Fermented milk products are prepared from whole or skim milk, in which, under the influence of pure cultures, lactic acid microorganisms cause lactic acid or simultaneously (depending on the type of product obtained) lactic acid and alcohol fermentation. Products of lactic acid fermentation include yogurt, acidophilus and acidophilus milk, sour cream, cottage cheese, and products of lactic and alcohol fermentation include kefir and kumiss. Under the influence of lactic acid microorganisms (Str. lactis, B. bulgaricum, etc.), lactose decomposes to form lactic acid, which, in turn, acting on calcium caseinate (caseinogen), removes calcium from the latter and replaces it with hydrogen, resulting in the formation of a clot .
Bacillus acidophilus has a better survival rate in the large intestine than other lactic acid bacteria. With its help, acidophilus and acidophilus milk are prepared. It is known that acidophilus bacillus, lactic yeast and some lactic acid streptococci are capable of producing antibiotic substances that have a detrimental effect on the causative agents of typhoid fever, dysentery, and tuberculosis. With the development of lactic acid bacteria in milk, the antibiotics diplococcin, streptocin, lactolin, etc. were isolated. Under the influence of lactic acid microorganisms and milk yeast, lactose decomposes with the formation of lactic acid, but at the same time, under the influence of milk yeast, galactose,
Formed during the breakdown of lactose, it turns into glucose - the source of alcohol formation.
Curdled milk is produced from whole or skim milk of cows (pasteurized or sterilized) by fermenting it with pure cultures of lactic acid streptococci with or without the addition of other types of lactic acid microorganisms. Dairy industry enterprises produce various types of curdled milk: ordinary, acidophilus, mechnikovskaya, fermented baked milk, southern, and Varenets. There are varieties of yogurt - yogurt, drinks “Kolomensky”, “Lyubitelsky”, “Russian”, “Molodist”, “Snezhok”, etc. Acidophilus yogurt is prepared from pasteurized milk with the addition of acidophilus culture, and ordinary milk is made from pasteurized milk with the addition of Bulgarian bacillus . Lactic acid and sometimes yeast are added to southern curdled milk. Varenets is obtained from sterilized milk with the addition of lactic acid bacillus.
In the food market, curdled milk is usually tested organoleptically; in doubtful cases, it is selectively examined for acidity, fat content and soda impurities. Curdled milk that goes on sale must meet the following requirements: the taste and smell are fermented milk, with their characteristic aroma, without foreign smells and tastes that are not characteristic of a fresh product; for curdled milk prepared with the addition of sugar or other flavoring and aromatic substances, a moderately sweet taste and the presence of an odor characteristic of the substances introduced into it are allowed; the consistency of curdled milk is thick, without a large amount of whey on its surface and gas formation; a clot of ordinary yogurt should be moderately dense, glossy at the break, stable, and clots of acidophilic and southern yogurt, prepared with the participation of mucous races of microorganisms, matsoni and fermented baked milk, should be slightly viscous; for yogurt, the consistency is homogeneous, like sour cream; for Varents, the presence of milk films is allowed; the color of yogurt is milky white or cream, Varenets with a brownish tint; Fat yogurt contains at least 3.2% fat; the acidity of acidophilic and ordinary yogurt, Varents can be in the range of 75-120°T, and the southern yogurt, matsoni and fermented baked milk - 85-150°T. In homemade fermented milk products, the fat content corresponds to the fat content of whole milk accepted in the area, but not less than 2.8%.
Curdled milk with pronounced odors and tastes (fodder, butyric acid, ammonia, bitter, greasy, alcoholic, with the exception of the alcoholic taste in southern curdled milk, moldy and bready), as well as contaminated, covered with milk mold, with gas formation, voids and crevices, liquid, flabby and with the presence of separated serum in an amount of more than 5% of the volume of the product.
Acidophilus and acidophilus milk are prepared from cow's whole or skim pasteurized milk. Sourdough is made using pure cultures of acidophilus bacillus with or without the addition of other lactic acid microorganisms and milk yeast. Lactic acid streptococcus and kefir starter are added to acidophilus milk, and lactic yeast is added to acidophilus milk.
In terms of organoleptic and chemical indicators, acidophilus and acidophilus milk must meet the following requirements: the taste and smell are fermented milk, with the aroma characteristic of these products. Acidophilus may have an alcoholic taste. If products are prepared with the addition of sugar or other flavoring and aromatic substances, a moderately sweet taste and odor characteristic of the substances introduced into them are allowed.
In terms of consistency and appearance, acidophilus and acidophilus milk are a fairly dense clot, when diluted, a homogeneous mass is obtained in the form of liquid sour cream. For acidophilus milk, a denser, slightly viscous consistency is allowed. Slight gas formation is possible in acidophilus. The color of these products is milky white, uniform throughout the mass; the amount of fat is at least 3.2%. The acidity of acidophilus is 75-130°T, milk - 90-140°T.
Sour cream is prepared from pasteurized cream obtained from cow's milk, fermented with lactic acid streptococcus. The taste and smell of sour cream are delicate, fermented milk, without any extraneous, pronounced tastes and smells that are not characteristic of fresh sour cream; A weakly expressed feed taste, the taste of containers (wood) and the presence of slight bitterness are allowed. The consistency of sour cream is moderately thick, homogeneous, without grains of fat and protein (cottage cheese); its appearance is glossy, color from white to slightly yellow.
Dairy industry enterprises produce sour cream with 10% fat content (dietary), 15-, 20- and 25% fat content (OST 49 90-85).
The acidity of sour cream with 15% fat content is in the range of 65-100°T, and that of dietary sour cream with 20 and 25% fat content is 65-70, 75-95 and 70-90°T, respectively.
The presence of admixtures of cottage cheese, starch, flour and other products is recognized as adulteration, and such sour cream is rejected.
Cottage cheese is a protein fermented milk product produced from whole or skim milk by fermenting it with pure cultures of fermented milk microorganisms, as well as from buttermilk. It is produced in the traditional (ordinary) way and separately. The technological process of producing cottage cheese in the traditional way includes milk cleaning, obtaining raw materials of the required composition, pasteurization, cooling to fermentation temperature, fermentation, ripening, crushing the curd, separating the whey, cooling the cottage cheese, and packaging. The process of producing cottage cheese using a separate method includes heating and separating milk, pasteurization and cooling of cream, pasteurization and cooling of skim milk, fermentation and fermentation of skim milk, dehydration of the curd, cooling of skim cottage cheese with cream, packaging.
Cottage cheese made from pasteurized milk is intended for direct consumption and preparation of curdled products. Cottage cheese from unpasteurized milk is used for semi-finished products (cheese cakes, dumplings, processed and baked cheese) and curd products, which must undergo heat treatment before use. The dairy industry produces three categories of cottage cheese: full-fat, semi-fat and low-fat; Depending on the acidity, in each category of cottage cheese there are 2 grades - the highest and the first (see Table 23).
Dietary cottage cheese is prepared from pasteurized milk with an acidity of no higher than 20°T and is sold within 24 hours from the moment of production.
In veterinary examination laboratories, fatty cottage cheese is considered to be one that has fat content of 9% or more; Cottage cheese with less content is classified as low-fat.
To prepare cottage cheese, you cannot use milk obtained during the first 7 days after calving and during the last 15 days before starting the cow. The presence of a weakly expressed feed taste, the taste of containers (wood), as well as the presence of slight bitterness is allowed in the cottage cheese. The color of the cottage cheese is uniform throughout the mass, white, slightly yellowish; the consistency is soft, spreadable, crumbly, heterogeneous is allowed, with the presence of graininess.
Kefir is prepared from whole or skim pasteurized milk (as well as from dry milk) by mixed lactic acid and alcohol fermentation. To do this, use starters prepared with kefir grains or with pure cultures of microorganisms specially prepared for this purpose that can cause lactic acid and alcohol fermentation. Kefir grains are a symbiosis of lactic acid rods, streptococci and milk yeast of the Torula kefiri type. In addition to lactic acid and alcohol fermentation, during the production of kefir there is a slight peptonization of protein substances caused by lactic acid and other microorganisms.
The dairy industry produces kefir of 1-, 2.5-, 3.2% fat content, low-fat, Tallinn 1% fat and Tallinn low-fat (OST 49 29-84). The acidity of 1-, 2.5-, 3.2% and low-fat is 85-120°T, Tallinn 1% fat and Tallinn low-fat is 85-130°T.
Medicinal kefir is divided into weak, medium and strong, which depends on the duration
Maturation, and consequently, on the chemical characteristics of the product. In weak kefir, the percentage of fat should be at least 3.2, alcohol - no more than 0.2 and acidity - no more than 80-90°T. In average kefir - respectively 3.2; 0.4; 80-105°T, and in strong - 3.2; 0.6 and 90-120°T. Weak kefir is obtained after ripening for 24 hours, medium kefir after ripening for up to 2 days, and strong kefir after ripening for up to 3 days.
Good quality kefir is characterized by: fermented milk, refreshing taste and smell, uniform consistency and milky white or yellowish color. Gas formation is allowed as a consequence of the development of normal microflora. Do not add coloring or preservatives to kefir. You should not use kefir for food with butyric acid, acetic acid, bitter, ammonia, musty and strong fodder smell (onion, garlic, wormwood, etc.) and with the smell of dirty dishes, basement, with lumps of cottage cheese, moldy, swollen, with serum released more than 5% of the volume, with the presence of foreign matter and abnormal coloring.
Kumis is obtained from mares' milk. In the southern regions of Kazakhstan, kumiss is prepared from camel milk and is called shubat. Kumis, like kefir, is a product of combined (lactic acid and alcohol) fermentation; It is prepared by fermenting milk with cultures of lactic acid bacteria and kumiss yeast. Kumis is a highly valuable food product; it is used for both preventive and medicinal purposes. Mares' milk used for making kumis comes from healthy animals, fresh, acidity - not higher than 7°T, pure, without foreign taste or smell. Skimmed cow's milk is pasteurized to make kumis.
The physico-chemical parameters of koumiss are as follows: weak - fat content - no less than 1.5%, dry matter - 9.5%, vitamin C - 10 mg%, acidity - no more than 95°T, alcohol - no less than 0.6%; medium - dry matter - 9.2%, vitamin C - 18 mg%, acidity - 110°T, alcohol - 1.1%; strong - fat 9%, vitamin C - 18 mg%, acidity - 130°T, alcohol - 1.6%. These indicators depend on the ripening period of kumys, which ranges from 5-6 hours to 2 days.
Good-quality kumiss is milky-white in color with some tint, and its consistency resembles thick sour cream with gas bubbles; the taste and smell are sour alcohol, specific, without foreign smells and tastes unusual for a fresh product. You cannot add preservatives or coloring substances to kumiss. Kumis should not contain pathogenic microorganisms; its permissible coli-titer is not higher than 0.3. Do not eat koumiss, which has the smell and taste of butyric and acetic acids, is putrid, moldy, etc., as well as large particles of curd.
Koumiss improves gastric secretion, has a positive effect on peristalsis and is a good remedy against intestinal autointoxication; the anti-tuberculosis properties of koumiss are known. Kumiss treatment is indicated for a number of human diseases: chronic bronchitis and chronic pneumonia, dry pleurisy, etc.
Usually the good quality of kumiss is determined organoleptically, but in doubtful cases they resort to bacteriological examination (microflora, coli-titer) and determination of the percentage of fat. When determining the raw materials used to prepare kumis (cow or mare's milk), a sedimentation test is performed. Koumiss from cow's milk stratifies within 30-60 minutes, kumys from mares' milk does not stratify during this period. This is explained by the relatively large amount of casein in cow's milk. Recently, the technology of kumiss from skim milk (cow) has been improved so that separation of the product does not occur when standing for 30-60 minutes.
