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• α-Tocopherol and γ-oryzanol showed antagonism in the oil-in-water emulsion. • Concentration of binary mixtures affected the degree of antioxidant interaction. • Inhibition of γ-oryzanol on α-tocopherol regeneration led to antagonism. The interaction between antioxidants is affected by many factors, such as concentration, ratio and system. In this study, different concentrations of α-tocopherol and γ-oryzanol showed antagonistic effect in the oil-in-water emulsion, and the distribution of α-tocopherol increased in aqueous phase after combined with γ-oryzanol. The concentration could affect the degree of antagonism. According to fluorescence quenching, cyclic voltammetry measurements and the oxidative decomposition of antioxidants during storage, the inhibitory effect of γ-oryzanol on the regeneration of α-tocopherol was proposed to be responsible for the antagonism. This work can provide suggestions for studying the mechanism of antioxidant interaction in emulsion system. [ABSTRACT FROM AUTHOR]

• Concentration of binary mixtures affected the total antioxidant capacity. • Ratio of binary mixtures affected the type or degree of antioxidant interaction. • Inhibition of phytosterol on α-tocopherol regeneration leads to antagonism. • Synergism of γ-oryzanol and phytosterol is related to the hydrogen bond. In this study, purified rice bran oil (RBO) was used as a lipid matrix model to study the individual and binary antioxidant capacity of the minor constituents (α-tocopherol, γ-oryzanol and phytosterol) added at different concentrations and ratios. The results revealed that concentration influenced on the oxidation stability and scavenging capacity, while ratio mainly affected the type of interaction or the degree of synergism or antagonism. It was important to notice that the antioxidant capacity of α-tocopherol would decrease under high concentration. Besides, the inhibition of phytosterol on α-tocopherol and the formation of hydrogen bond between γ-oryzanol and phytosterol were speculated by the interactions of these minor constituents. This work helps to select efficient combinations for stabilizing the anti-oxidation of nutrient enriched RBO or provide suggestions for moderate retain of minor constituents in RBO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mutual effect of α-tocopherol and γ-oryzanol during in vitro digestion. • Addition of minor constituents affected the stability of digestion system and lipid hydrolysis. • Binary mixture attributed to the bioaccessibility of γ-oryzanol while impeded that of α-tocopherol. • Antioxidant activity of binary mixture was higher than that of the single addition group. 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. [ABSTRACT FROM AUTHOR]