In vitro bioaccessibility of peptides and amino acids from yogurt made with starch, pectin, or β-glucan

The bioaccessibility of peptides and amino acids (AA) during in vitro gastrointestinal digestion of proteins from acid dairy gel (or yogurt) containing different polysaccharides (PS) was investigated. The nature of added PS was shown to modulate the kinetics of proteins gastric digestion. Yogurts with β-glucan and with pectin showed faster proteolysis, lower release of large peptides, and a higher proportion of free AA than those with starch or without PS. Segregation between β-glucan and dairy proteins was hypothesized to explain faster proteolysis by concentration of enzymes and proteins in a separated phase considered as “micro-reactors”. Kinetics of protein digestion during the buccal phase was not affected by the presence of PS in yogurts. At the beginning of duodenal phase yogurts with starch and with pectin showed a higher degree of hydrolysis; at the end of this phase proteins were fully digested (no native protein left and bioaccessible AA was increased).