Effect of casein hydrolysis on post-prandial amino acid profile as influenced by the behavior in the upper gastrointestinal tract in vivo

Abstract

Hydrolyzed proteins have been suggested as more effectively utilized substrates than intact proteins or free amino acids (Wang et al., 2014). This can be of special interest in products specifically formulated for postexercise recovery, or in elderly, to overcome the threshold of essential amino acids required for an optimal stimulation of muscle protein synthesis (Manninen, 2009; Walrand et al., 2016). In this study, we tested the hypothesis that the intake of a casein hydrolysate will provide faster amino acid/peptide absorption than the parent case in and this could be explained by the peptide and ami no acid profile found in duodenum. Adult pigs were fed both products and duodenal effluents at several post-ingestion times were analysed for peptides and free a mino acids while, in a parallel study, plasma a mino acids and metabolites were determined. The effect of hydrolysis on gastric emptying was assessed by determination of nitrogen anda marker of the liquid phase. Free amino acids and peptides in digests showed distinctive profiles with respect to protein hydrolysis. An earlier appearance of known resistant peptides was observed in digests from hydrolysed samples with higher abundance of mono or di-phosphorylated peptides in comparison with digests from casein intake. Plasma rates for branched amino acids such as leucine and other amino acids and metabolites such as arginine or aaminoadipic acid at one to three hours post-ingestion were consistently higher in the case of the hydrolysate. The study confirmed that protein hydrolysis determines the behaviour of casein in the upper gastrointestinal tract and has a clear influence on the plasma a mino acid profile.