Abstract:The digestibility of goat milk, casein (CN), whey protein (WP), and a mixture of CN and WP with a ratio similar to that in human breast milk (40:60, m/m) were assessed through in vitro simulation of digestion in the gastrointestinal tracts of adults and infants. The digestibility of all four proteins gradually increased during adult and infant in vitro digestion simulations. Mixed protein digestibility reached a maximum of 20.28% after 120 min of simulated infant gastric digestion, significantly higher than that of goat milk (P<0.05), suggesting that the mixed protein with a higher CN proportion was more easily digested. The mixed protein released up to 58.0 mg/mL peptide after 30 min of simulated infant gastrointestinal co-digestion. Dipeptidyl peptidase-4 inhibitory activity was relatively strong at the endpoint for the simulated infant gastrointestinal co-digestion. CN demonstrated the highest antioxidant activity of 34.11% during simulated infant gastrointestinal co-digestion. The mixed protein presented the lowest immunogenicity in simulated infant gastrointestinal digestion, indicating that the mixed protein is less likely to cause allergic reactions. Hence, the mixed protein combining CN and WP in a ratio similar to that in human breast milk provides improved digestibility, increased peptide content, reduced immunogenicity, and specific antioxidant activities. These findings provide important data to aid in the optimization of protein sources and ratios in whole goat milk-based infant formulas.
