Protection of fish oil from oxidation with sesamol

Abstract

The aim of this study was to determine whether sesamol may provide antioxidant protection for marine omega‐3 fatty acids. We tested the effectiveness of sesamol at two temperatures, 30 and 50°C and compared its antioxidant activity with butylated hydroxytoluene (BHT), a commercial rosemary extract, and gamma‐oryzanol. Each antioxidant system was tested at two concentrations, 0.84 and 8.4 mM except for BHT of which the concentration was fixed at 0.84 mM BHT (200 ppm, the regulatory limit allowed in oils). 0.84 mM phenolic diterpenes in the rosemary extract protected fish oil very well. 0.84 mM sesamol was not as good as the rosemary extract as indicated by peroxide values, conjugated diene values, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels, and volatile compounds formation. However, 8.4 mM sesamol performed better than the rosemary extract containing 8.4 mM phenolic diterpenes in peroxide values and headspace volatiles compounds during storage of the stripped fish oil for 14 days at 30 and 50°C, while it showed similar results as the rosemary extract in conjugated diene values and EPA and DHA levels. Gamma‐oryzanol was also evaluated for protection of fish oil. However, it was found that gamma‐oryzanol was less effective than the other antioxidants tested in this study.Practical applications: At 8.4 mM (0.13 wt%), sesamol, a natural antioxidant, showed better than or comparable antioxidant activity to a commercial rosemary extract toward fish oil during storage at 30 and 50°C. Considering problems of flavor, odor, and color associated with a rosemary extract and that a rosemary extract product is typically sold as a solution containing only a few percent of active ingredients for oil applications, such as omega‐3 oil supplements and frying oil due to the low solubility of active ingredients in oil, sesamol offers advantages over the rosemary extract as it can be used as a pure form without mixing with other ingredients.8.4 mM sesamol protected fish oil from oxidation better than the leading commercial natural antioxidant, rosemary extract, containing 8.4 mM phenolic diterpenes at 30 and 50°C. Gamma‐oryzanol was less effective than the other antioxidants tested in this study.