Digestibility and absorption of enzymatically hydrolyzed whey protein

The digestibility of whey protein-hydrolyzed peptide (WPP) prepared by hydrolysis of whey protein concentrate (WPC) with trypsin and papain was compared with that of WPC using an in vitro digestion test. WPP and WPC were rapidly digested by treatment with pepsin followed by pancreatin. WPP was easily digested with both enzymes. However, WPC was not digested completely by a single enzyme, and highmolecular-weight protein such as β-lactaglobulin and α-lactalbumin remained. In addition, nitrogen absorption in the rat intestine was evaluated in terms of changes in the amount of stomach contents and free amino acid concentration in plasma of rats administered WPP or WPC. At 7min after administration of WPP, the stomach contents decreased and the plasma free amino acid concentration reached maximum. The highest concentration of plasma free amino acid in rats administered WPC was observed after 30min. These findings demonstrate that WPP is a better-digestible and absorbable nitrogen source than WPC.