Antioxidant and bile acid binding activity of buckwheat protein in vitro digests

The objective of the study was to assess the antioxidant and bile acid removing potential of buckwheat protein (BWP) during a two-stage in vitro digestion (1 h of pepsin followed by 2 h of pancreatin). Antioxidant activity of the digests was analyzed by determining: (1) Fe(2+) chelation, (2) reducing power, (3) 2,2'-azinobis (3-ethylbenzothiszoline-6-sulfonic acid) (ABTS(+•)) radical scavenging capacity, and (4) TBARS formation in a liposome system. The initial pepsin digestion decreased the BWP antioxidant activity; however, subsequent pancreatin digestion fully recovered the reducing power and increased (P < 0.05) the ability to chelate Fe(2+) (45%), scavenge ABTS(+•) (87%), and curtail lipid peroxidation (45%) when compared with intact BWP. The final BWP digest exhibited a 67% increase (P < 0.05) in cholic acid binding capability over that of the nondigested BWP control but was comparable to the control in binding chenodeoxycholic and deoxycholic acids. Digestion-resistant peptides were largely responsible for bile acid elimination.