Composition and microstructure of colostrum and mature bovine milk fat globule membrane.

The microstructures of colostrum and mature bovine milk fat globule membrane (MFGM) were investigated using confocal laser scanning microscopy (CLSM) at different temperatures, and the relationships between microstructure variations and the chemical compositions of the MFGM were also examined. Using a fluorophore-labeled phospholipid probe, we found that non-fluorescent domains on the MFGM were positively correlated with the amount of sphingomyelin at both room (20 °C) and physiological (37 °C) temperatures. However, at the storage temperature (4 °C), there were more non-fluorescent domains on the MFGM. These results indicate that the heterogeneities in the MFGM are most likely to be the result of the lateral segregation of sphingomyelin at the room and physiological temperatures, and at the storage temperature, phospholipids with saturated fatty acids affect the formation of these domains.