Isolation of milk fat globule membrane (MFGM) material by coagulation and diafiltration of buttermilk

Due to the functional potential of milk fat globule membrane (MFGM), its isolation from buttermilk is receiving increasing attention by the food industry. However, extraction of MFGM proteins from buttermilk is challenging because of the high levels of serum proteins. In this study, a two-step approach was applied to obtain a MFGM isolate. First, native casein micelles from buttermilk were removed by rennet-induced coagulation. Next, the buttermilk whey obtained was filtered to remove the residual whey proteins. Purified MFGM isolate was collected after six diafiltration steps. The yield of MFGM proteins in the isolates was determined using sodium dodecylsulphate-polyacrylamide gel electrophoresis. In the MFGM isolates, 70% of peripheral membrane proteins were obtained, which is much more effective in comparison with recent isolation methods like cream washing or filtration of buttermilk. Further investigations on casein coagulation conditions of buttermilk may reduce losses, especially of integral MFGM proteins during renneting.