Cream is a concentrate of the fat fraction of milk. They are used to normalize milk in terms of fat content, in the production of ice cream, sour cream, homemade cheese, and are also produced for direct consumption. The high nutritional value of cream is due to the high content of milk fat and vitamins.
Cream is produced from fresh natural milk of healthy cows. Milk from the first 7-8 days after calving (colostrum) and the last 7-8 days of lactation (old milk) is not used for making cream. The prepared cream must meet the following requirements: clean, without foreign tastes and odors, the taste is slightly sweetish, mild feed taste and smell are allowed; the consistency is homogeneous, without sediment and mechanical impurities, from white to slightly yellow; titratable acidity - not higher than 20°T. Cream that does not meet these requirements may be accepted by dairy industry enterprises by agreement of the parties. Denatured cream, with the presence of preservatives and neutralizing substances, with mechanical admixtures, with flakes and clots, or unusual coloring are not accepted.
And a pronounced taste and smell: fodder (onion, garlic, wormwood), putrefactive, rancid, moldy, stable, metallic, medicinal, chemicals, petroleum products, etc.
The dairy industry produces pasteurized cream containing 8, 10, 20 and 35% fat. The acidity of 8 and 10% cream is 19°T, 20% - 18°T, 35% - 16-17°T. They also produce plastic cream containing 65-73% fat, intended for industrial processing in the production of various dairy products. Cream placed on the market for sale must contain at least 20% fat. Permissible bacterial contamination of pasteurized cream: category A - no more than 100 thousand bacteria in 1 ml, coli-titer equal to 3 ml; category B - no more than 300 thousand bacteria in 1 ml and coli-titer 0.3 ml.
Butter. The dairy industry produces sweet cream, sour cream, salted butter, amateur, sandwich and peasant butter, as well as ghee and butter with fillers (cocoa, honey, etc.). Sweet butter is made from fresh pasteurized cream; sour cream - from pasteurized cream fermented with pure cultures of lactic acid bacteria; salted butter - from pasteurized fresh or pasteurized fermented cream with the addition of table salt; amateur - from sweet pasteurized cream in continuous butter producers; sandwich - made from high-fat pasteurized cream. Ghee is butter or raw butter melted in hot water (85-90°C) with its own specific smell and taste.
Butter is produced in the following order. Cream is produced from milk that meets technological and sanitary-hygienic requirements. They are pasteurized, cooled and left to mature. When ripening, the cream is first kept for some time (from 0.5 to 12 hours) at a temperature of 8-2°C, and then additionally at a temperature of 8 to 0°C. At the same time, the fat globules become dense in consistency, and their lipoprotein shell becomes thinner, which facilitates better churning of the cream into butter. When producing cultured butter, the cream is pasteurized and then fermented by adding bacterial starter or lactic acid (biochemical ripening).
Ripe, fermented cream is churned. The essence of the process of formation of butter grains when churning cream has not yet been sufficiently studied. Belousov's flotation theory is currently the most truthful. According to this theory, fat globules are concentrated on the surface of air bubbles incorporated into the cream during churning. When pressed into air bubbles, the fat globules lose their protein shell and connect with each other. The resulting flat conglomerates of fat fall into the cream and again float on air bubbles, forming increasingly larger conglomerates of fat until the foam disappears. As a result of the connection of fat globules, an oil grain is formed. The latter is washed with water to remove the buttermilk, and if salted butter is prepared, salt is added to it. Next, they carry out their own oil processing, which consists of creating a continuous layer of oil grains and regulating the moisture content in the oil.
In our country, butter production is widespread by converting high-fat cream. When milk is separated, cream with a fat content of 35-40% is obtained, this cream is then pasteurized at a temperature of 85-87 ° C and separated again until cream with a fat content of at least 83% is obtained. Such cream is sent to an oil manufacturer, where it is processed and the oil is processed. Oil produced by industrial enterprises must meet the requirements of the standard in its chemical composition (Table 24).
The taste and smell of good quality butter and ghee are characteristic of this type of product, without any foreign tastes or odors. The color of butter is from white to light yellow, and melted butter is from straw to amber yellow. Its consistency is dense and homogeneous; The cut surface is slightly shiny and dry. Sometimes single droplets of moisture are found on it. Ghee has a soft consistency, and when melted it is transparent, without sediment. The consistency of chocolate butter is dense, without visible droplets of moisture.
During the veterinary and sanitary examination of oils on the market, they check it only organoleptically and only in doubtful cases determine the percentage of fat, moisture and the presence of impurities. Fat content - no less than 78%. Humidity - no more than 20%. Homemade butter should not contain any admixtures of water, milk, cottage cheese, lard, cheese, or boiled potatoes. Counterfeit oil is rejected.
When putrefactive microflora multiply in the oil, a putrid taste may appear. As a result of lipolysis, easily oxidized substances are formed: hydroxy acids, ketones, aldehydes, ethers, alcohols and other compounds that give the oil the smell of spoiled fat. This oil has an unpleasant, throat-scratching taste. The reason for this defect is the effect on the oil of light and microorganisms that produce the enzyme lipase. Rancidity is most often observed in sweet cream butter; sometimes it is also found in fresh butter, if it is produced from milk obtained from cows before they were started. The moldy taste and smell of oil is a consequence of the development of molds in it. Molds, as aerobes, develop on the surface of the oil, but their mycelium can penetrate into the thickness of the mass.
Fermented butter acquires a fishy or herring taste and smell when it is stored for a long time together with fish products or when fish meal is used as feed for dairy cows, as well as when fat is broken down by microorganisms. The appearance of the smell and taste of spoiled fish oil in the oil is explained by the decomposition of lecithin with the formation of trimethylamine. Feed flavors in oil are noted when feeding cows such feeds as garlic, wormwood, radish, onions, and sauerkraut. If cream is not pasteurized correctly, the butter will go rancid or develop a smoky smell. A metallic taste in butter occurs when the milk from which it is obtained is stored in poorly tinned containers, when low-quality starter cultures are used, when iron salts are ingested from the wash water, etc.
The greasy taste in butter occurs when it is stored in the light, from exposure to direct sunlight and other factors. In this case, small individual islands of pale and sometimes white color first appear in the oil, which subsequently occupy more and more space. The oil not only acquires color and flavor, but also becomes refractory. The essence of the desalination process is the oxidation of unsaturated fatty acids. The salting of butter is determined organoleptically. The depth of the process can be determined by determining the iodine number and melting point of the oil under study. Sometimes a taste reminiscent of vegetable oil (oleous taste) is detected.
When examining the oil, a change in the color and taste of the surface layer to a depth of 0.5 cm or more is also detected. It takes on a dark yellow color and the taste of greasy oil. Beyond this layer, the oil turns out to be normal in terms of organoleptic indicators and can be allowed for consumption. This defect is called “staff” and is found in unsalted sweet cream butter.
If a putrefactive, rancid, fishy, moldy smell and taste or smell and taste of petroleum products and chemicals is detected, the oil is not allowed to be consumed. Oil with a pronounced fodder, bitter, musty, burnt, smoky, metallic, greasy, oleous, moldy and damp smell and taste is also rejected.
Store butter in the refrigerator at a relative humidity of up to 90%. Sweet butter is stored for 7-12 months, salted butter - up to 6 months at a temperature of -9...-18°C, and ghee - 12 months at 3-8°C.
Cheeses are high-value food products produced from milk by coagulating proteins, separating the cheese mass, followed by processing and ripening. Based on technological characteristics, cheeses are divided into rennet and fermented milk cheeses. In the production of rennet cheeses, rennet enzyme (an enzyme obtained from calf rennet in the form of a powder of standard activity) is used to curdle milk. Fermented milk cheeses are produced by fermenting milk with a starter of lactic acid bacteria without rennet or with a small amount of enzyme. According to commodity evaluation, cheeses are divided into 4 groups: hard, soft, brine and pot (skin) cheeses.
Hard cheeses are rennet and are characterized by a dense (hard) consistency (Dutch, Kostroma, Yaroslavl, Stepnoy, Uglich, Estonian, Dniester, cheddar, Russian, Latvian, piquant, Soviet, Swiss, Altai, Carpathian). Soft cheeses can be rennet or fermented milk. They are characterized by high moisture content, large grains, and a large amount of lactic acid (Russian Camembert, Roquefort, dessert white). Brine cheeses have a high content of table salt (brynza, chanakh, Tushinsky, Ko-biysky). The characteristics of these cheeses are given in Table 24. Potted (skin) cheeses are not produced industrially.
Fermented milk cheeses are divided into aged (green) and fresh (tea, coffee, blade). The dairy industry also produces processed cheeses, which are classified as processed cheeses.
They are produced from natural cheeses with the addition of melting salts, dairy products, flavoring agents, herbs, and spices. Processed cheeses are packaged in aluminum foil.
Rennet cheeses are made from pasteurized cow's milk. Each cheese differs in its shape and dimensions in length, width, height and diameter. Good-quality cheeses have a pale yellow rind, a pungent taste and a slight ammonia smell, and a delicate oily consistency. On the cut, as a rule, there are no eyes, but they can be in small numbers and very small in size. The color of the cheese dough is white to creamy, uniform over the entire cut surface.
Snack cheese differs little from the named cheeses in terms of organoleptic indicators. The rind of snack cheese has small layers of blue-green or white mold. Unripened snack cheese has a delicate thin rind and is similar in color to dough. Roquefort has a thin layer of yellow or orange cheese mucus on the rind; its consistency is oily, slightly crumbly; at a depth of 1.5-3 cm from the side surface, blue-green mold is distributed throughout the entire mass of the cheese.
Good-quality cheeses must contain at least 45-50% fat in relation to dry matter, table salt - no more than 2.5% (snack without ripening) and 3.5% (snack mature and all others), in Roquefort up to 5%, in green cheese - up to 6.5%, in Russian cheese, salt 1.3-1.8%. The moisture in cheeses should not be more than 50-60%, in green cheese - 40%, in Russian cheese - 43% (Table 25).
Brynza is a soft pickled cheese. It is made from sheep and cow or a mixture of cow and sheep milk. Cheese cheese matures in strong salt brine (14-18%). It goes on sale after 15 days of ripening if it is made from pasteurized milk, and after 30 days - from unpasteurized milk. Bryndza, prepared from milk from animals from a herd unaffected by brucellosis, is aged for at least 60 days in brine of 20% concentration. Good-quality cheese does not have a crust; its surface is completely clean, the same color as the dough. The taste is sour milk and hotly salted. In 1st grade cheese, a slight fodder and sour taste, subtle bitterness and a musty smell are allowed. Bryndza with signs of rotting (rancidity), with a pronounced fodder, greasy and other taste and smell not characteristic of feta cheese is unsuitable for food. Fat in the dry matter of cheese is no less than 40-50%, table salt is 3-4%, moisture is no more than 49-52%.
Brine cheeses (Tushinsky, Kobiysky, Chanakh, etc.), like feta cheese, do not have a rind, and in terms of physical and chemical parameters they differ little from it.
Dutch, Kostroma, Yaroslavl, Uglich and Stepnoy cheeses have a thin, smooth, damage-free rind, which is coated with a paraffin mixture. The subcortical layer is thin. The surface of the cheese, with the exception of steppe and Uglich cheese, is covered with food paint. Cheddar and Altai cheeses are wrapped in gauze or calico and covered with a paraffin mixture. Swiss and Altai cheeses may have serpyanka marks on the surface and a dry grayish-white coating. The surface of Latvian and Volga cheeses is covered with a layer of dried mucus. All cheeses are white to slightly yellow throughout
Cut. The taste and smell of these cheeses are specific to each type. Good-quality Latvian or Volga cheese - with a slight ammonia smell; Dutch, Yaroslavl, cheddar, Mountain Altai and Uglich - with a slightly sour smell and taste. Altai, Soviet, Moscow and Swiss cheeses have a sweetish taste.
