Determination of antioxidant synergism between tocopherols and myricetin in bulk oil.

Lipid oxidation is a series of reactions affecting food quality and shelf life since it impacts flavor, color, and nutrition. The food industry utilizes different antioxidants to retard oxidation. Interaction between antioxidants can improve the ability of the industry to protect foods if the antioxidant combination is synergistic. This research aims to determine the conditions where tocopherols and myricetin exhibit synergistic activity in bulk oils. Soybean oil was stripped to remove present endogenous antioxidants to better understand tocopherol-myricetin interaction. The oxidative stability of the oil was determined by spectroscopically measuring lipid hydroperoxides and monitoring aldehyde formation by gas chromatography. Antioxidant degradation was determined by HPLC. α or mixed tocopherols (50 µM), myricetin (10, 25, 50, 100, 250 µM), and their combinations were added to stripped oil to determine how antioxidant ratios impacted synergism. The interaction index is the ratio of the observed lag phase to the expected lag phase of the antioxidant combination. Interaction indexes were 1.14, 1.50, 1.55, 1.30, and 1.16 when tocopherol: myricetin ratio was 5:1, 2:1, 1:1, 1:2, and 1:5, respectively, implicating synergistic activity (interaction index >1). Synergism was greatest when antioxidant concentrations were similar. Tocopherol and myricetin degraded at different rates, suggesting that synergism could be due to either regeneration of one antioxidant by another or preferential oxidation of one antioxidant followed by another. Synergism could also occur by chelating properties of myricetin, which could decrease the tocopherol loss. Tocopherols were found to be completely degraded just before the oxidation of fatty acids. This suggests that modeling the rate of tocopherol degradation could predict shelf-life. This project is significant for the Lipid Oxidation and Quality Division since it supplies ideas and learning opportunities to members who share similar interests in synergistic activity, antioxidant degradation kinetics, and unique strategies to decrease food waste caused by lipid oxidation.