yeasts of the genus Kluyveromyces. It is with the participation of these yeasts, isolated from kefir fungi, that the production of nisin in bacteria of the genus Lactococcus, alcohol and esters are actively produced. Compared to other dairy products, kefir is richer in B vitamins and folic acid. You should also pay attention to the high content of low molecular nitrogenous compounds (peptides and amino acids).
For many years, kefir has been used in the prevention and treatment of various diseases. Scientific medical studies show that its medicinal properties are based on the probiotic and symbiotic properties of the diverse intestinal microflora.
- for daily consumption in case of digestive disorders;
- improving the work of intestinal motility;
– mitigation of the consequences of excessive consumption of alcoholic beverages;
- increasing the digestibility of milk components (protein, calcium, iron);
- assimilation of lactose in a partially split form into simple types of sugars;
- cholesterol assimilation;
- inhibition of the development of pathogenic intestinal microflora.
In our country, kefir traditionally and deservedly takes pride of place in the diet of people, so this product is included in the range of most producers of fermented milk drinks. The process of lactic-alcohol fermentation, specific for kefir, strongly affects the shelf life of the product and creates significant problems in its implementation. In addition, the process of cultivating kefir fungi is laborious and requires additional costs to ensure the operation of the starter department. It is possible to solve these problems by using lyophilized kefir cultures. The production process of lyophilized kefir cultures is strictly regulated and meets the requirements of quality standards. They are lyophilized granular microflora of kefir fungi.
According to GOST R 52738–2007 “Milk and milk products. Terms and definitions "kefir can be called a product made by fermenting milk with a starter prepared on kefir fungi. Kefir fungus is a natural, microbiologically complex symbiotic starter culture. So far, it has not yet been possible to analyze and isolate in the form of pure cultures all the elements included in it.
Kefir fungi always have a certain structure and behave biologically like a living organism: they grow, divide and pass on their properties and structure to subsequent generations. Therefore, despite repeated attempts, it was not possible to obtain a new kefir fungus with the structure and properties inherent in this organism from a mixture of individual microorganisms that make up the microflora of the kefir fungus. In addition, with all the careful selection of starter cultures, it was not possible to create a symbiosis, the use of which would make it possible to obtain a starter culture with a stable composition of microflora. Sourdough on pure cultures does not have the ability to self-regulate the microflora inherent in kefir fungi. When cultivated under industrial conditions, its composition inevitably changes. Therefore, a fermented milk product made by fermentation not with kefir fungi, but with direct ferments, has an uncharacteristic taste and smell for kefir and can only be attributed to kefir products.
The product fermented by lyophilized kefir cultures has the right to be called "Kefir product". Despite the inconvenience in terminology, the manufacturer, using such a starter, although it loses the real kefir taste in the product, retains its useful properties and receives a number of advantages.
The microflora of kefir starter is relatively undemanding to the quality of milk. In the production of kefir, it is very important to get a good starter from dry kefir fungi. The process of reviving the fungi and obtaining the starter culture is as follows. Dry kefir fungi are allowed to swell in freshly boiled and chilled water for 1–2 days, while changing the water 2–4 times. Then the swollen kefir fungi are transferred to warm skimmed milk, which is replaced daily with new one. The revival of kefir fungi in milk continues until, due to the onset of gas formation and swelling, they begin to float to the surface of the milk. Then the fungi are washed in a sieve with water and poured with milk at the rate of 1 part of the fungi 10 parts of milk. Milk with fungi is kept at 18–20 °C for 12–16 hours, shaken 3–4 times during this time. The resulting sourdough is filtered through a sieve and the grains collected on the sieve are again poured with milk to prepare a new portion of the sourdough. The sourdough should have a thick texture, pleasant taste and smell, slightly foamy.
In the production of kefir, the normalized mixture is pasteurized at 85–87 °C with an exposure of 10–15 minutes, cooled to 20–25 °C and fermented with fungal starter in an amount of 1–3%, production 3–5%. The duration of fermentation is 8–12 hours until the formation of a clot with an acidity of 85–100 °T, the viscosity of the clot is 20–25 s. Supply of ice water for cooling within 60–90 min, the duration of mixing the clot 10–30 min. Cooling down to ripening temperature (14 ± 2.0 °C). The duration of maturation is 9–13 hours. During maturation, alcohol accumulates (0.2–0.6%). Cooling kefir to 6 °C.
2.3.2. curdled milk
Yogurt is a fermented milk product produced using starter microorganisms - lactococci and(or) thermophilic lactic streptococci.
Yogurt has been known since ancient times and is the most common fermented milk product. There are many varieties of it, differing mainly in the composition of the microflora of starter cultures and fermentation modes. Each locality produces its own national types of curdled milk: in Ukraine - ryazhenka, in Armenia - matsun, Georgia - matsoni, Turkmenistan - kuranga, in Northeast Asia - airan, in Tatarstan - katyk, etc. A number of drinks are also produced by type curdled milk (Table 2.7).
Table 2.7
The main indicators of the production of curdled milk
In all types of yogurt, varieties of thermophilic milk sticks, mainly Bulgarian, prevail, in acidophilic yogurt, acidophilus bacillus is additionally, but the drink can also be made on one lactic streptococcus (common yogurt, varenets), and yeast prevails in southern yogurt.