The ripening time (age of the cheese) of Dutch Lilliputian is 35 days; Dutch round and bar large, Kostroma (large and small) and steppe - 2.5 months; Dutch bar small, Yaroslavl, Uglich, Latvian and Volga - 2 months; Mountain Altai and cheddar - 3 months; Altai, Soviet and Moscow - 4 months; Swiss - 6 months; Russian - 2 months.
Rennet cheeses are produced from sheep's milk: Aragad sheep, southern sheep and Moldavian smoked. Good-quality sheep's milk cheeses have a thin, smooth rind without wrinkles or damage, a thin subcortical layer, and the color of the dough is uniform throughout the entire mass - from white to slightly yellow. Moldavian cheese has the taste and smell of smoking, and the consistency is elastic throughout the mass. These cheeses contain 50-55% fat, no more than 40-42% moisture and 1-3.5% salt.
Processed cheeses - Soviet, Altai, Yaroslavl, Volzhsky, Mountain Altai, pasteurized in jars, Kostroma, Latvian, spicy, new, smoked sausage - come in different fat contents. Inspection of processed cheeses should begin with the foil in which they are wrapped. It must be intact, without damage. After removing the foil, inspect the surface of the cheese. Do not allow the surface to dry out or have mold on it. Air voids found in cheese are not a defect.
Sausage smoked cheese has an intestinal, cellophane or parchment casing of light or dark brown color, coated with a paraffin mixture. The color of the sausage cheese dough is somewhat uneven: under the shell at a depth of approximately 0.5-1 cm the color is yellow, and in the center of the loaf it is light yellow. The coloring of cheeses with spices is characteristic of the filler. The consistency of processed cheeses is plastic, non-crumbly and without grains. Latvian and Volga cheeses have a spreadable surface.
Green cheese is produced in the form of heads (in the shape of a truncated cone) or powder. The color and specific smell of this cheese are due to the presence of blue or yellow sweet clover powder (trigonella). A wheel of cheese with a rough surface, without cracks, mold, mucus or other defects. The powdered cheese is homogeneous, grayish-green, tastes salty, spicy, with the smell of sweet clover. Green cheese contains no more than 40% moisture, table salt - 6.5% and sweet clover powder - up to 2.5%.
Unsuitable for food are cheeses that are swollen, with deep cracks and breaks in the rind, that are blurred, with a very softened rind, that are affected by mold when the mold mycelium has penetrated under the crust layer or into cavities filled with air, as well as cheeses with a putrefactive odor and peeled by more than 2 - 3 cm deep.
When examining feta cheese and other home-made cheeses sold on the market, owners must present a certificate from the sanitary inspection of permission to prepare cheese for sale at home. Typically, cheese is assessed organoleptically, and in doubtful cases, the percentage of fat in dry matter and the amount of table salt are determined. Homemade cheese and feta cheese should not have any foreign odors or tastes. They contain 40-50% fat (in dry matter), no more than 52% moisture and no more than 7% salt. Cheese and feta cheese that do not meet the requirements are not allowed to be sold.
Approved by the Main Directorate of Veterinary Medicine of the USSR Ministry of Agriculture, agreed with the Main Sanitary and Epidemiological Directorate of the USSR Ministry of Health on July 1, 1976.
Instead of the rules of February 10, 1959, agreed with the USSR Ministry of Health on November 26, 1958 N 123-1/76
1. Sanitary and veterinary requirements for the sale of milk and dairy products in markets
1. Sanitary and veterinary requirements for the sale of milk and dairy products in markets
1.1. Milk and dairy products supplied for sale to markets (including stalls and stores on collective farms, state farms and consumer cooperatives) are subject to veterinary and sanitary examination. The sale of milk and dairy products that have not passed veterinary and sanitary examination at the meat, dairy and food control station of the market (except for state trade) is prohibited.
1.2. Milk and dairy products coming from farms that are free from contagious animal diseases are allowed for sale, which must be confirmed by a certificate issued by a veterinarian (paramedic) for a period of no more than one month (Appendix 1). In the certificate, the veterinarian (paramedic) serving the farm (settlement) must indicate the date of the test for subclinical mastitis, anthrax vaccinations, tests for tuberculosis, brucellosis and other studies provided for by the current instructions of the Main Directorate of Veterinary Medicine of the USSR Ministry of Agriculture.
1.3. The sale of milk and dairy products is prohibited: from farms (including households), farms affected by anthrax, emphysematous carbuncle, rabies, paratuberculosis, tuberculosis, brucellosis, foot-and-mouth disease, smallpox, catarrhal fever, leptospirosis, salmonellosis; from animals that are sick and react positively when tested for brucellosis or tuberculosis; from cows clinically sick with leukemia, actinomycosis and necrobacteriosis of the udder, mastitis, gastroenteritis and endometritis, as well as in other cases provided for by the instructions of the USSR Ministry of Agriculture.
If milk from cows (buffaloes), sheep, goats and mares sick with these diseases is submitted for veterinary and sanitary examination, it is subject to destruction under the supervision of a veterinarian in the presence of a representative of the farm (owner). An act on the destruction of milk and dairy products is drawn up in two copies, one of which is handed over to the owner, and the second is kept in the files of the veterinary service (Appendix 2).
1.4. Milk and dairy products with the addition of neutralizing and preservative substances, with an odor unusual for milk (petroleum products, onions, garlic, etc.), with residual amounts of plant and animal protection chemicals, antibiotics, as well as those that do not meet established physical requirements are not allowed for sale. -chemical indicators (density, acidity, fat content) and bacterial contamination.
1.5. It is prohibited to sell milk and dairy products with falsification: for milk - removing fat, adding water, starch, soda and other impurities; for sour cream and cream - an admixture of cottage cheese, starch, flour, kefir; for butter - an admixture of milk, cottage cheese, lard, cheese, boiled potatoes, vegetable fats; for cottage cheese, varents, matsoni, fermented baked milk, yogurt and other fermented milk products - skimming, adding soda, etc.
1.6. Milk from vaccinated cows (buffaloes), sheep and goats against anthrax (STI vaccines - dry, liquid, VGNKI - dry) is allowed to be used without restrictions, except in cases where the animal’s body temperature rises after vaccination, significant swelling appears at the injection site, general depression occurs or other signs of the disease appear. In these cases, the milk is destroyed.
1.7. It is prohibited to sell milk (colostrum) obtained from cows during the first 7 days after calving and the last 7 days until the end of lactation.
1.8. If it is suspected that milk received from cows that react positively to brucellosis has been submitted for veterinary examination, it is checked with a ring test.
If a positive or questionable reaction is received, milk is not allowed for sale. Such milk is destroyed at the meat, dairy and food control station in accordance with clause 1.3 of these rules in the presence of the owner and the chief veterinarian of the district (city) where the milk came from is informed about this.
1.9. Bacterial contamination, acidity and fat content of milk are determined once a month when it is systematically sold by individual distributors and at least once every 10 days when sold by collective and state farms, as well as for one-time sales.
1.10. All dairy products delivered in separate containers are subject to inspection and analysis. Samples are taken from different layers of the product in the amount of: milk, at least 250 ml; sour cream and cream 15 g; oils 10; cottage cheese and feta cheese 20 g; Varenza, matsoni, fermented baked milk, yogurt and other fermented milk products 50 ml.
Before taking milk samples, it is thoroughly mixed with a whorl.
After mixing, an average sample of milk intended for determining physicochemical and organoleptic parameters is brought to a temperature of 20°±2°C.
Remains of samples of milk and dairy products after the study are denatured with surrogate coffee and subsequently disposed of at a meat, dairy and food control station.
1.11. Each milk sample must be examined organoleptically for purity, density and acidity no later than 1 hour after it is taken. In the warm season, 2 hours after release for sale or at the request of the buyer, milk is checked for acidity again.
Milk delivered for sale initially must be tested for fat content in 100% of cases. When re-determining the fat content in milk delivered in large quantities (more than 10 places), the determination is carried out selectively, but not less than 10% of the total number of places, and in doubtful cases from each container.
1.12. Before taking samples of milk and dairy products for examination, the sanitary condition of the container (ware) in which they are delivered to the market is determined.
The containers in which milk and dairy products are delivered must be made of materials approved by health authorities for contact with food.
Milk and dairy products delivered to the market in galvanized and dirty containers are not allowed for sale.
1.13. Samples of milk and dairy products that require more complex testing (for pesticides, etc.) are sent to a veterinary laboratory and examined according to methods approved by the Main Directorate of Veterinary Medicine of the USSR Ministry of Agriculture.
Samples sent for testing to the laboratory must be in glass containers, tightly sealed and sealed with sealing wax.
A label is placed on the container with the name of the product and the date the sample was taken, accompanied by a cover letter signed by the person (indicating the position) sending the sample.
If the shipment of selected milk samples is delayed, it is stored at a temperature of 4°C and preserved with one of the following substances (per 100 ml of milk): formaldehyde - 1-2 drops, hydrogen peroxide - 2-3 drops, potassium dichromate - 1 ml 10% - no solution.
Until the results of the study are received, milk and dairy products are not allowed to be sold.
1.14. The sale of milk and dairy products in markets is permitted to persons who have personal sanitary medical records or certificates of passing medical examinations established for employees of food enterprises and subject to their compliance with the sanitary rules for trading these products.
Containers containing milk (dairy products) must have a veterinary and sanitary inspection label (Appendix 3).
1.15. Cow's (sheep's, goat's) milk is allowed for sale in markets in terms of purity - not lower than the second group, and in terms of bacterial contamination not lower than class II.
Mare's milk is allowed for sale at least class 1 in terms of purity and class 2 in terms of bacterial contamination.
1.16. The results of veterinary and sanitary examination of milk and dairy products at meat, dairy and food control stations are recorded in the appropriate journal (Appendix 4).
1.17. In case of violation of veterinary and sanitary rules for the trade of milk and dairy products in markets, the head of the meat, dairy and food control station may apply penalties to those responsible in accordance with the “Instructions on the procedure for imposing fines for violation of animal quarantine rules and other veterinary and sanitary rules.” , provided for by the Veterinary Charter of the USSR, as well as decisions of local Councils of People's Deputies and their executive committees on the issues of combating epizootics", approved by the USSR Ministry of Agriculture on October 16, 1964.
2. Veterinary and sanitary examination of milk
2.1. Cow's milk in appearance and consistency should be a homogeneous liquid from white to slightly yellow in color, without sediments or flakes.
The taste and smell are specific to milk, without extraneous, pronounced tastes and smells that are not characteristic of fresh milk. Fat content not less than 3.2%. Density 1.027-1.035 g/cm. Acidity in degrees Turner (°T) 16-20. Milk with acidity below 16°T is not allowed for sale until the reasons for the decrease in acidity are clarified. If a study of milk samples shows that its low acidity is due to feed factors, then, as an exception, the sale of milk with an acidity of up to 14°T is allowed.
Note. In each region, territory, republic, taking into account local conditions, the Councils of Ministers of the union and autonomous republics, the executive committees of regional (territorial) Councils of People's Deputies can establish higher standards for the fat content in milk.
2.2. Sheep's milk is close in taste and smell to cow's milk, but may have a specific odor for sheep's milk.
The color is white with a faint yellowish tint. The consistency is homogeneous, without flakes and sediment. Fat content not lower than 5%. Purity according to the standard is not lower than the second group. Density 1.034-1.038 g/cm. Acidity no more than 24°T.
2.3. Goat milk is close in taste and smell to cow milk, but may have a specific goat smell. White color. Fat content not less than 4.4%. Density 1.027-1.038 g/cm. Acidity no more than 15°T.
