COW FEEDING SYSTEM VS. QUALITY OF MILK USED FOR ACID-CURD CHEESE (TVAROG) PRODUCTION

摘要

The study focused on processing quality of milk used for acid-curd cheese (tvarog) production, obtained from Polish Holstein-Friesian cows (Black-and-White variety) either fed a total mixed ration (TMR) or conventional feeds. Milk for analyses was collected six times per year, in about two months' intervals. The milk was analysed for density, acidity, and the content of fat, protein, and lactose. Fat dry matter content, non fat dry matter content, and protein:fat ratio were calculated. Thermal stability of milk was evaluated using alcohol (ethanol) tests. Titratable acidity, pH, hardness, and drip loss were measured in ready tvarog products. The cheese was also subjected to sensory evaluation. A marked effect of the feeding system on the composition and physico-chemical properties of milk was observed. Milk of cows fed conventional feeds contained more fat and dry matter, whereas that obtained from cows fed a TMR usually contained more crude protein, casein, and fat-less dry matter; it was also of higher density. Acid-curd cheeses produced from milk of a TMR-fed cows had a slightly better flavour, and also contained more water. Tvarogs made from milk of conventionally fed cows, on the other hand, contained more fat. The latter product was usually harder in texture. No direct linkage was found between acidity of tvarog or a drip loss thereof and the feeding system of cows.