Modulating the interfacial protein profile to develop novel fat globules with enhanced plasmin resistance and improved fat stability

The rapid destabilization of fat in direct ultra-high-temperature (UHT) milk during storage is mainly caused by plasmin through the cleavage of interfacial proteins. In this study, novel fat globules were developed by modulating the interfacial proteins (milk fat globule membrane material homogenized with large fat globules) to resist plasmin hydrolysis and improve fat stability. Compared to simulated homogenized milk (milk proteins homogenized with large fat globules), the novel fat globules contained more proteins at the interface and showed a greater stability. Proteomics revealed that the protein types at the interface of novel fat globules are predominantly membrane proteins, while the interface of simulated homogenized milk is mainly composed of milk proteins. The relative abundance ratio of major MFGM proteins to casein in the novel fat globules was approximately 30 times higher than in simulated homogenized milk. After plasmin hydrolysis, the novel fat globules showed minimal changes in stability, with only small amounts of XO and casein being hydrolyzed. In contrast, the fat globules in the simulated homogenized milk underwent coalescence, and a large amount of casein was hydrolyzed at the interface. Furthermore, the novel fat globules were more stable than commercial direct UHT milk, both before and after plasmin intervention. • Large fat globules were homogenized with MFGM material to develop novel fat globules. • The interface of novel fat globules showed a membrane protein phenotype. • Small amounts of XO and casein were hydrolyzed by plasmin in the novel fat globules. • The novel fat globules could resist plasmin hydrolysis and improve fat stability.