Protection against Oxidation of Omega-3 Fatty Acids with Natural Antioxidants in Clove (Szygium aromaticum) Water Extracts during Storage of Sun dried Sardines (Ratrineobola argentea)

Omega-3 fatty acids are a family of polyunsaturated fatty acids (PUFAs) with beneficial health effects to humans if consumed in required amounts. Fatty fish species are known to be rich in marine-based omega-3 fatty acids, eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and docosapentaenoic acid (DPA, C22:5n-3). Sardines (Rastrineobola argentea) from Lake Victoria are a good source of health promoting omega-3 fatty acids. Open sun drying is a common and traditional sardine processing and preservation method. Due to their chemical instability omega-3 fatty acids in sun dried sardines are prone to lipid oxidation during processing and subsequent storage. This study investigated the use of clove (Syzygium aromaticum) water extracts as natural antioxidants to protect omega-3 fatty acids against oxidative damage during storage of sun dried sardines. Lipid oxidation was assessed by peroxide value, volatile secondary oxidation products and fatty acid profiles. The antioxidant capacity of extracts was evaluated by total phenolic content, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and iron (Fe2+) chelating ability. Clove extracts resulted into significantly higher retention of total PUFAs, DHA, EPA and DPA at the end of 30 days storage period and lower concentrations of secondary lipid oxidation products. This is an evidence of their enhanced oxidative stability in the real food system due to presence of natural clove antioxidants.