Processing technology for purifying casein made from Yak"Qula"

The main reasons for the low quality of the traditional Yak‘Qula’ casein are the oxidation of fats and high contents of impurity. The influences of enzyme agents and centrifugal conditions on the product quality were researched by using L₉(3⁴) orthogonal experiment with the improved technology. The results show that the optimal using conditions of enzyme agents are as follows: the temperature of the liquid material is 38℃, pH value is 4.2, the concentration of trypsase is 1.0 g/kg, reacting time is 5 min, the concentration of lipase is 0.01 g/kg and lactase is 0.03 g/kg; and the optimal centrifugal operation parameters are that the speed of rotation is 16000 r/min, time is 10 min, temperature is 50℃. The centrifuging method and enzyme treatment could not only remove the fat, lactose and the impurity in the liquid material, but also obviously improve the soluble viscosity, the color and the smell of the product. The infrared spectrum scan show that the quality of the product excells the quality of traditional products.