Evaluation of Antioxidant Effect of Free and Nanoencapsulated Polyphenol of Sesame on Changes in Fatty Acid Profile of Kilka Fish Oil Under Accelerated Conditions

Fish oil is a valuable source of polyunsaturated fatty acids that are highly sensitive to oxidation. In this study, the antioxidant effect of free and nanoencapsulated polyphenols of sesame on the fatty acid profile of kilka fish oil was investigated. Free and bonded phenolic compounds of black (Oltan) and white (Yekta) sesame cultivars were extracted and their antioxidant activity was investigated by ABTS free radical scavenging and beta-carotene: linoleic acid bleaching method. By increasing the concentration of phenolic compounds from 250 to 1000 mg/l, antioxidant activity increased and free phenolic compounds and Oltan cultivar showed higher antioxidant activity and therefore were used for nanoencapsulation in the wall of Trigonella foenum-graecum and Portulaca oleracea seed gum. Phenolic compounds (7%)were added to oil phase containing 25 % of tween 80 and 68 % kilka fish oil.The free polyphenol nanoparticles of Oltan cultivar had smaller particle sizes (417.3 nm) and higher zeta potential (-26.2 mv) in comparison to Yekta cultivar, and were used to add to antioxidants free kilka fish oil. The results showed that during thermal process for 40 days at 60 °C in all samples the fatty acid profile changed, which was in the form of increasing in saturated fatty acids and decreasing in unsaturated fatty acids. The highest and lowest degradation and changes in fatty acid profiles were observed in the control sample and the fish sample containing nanoencapsulated polyphenols, respectively. The results of this study introduce the use of nanoencapsulatedpolyphenols of Oltan cultivar as a natural antioxidant to increase in the stability of Kilka fish oil.