MIGENA HOXHA1*, VLASH MARA1, PIRO ZOGA2
1* Faculty of Biotechnology and Food, Agriculture University of Tirana, Tirana, Albania
2 Department of Mineral Resources Engineering, Polytechnic University of Tirana, Tirana, Albania
Abstract: The syneresis process is influenced by various factors such as milk pH, curd incubation temperature, fat content, heat treatment of milk, acidity, salt, curd dimension and gel firmness at cutting time. The aim of this study was to investigate balance of protein, the syneresis kinetic of whey drainage and evaluation of velocity constant k (drained rate) on curd incubation temperature (25 and 30oC) and heat treatment (at 70oC for 5 minutes). Milk was sampled from cow, sheep and goat breeds. The milk samples were analyzed for physical and chemical properties (pH, acidity, protein, casein, fat and lactose), coagulation parameters (R coagulation time in minutes, curd firmness measured in volt after 20 minutes (A20) or 30 minutes (A30) and the rate of firming K20 in minutes) as well as for whey volume drained after 30, 50, 70, 90, 110, 130 and 150 minutes. During this study it was observed that the curd incubation temperature is the major factor affecting syneresis. Velocity constant k value (drained rate) is increased with higher temperature, but can be decrease significantly at low temperature. The syneresis rate differs between breed’s milk and is influenced by their coagulation properties. Regarding balance of protein, protein recovery and curd yield results to be higher at incubation temperature of 25oC, in spite of breed. Whey protein loss result to be higher for goat’s milk on two incubation temperature (41.05–58.35%), while the whey loss on sheep’s milk result to be lower (14.01–37.61%).
Key Words: Syneresis, protein balance, k value (drained rate), milk