Comparative digestibility and peptide profiling of β-casein from cow, goat, and donkey milk following static in vitro...

In this study, we systematically compared the digestion characteristics of cow, goat, and donkey β-CN and the differences in their peptide profiles by simulating an infant digestion model in vitro. The results showed that the hydrolysis degree of goat and donkey β-CN was significantly higher than that of cow β-CN, and their superiority in digestive efficiency was closely related to the large variation in particle size and high surface charge density. Secondary structure analysis showed that the proportion of disordered structures of the 3 β-CN increased during the digestion process, and the digestion resulted in different degrees of surface hydrophobicity and fluorescence reduction, as well as interfacial activity attenuation of the 3 β-CN. Peptide profiling further revealed that goat and donkey β-CN digestion products were dominated by <2,000 Da small-molecule peptides (>91%), the proportion of short peptides (5-10 AA) was significantly higher than that of cow β-CN, and the donkey β-CN specifically generated the high-abundance antioxidant peptide VAPFPQPVVPYPQR (28.13%). Sequence homology comparisons indicated that donkey β-CN is more heterologous than cow and goat β-CN, resulting in a unique peptide generation pattern. The present study elucidates the differentiation of the 3 milk-derived β-CN in terms of digestive kinetics, structural evolution, and release of bioactive peptides to provide a scientific basis for infant formula selection.