In vitro gastrointestinal digest of catechin-modified β-conglycinin oxidized by lipoxygenase-catalyzed linoleic acid peroxidation.

The aim of the present study was to enhance oxidative stability and bioaccessibility of β-conglycinin (7S) prepared from low denatured defatted soybean flours with residual lipids and high lipoxygenase (LOX) activity. The model system consisting of linoleic acid (LA), LOX and unheated 7S (UH-7S)/heated 7S (H-7S) or UH-7S-catechin/H-7S-catechin complex, and in vitro gastrointestinal (GI) digestion model were used to investigate the effect of complexation with catechin on protein oxidation and characterisation of GI digest. The interaction of UH-7S/H-7S with catechin dramatically inhibited LOX-catalyzed LA peroxidation-induced protein oxidation. The interaction also promoted the degree of proteolysis in GI digestion and intestinal absorption for oxidized UH-7S/H-7S, increasing the antioxidant activity of oxidized UH-7S/H-7S, bioaccessibility for catechin and release of di-/tripeptides with dipeptidyl peptidase-IV/angiotensin converting enzyme inhibitory effects or antioxidant activities during GI digestion. The complexation with catechin is a potential strategy to enhance the oxidative stability, GI digestibility and bioaccessibility of 7S.