Bioactive peptides released from in vitro digestion of human milk with or without pasteurization

BACKGROUND: Pasteurized donor human milk (HM) serves as the best alternative for breast-feeding when availability of mother's milk is limited. Pasteurization is also applied to mother's own milk for very low birth weight infants, who are vulnerable to microbial infection. Whether pasteurization affects protein digestibility and therefore modulates the profile of bioactive peptides released from HM proteins by gastrointestinal digestion, has not been examined to date. METHODS: HM with and without pasteurization (62.5 degrees C for 30 min) were subjected to in vitro gastrointestinal digestion, followed by peptidomic analysis to compare the formation of bioactive peptides. RESULTS: Some of the bioactive peptides, such as caseinophosphopeptide homologues, a possible opioid peptide (or propeptide), and an antibacterial peptide, were present in undigested HM and showed resistance to in vitro digestion, suggesting that these peptides are likely to exert their bioactivities in the gastrointestinal lumen, or be stably transported to target organs. In vitro digestion of HM released a large variety of bioactive peptides such as angiotensin I-converting enzyme-inhibitory, antioxidative, and immunomodulatory peptides. Bioactive peptides were released largely in the same manner with and without pasteurization. CONCLUSION: Provision of pasteurized HM may be as beneficial as breast-feeding in terms of milk protein-derived bioactive peptides.