ABSTRACT
The protein quality (proportion of whey and casein proteins) of human milk (30% casein, 70% whey) differs from that in bovine milk (82% casein, 18% whey) (14). The caseins are a group of proteins with low solubility in acid media. Whey proteins remain in solution after acid precipitation. Generally, the soluble proteins in the whey fraction are more easily digested and tend to facilitate more rapid gastric emptying (17). The whey protein fraction provides lower concentrations of phenylalanine, tyrosine, and methionine and higher concentrations of taurine than the casein fraction of milk (18-21). The pattern of amino acids in the plasma of breastfed infants is used as a reference in infant nutrition (22).