Ordinary curdled milk– fermented milk product made from pasteurized milk by fermenting it with a starter containing only pure cultures of lactic acid streptococcus. Fermentation temperature 30–35 °C. Ordinary curdled milk has a very dense, prickly clot and a somewhat bland taste.
Mechnikov yogurt It is produced from pasteurized milk, which is fermented with cultures of lactic acid streptococcus with the addition of a culture of Bulgarian sticks. The fermentation temperature is about 40–45 °C. The acidity of the finished curdled milk is 80–110 °T. The product has a slightly pronounced spicy taste and delicate texture. The clot is moderately dense, without gas bubbles and without released serum.
Southern curdled milk prepared by fermenting pasteurized milk with pure cultures of bulgaric acid and thermophilic lactic streptococci, with or without the addition of pure cultures of lactic yeast. Southern curdled milk is produced at elevated fermentation temperatures of 45–50 °C. The finished product has a sour taste and a very delicate creamy texture. The acidity of southern curdled milk is 90–140 °T. The temperature during implementation should not exceed 8 °C.
Acidophilic curdled milk It is produced from milk using a starter, which includes pure cultures of lactic streptococcus and acidophilus bacillus. Fermentation temperature 40–45 °C. Acidophilic yogurt may have a slightly viscous clot if the mucous races of acidophilus bacilli are used for fermentation. The acidity of the finished product is 110–140 °T.
Ryazhenka(Ukrainian curdled milk) prepared from milk, normalized by the addition of cream. Milk is kept at a temperature of 92-98 ° C for 3-4 hours in order to give it the taste and color of baked milk. Fermentation temperature 40–45 °C. The composition of the starter includes thermophilic races of lactic acid streptococcus. Ryazhenka has a pure sour-milk taste with a pronounced aftertaste of pasteurization and a gentle, moderately dense clot, without gas bubbles. The color of the product is creamy with a brownish tinge. Acidity 80–110 °T.
Varenets prepared from milk subjected to the same heat treatment as in the production of fermented baked milk. The composition of the sourdough includes lactic acid streptococcus and Bulgarian stick.
Turah– fermented milk product prepared in Chuvashia. Whole milk with a fat content of about 4.0% is heated to 95-98 ° C and kept at this temperature for 3-4 hours until brown. Then it is cooled to 27-30 ° C and 5% of the starter is added, consisting of a mixture of lactic streptococci and acidophilus bacillus in a ratio of 10: 1. Fermentation continues for 12–14 hours. The resulting product resembles ryazhenka or varenets, but has a more viscous consistency. Its acidity is up to 120 °T.
Ayran - fermented milk drink of the peoples of the North Caucasus, reminiscent of kefir, but has its own characteristics. It is produced from whole and skimmed milk - cow, sheep or goat. The sourdough includes mainly lactic acid bacilli, including Bulgarian, in a smaller amount - lactic acid streptococci and yeast. Alcoholic fermentation in ayran is insignificant, and only traces of alcohol are found in the finished product. Ayran fermentation temperature: in summer - 20-25 °C, in winter - 25-35 °C. Ripening temperature - 6-8 ° C, ripening time - one day. Ayran has a delicate, delicate sour-milk taste and aroma. Consistency with small flakes of casein. Alcohol content 0.1%. Aged ayran can have up to 0.6% alcohol. Acidity 100–150 °T. With some modification of the output, salt is added at the end of fermentation, and the clot is mixed until a homogeneous consistency. Bottles with a capacity of 0.5 liters are half filled with a salted clot and topped up with boiled and cooled to 10 ° C drinking water, pre-carbonated. The bottles are corked. The product is put on ripening at a temperature of 6-10 ° C during the day. Ayran is stored at this temperature until consumed. In this case, the product is a lightly salted carbonated drink with a slight smell of yeast. The salt content in the product is 1.5–2.0%.
Yogurt traditionally produced from goat, sheep or buffalo milk, the content of solids and fat in which is much higher than in cow's. When making yogurt from cow's milk, it is pre-condensed or cream is added, whole or skimmed milk powder, spray dried, solids in milk should be at least 14-16%. The composition of the sourdough includes pure cultures of thermophilic streptococcus, Bulgarian stick. Fermentation temperature 40–42 °C. Currently, low-fat yogurt is also being produced: 1.5; 2.5; 3.2; 3.5%, with or without added skimmed milk powder, added sugar, food flavors, fruit fillers, etc.
The milk selected for the production of yogurt is normalized in terms of fat and skimmed milk powder is introduced at its temperature of 35–40 ° C, the mixture of the stabilizer with sugar and after some holding for swelling is homogenized at 50–85 ° C and a pressure of 15 ± 2 MPa, and then pasteurized at 92 ± 2 °C with a holding time of 10–15 min. Then the mixture is cooled to the fermentation temperature and the ferment is added in the amount of 3-5%. Reservoir fermentation is carried out until the clot reaches an acidity of 85–90 °T. The duration of fermentation is 3-4 hours. Then the clot is cooled with periodic stirring to 20-25 ° C and fruit fillers are added. The clot with fruit fillings is subjected to heat treatment at 65–72 °C, after which the product is sent for bottling, and then to the refrigerator, where it is cooled to 6 ± 2 °C.
