Extraction of protein concentrate from red bean (Phaseolus vulgaris L.): antioxidant activity and inhibition of lipid peroxidation

Red Bean Protein Concentrate (RBPC) and their hydrolysates were used to evaluate the antioxidant capacity. TheRBPC protein content was in the range of 57.38%–72.68% of the total sample content. RBPC protein profile showeda range of 15–100 kDa. Phaseolin protein was identified with bands of 45 and 50 kDa. Phaseolin protein was foundin all the RBPC samples at the different pHs assayed. In the gastric digestion phase, bands from 60 to 100 kDa weretotally hydrolyzed with pepsin. Phaseolin protein (45 and 50 kDa) presented resistance to gastric hydrolysis. All theRBPCs and gastrointestinal digest presented antioxidant activity using ferric-reducing antioxidant power (FRAP),2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), oxygen radical absorbance capacity (ORAC), andthiobarbituric acid reactive substances using the in vitro and in vivo methods. RBPC at pH 7.0 presented a value of95.80 µmoL TE/g of RBPC (FRAP); 257.12 µmoL TE/g of RBPC (ABTS), and 1960 µmoL TE/g of RBPC (ORAC).Duodenal digest of RBPC presented high antioxidant activity with 225.77 µmoL TE/g of digest (FRAP); 345.21 µmoLTE/g of digest (ABTS); and 3256 µmoL TE/g of digest (ORAC). Gastric and duodenal digest of RBPC were usedto inhibit lipid peroxidation using the in vitro method presenting a value of 87.95% and 93.0%, respectively. Whenthe in vivo method in zebrafish larvae was used, values were 79.03% and 86.76%, respectively. RBPCs showed noreactive oxygen species (ROS) inhibition. However, RBPCs with gastric and gastrointestinal digests, presented ROSinhibition, 75.30% for gastric digests and 66.40% for gastrointestinal digests.