Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/13/2013
Publication Date: 7/17/2013
Citation: Moser, J.K., Hwang, H., Bakota, E.L. 2013. Influence of phytosterol structure on antioxidant activity of steryl ferulates in frying oils [abstract]. Institute of Food Technologists.
Technical Abstract: Steryl ferulates (SFs) occur in rice, corn, wheat, and rye, and are composed of plant sterols (phytosterols) esterified to ferulic acid. The structures of SFs from each cereal source differ due to differences in the phytosterol head group and these structural differences have been demonstrated to influence their antioxidant activity. We previously demonstrated corn SFs had much better antipolymerization activity and tocopherol protection compared to rice SFs in soybean oil used for frying. The objectives of these studies were to develop a better understanding of how the structural differences of corn and rice SFs influence their antioxidant activity in oil at frying temperatures, and to understand the interaction between tocopherols and SFs. Our hypothesis was that the increased antioxidant activity of corn SFs was because they are more stable at frying temperatures compared to rice SFs. Heating studies were carried out in antioxidant-stripped soybean oil, with either corn or rice steryl ferulate SFs, and with or without added tocopherols. Additional studies with synthesized SFs will also be presented. Antioxidant activity was assessed by measurement of triacylglycerol polymers by HPLC, and loss of double bonds by NMR. In heating studies, corn SFs degraded significantly (p<0.05) faster than rice SFs, contrary to frying study results. However, the phytosterol portion of the corn SFs degraded significantly more slowly than the phytosterols in rice SFs. Also, tocopherols significantly protected both corn and rice SFs from degradation, but only significantly improved the antioxidant activity of rice SFs. These results confirmed that the phytosterol portion of corn SFs are more stable than the phytosterols in rice SFs, but this did not improve stability of the whole compounds and did not support the hypothesis that this improved stability is the reason for the increased antioxidant activity. Steryl ferulates from corn have immediate potential as frying oil antioxidants.