Oxidative Stability and Antioxidant Changes in Perilla Seeds and Perilla Oil Affected by UV Irradiation

摘要

Effects of UV irradiation on lipid oxidation in perilla seeds and perilla oil were evaluated by determining the contents of peroxides, conjugated dienoic acids, and thiobarbituric acid reactive substances, and analyzing fatty acid composition. Tocopherols and polyphenol contents were also determined. Perilla seeds were unroasted or roasted at 180°C for 20 min, and perilla oil was obtained by pressing the roasted perilla seeds. Lipid oxidation during UV irradiation was higher and faster in perilla oil than that in perilla seeds, with a slight loss of linolenic acid. Unroasted perilla seeds were more oxidation-stable than roasted seeds. Tocopherols and polyphenols were degraded during UV irradiation, with a higher degradation rate observed in unroasted perilla seeds than in roasted ones. Antioxidant concentration dependency of the lipid oxidation during UV irradiation was higher in perilla oil than that in perilla seeds, and the contribution of polyphenols to oxidative stability was higher than thatof tocopherols in all samples.