Yellow pea flour and protein isolate as sources of antioxidant peptides after simulated gastrointestinal digestion

Abstract

Although peas are widely consumed legumes throughout the world, the bioactivity ofthe peptides released by the gastrointestinal digestion has not been sufficiently studiedso far. The objective of the present work was to evaluate the potential of floursand protein isolates obtained from two varieties of yellow peas as sources of antioxidantpeptides. Flours and protein isolates were prepared and submitted to a simulatedgastrointestinal digestion. Protein hydrolysis degree (TNBS method) andprotein solubility (in phosphate buffer saline, pH = 7.4) values were independent onthe starting material. Antioxidant activity measured by oxygen radical absorbancecapacity (ORAC) and hydroxyl radical averting capacity (HORAC) showed no differencesbetween varieties. A lower activity was registered for protein isolates withrespect to flours in the case of HORAC, which could be associated with a loss of moleculeswith molecular masses lower than 43 kDa in the protein isolates. A significantincrease in activities was evidenced by both methods after gastrointestinal digestion,except in the case of HORAC activity of flours. Digested from protein isolates presenteda greater ratio of molecules smaller than 1.4 kDa and a lower ratio of thoselarger than 6.5 kDa with respect to digested flours, according to electrophoresis andgel filtration chromatography studies. Results suggested that the presence of othercomponents or/and the initial state of proteins would affect proteolytic attack ofdigestive enzymes. Both, pea flours and protein isolates, present interesting potentialas antioxidants food ingredients.