Isolation and identification of antimicrobial peptides derived by peptic cleavage of whey protein isolate

► Whey proteins hydrolyzed for 45-90 min by pepsin exhibited significant antibacterial activity. ► Fractionation of 60-min hydrolysate by RP-HPLC yielded 5 antibacterial fractions (MICs = 20-35 μg/mL). ► Peptide KVAGT from β-lgis found in antimicrobial sequences of diverse origin. ► Five other peptides from β-lg, and 1from α-la, were also identified as antibacterial. ► Identified peptides do not match pepsinaction exactly, indicating modified proteolysis of unknown origin.