Matsoni(matsun) - fermented milk product, widespread in Transcaucasia. It is made from cow, buffalo or sheep milk. The composition of the sourdough includes lactic acid bacilli, close to Bulgarian, streptococci (mostly thermophilic, i.e. heat-loving cultures) and lactic yeast. As a starter, a good matsun of the previous day of production is usually used in the amount of 3-5% of the fermented milk. Fermentation temperature 42–45 °C. Duration 3–5 hours. After fermentation, matsun is transferred to a cold room, where the temperature is maintained at 6–10 °C. Ripening lasts 18–24 hours. A good matsun should be of a dense texture (the denser it is, the more appreciated), it is characterized by a pleasant spicy taste and a characteristic aroma. It contains up to 0.3% alcohol, the acidity of matsun from sheep and buffalo milk is 120-150 °T, and from cow's - 80-105 °T. The local population prepares for the future matsun, separated by filtration from whey (matsun paste), and stores it in this form for the winter.
curanga– a product very common among the Buryats, Mongols, Khakasses, Tuvans, etc. It is prepared from whole or skimmed milk by adding a combined bacterial starter. The starter includes lactic streptococcus - 10%, lactic acid bacilli (acidophilic) - 80%, yeast - 10%. Fermentation is carried out at a temperature of 25–30 °C, alcoholic fermentation at 6–10 °C. In the process of fermentation and maturation, the milk is periodically mixed. The product, by its nature, is very close to kefir, but differs in a more liquid consistency, a higher content of lactic acid and alcohol. Kurunga contains 1-2% alcohol, has a pleasant sour-milk yeast taste and smell, a uniform texture with finely divided protein and fat. Kurunga is sometimes considered koumiss made from cow's milk. Kurung contains a lot of vitamins A and group B - 1.5 times more than in koumiss, but 2 times less than vitamin C. The product has well-pronounced antibiotic properties in relation to saprophytic microorganisms, inhibits the growth of micrococci, spore-forming and intestinal bacteria. sticks.
Drink "Southern» produced by the tank method. It belongs to the type of curdled milk, has a creamy consistency, is made on the same leaven and the same fermentation technological regime as yogurt. Upon reaching the acidity of 75–80 °T, the clot is cooled with stirring. To obtain a thicker product, cooling and mixing of the clot begins at an acidity of 85–90 °T. The acidity of the finished drink should be 90–120 °T. Packing is carried out at 20 °C, subsequent cooling is carried out in a refrigerator to 8 °C. If the drink is cooled in a flow, then the clot from the tank is fed by a pump for viscous liquids to a tubular cooler or plate installation, where it is cooled to 6 ° C and then sent through an intermediate container for packaging.
Drink "Snowball"» – sweet fruit fermented milk drink, produced by the reservoir method like yogurt, on the starter of thermophilic streptococcus and bulgarian stick. The consistency of the drink should be slightly viscous and dense. The drink acquires an attractive appearance if two or three varieties of fruit and berry drink mixed with sweet are poured into one container in layers. Packing should be done in a wide-mouth container after cooling and so that the layers do not mix.
Drink "Russian» are produced from a mixture of normalized milk and sodium caseinate with or without the addition of fruit and berry syrups by fermentation with lactic acid streptococci. The mixture is homogenized and pasteurized under the regimes adopted for fermented milk drinks. Fermentation is carried out at a temperature of 37 °C for 4–6 hours. The acidity of the finished product is 80–120 °T.
2.3.3. Acidophilic sour milk drinks
Acidophilic drinks have the highest preventive and therapeutic properties. For their production, starter cultures are used, prepared in whole or in part on pure cultures of acidophilus bacilli. They are produced by both reservoir and thermostatic methods.
acidophilus milk obtained by fermentation of pasteurized milk at a temperature of 38–42 ° C for 3–4 hours. For fermentation, ferment is used on an acidophilus bacillus of mucous and non-mucous races in a ratio of 1: 4, which can be changed depending on the desired consistency and taste. The product can also be produced with fillers (sugar, vanillin, etc.). The consistency of the product is homogeneous, reminiscent of sour cream, slightly viscous. Acidity is in the range of 80–130 °T, but the drink has the most pleasant taste at an acidity of 110–115 °T, a further increase in acidity can lead to a metallic taste. Sugar in a sweet drink should not be less than 5%.
acidophilus It is produced on a leaven consisting of pure cultures of acidophilus bacillus, lactic acid streptococcus and kefir starter in equal quantities. Fermentation is carried out at 30–35 °C for 6–8 hours. Depending on the fermentation temperature, the product acquires the taste of kefir, acidophilic milk or curdled milk.
The product is produced by thermostatic and reservoir methods, fermented to a clot acidity of 80 °T. Acidity 75–130 °T, the most pronounced taste at an acidity of 100–110 °T.
acidophilic yeast milk is made on a combined sourdough, consisting of acidophilus bacillus and lactic yeast. Due to this, the product has the most valuable dietary and medicinal properties, bactericidal action against tubercle bacillus, staphylococci, pathogens of dysentery and typhoid. Consumption of the product improves appetite, promotes the absorption of other substances from food. The antibiotic properties of acidophilus bacillus and yeast are enhanced by co-cultivation. The drink has a pleasant, refreshing, slightly spicy sour-milk taste with a yeasty aftertaste. Its consistency is homogeneous, fairly dense, of low viscosity, slightly viscous. Slight gassing and foaming caused by yeast development is acceptable. Mass fraction of fat in the finished product 3.2%, acidity 80–120 °T. For baby food, 7% sugar is added to the product.
