Abstract: Changes in milk fat globule size and membrane protein composition determine the stability of fat globules, thereby affecting the stability of pasteurized milk during storage. In the present study, the effects of different preheating temperatures (50, 60 and 70 ℃) and homogenization pressures (20, 30, 40 and 45 MPa) on milk fat globule membrane (MFGM) proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the relationship between changes in MFGM protein composition and stability was explored using a stability analyzer. The results showed that homogenization affected the amounts but not types of MFGM proteins. The lowest levels of xanthine dehydrogenase/oxidase (XO) activity, butyrophilin (BTN) and adipophilin (ADPH) and the highest content of mucin 1 (MUC1) were obtained after preheating at 60 ℃. The contents of fatty acid binding protein (FABP) and periodic acid Schiff 6/7 (PAS6/7) decreased with the increase of preheating temperature, whereas the opposite was observed for cluster of differentiation 36 (CD36). XO, PAS6/7, BTN, ADPH and FABP reached the lowest values at a homogenization pressure of 40 MPa, and CD36 decreased with the increase of homogenization pressure. The analysis of MFGM protein composition showed that the contents of bovine serum albumin (BSA), αs1-casein (CN) and β-CN increased, with the largest increase being observed for BSA. From the above results, it can be inferred that homogenization can lead to the involvement of BSA, αs1-CN and β-CN in the composition of MFGM and have a positive effect on the stability of milk fat globules.

Key words: milk fat globule membrane, protein composition, pasteurization, homogenization, fat stability