Protein structure in model infant milk formulas impacts their kinetics of hydrolysis under in vitro dynamic digestion

The impact of protein structure in model infant milk formulas (IMFs) on digestion was evaluated using an in vitro dynamic digestion model. IMFs differed by their whey protein profile and the heating conditions. Digesta microstructure was followed by laser light scattering and confocal laser scanning microscopy. Proteolysis kinetics were monitored by SDS-PAGE and OPA assay and peptide release kinetics by tandem mass spectrometry. The gastric digesta microstructure depended on the protein structure within IMFs, with the highest protein particle size in IMF containing native casein micelles. Among whey proteins, denatured/aggregated lactoferrin was the most sensitive to pepsin hydrolysis. The peptidomic profile during digestion varied among IMFs. More numerous and resistant intestinal bioactive peptides were observed for the unheated IMF having a whey protein profile closer to that of human milk. Further physiological studies are required to investigate the benefits of adapting the IMF whey protein profile on infant health.