Pasteurized milk is fermented at 30–34 °C for 4–6 hours. The finished clot is cooled to 10–17 °C and kept for at least 6 hours for yeast development, alcohol and carbon dioxide formation. The product is then sent to a cold store at 6–8 °C, where it is stored until sold.
Drink "Moscow» according to the technology it is similar to acidophilic milk, it is produced with an increased mass fraction of SOMO (12%) and a reduced fat content (1%). It can be produced with 6% sugar and with fruit and berry syrup.
2.3.4. Drinks with bifidoflora
Currently, sour-milk drinks enriched with bifidobacteria are widely used. When using bifidoflora in the production of kefir, products such as "Bifidokefir", "Bifidok" are produced; yogurt - "Bioyogurt", fermented baked milk - "Bioryazhenka", "Bifidoryazhenka"; acidophilic drinks - "Bifilife", etc. The technological process of production and recipes of the above products are similar to the technology and recipes of the corresponding drinks and differ only in the composition of the microflora. Fermented milk drinks with bifidobacteria, which are normal intestinal microflora, have biological value and therapeutic properties. Bifidobacteria contained in fermented milk drinks have a protective effect and inhibit the development of many pathogenic microbes. Therefore, fermented milk drinks with bifidobacteria are an effective tool in the fight against intestinal dysbacteriosis. In particular, in our country, a method has been developed for preparing an active starter on a strain of one of the bifidobacteria species obtained from the intestinal microflora of an infant. This strain exhibits great antibiotic activity and is used for the preparation of medicinal fermented milk products, in particular, for the production of fermented milk mixture "Bifilin" for feeding infants and dry fermented milk product "Bifidin", recommended for normalizing the microflora of the human intestinal tract.
Fermented milk drinks prepared using a combined starter of pure cultures of bifidobacteria, Bulgarian bacillus and fungal kefir have high antibiotic properties. The starter components are cultivated separately at optimal development temperatures. With the use of a combined starter, new products for baby and diet food are created. Based on the use of bifidobacteria, technologies have been developed for such products as "Bifivit" (on sterilized milk or pasteurized at 95 ° C with an exposure of 30 minutes); "Bifidok", which is kefir enriched with bifidobacteria (produced with a fat content of 2.5%, protein - 2.9% and carbohydrates - 3.3%); “Sour-milk bifidumbacterin” (produced with a content of 10 9–10 10 in 1 cm 3 of living cells of bifidobacteria using a special starter and is recommended as a medical food product; “Bifilife” and others. “Bifilife” is produced by fermenting milk with a symbiotic starter of bifidobacteria of the full species composition with the inclusion of thermophilic streptococcus.Unlike other bioproducts enriched with only one or two strains of bifidobacteria, the fermented milk product "Bifidobacteria" is fermented by five strains.Moreover, this combination of bifidobacteria develops in milk more actively than a monoculture of each species, which is of great practical importance both for manufacturers, as it allows to speed up the technological process, and for consumers, since the activity of these bifidobacteria in the intestine is higher than the activity of each individual species.
During the production process, the normalized product mixture is pasteurized at a temperature of 95 ± 2 °C with a holding time of 2 to 40 minutes or sterilized by ultra-high temperature processing. The fermentation temperature of the normalized mixture is 39 ± 2 °C. The fermentation time of the product is 5-6 hours.
Depending on the fat content and the addition of fruit and berry fillers, "Bifilife" is produced without additives, fruit and berry and flavored. In all cases - fat content 3.2; 2.5; 1.0% and non-greasy.
2.3.5. Kumys
Kumis is a fermented milk product produced by mixed(lactic acid and alcohol) fermentation and fermentation of mare's milk using starter microorganisms - Bulgarian and acidophilic lactobacillus and yeast.
Kumis has long been known among the nomadic peoples of Russia for its medicinal properties.
Of all fermented milk drinks, koumiss has the most valuable dietary and pronounced therapeutic properties. The lactic acid, alcohol and carbon dioxide contained in it, acting on the stomach and pancreas, stimulate the secretion of digestive juices, cause peristalsis of the stomach and intestines. Koumiss proteins, which are in a partially peptonized and finely dispersed state, are easily absorbed and digested. In koumiss, the microflora produces the antibiotic nisin, synthesizes vitamins of group B, and several times more than in cow's milk, vitamin C. Kumis heals the digestive tract, raises the tone of the body, normalizes ESR, increases the content of hemoglobin in the blood, inhibits the development of tubercle bacillus, promotes healing upper respiratory tract, chronic bronchitis and pneumonia. Compared to cow's milk, mare's milk contains significantly more milk sugar, less fat and protein, while casein and albumin are in equal amounts. Therefore, when fermenting, mare's milk protein does not form a clot, but falls out in the form of loose, small, almost imperceptible flakes that do not form sediment, the product remains a liquid consistency.
