Component analysis and protein heat stability of yak milk fat globule membrane

To analyze the component and protein heat stability of yak milk fat globule membrane (MFGM), physical method was used to extract and separate MFGM from yak milk fat. The results show that the wash times to separate MFGM is very critical, and the optimum wash time is three. The yak MFGM mainly contains protein (26.93%) and lipids (70.34%), and there are other minor components in MFGM such as hexane, sialic acid and ash. The predominant amino acids in yak MFGM are Glu, Leu, Ser, Lys and Vla, and among these amino acids, the essential amino acids account 49.48% of total amino acids. When heated to 60°C the MFGM protein, especially for xanthine oxidase (XO) and Periodic acid Schiff 6/7 (PAS6/7), lose markedly. However, the SDS-PAGE under reducing conditions shows that the β-lactoglobulin and α-lactalbumin begin to associate with the MFGM at 60°C the MFGM protein is heat unstable protein.