2.4. Mares' milk has a sweetish, slightly tart taste, with a specific smell, fresh milk without any foreign tastes or odors. The color is white with a bluish tint. Fat content not less than 1%. Density 1.029-1.033 g/cm. Acidity no more than 7°T.
2.5. Buffalo milk in appearance and consistency is a viscous, white, odorless liquid. Fat content 7-8%. Density 1.028-1.030 g/cm. Acidity 17-19°T.
3. Milk research methods
3.1. Organoleptic examination determines the color, taste, smell and consistency of milk. The taste test is carried out only after boiling the milk. The color of the milk is determined in a white glass cylinder in rays of reflected light, the smell and taste are determined by sensory means, and the consistency is determined by the mark left on the wall of the cylinder after a stream of milk has flowed down.
3.2. Determination of density. Density is determined by lowering a milk lactodensimeter into a glass cylinder filled with the test milk, previously thoroughly mixed (without foam), in an amount of up to 250 ml at a milk temperature of 20±5°C. When determining density, the lactodensimeter should not touch the walls of the cylinder.
1-2 minutes after placing the lactodensimeter in a stationary state, the readings of the lactodensimeter scale are counted. The density of milk is measured using a lactodensimeter to a whole division, and the temperature is measured with an accuracy of 0.5°C. Based on the readings of the milk lactodensimeter, the density of the milk is determined according to the table (Appendix 5).
In Table 5, the density of milk is expressed in degrees of lactodensimeter, which is the fractional part of the density increased by a thousand times.
Example. The density of milk d=1.0265 g/cm corresponds to 26.5° lactodensimeter.
When using the table, the reading data is converted into degrees; for this, the density value in degrees is found in the left column, and the temperature at which the reading was made is found in the upper part of the column. At the intersection of the lines, the density of milk at 20°C is obtained.
Example. Milk temperature 18°C, density 1.0305 g/cm. We convert the density g/cm into degrees: 1.0305 g/cm corresponds to 30.5°. According to the table, the value of 30.5° at T = 18° corresponds to a density of 30° lactodensimeter (d = 1.030 g/cm).
3.3. Determination of acidity. Acidity is determined by the titrimetric method and calculated in degrees Turner. The degree of acidity is the number of milliliters of decinormal solution of sodium hydroxide (potassium) used to neutralize 100 ml of milk or 100 g of product.
To determine acidity, pour 10 ml of milk, 20 ml of distilled water (freshly boiled and cooled to room temperature) and 3 drops of a 1% alcohol solution of phenolphthalein into a conical flask with a capacity of 150-200 ml. The contents of the flask are thoroughly mixed, and then a decinormal alkali solution is added dropwise from the burette into the flask until a faint pink color appears, which does not disappear within one minute (compare with the standard). The number of milliliters of decinormal alkali solution used for titration, multiplied by 10, will indicate the degree of titratable acidity of the milk.
In some cases, it is allowed to check the acidity of milk without adding distilled water, but the resulting acidity must be reduced by 2°.
To prepare a control standard for coloring, pipet 10 ml of milk, 20 ml of water and 1 ml of a 2.5% solution of cobalt sulfate into a flask with a capacity of 150-200 ml (2.5 g of cobalt sulfate is added to a volumetric flask with a capacity of 100 ml and topped up with distilled water up to the mark). The shelf life of cobalt sulfate solution is 6 months.
The reference standard is suitable for use for one day. To increase the shelf life of the standard, it is necessary to add one drop of formaldehyde to it.
Note. Meat, dairy and food control stations must receive decinormal solution of sodium hydroxide (potassium) and sulfuric acid from veterinary laboratories (from veterinary and sanitary stations). If appropriate conditions exist, it is allowed to prepare these solutions at a meat, dairy and food control station.
3.4. Determination of fat content. Pour 10 ml of sulfuric acid (density 1.81-1.82) into a clean milk butyrometer, without wetting the neck, and carefully, so that the liquids do not mix, add 10.77 ml of milk with a pipette, placing its tip against the wall of the butyrometer neck at an angle ( The milk level in the pipette is set at the lower level of the meniscus). Blowing milk out of a pipette is not allowed. Then 1 ml of isoamyl alcohol (density 0.810-0.813) is added to the butyrometer.
The butyrometer is closed with a dry rubber stopper, inserting it a little more than halfway into the neck, turning it over 4-5 times until the protein substances are completely dissolved and mixing evenly, after which it is placed with the stopper down for 5 minutes in a water bath at a temperature of 65±2°C .
Having been removed from the bath, the butyrometers are inserted into the cartridges (glasses) of the centrifuge with the working part towards the center, placing them symmetrically one against the other. If there is an odd number of butyrometers, a butyrometer filled with water is placed in the centrifuge. After closing the centrifuge lid, the butyrometers are centrifuged for 5 minutes at a speed of at least 1000 rpm. Then each butyrometer is removed from the centrifuge and the column of fat in the butyrometer is adjusted by moving the rubber stopper so that it is in the tube with the scale. The butyrometers are then re-immersed, plug side down, in a water bath at a temperature of 65±2°C. After 5 minutes, the butyrometers are removed from the water bath and the fat is quickly read. To do this, the butyrometer is held vertically, the fat border should be at eye level. By moving the plug up and down, the lower limit of the fat column is set on a whole division of the butyrometer scale and the number of divisions is counted from it to the lower level of the meniscus of the fat column. The interface between fat and acid should be sharp and the fat column transparent.
If there is a ring (plug) of brownish or dark yellow color, as well as various impurities in the fat column, the analysis is repeated.
The butyrometer readings correspond to the fat content in milk as a percentage. The volume of 10 small divisions on the milk butyrometer scale corresponds to 1% fat in the product. Fat counting is carried out with an accuracy of one small division of the butyrometer. The difference between parallel determinations should not exceed 0.1% fat. The arithmetic mean of two parallel determinations is taken as the final result.
To determine the fat in the milk of sheep and buffaloes, a butyrometer with a measurement limit of 0 to 10 is used.
When conducting analyses, safety precautions must be observed. When diluting sulfuric acid, carefully pour it into water in small portions along the wall of the vessel (water cannot be poured into acid), periodically stirring the contents of the flask in a circular motion. When turning over, butyrometers should be wrapped in a napkin or towel.
3.5. Determination of milk purity. To determine the degree of purity of milk, 250 ml of well-mixed milk is taken with a measuring cup and passed through a filter vessel of the Record device, which has a cotton or flannel filter. To speed up filtering, it is recommended to heat the milk to a temperature of 35-40°C.
After filtering the milk, the filter is placed on a sheet of paper, preferably parchment, and dried in air, protecting it from dust.
Depending on the amount of mechanical impurities on the filter, milk is divided into three groups according to the GOST standard 8218-56.
First group: there are no particles of mechanical impurities on the filter.
Second group: individual particles of mechanical impurities on the filter.
Third group: there is a noticeable sediment on the filter of small or large particles of mechanical impurities (hairs, particles of hay, sand).
3.6. Bacteriological examination of milk. For bacteriological research with an accelerated test for reductase, take 10 ml of milk, heat it in a water bath to 38-40°C and add 1 ml of a working solution of methylene blue.
The test tubes are closed with sterile rubber stoppers, mixed thoroughly and placed again in a water bath at a temperature of 38-40°C (the water level in the bath should be higher than the level of the contents of the test tube).
Based on the time of onset of milk discoloration, bacterial contamination and the class of milk are determined according to the table.
For control, the same milk sample is placed in a test tube, but without the addition of methylene blue, which is examined 10 minutes and 1 hour after the sample is taken.
|
Discoloration rate |
Milk class and rating |
|
|
Less than 10 minutes |
More than 20 million |
IV, very bad |
|
From 10 minutes to 1 hour |
Up to 20 million |
III, bad |
|
From 1 hour to 3 hours |
Up to 4 million |
II, satisfactory |
|
More than 3 hours |
Up to 500 thousand |
I, good |
Note. To prepare a saturated alcohol solution of methylene blue, take 10 g and mix with 100 ml of 96° ethyl alcohol. The solution is placed in a thermostat at 37° for 24 hours, then filtered.
To prepare a working solution of methylene blue, take 5 ml of a saturated alcohol solution of methylene blue + 195 ml of distilled water, and then this solution is diluted 10 times, i.e. 1 ml of 2.5% solution + 9 ml of distilled water. The solution must be prepared before testing.
4. Veterinary and sanitary examination of dairy products
4.1. Sour cream. The taste and smell are clean, delicate, fermented milk, without any extraneous, pronounced tastes and smells that are not characteristic of sour cream.
Consistency and appearance - homogeneous, moderately thick, without grains of fat and protein (cottage cheese), glossy appearance. The color is from white to slightly yellow, uniform throughout the entire mass, without any extraneous shades. Fat content not less than 25%. Acidity ranges from 60-100°T.
4.2. Cream. The taste and smell characteristic of this product, without any foreign tastes or odors; the taste is slightly sweet.
The consistency and appearance are homogeneous, without whipped lumps of fat and casein flakes. The color is white with a yellowish tint. Fat content not less than 20%. Acidity 17-19°T.
4.3. Sour cream and cream are checked organoleptically for the absence of cottage cheese admixtures and selectively for fat content, starch admixtures and acidity.
4.3.1. Study of sour cream and cream for fat content. Before analysis, thick sour cream is slightly heated. 5 g of the product are weighed into a clean cream butyrometer, 5 ml of water, 10 ml of sulfuric acid (density 1.8-1.82) and 1 ml of isoamyl alcohol are added along the wall of the slightly inclined butyrometer. Further determination is carried out as indicated in paragraph 3.4. The volume of two divisions on the cream butyrometer scale corresponds to 1% fat in the product.
4.3.2. Testing sour cream and cream for acidity. Add 20 ml (for cream) or 30-40 ml (for sour cream) distilled water into a conical flask with a capacity of 100-250 ml, add 10 ml of cream (5 g sour cream) with a pipette, mix thoroughly and add 3 drops of a 1% alcohol solution phenolphthalein. The mixture is titrated with 0.1 N. solution of sodium hydroxide (potassium) until a faint pink color corresponds to the control color standard, which does not disappear within 1-2 minutes.
To prepare a color standard, add 20 ml of distilled water to the flask, add 10 ml of cream (5 g sour cream) with a pipette, mix thoroughly and add 1 ml of 2.5% cobalt sulfate solution, and if the fat content of the cream is over 20%, then add 2 ml of cobalt solution.
Quantity 0.1 n. solution of sodium hydroxide (potassium), used to neutralize 10 ml of cream or 5 g of sour cream, is multiplied by 10 or 20, respectively. The resulting figure expresses the acidity of the product in Turner degrees.
4.4. Cottage cheese. The taste and smell are fermented milk, clean, delicate, without excessive acidity, foreign tastes and odors.
Consistency and appearance - homogeneous mass, without lumps, non-flowing and not grainy. The color is from white to slightly yellowish, uniform throughout the entire mass of cottage cheese and without any extraneous shades. Acidity is not higher than 240°T. Cottage cheese containing 18% fat is considered fatty, and containing 9% fat is considered semi-fat. Moisture content: in fatty cottage cheese no more than 65%, and in low-fat cottage cheese no more than 80%.
The cottage cheese is checked organoleptically and for acidity, and, if necessary, examined for the content of fat, moisture and soda impurities.
4.4.1. Testing cottage cheese for acidity. Add 5 g of product into a porcelain mortar or beaker with a capacity of 150-200 ml. Mix thoroughly and grind it with a pestle. Then add in small portions 50 ml of distilled water (35-40°C), 3 drops of a 1% alcohol solution of phenolphthalein and titrate with 0.1 N. solution of sodium hydroxide (potassium) until a faint pink color appears that does not disappear within 1-2 minutes.