To ferment milk, a special koumiss sourdough is used, which includes lactic acid sticks, a small amount of streptococci and lactic yeast. The production of koumiss very often has a pronounced seasonal character (3–5 months a year), so koumiss of the previous year is usually the material for starter culture. Kazakhs and Kirghiz keep it for years, leaving washed and dried koumiss sediment in autumn, in which microorganisms do not lose their viability until the next koumiss season. The Bashkirs usually prepare a new starter in the spring, using katyk (sour cow's milk) for this purpose. Specially prepared katyk is methodically diluted 1:1 with raw mare's milk (perekured) for several days. In parallel with the increase in the proportion of mare's milk, the microflora of the mixture is rearranged. Ready leaven is considered when koumiss fermentation has developed well, and katyk microflora has been replaced by koumiss. Koumiss microflora is a specific microflora grown on raw mare's milk under certain conditions of temperature and aeration. The acidity of such a starter is 150–160 °T. For the production of koumiss from mare's milk, fresh milk from healthy mares is used. It should be clean, without foreign tastes and odors, acidity not higher than 7 °T. Starter is added to fresh milk in an amount of 15-30%, thoroughly mixed for 15 minutes and kept for 3-5 hours at a temperature of 25-28 ° C for the development of lactic acid fermentation. When the acidity rises to 65-70 °T, the fermented milk is kneaded for 1 hour and bottled, tightly closed with corks. Bottles with koumiss are placed in a refrigerator at 6-10 ° C for the development of alcoholic fermentation (ripening). Depending on the duration of maturation, koumiss is divided into weak, which ripens in 1 day, medium -2 and strong - 3 days. Kumis has a peculiar sour taste and smell, liquid consistency. The color is milky white with a bluish tinge. The acidity of weak koumiss is 70-80 °T, medium - 81-100 °T, strong - 101-120 °T; alcohol contains respectively 1.0; 1.5 and 2.5–3%.
Where little or no mare's milk is produced, it is quite possible to organize the production of koumiss from cow's milk ( koumiss product). The use of cow's milk for the production of koumiss has a great advantage: it is several times cheaper than mare, and it is obtained in all areas of the country throughout the year.
Koumiss product is a fermented milk product made from cow's milk in accordance with the koumiss production technology..
Koumiss from cow's milk is obtained from pasteurized cow's milk, in which up to 5% sugar is added beforehand. The leaven is added in the amount of 10%. The composition of the sourdough includes lactic acid sticks and lactic yeast. Fermentation temperature 26–28 °C. With constant stirring, the product is fermented for about 5 hours to an acidity of 85–90 °T. The duration of ripening at 16–18 °C is 1.5–2 hours. During maturation, stirring is carried out every 15–20 minutes. The acidity of the finished koumiss from cow's milk is 100–150 °T. In a three-day koumiss, alcohol accumulates up to 1%. The technology for making koumiss from skimmed cow's milk can be as follows. 20% whey and 3% sugar are added to fresh skimmed cow's milk in the form of syrup. The mixture is pasteurized at a temperature of 92–95 °C, kept for 20 minutes, cooled to 30 °C and fermented with a pre-prepared combined starter. Koumiss from cow's milk is prepared on a culture isolated from koumiss made from mare's milk. The composition of the sourdough includes a mixture of yeast and Bulgarian sticks. Fermented milk is in long-term pasteurization baths (LTP) until complete fermentation, while it is constantly stirred. When a clot is obtained, the product is cooled to 16–18 °C and kept at this temperature for 15–20 hours. Then the product is bottled, hermetically sealed with corks and stored at a temperature of 4–6 °C. Before use, the bottle with koumiss must be shaken. Weak koumiss should have an acidity of 100-120 °T, medium -120-140 and strong - 140-150 °T, the mass fraction of alcohol, respectively, 0.1-0.3; 0.2–04; 1 %.
2.4. Defects of liquid fermented milk products
The defects of fermented milk drinks and measures for their prevention are presented in Table. 2.8.
Table 2.8
Vices and measures to prevent them
2.5. Cottage cheese and products from it
Cottage cheese is a fermented milk product produced using starter microorganisms - lactococci or a mixture of lactococci and thermophilic lactic streptococci and by the method of acid or acid-rennet coagulation of proteins, followed by the removal of whey by self-pressing, pressing, centrifugation and(or) ultrafiltration.
The high nutritional and biological value of cottage cheese is due to the significant content of not only fat, but also proteins that are especially complete in amino acid composition, which makes it possible to use cottage cheese for the prevention and treatment of certain diseases of the liver, kidneys, and atherosclerosis. Curd contains a significant amount of Ca, P, Fe, Mg and other minerals necessary for the normal functioning of the heart, central nervous system, brain, for bone formation and metabolism in the body. Particularly important are the Ca and P salts, which are in the curd in the most convenient state for assimilation.
In addition to direct consumption, cottage cheese is used to prepare various dishes, culinary products and a wide range of curd products. The list of the main types of cottage cheese with an indication of the mass fraction of dry substances is presented in Table. 2.9.
Table 2.9
Assortment of cottage cheese
According to organoleptic, physicochemical and microbiological indicators, cottage cheese and curd products must meet certain requirements (Table 2.10–2.12).
