Comparative Lipidomics and microstructural characterization of Milk fat globule membrane protein powders from bovine buttermilk and cheese whey.

The functionality of milk fat globule membrane (MFGM) ingredients is largely determined by their lipid composition and microstructure. We combined lipidomics with microstructural characterization to analyze four MFGM protein powders (MFGMPs) derived from key dairy by-products: sweet buttermilk (SB), acid buttermilk (AB), sweet cheese whey (SW), and acid cheese whey (AW). A total of 573 lipid species spanning 23 classes were identified. Processing, particularly acidification, was associated with lower relative abundance of nutritionally valuable glycerophospholipids, primarily phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS), while sphingomyelin (SM) remained relatively stable. Microstructural analysis revealed that acidification induced extensive particle aggregation and membrane disruption, with acid-treated samples exhibiting substantially larger particle sizes and broader size distributions compared to their sweet counterparts. Multivariate analysis distinguished MFGMP types and identified candidate lipid markers, such as PC(18:0_20:4) for SB-MFGMP (SBMP) and PE(21:0_22:1) for acid-treated samples. Network and pathway analyses identified co-regulated lipid modules, with sphingolipid metabolism emerging as a lipid metabolism pathway potentially influenced by processing. Together, these results suggest that acid processing is a key factor associated with differences in both the lipidome and microstructure of MFGMPs, providing a rationale for tailoring processes to preserve sensitive phospholipids (PLs) and for using specific lipid markers in quality control. This work provides guidance for the development of MFGM ingredients with optimized physicochemical properties and suggests candidate lipid markers for quality control in nutritional applications.