Acidity (in degrees Turner) is equal to the number of milliliters of 0.1 N. solution of sodium hydroxide (potassium), used to neutralize 5 g of product, multiplied by 20.
4.4.2. Determination of moisture in cottage cheese. A porcelain cup with a glass rod and 20-25 g of sand, previously well washed and calcined, is placed for 1 hour in a drying cabinet at a temperature of 102-105°C. Without cooling, place a cup with sand and a glass rod on a tripod located on the scales, weigh with an accuracy of 0.01 g and weigh 5 g of the product into the cup.
Note. The tripod (a porcelain triangle with curved wire ends) should fit on the left pan of the scale and be about 60mm high.
After weighing, the product is carefully and carefully (to avoid losses) mixed with sand with a glass rod. Then the cup is placed in a drying cabinet at a temperature of 160-165°C. After 20 minutes, the cup with the product is removed, immediately, without cooling, placed on a tripod located on the left pan of the scale, and quickly weighed.
The moisture content of the product (A) as a percentage is calculated using the formula:
where B is the weight of the cup with a tripod, sand, glass rod and sample before drying, g;
C is the weight of the cup with a tripod, sand, glass rod and sample after drying, g;
5 - weight of product, g.
The discrepancy between parallel determinations should be no more than 0.2%.
4.5. Fermented milk products (varenets, matsoni, fermented baked milk, yogurt). The taste and smell are fermented milk, clean, without extraneous tastes and odors unusual for a benign product.
Consistency and appearance - the clots are moderately dense, glossy, stable, without gas formation and significant serum release on the surface of the product. For matsoni and fermented baked milk, the curd is slightly viscous; for yogurt, the consistency is homogeneous, reminiscent of sour cream; For Varents, the presence of milk foam is allowed.
The color of fermented baked milk and matsoni is milky white or cream, Varenza has a brownish tint, and yoghurt is milky white. The fat content corresponds to the fat content accepted in the area for whole milk, but not less than 2.8%, and for yogurt not less than 6%. Acidity: for Varents 75-120°T, for matsoni and fermented baked milk 85-150°T, for yogurt 80-140°T.
Varenets, matsoni, fermented baked milk, yogurt and other fermented milk products are checked organoleptically, selectively for acidity and fat content.
4.5.1. Determination of fat content in fermented milk products. 11 g of dairy product are weighed into a clean milk butyrometer, 10 ml of sulfuric acid (density 1.81-1.82) and 1 ml of isoamyl alcohol (density 0.810-0.813) are poured. Next, fat determination is carried out as indicated in paragraph 3.4.
The indicator calculated on the butyrometer scale is multiplied by 2.2. The resulting number indicates the fat content in grams per 100 ml of product.
4.5.2. Determination of acidity of fermented milk products. Add 20 ml of distilled water to a 100-250 ml conical flask and add 10 ml of dairy product with a pipette. The remaining product from the pipette is transferred to the flask by washing it with water in the flask. Mix the contents of the flask thoroughly, add 3 drops of a 1% alcohol solution of phenolphthalein and titrate with 0.1 N. solution of sodium hydroxide (potassium) until a faint pink color does not disappear within 1 minute. The calculation is carried out as indicated in paragraph 3.3.
4.6. Butter. The taste and smell are characteristic of this type of oil, without extraneous, pronounced tastes and odors. Consistency and appearance - dense, homogeneous. When cut, the surface is slightly shiny; the presence of single tiny droplets of moisture is allowed.
Color from white to light yellow. Fat content not less than 78%. Humidity no more than 20%. The content of table salt in salted butter is no more than 1.5%.
Ghee butter. The taste and smell are pure, characteristic of this type of oil, without extraneous, pronounced tastes and odors.
Consistency and appearance - soft, grainy. When melted, the butter should be transparent, without sediment.
Color from white to light yellow, uniform throughout the mass. Humidity no more than 1%. Fat content not less than 98%.
The oil is checked organoleptically and, if necessary, the fat content, the concentration of table salt, the presence of moisture and impurities are determined.
4.6.1. Determination of fat content in butter. The amount of fat in unsalted butter is determined by the formula:
Where B is the moisture content in the oil, %;
C is the content of fat-free dry matter in oil, %;
- salt content in salted butter, %.
4.6.2. Determination of moisture in butter. On a technochemical scale, weigh 5 g of oil into a dry aluminum glass and heat it to a calm, uniform boil. Do not allow oil to splash during boiling. The end of water evaporation is determined by the disappearance of foam on the surface of the oil, the absence of characteristic crackling and the appearance of slight browning of the sediment in the glass. After removing moisture, the glass is cooled, weighed and the moisture content is determined using the formula:
Where B is moisture, %;
C is the mass of the glass with oil before heating;
O is the mass of the glass with oil after removing moisture;
5 - weighed amount of oil.
4.6.3. Determination of table salt in butter. Weigh 5 g of oil into a glass, add 50 ml of water heated to 40-50°C. The contents of the glass are thoroughly mixed and left until the oil rises to the top and hardens. The frozen layer of oil is pierced with a pipette and 10 ml of extract is collected, which is transferred to a conical flask. Then 0.5 ml of a 10% solution of potassium chromate is added to the extract and titrated with a solution of silver nitrate (2.906 g of silver nitrate is dissolved in 100 ml of distilled water) until a weak brick-red color is obtained, which does not disappear when shaking and crushing large particles with a glass rod. draft.
Number of milliliters 0.1 N. of silver nitrate solution used to titrate 10 ml of extract will express the percentage of salt.
Note. 1 ml 0.1 n. solution of silver nitrate used for titration corresponds to 0.01 g of sodium chloride.
4.7. Brynza and homemade cheese. These products must be made from whole milk obtained from healthy cows, buffaloes, sheep and goats from farms free from infectious animal diseases. The taste and smell are typical for this type of product, without any foreign tastes or odors. Fat content in dry matter is at least 40-50%. Moisture content is no more than 52%, and table salt is no more than 7%.
Bryndza and cheese are checked organoleptically and, if necessary, for fat content, table salt and moisture content.
4.7.1. Determination of fat content in feta cheese and homemade cheese. Place 2 g of feta cheese into a clean milk butyrometer and pour in 19 ml of sulfuric acid (density 1.50-1.55) so that the liquid level is 4-6 ml below the base of the butyrometer neck. Then 1 ml of isoamyl alcohol is added to the butyrometer. The butyrometer is closed with a dry rubber stopper and placed in a water bath heated to a temperature of 70-75°C, where it is kept until the protein substances are completely dissolved, shaking occasionally. Further determination of fat is carried out as indicated in paragraph 3.4.
4.7.2. Determination of moisture in feta cheese and homemade cheese. The study is carried out as described in paragraph 4.4.2.
4.7.3. Determination of table salt in feta cheese and homemade cheese. 2-3 g of the product are placed in a porcelain crucible and dried in an oven (with a gradual increase in temperature to 120-140°C) until a dark gray precipitate is obtained.
The resulting mass is carefully crushed with a glass rod and treated with 4-5 parts of water heated to 80-90°C. The liquid portion is then filtered through a paper filter into a conical flask. The residue in the crucible and on the filter is washed with water (temperature 70-80°C) until the reaction of the last portions of the filtrate with silver nitrate stops. To do this, a small portion of the filtrate in a test tube is acidified with 1-2 drops of nitric acid and 1-2 drops of silver nitrate solution are added. Further research is carried out as indicated in paragraph 4.6.3.
4.8. Kumis is made from the milk of healthy mares, subject to technological standards and rules for its preparation.
Kumis must meet the following requirements. The taste and smell are pure, specific for natural kumys, without extraneous tastes and odors that are not characteristic of a benign product; slightly sweet for weak koumiss.
The consistency is liquid, homogeneous, carbonated, foaming. The color is milky white. Fat content not less than 1%. Acidity: in weak koumiss (ripening 5-6 hours) 60-80°T, average (ripening 1 day) 80-100°T and strong (ripening 2 days) 101-120°T.
Alcohol content in kumys: weak 1%, average 1.5%, strong 3%.
Kumiss is checked for fat content and acidity, as indicated in paragraphs 4.5.1 and 4.5.2.
4.8.1. Kumis should not contain residual amounts of pesticides and antibiotics, and the presence of pathogenic microorganisms is not allowed. The titer of E. coli should be no lower than 0.3.
4.8.2. Kumiss that does not meet the above requirements is not allowed for sale.
5. Additional research into milk and dairy products
5.1. Testing milk samples for the detection of peroxidase. If it is suspected that the milk has been heated or that raw milk has been added to it after boiling, it is checked by testing for the presence of peroxidase. To do this, add 5 drops of potassium iodide starch and 5 drops of 0.5% hydrogen peroxide to a test tube with 5 ml of the milk being tested.
After thorough shaking, a dark blue color quickly appears in a sample of raw milk, while the color does not change in a sample of heated (80°C) or boiled milk.
5.1.1. To prepare a solution of potassium iodide starch, take 3 g of starch (with an accuracy of 0.05 g) and dissolve it in a small amount of cold water until a homogeneous mass is obtained. Separately, bring 100 ml of water to a boil in a flask and, with continuous stirring, add water to the diluted starch, avoiding the formation of lumps. The resulting solution is brought to a boil. After cooling, add 3 g of potassium iodide to the starch solution, stirring until the crystals dissolve.
5.1.2. To prepare a 0.5% solution of hydrogen peroxide, take a concentrated solution and, depending on the content of hydrogen peroxide in it (indicated on the label), dilute it to the required concentration with pre-boiled and cooled water.
The solution is unstable and should be prepared in small quantities and stored in a dark, cool place.
5.2. A test for reductase is carried out in arbitration cases. To do this, pour 1 ml of a working solution of methylene blue and 20 ml of test milk into a test tube, close it with a stopper, mix by slowly inverting the test tube three times and place it in a reductant with a water temperature of 38°C. In the absence of a reductant, you can use a water bath at a temperature of 38-40°C.
The water in the reductant or water bath after immersing the test tube with milk should reach the level of the liquid in the test tube or be slightly higher, and its temperature should be maintained during the entire determination time within 38-40°C.
The moment the tubes are immersed in the reductive tank is considered the beginning of the analysis. Observation of color changes is carried out after 20 minutes, 2 hours and 5 hours 30 minutes after the start of the analysis. The end of the analysis is considered to be the moment the color of the milk discolors, while the remaining small ring-shaped colored layer at the top (about 1 cm) or at the bottom of the tube is not taken into account. The appearance of milk coloring in these test tubes during shaking is not taken into account.
Depending on the time of discoloration, milk is classified into one of four classes according to the degree of its good quality and the approximate bacterial contamination is determined by the number of microorganisms that produce reductase.
|
Discoloration rate |
Number of bacteria in 1 ml of milk |
Milk class and rating |
|
Over 5 hours 30 minutes |
Less than 500 thousand |
I, good |
|
>2 hours to 5 hours 30 minutes |
From 500 thousand to 4 million |
II, satisfactory |
|
>20 minutes to 2 hours |
From 4 million to 20 million |
III, bad |
|
20 minutes or less |
20 million and above |
IV, very bad |
Notes 1. The preparation of a saturated alcohol and working solution of methylene blue is indicated in the note to clause 3.6.
2. Preparation of a working solution of methylene blue from fixanal; the contents of the ampoule are transferred to a 200 ml volumetric flask and distilled water is added to the mark.
5.3. Examination of milk for the presence of staphylococcal toxin.
5.3.1. 2 ml of each milk sample under study is poured into bacteriological test tubes, and for control, 2 ml of physiological solution is poured into one test tube. Add 1 drop of rabbit erythrocytes diluted with a 5% solution of sodium citrate to all test tubes, shake thoroughly and place in a thermostat at 37°C for 1 hour, then incubate for 1 hour at room temperature, then centrifuge at 1000 rpm in for 10 minutes and take into account the reaction.