Table 2.10
Physical and chemical indicators of cottage cheese
Table 2.11
Organoleptic characteristics of cottage cheese
Table 2.12
Microbiological indicators of cottage cheese
Depending on the mass fraction of fat, cottage cheese is divided into:
- for fat-free (no more than 1.8% F);
- non-fat (at least 2.0; 3.0; 3.8% F);
- classic (not less than 4.0; 5.0; 7.0; 9.0; 12.0; 15.0; 18.0% F);
- fatty (not less than 19.0; 20.0; 23.0% F).
According to the method of clot formation, two methods for the production of cottage cheese are distinguished: acid rennet And acid.
acid method. It is based only on the acid coagulation of proteins by fermenting milk with lactic acid bacteria, followed by heating the clot to remove excess whey. In this way, low-fat and low-fat cottage cheese is produced, since when the clot is heated, significant fat losses occur in the whey. In addition, this method ensures the production of low-fat cottage cheese with a more delicate texture. The spatial structure of clots of acid coagulation of proteins is less strong, is formed by weak bonds between small particles of casein, and releases whey worse. Therefore, to intensify the separation of whey, heating of the clot is required.
At rennet-acid method coagulation of milk clot is formed by the combined action of rennet and lactic acid. Casein, when converted to paracasein, shifts the isoelectric point from pH 4.6 to 5.2. Therefore, the formation of a clot under the action of rennet is faster at lower acidity than when proteins are precipitated by lactic acid; the resulting clot has a lower acidity, the technological process is accelerated by 2–4 hours. During rennet-acid coagulation, calcium bridges formed between large particles provide high clot strength. Such clots are better at separating whey than acidic ones, since the compaction of the spatial structure of the protein occurs faster in them. Therefore, heating of the clot to intensify the separation of whey is not required at all, or the heating temperature is reduced.
The rennet-acid method is used to produce fatty and semi-fat cottage cheese, which reduces the waste of fat into whey. With acid coagulation, calcium salts go into the serum, and with rennet, they remain in the clot. This must be taken into account when producing cottage cheese for children who need Ca for bone formation.
In the production of cottage cheese, the raw materials used are milk harvested not lower than the 2nd grade, powdered spray-dried milk of the highest grade, skimmed milk with an acidity of not more than 21 °T, cream with a fat content of 50–55% and an acidity of not more than 12 °T, cream plastic, meeting the requirements of regulatory documentation.
There are two ways to produce cottage cheese (Figure 2.3):
– traditional- from normalized milk;
– separated- from skimmed milk, followed by enrichment of skimmed cottage cheese with cream.
Rice. 2.3. Methods for the production of cottage cheese
2.5.1. Production of cottage cheese in the traditional way
Depending on the equipment used, there are several options for the production of cottage cheese in the traditional way (from normalized milk).
The usual way(V pouches) (Fig. 2.4)
Rice. 2.4. Technological scheme for the production of cottage cheese in the usual way (in bags)
When producing cottage cheese in the usual way, milk is fermented in special baths VK-1 or VK-2.5.
The prepared milk is normalized in order to establish the correct ratio between the mass fractions of fat and protein in the normalized mixture, which ensures that the product is standard in terms of the mass fraction of fat and moisture. Normalization is carried out taking into account the actual mass fraction of protein in the processed raw materials and the normalization coefficient, which is set in relation to the type of cottage cheese, specific production conditions, methods of producing cottage cheese. In order to correctly establish the normalization coefficient, quarterly control production of cottage cheese is carried out. Normalized milk is sent for pasteurization at 78–80 °C with a holding time of 10–20 s. Pasteurized and cooled to a temperature of 4 ± 2 °C, milk can be stored for no more than 6 hours before being processed into cottage cheese. For optimal conditions for the development of lactic acid microflora, milk is fermented with pure cultures of mesophilic lactic streptococci at a milk temperature of 30 ± 2 °C in cold weather years and 28 ± 2 ° C - in warm. With the accelerated fermentation method, a symbiotic ferment is used, prepared on pure cultures of mesophilic and thermophilic streptococci at a milk fermentation temperature of 32 ± 2 °C.
With the rennet-acid method of producing cottage cheese, in addition to the starter culture, calcium chloride and milk-clotting enzymes are added to milk. CaCl is added at the rate of 400 g of anhydrous CaCl per 1000 kg of milk in the form of a solution with a mass fraction of CaCl of 30–40%. After that, rennet powder or pepsin or the enzyme preparation VNIIMS is introduced into the milk in the form of a solution with a mass fraction of the enzyme not more than 1%. The dose of an enzyme with an activity of 100,000 IU per 1000 kg of fermented milk is 1 g. Rennet powder or the VNIIMS enzyme preparation is dissolved in drinking water preheated to 36 ± 3 °C, and pepsin is dissolved in fresh filtered whey at 36 ± 3 °C. After fermentation, the milk is stirred for 10–15 minutes and left alone until a clot forms. With the acid-butter method, milk is fermented until a clot is obtained with an acidity of 60–65 (±5) °T, depending on the type of cottage cheese. The higher the fat content of the curd, the lower the acidity of the clot. The duration of milk fermentation is 6–10 hours. With the acid method, milk is fermented until a clot with an acidity of 75–80 (±5) °T is obtained. The duration of fermentation of milk is 8–12 hours. It is important to correctly determine the end of fermentation, since with an under-fermented clot, sour curd of a smeared consistency is obtained. The clot is cut with wire knives into cubes measuring 2 x 2 x 2 cm. First, the clot is cut along the length of the bath into horizontal layers, then along the width into vertical ones. The clot is left alone for 30-60 minutes to isolate the serum. To intensify the release of whey, the clot is heated in the acid method to a whey temperature of 40–44 (± 2) °C, depending on the type of cottage cheese. The higher the fat content of the curd, the higher the heating temperature. With the rennet-acid method, the clot heating temperatures are reduced and amount to 36–40 (± 2) °С. The clot is kept at these temperatures for 15–40 min.
