Comparison of lipid structure and composition in human or cow's milk with different fat globules by homogenization

Homogenization is used in human milk to add supplements for premature infants and in cow's milk to make it more uniform and stable for commercial purposes. However, it may destroy the milk fat globule (MFG) structure and composition, affecting its functional characteristics. This study aims to compare human and cow's milk with particle size ranges of 4-6 μm (large-sized), 1-2 μm (medium-sized), and 0.3-0.5 μm (small-sized) before and after homogenization at different pressure levels. CLSM and SDS-PAGE were used to perform the structural characterization. The lipid compositions were analyzed using GC and LC-MS. The results showed that homogenization obviously changed the MFG structure and its lipid composition. After homogenization, more caseins and whey proteins were adsorbed on both the human and cow's milk fat globule interface, while the proteins observed in human milk were dispersed. This could be attributed to the different types and contents of proteins initially. The influence of homogenization on milk phospholipids was higher than triacylglycerols and fatty acids, which was highly correlated with their initial distributions in MFGs. These results provide new information about the interfacial composition of human and cow's milk fat globules upon homogenization and establish the scientific basis for homogenization application in human and cow's milk to help explore their potential functions.