In vitro digestion of binary mixture of α-tocopherol and γ-oryzanol in oil-in-water emulsion: Changes in stability and antioxidant potential.

Minor constituents ought to be digested before they enter the body to exert functional effect, the stability and antioxidant potential play an important role to evaluate the function of minor constituents. In this study, in order to know the stability and antioxidant potential of single and binary addition of α-tocopherol and γ-oryzanol at different concentrations during in vitro digestion, the physical characteristics of digestion system and concentration as well as oxygen radical absorption capacity of minor constituents were determined. Besides, cellular antioxidant activity (CAA) of micelles was detected to evaluated antioxidant potential of these two minor constituents after in vitro digestion from a biological aspect. The increase of particle size (from 184.5 nm to 274.6 nm) and the decrease of the absolute potential value (from -48.9 mV to -33.5 mV) in the initial emulsion caused by the addition of minor constituents, leading to the decrease of the lipolysis extent (from 92% to 62%). However, binary mixture attributed to the bioaccessibility of γ-oryzanol and impeded that of α-tocopherol. Oxygen radical absorption capacity performed well in small intestine and micelles, the maximum reached 477.94 ± 45.3 μmol TE/mL digests. Importantly, the antioxidant activity of the binary mixture group was higher than that of the single addition group. However, after in vitro digestion, the CAA results showed that these two minor constituents were hardly significantly different from control group (p > 0.05), indicating unsatisfactory antioxidant activity in cells. Moreover, the antioxidant activity of minor constituents depends greatly on the reaction system. This study provides a theoretical reference and research basis for the better usage of natural antioxidants.