The released serum is released from the bath through a fitting and collected in a separate container. The clot is poured into calico or lavsan bags measuring 40 x 80 cm, 7–9 kg each, the bags are filled to three quarters of the volume. They are tied and placed in several rows in a press trolley. Under the influence of its own mass, serum is released from the clot. Self-pressing takes place in the workshop at a temperature of no more than 16 °C and lasts at least 1 hour. The end of self-pressing is determined visually, by the surface of the clot, which loses its luster and becomes matte. Then the curd is pressed under pressure until tender. In the process of pressing, the bags with cottage cheese are shaken several times and shifted. In order to avoid an increase in acidity, pressing should be carried out in rooms with an air temperature of 3-6 ° C, and after it is completed, immediately send the curd for cooling to 12 ± 3 ° C using coolers of various designs or in bags, in trolleys in a refrigerator. The finished product is packaged in small (consumer) and large (transport) containers. Cottage cheese is stored until sale for no more than 36 hours at a temperature of no more than 4 ° C and a humidity of 80-85%, including at the manufacturer for no more than 18 hours.
At curd makers with a pressing bath
Curd makers with a pressing bath (TI-4000) are used to produce all types of curd, while the laborious process of pressing curd in bags is excluded.
The cottage cheese maker consists of two double-walled bathtubs with a capacity of 2000 liters with a crane for draining whey and a hatch for unloading cottage cheese. Pressing baths with perforated walls are fixed above the baths, on which the filter cloth is stretched. The pressing vat can be hydraulically raised or lowered almost to the bottom of the fermentation vat.
Properly prepared milk enters the baths. Here, sourdough, solutions of calcium chloride and rennet are added to it, and, just as in the usual way of producing cottage cheese, they are left for fermentation. The finished clot is cut with knives included in the kit of the curd manufacturer and kept for 30-40 minutes. During this time, a significant amount of serum is released, which is removed from the bath with a sampler (a perforated cylinder covered with a filter cloth). In its lower part there is a pipe that slides into the pipe of the bath. The separated whey through the filter cloth and the perforated surface enters the sampler and exits the bath through the nozzle. This pre-removal of whey increases the efficiency of curd pressing.
For pressing, the perforated bath is quickly lowered down until it comes into contact with the surface of the clot. The speed of immersion of the pressing bath into the clot is set depending on its quality and the type of curd produced. The separated whey passes through the filter cloth into the perforated surface and is collected inside the pressing bath, from where it is pumped out every 15–20 min.
The downward movement of the pressing bath is stopped by the lower limit switch, when a space remains between the surfaces of the baths, filled with pressed curd. This distance is established during experimental workings of cottage cheese. Depending on the type of cottage cheese being produced, the duration of pressing is 3-4 hours for fatty cottage cheese, 2-3 hours for semi-fat, 1-1.5 for low-fat. With the accelerated fermentation method, the duration of pressing fatty and semi-fat cottage cheese is reduced by 1–1.5 hours.
At the end of the pressing, the perforated tub is lifted, and the curd is unloaded through the hatch into the carts. The trolley with cottage cheese is lifted up and overturned over the cooler bunker, from where the cooled cottage cheese is supplied for packaging.
On mechanized lines using mesh baths (Fig. 2.5)
Rice. 2.5. Production of cottage cheese on mechanized lines using mesh baths
In this technology there is no such operation as pressing curd. Therefore, in order to create conditions for a more efficient whey separation, the temperature and other parameters in this case differ from the traditional ones. Prepared milk is fermented with sourdough at a temperature of 28–32 ° C in the cold season and 26–30 ° C in the warm season; with the accelerated fermentation method, a symbiotic ferment of mesophilic and thermophilic streptococci is used and fermented at 30–34 ° C. The amount of starter is 3-5% of the amount of fermented milk.
The end of milk fermentation is considered to be the formation of a moderately dense clot with an acidity of 70–95 °T, depending on the type of cottage cheese. The fatter the curd, the lower the acidity of the clot. The duration of fermentation is 5–12 hours. To speed up the separation of whey, the finished clot is slowly heated by introducing steam or hot water into the interstitial space of the bath. The optimal clot heating temperature (according to whey) is 45–50 (±10) °C. The heated clot is kept for 20–30 min and stirred 3–5 times during the holding period. The total duration of heating, including the holding time, should not exceed 2 hours. The heated curd is cooled by at least 10 °C by supplying cold or ice water.
