摘要：Since it is known that low concentration of κ--casein in milk has caused milk to become a heat-labile milk (HL milk). Efforts were made to study the nutritional problems of dairy cows in order to accert the cause of HL-milk. Fat-soluble vitami in the blood of HL-milk and normal milk (N-milk) dairy cows were determined. It was found that the average vitami A, D, E and K of HL-milk were 0.37 mg/ml, 1.37×10-4 mg/ml, 5.9×10-4 mg/ml, 5.9×10-2 mg/ml and 3.7×10-2 mg/ml in comparison with the normal milk of having 0.36 mg/ml, 1.30×10-4 mg/ml, 5.7 ×10-2 mg/ml and 4.6×10-2 mg/ml, respectively. It showed that HL-milk had slightly low concentration of vitamin k. SDS-gel electrophoresis studies showed there was little difference in the protein composition of blood between HL-milk and normal dairy cows.Some properties of he casein micelle (CM)in HL-milk was also characteri-zed. Its size was found to be about 0.9 of the normal size of casein micelle. As determined by turbidity measurement. Sedimentation analysis exhibited 190S and 235S sedimentation coefficient for the casein micelle of HL-milk and normal milk respectively further demotrating that the size of casein micelle of HL-milk was smaller than that of normal one. The result of viscosity measurement suggested that the intriic viscosity of the casein micelles in HL-milk was greater than the normal ones, as well as the viscosity of HL-milk was greatly influenced by casein micelle concentration. It had shown that the viscosity raised as the concentration of the casein micelle increased. However, from the result of turbidity measurement, HLCM and NCM show similar behavior of micellar interaction at their low concentration. Here it is concluded that the casein micelle of HL-milk is small in size and strong in micellar interaction at their higher concentration and lead to coagulation as heating.
