Effect of apple peel extract as natural antioxidant on lipid and protein oxidation of rainbow trout (Oncorhynchus mykiss) mince

Abstract

The aim of this study was to use apple peel extract (APE) as antioxidant for inhibition of lipid and protein oxidation in rainbow trout (<em>Oncorhynchus mykiss</em>) mince during refrigerated storage. Apple peel extract had high 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobios-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and hydroxyl radical scavenging activity and ferric reducing antioxidant power (FRAP) comparable to ascorbic acid. Lipid oxidation was effectively inhibited in mince during 96 h of refrigerated storage as indicated by significantly lower peroxides and thiobarbituric acid-reactive substances (TBARS) (<em>P</em> < 0.05) compared to control. APE could reduce protein oxidation as evidenced by lower protein carbonyls and higher total sulfhydryl group content (<em>P</em> < 0.05) compared to control. This was coincidental with higher polyunsaturated fatty acids (PUFA)/saturated fatty acids (SFA) and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)/palmitic acid (C16:0) ratio in mince with added apple peel extract, especially at 20 mg of gallic acid equivalent/kg mince. Apple peel extract retarded fish mince lipid and protein oxidation during refrigerated storage and might be considered as natural antioxidant in rainbow trout mince.