The separation of whey from the clot on lines with mesh baths complete with VK-2.5 baths is carried out by removing whey (no more than two-thirds of the total mass) through the drain valve of the bath. To separate the remaining whey, the grid bath is raised above the bath with the help of a telpher device. In this case, the whey flows into the bath, and the curd is subjected to self-pressing. The duration of serum separation from the clot is 10–40 min. The separation of whey from the clot on lines with a set of equipment YA2-OVV is carried out as follows: part of the released whey (no more than 2/3 of the total mass) is removed through a whey drain valve. The remaining whey, together with the clot, is carefully poured along the tray into a mesh bath located in a self-propelled cart. To separate the whey from the clot, the grid bath is lifted above the trolley with the help of a traverse. In this case, the whey flows into the bath, and the curd is subjected to self-pressing (10-40 minutes). The subsequent cooling of the curd is carried out by immersing the mesh bath with curd into the cooled whey and keeping it in it for 20-30 minutes. The curd is cooled to 13 ± 5 °C. As a cooling medium, fresh curd whey, pasteurized, cooled to a temperature of not more than 5 ° C is used. Duration of storage of whey at a temperature not exceeding 8 ° C 1 day. After cooling 2 bath-grids with cottage cheese, the cooling medium is replaced with a fresh one. To separate the whey, the mesh bath is lifted above the bath with the help of a hoist device. In this case, the whey flows into the bath, and the curd is subjected to self-pressing. The duration of the separation of the cooling medium from the curd is 20–30 minutes. The curd is unloaded into the accumulator bath with the help of a tilting device and fed to the packaging by the auger.
On mechanized lines Ya9-OPT-2.5 and Ya9-OPT-5
The Ya9-OPT-5 mechanized line with a milk capacity of 5000 l/h is the most advanced and is used to produce classic cottage cheese. The finished clot is mixed for 2–5 min and is fed by a screw pump to a once-through heater with a jacket. Here, the clot is quickly (2–5 min) heated to a temperature of 42–54 °C (depending on the type of cottage cheese) by supplying hot water (70–90 °C) to the jacket. The heated clot is cooled in a cooler with water to 25–40 °C and sent to a two-cylinder dehydrator covered with a filter cloth. The moisture content in the finished curd is regulated by changing the angle of inclination of the dehydrator drum or changing the heating and cooling temperature of the curd.
Ready cottage cheese is sent for packaging and then to the refrigerating chamber for additional cooling.
2.5.2. Separate method for the production of cottage cheese
The separate method has a number of advantages. Significantly reduced fat loss in production; saving fat per 1 ton of fat cottage cheese is 13.2, bold - 14.2 kg. The separation of whey from the clot is facilitated, a greater possibility of mechanization of technological operations is created, as a result of which labor productivity increases. The quality of cottage cheese increases as a result of a decrease in acidity. This is facilitated by the addition of fresh pasteurized cream to low-fat cottage cheese, the acidity of which is almost 20 times less than the acidity of cottage cheese, and at the same time, chilled cream reduces the temperature of the cottage cheese, which prevents a further increase in the acidity of the finished product.
The production of cottage cheese from skimmed milk can be carried out on any available equipment, including cottage cheese separator, with further mixing it with cream (Fig. 2.6).
With this method of production, milk intended for the production of cottage cheese, after being heated to a temperature of 40–45 ° C, is sent for separation to obtain cream with a fat content of at least 50–55%, which is then pasteurized at a temperature of at least 90 ° C, cooled to 2 -4 °C and sent for temporary storage.
Rice. 2.6. Technological scheme for the production of cottage cheese in a separate way
The resulting skimmed milk is subjected to the usual preparation for curdling, as mentioned above, namely: pasteurization at 78–80 °C for up to 20 seconds, cooling to a fermentation temperature of 30–34 °C, and sent to a fermentation tank with a special stirrer. It also serves sourdough, calcium chloride, milk-clotting enzyme. The mixture is thoroughly mixed and left for fermentation until the acidity of the clot is 90–100 °C, since during the subsequent separation of the clot into curd and whey in a special separator-curd separator, the nozzles of this separator may become clogged if the clot has a lower acidity.
In order for the curd clot to be better separated into the protein part and whey, after thorough mixing, it is fed by a special pump into a plate heat exchanger, where it is first heated to 60-62 ° C, and then cooled to 28-32 ° C and sent under pressure already to separator-cottage cheese manufacturer, where it is divided into whey and cottage cheese.
In the production of fatty cottage cheese by dehydration, separation is carried out to a mass fraction of moisture in the clot of 75–76%, and in the production of semi-fat cottage cheese - up to 78–79%. The resulting curd mass is cooled on a plate cooler for cottage cheese to 8 ° C and sent to the mixer, where pasteurized chilled cream (50–55% fat content) is fed by a dosing pump, and everything is thoroughly mixed.
The finished cottage cheese is packed on automatic machines and sent to the storage chamber.
Cottage cheese grained with cream
Cottage cheese is a crumbly dairy product made from cottage cheese raw materials with the addition of cream and table salt. Heat treatment of the finished product and the addition of consistency stabilizers is not allowed.
End of introductory segment.
Loading...