If the reaction is positive (the toxin is present), the red blood cells are lysed and the milk column turns uniformly red. If the milk curdles during the study, then such samples are not subject to recording.
If the reaction is negative (absence of toxin) in the test sample, the milk above the settled red blood cells remains white.
In the control tube, red blood cells settle to the bottom, and the physiological solution above them is not stained.
5.3.2. Milk samples that give positive reactions are retested with specific antitoxic staphylococcal serum. To do this, take two test tubes, pour 2 ml of test milk into each, add 1 drop of rabbit erythrocytes to the first, 1 drop of rabbit erythrocytes and 2 AE (antitoxic units) of the specified serum to the second. The samples are kept in a thermostat at 37°C for 1 hour and 1 hour at room temperature, then centrifuged at 1000 rpm for 10 minutes and the result is finally taken into account. If there is hemolysis in a test tube without serum, but there is no hemolysis in a test tube with serum and the milk column above the red blood cells remains white, the reaction is considered specific.
If there is hemolysis in both tubes, the reaction is considered nonspecific.
Notes 1. To obtain red blood cells, take blood from a rabbit’s ear into a test tube with a 5% solution of sodium citrate (1 part solution to 4 parts blood). The resulting blood is centrifuged, the plasma is sucked off, and the red blood cells are washed three times in a centrifuge with saline. Then the red blood cells are diluted with physiological solution in a ratio of 1:2 and stored in the refrigerator at a temperature of 3-5°C.
2. Antitoxic staphylococcal serum is obtained at the All-Russian Research Institute of Veterinary Sanitation.
3. If the dried serum contains 60 AE in 1 ml, then 3 ml of physiological solution is added to the ampoule, and at 80 AE - 4 ml (0.1 ml of such a dilution contains 2 AE). Native (undried) whey is added in an amount of 2 AE without dilution with saline.
5.4. Testing cottage cheese and sour cream for the presence of staphylococcal toxin.
5.4.1. To detect staphylococcal toxin in cottage cheese and sour cream, their acidity is first determined according to Turner. Then 5 g of sour cream or cottage cheese is placed in a glass jar with a capacity of 20-25 ml, 10 ml of saline is added and thoroughly rubbed with a glass rod.
If the acidity of the sample is within 100°T, then 0.3 ml of normal sodium hydroxide solution is added to neutralize the acid. For acidity above 100°T, add 0.5 ml of normal sodium hydroxide solution. Then the suspension of cottage cheese or sour cream is centrifuged for 10 minutes at 2000 rpm. The supernatant is sucked off, 2 ml from each test sample is poured into bacteriological tubes and 1 drop of diluted rabbit erythrocytes is added. Further research, with the exception of centrifugation (which is not carried out), and recording of the reaction results are carried out in the same way as when examining milk.
5.5. The test method for the presence of staphylococcal toxin indirectly indicates the possible presence of staphylococcal enterotoxin in milk and dairy products, which is in most cases an integral part of the toxin.
5.6. Samples of milk, cottage cheese, and sour cream that give a positive specific hemolysis reaction contain, in addition to the toxin, up to 1.6 billion pathogenic staphylococci. Such products are unsuitable for food.
5.7. Examination of milk by ring test for brucellosis. 1 ml of milk and 1 drop of colored brucellosis antigen (a suspension of brucella stained with hematoxylin) are poured into a test tube with a diameter of 5-8 mm and placed in a thermostat at a temperature of 37°C for 40-45 minutes. A positive reaction is characterized by the appearance of a blue ring in the upper layer of liquid; in a questionable reaction, a slightly colored bluish ring; in a negative reaction, no changes occur.
5.8. Method for determining the fat-free dry matter content of oil without fillers. The content of fat-free dry matter in the oil is determined after determining its moisture content. (Moisture content is determined as specified in paragraph 4.6.2.)
A glass rod is placed into an aluminum beaker and weighed. A sample of the butter being tested is weighed into a glass (with an accuracy of 0.01 g): 10 g butter or 20 g ghee.
After determining the moisture content, the remainder in the aluminum glass is slowly heated until the fat melts, 50 ml of gasoline or ethyl ether is added, the mixture is thoroughly mixed with a stick and left alone for 3-5 minutes to allow sediment to settle. Particles floating on the surface of gasoline that do not settle to the bottom indicate incomplete evaporation of moisture. In this case, the determination of the presence of nonfat dry matter must be repeated.
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Smirnov A.V.
SUMMARY
This article discusses and analyzes the requirements of regulatory documents in force in the Russian Federation for the quality and safety of kumiss made from mare’s milk and methods for its control.
INTRODUCTION
Kumis is one of the main fermented milk products made from mare's milk. The preparation of kumis has a history of more than 5000 years. This fermented milk product has excellent nutritional, dietary and immunobiological properties. Kumis is used in the treatment of tuberculosis, digestive diseases and as a general tonic. However, it should be remembered that only kumiss made from natural mare’s milk has dietary and medicinal properties. In addition, kumis produced from the milk of sick mares, or if its production technology, storage, transportation and sale conditions are violated, can be a source of zooanthroponotic diseases, foodborne diseases and human poisoning. Therefore, the correct organization of veterinary and sanitary examination of kumys is especially relevant.
When conducting a veterinary and sanitary examination, it is necessary to determine organoleptic and laboratory indicators of the safety quality of this drink using methods established by current regulatory documents.
The main objective of our article is to consider and analyze the requirements imposed by regulatory documents on the quality and safety of mare's milk, and the methods of their research in the Russian Federation.
MATERIAL AND RESEARCH METHODS
We conducted a documentary analysis of regulatory documents regulating the requirements for quality, safety, identification of kumiss and methods of its veterinary and sanitary examination, operating on the territory of the Russian Federation. An analysis of the mandatory requirements for kumis imposed by Federal Law-88 was carried out. “Technical regulations for milk and dairy products dated June 12, 2008, as amended July 22, 2012.” and requirements for this product according to GOST R 52974-2008 “Koumiss. Technical conditions".
RESEARCH RESULTS AND THEIR DISCUSSION
Until recently, in the Russian Federation there was no single regulatory document regulating the quality requirements for kumys. The safety requirements for this product were determined according to SanPiN 2.3.2.1078-01. Recently the situation has changed radically. Federal Law-88 “Technical Regulations for Milk and Dairy Products dated June 12, 2008, as amended on July 22, 2010” was adopted, which contains requirements for the safety of kumys, its processing, storage, sales, certification, etc., and the national GOST R 52974-2008 standard, which defines the quality requirements for this product.
Federal Law-88 and GOST R 52974-2008 define kumys as a fermented milk product produced by mixed (lactic and alcoholic) fermentation and ripening of mare's milk using starter microorganisms - Bulgarian and acidophilic lactic acid rods and yeast. Fermented milk products made not from mare's milk, but from normalized cow's milk should be called kumys product. Kumiss product is a fermented milk product made from cow's milk in accordance with the technology of kumys production.
In accordance with the requirements of these regulatory documents, kumiss must be made from mare's milk obtained from healthy horses in farms free from infectious diseases of animals. Mare's milk used for the production of kumys must comply with GOST R 52973-2008.
When conducting a veterinary and sanitary examination of kumys, it is necessary to determine indicators of its quality and safety: organoleptic (appearance, taste, color, smell, consistency) and laboratory (density, amount of protein, fat content, alcohol content, temperature).
The main requirements for the quality of mare's milk according to GOST R 52974-2008 are presented in Table 1.
Table 1.
Quality indicators of kumys
|
Quality indicator of kumys / unit. measurements |
|
|
Appearance |
Opaque liquid |
|
Consistency |
Liquid, carbonated, foaming, homogeneous without stray lumps of fat and flakes |
|
Taste and smell |
Pure fermented milk, slightly spicy specific to kumys be? foreign tastes and odors (yeast is allowed) |
|
Color |
Milky white throughout |
|
Acidity D T |
up to 80 |
|
Fat content b % |
0 t 1 |
|
Protein % |
From 2 |
|
Temperature in °C |
|
|
Phosphotase |
Not allowed |
|
Ethanol |
Footprints |
In addition to the quality and safety indicators of kumys and the kumys product, in accordance with the requirements of Federal Law-88, the indicators of its toxicological, microbiological and radiobiological safety are periodically monitored, see table. 2.
Table 2.
Maximum permissible levels of potentially hazardous substances in kumys and kumys product according to the “Technical Regulations for Milk and Dairy Products dated June 12, 2008 (as amended on July 22, 2010).”
|
Toxic substances |
Unit measurements . |
|
|
Heavy metals |
||
|
Lead |
od |
mg/l |
|
Arsenic |
0,05 |
mg/l |
|
Cadmium |
0,03 |
mg/l |
|
Mercury |
0,005 |
mg/l |
|
Mycotoxins |
||
|
Aflotszhsin Ml |
0,0005 |
mg/l |
|
Antibiotics |
||
|
Levomycetin |
0,01 |
mg/l |
|
Tetracyclips |
0,01 |
U/g |
|
Streptomycin |
U/g |
|
|
Penicillin |
0,01 |
U/g |
|
Inhibiting substances |
Not allowed |
|
|
Pesticides |
||
|
Hexachlorocyclotexane |
0,05 |
mg/l |
|
DDT and its metabolites |
0,05 |
mg/l |
|
Radionuclides |
||
|
Cesium -137 |
Bq/g |
|
|
Strontium -90 |
Bq/g |
|
|
Microorganisms |
||
|
Titer SaLmoneLLa, Listeria and etc . Pathogenic] |
Ml |
|
|
Title E. Coii |
Ml |
|
|
St.Aureus |
Ml |
|
|
Yeast |
Up to MO 5 |
cfu/cm3 |
|
Lactic acid bacteria no less |
Up to 1]0 7 |
cfu/cm3 |
As our analysis of the toxicological, microbiological and radiobiological requirements for the safety of kumys contained in the Technical Regulations showed, they do not differ significantly from those previously in force (SanPiN 2.3.3.1078-01).
In order for the results of the veterinary and sanitary examination of mare's milk to be legitimate, when conducting all studies it is necessary to use the methods prescribed by Federal Law-88 and GOST R 52974-2008: determination of taste and smell GOST 28279-89, determination of the amount of protein - GOST 23327-98, determination of fat content - GOST 5867-90, determination of acidity - GOST
3624-84, temperatures - GOST 26754-85, determination of the presence of phosphatase
GOST 3623-73, determination of alcohol GOST 3629-47, determination of lactic acid bacteria GOST 10444.11-85, determination of yeast - GOST 10444.12-88, determination of the presence of antibiotics - GOST R 51600-2000, etc.
For the first time, the requirements of regulatory documents in force in the Russian Federation for the quality and safety of koumiss and koumiss product and methods for their control were comprehensively reviewed and analyzed.
In general, the study showed that currently in the Russian Federation there are all the necessary regulatory documents for the production, sale of kumys and methods for monitoring its quality and safety.
LITERATURE
1. GOSTR 52974-2008. Kumis. Technical conditions.
2. Inikhov G.S. Biochemistry of milk and dairy products. - M.: Food industry, 1970. -317 p.
3. Smirnov A.V. Documents regulating the veterinary and sanitary examination of milk and its processed products. Issues of legal regulation in veterinary medicine No. 3 St. Petersburg, 2008.
4. Smirnov A.V. Veterinary and sanitary examination of raw mare's milk. Questions of hippology and veterinary medicine No. 3. 2012.
1. Sampling
To control the quality in consumer packaging based on organoleptic and physico-chemical indicators, a sample is taken from each batch of products.
