Identification of casein phosphopeptides released after simulated digestion of milk-based infant formulas.

Adapted, follow-up, probiotic follow-up, toddler, and probiotic toddler infant formulas were subjected to an in vitro enzymatic procedure simulating physiological digestion. The formation and identification of casein phosphopeptides (CPPs) in the milk-based infant formulas were studied using reversed phase high-performance liquid chromatography coupled on line to an ion trap mass spectrometer. Most CPPs formed contained the cluster sequence SpSpSpEE, a mineral binding site. Phosphopeptide alpha(s2)-CN(1-19)4P was present in all formulas analyzed. Probiotic formulas released CPPs not detected in nonprobiotic formulas and probably formed by bifidobacteria action. These observations suggest that physiological digestion of these products promotes the formation of bioactive peptides with mineral carrier properties in the gastrointestinal tract, which resist further proteolysis.