Natural antioxidants from clove for protecting omega-3 fatty acids in sardines (Rastrineobola argentea) during deep frying process.

Abstract

Sardines (Rastrineobola argentea), popularly known as “dagaa” is one of the leading commercial fish species of Lake Victoria. The fatty fish species are attracting great attention because they are good source of omega-3 polyunsaturated fatty acids which are vital for a wide range of biological functions and are implicated in the prevention of numerous diseases. While nutritionally valued omega-3 fatty acids are highly susceptible to oxidation during fish processing due to their unsaturated nature. Oxidation reactions result in loss of omega-3 fatty acids and production of undesired off-flavours which discourage consumption and limit diversification of sardine products.Synthetic antioxidants may be used to prevent lipid oxidation but have been claimed to be carcinogenic at higher levels. The replacement of synthetic antioxidants with ones of natural origin is now in demand. In this study, natural antioxidants rich extracts from clove buds were applied on sardines in a bid to impede lipid oxidation during deep frying process. Lipid oxidation was assessed by peroxide value (PV), volatile compounds and fatty acid profiles using Gas chromatograph (GC-MS and GC-FID).The results showed that natural antioxidants from clove buds reduced peroxidation and protected highly unsaturated omega-3 fatty acids from oxidation during deep frying process. Total polyunsaturated fatty acids amounted 7.30 % in pre-treated deep fried sardines.Retention of omega-3 fatty acids was 0.70 % more in pre-treated than untreated fish. Significantly lower amounts of representative volatile compounds were produced in sardines pre-treated with clove extracts. The study demonstrated feasibility to pre-treat sardines with natural antioxidants for protecting omega-3 fatty acids against oxidation during deep frying.