A batch is considered to be a set of units of products of the same name, in a homogeneous container, with the same physical and chemical characteristics, intended for control, produced at the same manufacturing plant, on the same technological equipment, during the same technological cycle, according to a single production mode, with the same production date and issued one accompanying document.
Sampling and preparation for analysis is carried out in accordance with the requirements: GOST 3622-68, GOST 9225-84, GOST 26809-86.
Liquid fermented milk products in consumer containers are mixed depending on the consistency of the product by turning the bottle, bag or spatula five times for about 1 minute after opening the container and poured into a container, making up a combined sample.
Pour kefir into kumiss into a beaker, place it in a water bath at a temperature of 30-35°C for 10 minutes, stir to remove carbon dioxide.
From the combined sample after mixing, a volume of about 0.1 dm 3 is isolated for analysis.
Products are examined no later than 4 hours after taking average samples.
2. Organoleptic studies.
The organoleptic properties of fermented milk products depend on the quality of raw materials - milk, cream, skim milk and other dairy products used for normalization, the type and quality of starter cultures, additives (fillers), the equipment used and technological process parameters, the type and quality of packaging material, assortment and conditions storage
One of the most important factors determining the organoleptic properties of fermented milk products is the development of starter microflora. Organoleptic properties. the energy of acid and aroma formation are the main parameters when selecting and using starter cultures, taking into account the production method and the target properties of the product.
During the production of fermented milk products and sour cream, acid coagulation of casein occurs, which determines their structure and consistency. In this case, the amount of dispersion of protein and fat particles is important; the higher it is, the more stable the structure is in storage, and the more homogeneous the consistency.
The structure and consistency of fermented milk products are significantly influenced by the heat treatment modes of milk and cream.
The structure and consistency of fermented milk drinks of the tank production method largely depend on the timely termination of ripening, the start of mixing and cooling conditions of the curd, the degree of mechanical impact during its pumping and bottling. At pH 4.5 - 4.3, the curd already has sufficient density with a small degree of syneresis.
A huge role in creating the smell and taste of fermented milk products is played by the development of starter microflora, the organoleptic characteristics of which are regulated by TD depending on the type of product. Lactic acid, diacetyl, acetoin, acetic and other aldehydes, esters, ethanol, terpenes, CO2, VFAs, etc. are involved in the formation of the taste and smell of these products.
Flavor-forming and acetic acid bacteria and yeast have a significant influence on the smell and taste of kefir.
An important factor in preserving the organoleptic properties of fermented milk products during storage (especially long-term) is the material in which the product is produced and stored. For example, in the production of kumys, the best material for the tank is wood (linden); when using stainless steel, the smell and taste characteristic of this product are not expressed.
Appearance and consistency. When inspecting paper containers, deformed, heavily wrinkled, dirty and torn bags are rejected.
There is fat deposits on the surface of non-homogenized milk products. Then the nature of the clot is determined, by which the intensity of the biochemical processes occurring during the manufacture and storage of products is judged. The condition of the clot depends on the production method: when pouring the product from a bottle or bag, a thin layer of it remains on the inside.
To determine the consistency of mixed-fermentation dietary products, the contents of the bottles are thoroughly shaken and poured into a glass. The nature of the consistency is judged by how the product flows into the glass. Pay attention to the presence of released serum.
Color. The color of dietary products in white glass containers is determined without opening the packaging. In other cases, the products are poured onto a saucer and viewed in diffuse daylight.
Taste and smell. To determine taste and smell, the product is shaken vigorously and then poured into a glass for testing.
In terms of organoleptic indicators, products must meet the requirements specified in GOST R 52093-2003 (kefir), GOST R 52094-2003 (ryazhenka), GOST R 52095-2003 (yogurt), GOST R 52974-2008 (kumys).
The kefir product must meet the following requirements:
Taste and smell - pure, fermented milk without foreign tastes and odors, slightly spicy taste, yeast is allowed. When produced on the basis of kefir cultures without the addition of non-dairy components - pure, fermented milk. When produced with food-flavoring products or food additives - with the taste and aroma of the added ingredient; when made with sugar or sweetener - moderately sweet.
When produced with food-flavoring products or food additives, it is determined by the color of the added ingredient.
Consistency and appearance - homogeneous, with a broken or undisturbed clot. Gas formation in the form of single bubbles is allowed, caused by the action of the sourdough microflora. When using food-flavoring products, inclusions may be present.
Curdled milk must meet the following requirements:
The taste and smell are pure, fermented milk, without foreign tastes and odors; for curdled milk, matsoni tastes slightly spicy.
The color is milky white, uniform throughout the mass.
Consistency and appearance - homogeneous, with a broken or undisturbed clot.
Ryazhenka must meet the following requirements:
Taste and smell - clean, fermented milk with a pronounced taste of pasteurization, has no foreign odors or tastes.
The color is light cream, uniform throughout the mass.
Consistency and appearance - homogeneous, with a broken or undisturbed clot, without gas formation.
Kumis must meet the following requirements:
When conducting a veterinary and sanitary examination of kumys, it is necessary to determine indicators of its quality and safety: organoleptic (appearance, taste, color, smell, consistency) and laboratory (density, amount of protein, fat content, alcohol content, temperature).
Quality indicators of kumys:
In addition to the quality and safety indicators of kumys and kumys product, in accordance with the requirements of Federal Law-88, the indicators of its toxicological, microbiological and radiobiological safety are periodically monitored.
Acidophilus and acidophilus milk must meet the following requirements:
Taste and smell - an alcoholic aftertaste is allowed if the product is prepared with the addition of sugar or other flavoring and aromatic substances; a moderately sweet taste and odor characteristic of the introduced substances are allowed.
Appearance and consistency - a dense clot, when diluted, a homogeneous mass in the form of liquid sour cream is obtained; for acidophilus milk, a dense, viscous, slight gas formation is allowed.
The color is milky white, uniform throughout the mass.
3. Physico-chemical studies.
In terms of physical and chemical indicators, products must meet the following requirements:
Mass fraction of fat 0.1-9.5%; kumiss 1%
Mass fraction of protein is not less than 2.6-2.8%; kumiss 2%
Acidity no more than: kefir, yogurt 85 - 130 T; fermented baked milk 70 - 110 T; kumys 80 T
Temperature upon release from the factory 4±2° C
Determination of acidity of products.
Acidity is determined in conventional units - Turner degrees (GOST 3624-92). Pipette 10 ml of the test product into a 100-150 ml flask or glass. The remaining product on the walls of the pipette is washed off with 20 ml of distilled water, 3 drops of a 1% phenolphthalein solution are added to the vessel and titrated with a 0.1 N alkali solution until a pale pink color appears, which does not disappear within 1 minute. The amount of alkali used for titration is multiplied by 10 in terms of 100 ml of product.
Acidity is calculated using the formula: K*T=V*10
Determination of mass fraction of fat.
Into a clean milk butyrometer (butyrometer) (GOST 5867-90), without wetting the neck, pour 10 ml of sulfuric acid and carefully add 10.77 ml of product with a pipette, add 1 ml of isoamyl alcohol, close the butyrometer tightly with a dry rubber stopper, turn over 4-5 times, place the stopper down in a water bath at a temperature of 65±2? C for 5 minutes. Having placed the butyrometers in centrifuge cartridges (with the stopper towards the periphery), centrifuge for 5 minutes at a rotation speed of at least 1000 minutes, after which they are placed in a water bath at 65±2? C for 5 minutes.
The butyrometer indicators correspond to the fat content in milk as a percentage. The volume of 10 small divisions on the milk butyrometer scale corresponds to 1% fat in the product. Fat counting is carried out with an accuracy of one small division of the butyrometer. The difference between parallel determinations should not exceed 0.1% fat. The arithmetic mean of two parallel determinations is taken as the final result.
Control of pasteurization of products. (GOST 3623-73).
Peroxidase reaction with potassium iodide starch. Add 2-3 ml of the product into a test tube, add 3-5 ml of water, 5 drops of a 1% solution of hydrogen peroxide and 5 drops of a 1% solution of potassium iodide starch. The appearance of a blue color indicates that fermented milk products are made from unpasteurized milk or cream.
In addition to organoleptic and physicochemical indicators confirming the quality and nutritional value of the product, an examination is carried out on safety indicators: toxic elements (lead, cadmium, copper, zinc, mercury, arsenic); mycotoxins (aftoxin M); antibiotics (tetracycline group, penicillin, streptomycin); hormonal drugs; pesticides; radionuclides (cesium-134-137 and strontium-90).
Taking an average sample
The fermented milk product is thoroughly mixed. For all products, an average sample of 50 ml is taken. The exceptions are sour cream (15 g) and cottage cheese (20 g). In all cases, fermented milk products are examined organoleptically and the fat content and acidity are selectively determined. If necessary, examine for falsification and control the pasteurization or boiling regime.
Products are examined no later than 4 hours after taking average samples. If the product contains a lot of carbon dioxide and has a pronounced ability to foam (kumys, kefir, etc.), then it is examined after removing carbon dioxide by heating at 40-45? C for 10 minutes and then cooling to 18-20? C .
Organoleptic studies
The color of the product is determined in a clean glass made of colorless glass. It depends on the type of fermented milk product.
The consistency should be uniform, moderately thick, stable, without disturbing the surface and without pores of gas formation. There may be a slight separation of whey on the surface (no more than 5% of whey to the total volume of the product is allowed). Matsoni and fermented baked milk should have a slightly viscous curd. For Varents, the presence of milk films is allowed. The taste and smell of benign products is fermented milk, without any foreign tastes or odors. Fermented milk products that are unleavened, swollen, excessively sour, with gas formation, with a pronounced foreign odor or taste, with a sour (bitter) taste, unusual color, friable, with mold on the surface and with the release of whey of more than 5% of the total are not allowed for sale. volume of product. Mild defects are allowed in first-grade sour cream and cottage cheese: tastes of feed origin, wooden containers or slight bitterness.
Determination of fat content in fermented milk products.
In two milk butyrometers (types 1 - 6 or 1 - 7), weigh out (counting to 0.005 g) 11.00 g of fermented milk product, 5.00 g of sour cream or cottage cheese. Carefully pour 10 cm3 of sulfuric acid (density from 1810 to 1820 kg/m3). Using a dispenser, add 1 cm3 of isoamyl alcohol to the butyrometers.
The level of the mixture in the butyrometer is set to 1-2 mm (when determining fat in sour cream 4-5 mm) below the base of the butyrometer neck, for which it is allowed to add a few drops of distilled water.
Butyrometers are closed with dry stoppers and shaken until the protein substances are completely dissolved, turning at least 5 times. Place the butyrometers with the plug down for 5 minutes in a water bath at a temperature of 65±2°C. After removing from the bath, the butyrometers are centrifuged for 5 minutes. Then the butyrometers are immersed with their plugs down in a water bath for 5 minutes at a temperature of 65±2°C, while the water level in the bath should be slightly higher than the level of fat in the butyrometer.
Butyrometers are removed one at a time from the water bath and the fat is quickly measured. When counting, the butyrometer is held vertically, the fat border should be at eye level. By moving the plug, the lower limit of the fat column is set at zero or a whole division of the butyrometer scale. From it the number of divisions is counted to the lower point of the meniscus of the fat column with an accuracy of the smallest division of the butyrometer scale.
The interface between fat and acid should be sharp and the fat column transparent. If there is a “ring” (plug) of a brownish or dark yellow color, various impurities in the fat column or a blurred lower boundary, the measurement is repeated.
The measurement result is taken as the arithmetic mean of the results of two parallel observations, the discrepancy between which (convergence) does not exceed 0.1 for fermented milk products and 0.5 for sour cream and cottage cheese.
The butyrometer readings during measurements correspond to the mass fraction of fat in these products as a percentage.
Determination of acidity of fermented milk products.
