Lactic acid products (fermented milk products) are products of lactic acid or mixed (lactic acid and alcohol) fermentation. Lactic acid products are prepared from pasteurized cow's milk or cream by fermenting them with starter, prepared on pure cultures of lactic acid bacteria with or without the addition of dairy yeast. The main types of lactic acid products are yogurt, acidophilus, acidophilic milk and kefir, sour cream and cottage cheese. The fat content of lactic acid products prepared from whole milk should not be lower than 3.2%. Fatty sour cream amateur - 40%, diet - 10%, the highest and first grade - 30%. For yogurt, pure cultures of lactic streptococci are used or in combination with other lactic acid bacteria. Acidophilus and acidophilus milk are produced in starter cultures from pure cultures of acidophilus sticks or in combination with other lactic acid bacteria and dairy yeast. Kefir is prepared in yeast from kefir fungi. In terms of ripening kefir is divided into weak (one-day), medium (two-day) and strong (three-day). Lactic acid products include koumiss, made from mare's or cow's milk, using fermentation cultures of lactic acid bacteria and lactic acid yeast. Like kefir, koumiss is divided into weak (one-day), medium (two-day) and strong (three-day). These varieties differ from each other mainly in alcohol content and acidity. In all types of koumiss, the fat content should be at least 0.8%, and the alcohol content should not exceed 2%. Lactic acid products can be produced low-fat, prepared from skimmed milk (skim milk). Fat content in low-fat milk products GOST does not provide.Go
Nutritional value of lactic acid products - see table.
|Product name||Chemical composition in%||Calories (large) per 100 g of product|
| Sour milk, acidophilus, acidophilus milk, kefir (fatty, whole milk) |
The same (from skimmed milk)
Koumiss medium, fat
The nutritional and nutritional values of lactic acid products (except for koumiss) are equivalent to cow's milk. However, in terms of digestibility, they are superior to milk. If milk is absorbed by 32% within an hour after consumption, then lactic acid products are absorbed by 91% for the same period. Lactic acid products have a normalizing effect on human intestinal microflora and inhibit the development of putrefactive germs in the intestine.
Lactic acid products have healing and healing properties in many intestinal diseases, especially colitis; they improve gastric and intestinal secretion, normalize intestinal motility, reduce gas formation. Lactic acid products have a tonic, tonic effect, contribute to a better metabolism, a positive effect on the nervous system.
Lactic acid products are perishable (see).
Lactic acid products also include cheeses, which are obtained from milk as a result of coagulation of casein (see) and its subsequent processing. Depending on the method of processing and ripening, cheeses are subdivided into hard (36-43% moisture), soft (moisture up to 55%), brine (cheese) and melted. In their composition, they contain 15–25% protein, 20–30% fat, 700–1000 mg% calcium, 400–600 mg% phosphorus, about 0.2 mg% vitamin A, 0.1 mg% thiamine and 0.5 mg% riboflavin . Caloric content of 100 g of cheese is 300 - 400 kcal. The most favorable storage of cheese is 8-10 °. Disruption of the physico-chemical processes of cheese production and the recommended storage regimes leads to the formation of various defects in them. Swelling and rancidation of cheeses is caused by bacteria from the group of Escherichia coli or the development of butyric and putrefactive anaerobic microorganisms; sour and bitter taste is inherent in "young", unripe cheeses. The coloring (blue, red) unusual for cheeses is caused by pigment-forming microorganisms. A very frequent defect of cheese is the molding of the surface and subcortical layer. Cheese with such types of spoilage cannot be sold and should be sent to industrial processing (production of processed cheese after removal of the affected parts) or technical utilization. Cheeses affected by cheese mites and cheese fly larvae are not suitable for feeding. Cheese can be the cause of food poisoning staphylococcal and Salmonella nature. There are cheeses for the manufacture of which molds are used (Roquefort, Brie, Camembert).Go
In order to prevent the ingress of pathogenic microflora, cheeses should be made only from pasteurized milk with the observance of ripening terms established for each type of cheese.
Cottage cheese is produced from milk by ripening it with lactic acid bacteria, followed by removal of whey from the clot in order to obtain a concentrated protein product.
Depending on the source of raw materials distinguish fat, bold and low-fat cottage cheese, and the production method - acid and acid-rennet. Curd, made from pasteurized milk, is intended for direct consumption and for the production of curd products from it; from unpasteurized milk, cottage cheese is used only to produce semi-finished products subjected to heat treatment.
The curd contains: protein (13–16%), including essential amino acids (tryptophan, lysine, methionine); fats (9–20%); mineral salts ( calcium 140-160 mg%, phosphorus 130-150 mg%). The caloric content of 100 g of fat cottage cheese is 250 kcal, of defatted - 75 kcal.
Cottage cheese is sold within 12 hours. from the time of manufacture, and under cooling conditions (t ° not higher than 8 °) - 36 hours. Dietary cottage cheese is implemented within 24 hours. (after 12 hours cooling is performed). Frozen cottage cheese should be stored in refrigerators at t ° from -8 to -12 ° not more than 7 months.
In lactic acid products, intensive vital activity of lactic acid bacteria proceeds, preventing the development of pathogenic microbes in them. However, in case of improper preparation of lactic acid products, non-observance of hygienic rules, violation of the terms and temperature of storage in lactic acid products, bacteria of typhoid fever , dysentery, etc., as well as food poisoning pathogens may persist. Especially dangerous in this regard, lactic acid products obtained as a result of spontaneous souring of milk ("samokvas"). In the public catering such lactic acid products are not allowed for sale. When preparing lactic acid products at home, one must observe the strictest cleanliness of the dishes, boil the milk beforehand and, after cooling, add a special leaven or yeast from previously prepared lactic acid products. The process of ripening should occur at t ° 25-30 ° and not stretch for a long time. Consumption of obtained lactic acid products should be made on the same or the next day. Lactic acid products should not be stored outside the refrigerator.