Distilled water and fermented milk product in volumes of 10 and 20 cm3, respectively, and three drops of phenolphthalein are measured into a flask with a capacity of 100 or 250 cm3. The remaining fermented milk product is transferred from the pipette to the flask by washing the pipette with the resulting mixture 3 - 4 times. The mixture is thoroughly mixed and titrated with 0.1 N sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.
In sour cream, acidity is determined in the following way: in a flask with a capacity of 100 or 250 cm3, weigh out 5 g of the product, add 30 cm3 of water and three drops of phenolphthalein. The mixture is thoroughly mixed and titrated with sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.
To study cottage cheese, add 5 g of the product to a porcelain mortar. Mix thoroughly and grind the product with a pestle. Then add in small portions 50 cm3 of water heated to a temperature of 35 - 40 ° C and three drops of phenolphthalein. The mixture is stirred and titrated with sodium hydroxide solution until a faint pink color appears, which does not disappear within 1 minute.
Acidity, in degrees Turner (°T), is found by multiplying the volume, cm3, of sodium hydroxide solution spent on neutralizing the acids contained in a certain volume of the product by the following factors: 10 - for fermented milk products, 20 - for sour cream, cottage cheese and curd products.
The permissible error of the analysis result with the accepted confidence probability P = 0.95 is: ±1.9°T - for fermented milk products; ±2.3°T - for sour cream; ±3.6°T - for cottage cheese and curd products.
The discrepancy between two parallel determinations should not exceed: 2.6°T - for fermented milk products; 3.2°T - for sour cream; 5.0°T - for cottage cheese and curd products.
Control of pasteurization of fermented milk products
The analyzed product and distilled water are measured or weighed into a test tube. When studying fermented milk drinks, the product should be 5 cm3, and no water should be added. When studying sour cream and cottage cheese, the product should be 2-3 g, and water - 2-3 cm3.
Fermented milk drinks with fruit and berry fillings are filtered through a paper filter.
Pasteurization is determined by the reaction of the filtrate with potassium iodide starch.
2.5 cm3 of the buffer mixture is poured into a test tube with the specified amount of product and water, thoroughly mixed with a glass rod and placed in a water bath with a water temperature of 35±2°C, where it is kept for 3-5 minutes so that the contents of the test tube reach this temperature. Then add 6 drops of 0.5% hydrogen peroxide solution and 3 drops of paraphenylenediamine hydrochloride solution, mix the contents of the test tube with rotational movements after adding each reagent. After this, place the test tube in a water bath again and observe the change in color of the liquid.
In the absence of the peroxidase enzyme, the color of the contents of the tube does not change. Consequently, dairy products were pasteurized at a temperature of at least 80°C.
In the presence of peroxidase in fermented milk products, the contents of the test tubes acquire a gray-violet color, gradually turning into a dark blue color. Therefore, the dairy products were not pasteurized or were pasteurized at temperatures below 80°C, or were mixed with unpasteurized products. The sensitivity of the method allows you to detect the addition of at least 5% of unpasteurized dairy products to pasteurized ones.
Method for determining the number of Staphylococcus aureus
Determination method with preliminary enrichment.
A series of tenfold dilutions are prepared from a sample of the product in accordance with GOST 9225 so that it is possible to determine the presence or absence of Staphylococcus aureus in a certain mass (volume) specified in the regulatory document for a specific product.
A 1 cm3 sample of the product or its dilution is inoculated into test tubes or flasks with saline broth. The ratio between the amount of product sown or its equivalent dilution and the nutrient medium is 1:10. Test tubes and flasks with inoculations are kept in a thermostat at a temperature of 37±1°C for 24 hours.
To confirm that microorganisms grown in salt broth belong to Staphylococcus aureus, subculture with a loop from the broth is done to obtain isolated colonies on Petri dishes with dried media such as Baird-Parker, yolk-salt agar or milk-salt agar. Cups with crops are kept in a thermostat at a temperature of 37±1°C for 24-48 hours.
After thermostatting, the crops are examined and the growth of characteristic colonies is noted. On yolk-salt agar, Staphylococcus aureus colonies have the shape of flat discs with a diameter of 2-4 mm of white, yellow, cream, lemon, golden color with smooth edges; A rainbow ring and a zone of turbidity of the medium are formed around the colonies. On milk-salt agar, Staphylococcus aureus colonies grow as opaque round colonies, white to orange in color, 2-4 mm in diameter, slightly convex. On Baird-Parker medium, Staphylococcus aureus colonies grow in the form of black, shiny, convex colonies with a diameter of 1-1.5 mm, surrounded by a clearing zone of the medium 1-3 mm wide.
At least five characteristic colonies are selected from each Petri dish and transferred to the surface of a nutrient agar slant without the addition of sodium chloride and yolk emulsion. The crops are kept in a thermostat at a temperature of 37±1°C for 24 hours.
From five isolated colonies characteristic of Staphylococcus aureus, preparations are made, Gram stained and microscopically examined.
To prepare the preparation, a drop of distilled water is applied in a loop to a clean and cooled glass slide after filling, into which a small amount of agar culture is added in a loop without stirring in the water. Then add a drop of reagent 1 in a loop, prepared as follows: 0.5 g of crystal violet is dissolved in 100 cm of ethyl alcohol. The mixture is distributed over an area of approximately 1 cm², dried at a temperature of 20±2 °C and fixed by slowly passing a glass slide over the burner flame. You can prepare 6-8 strokes on one glass, separating them from one another with lines drawn from the front side of the glass.
The preparation is rinsed with water and thoroughly dried with filter paper. After drying, an excess of reagent 2 is applied to the preparation (to 96 cm3 of an alcohol solution of potassium iodide with a mass concentration of 50 g/dm3 and 2 cm3 of an alcohol solution of iodine with a mass concentration of 50 g/dm3; potassium iodide is dissolved in alcohol in a water bath at a temperature of 45±5 ° With constant stirring), so that the liquid covers the entire surface of the glass. Duration of staining is 0.5-1 min. After staining, the preparation is quickly rinsed with running water, directing the stream at an angle onto glass placed vertically. The preparation is dried with filter paper and viewed under a microscope with an immersion system. Microbes that stain positively on the Gram have a spherical shape and are located in clusters, most often resembling bunches of grapes.
To set up a plasma coagulation reaction, a loop of a 24-hour agar culture is added to a test tube with 0.5 cm3 of diluted rabbit plasma. The introduced culture is thoroughly stirred. One tube with plasma is left uninoculated, and the other is inoculated with a control strain of Staphylococcus aureus (coagulase-positive staphylococcus). The test tubes are placed in a thermostat and kept at a temperature of 37±1 °C for 3-6 hours. If after 6 hours coagulation of the plasma has not occurred, then these test tubes are left for up to 24 hours. If after 24 hours the plasma has not coagulated, then the test staphylococcus culture is classified as to coagulase negative.
When determining coagulase activity, the reaction is considered negative in cases where individual threads or clots do not form in the plasma, or in cases where individual threads appear in the plasma (the plasma coagulation reaction is assessed as one plus).
The reaction is considered positive if:
The clot is dense;
A clot having a small compartment;
A clot in the form of a suspended sac.
If a positive reaction is obtained, it is considered that Staphylococcus aureus was detected in the cultures.
The results are assessed for each sample separately.
Morphological, cultural properties and a positive plasma coagulation reaction indicate the presence of coagulase-positive staphylococci in the inoculated mass of the product.
Determination method without pre-enrichment.
1 cm3 of liquid product or its dilution is applied to the surface of the nutrient media in 3 Petri dishes, carefully rubbed with a spatula over the surface of the nutrient medium. The crops are incubated at a temperature of 37±1 °C for 24-48 hours. Petri dishes with the crops are incubated with the bottom up.
After thermostatting, the number of characteristic colonies on each Petri dish is counted. From each Petri dish, at least five characteristic and/or suspicious colonies of Staphylococcus aureus are selected and transferred to the surface of a nutrient agar slant poured into test tubes. Test tubes with inoculations are kept in a thermostat at a temperature of 37±1 °C for 24 hours.
In grown cultures, the relationship to Gram staining and coagulation of rabbit plasma is determined.
The results are assessed for each sample separately. If, when studying characteristic colonies, in 80% of cases, that is, in at least 4 out of 5 colonies, the growth of Staphylococcus aureus is confirmed, then it is considered that all characteristic colonies grown on Petri dishes belong to Staphylococcus aureus. In other cases, the number of Staphylococcus aureus is determined based on the percentage of confirmed colonies to the total number of representative colonies taken for confirmation.
The number of colonies of Staphylococcus aureus in 1 g or 1 cm3 after its determination in a certain sample of the product is calculated by the formula:
Х= (Уn1 Х 10? + Уn2 Х 10?) : 2,
where Уn1; Уn2 is the number of colonies grown on all Petri dishes within one dilution or inoculated volume; n is the number of tenfold dilutions.
Determination of ethyl alcohol in kefir and kumis
First, prepare a pycnometer, which is thoroughly washed successively with a weak alcohol solution of alkali, water, a chrome mixture and again with water, then dried at a temperature of 100-105 ° C, cooled in a desiccator and weighed.
Weigh 100 g of the product into the distillation flask with an error of no more than 0.1 g, add dropwise a solution of sodium (potassium) hydroxide until a neutral or slightly alkaline reaction (according to litmus paper), place several glass capillaries there and close the flask with a stopper. Then connect the flask to reflux and slowly carry out distillation under moderate heating. A volumetric flask with a capacity of 100 cm3 is used as a receiver. The distillation is stopped after filling the flask to approximately 2/3 of the volume.
When a not very pure solution is obtained, it is quantitatively transferred to a clean distillation flask, in which the volume of the solution is adjusted to approximately 100 cm3 with water and distilled a second time. At the end of the distillation, the volumetric flask with the water-alcohol mixture is filled with water to the mark and mixed thoroughly. A water-alcohol mixture is poured into a pycnometer, previously weighed and prepared (with a pipette or a tube with a drawn capillary) from a volumetric flask to a level slightly above the mark, and the determination is carried out. Just like a solution, water is added to it.
A pycnometer with water is suspended on a thin thread from a glass rod placed on a tripod ring, and lowered into a glass of water, which should be approximately at the same level with the water of the pycnometer. To maintain a constant temperature (30.0±0.2°C), the glass is placed in a thermostat.
After 40 minutes, using filter paper or a tube with a retracted capillary, the meniscus of the pycnometer is set exactly on the mark, after which the pycnometer is closed with a stopper, removed from the glass, thoroughly wiped outside with filter paper and weighed.
The water number of a pycnometer P (the mass of water in the volume of a given pycnometer at 20°C) is calculated using the formula:
where m1 is the mass of an empty pycnometer with a plug, g; m2 - mass of the pycnometer with water and stopper, g.
The relative mass of ethyl alcohol solution d is calculated using the formula:
m3 is the mass of the pycnometer with a water-alcohol mixture, g.
The discrepancy between parallel determinations of the relative mass of the distillation solution should be no more than 0.0002.
The mass fraction of ethyl alcohol in the product is determined by relative mass.
Determination of moisture content in cottage cheese.
A porcelain cup with a glass rod and 20-25 g of sand is placed for 1 hour in a drying cabinet at a temperature of 102-105 ° C, after which, without cooling, it is weighed with an accuracy of 0.01 g. Then 5 g of the product is weighed into the cup and mixed it with sand and placed in a drying oven at a temperature of 160-165°C for 20 minutes. After which the cup is quickly weighed without cooling.
B = (A - B)*100/5,
Determination of cottage cheese or yogurt impurities in sour cream.
Add a tablespoon of sour cream to a glass of hot water. If there is falsification, the fat floats to the surface, and the casein of cottage cheese, curdled milk and other impurities settles to the bottom. Sour cream should not have sediment or, as an exception, only traces of it.
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