Extraction of Omega-3 rich fish oil and determination of fatty acid composition from Indian mackerel

Abstract

Indian mackerel (Rastrelliger kanagurta) is one of the most common fish available and consumed by Malaysian. It was believed to has a high nutrient fish oil content. The omega-3 polyunsaturated fatty acids available in the fish oil have many benefits to the human health. They were proved to maintain the heart health, decrease the risk of getting the cardiovascular disease and improve one’s intelligence, eyesight as well as the memory. The main purpose of this research is to extract the fish oil from Indian mackerel (Rastrelliger kanagurta) by solvent extraction and concentrate high omega-3 content fish oil from the extracted fish oil by enzymatic hydrolysis. The chemical solvent extraction of fish oil was done by using ethanol and ethyl acetate which mixed at a desired ratio. After that, lipase (Candida rugosa) was used to concentrate the omega-3 polyunsaturated fatty acids from the solvent extracted fish oil through enzymatic hydrolysis. Then, the acid value and peroxide value of the fish oil were analysed to determine the quality of the oil extracted. The fish oil undergone enrichment process was converted into fatty acid methyl ester (FAME) form to analyse the fatty acid compositions within it by using gas chromatography with flame ionisation detector (GC- FID). Design of Expert (DOE) software was used to analyse the optimum conditions for solvent extraction of fish oil from Indian mackerels. It shown that the highest oil yield was produced from large size fish with ethanol- ethyl acetate solvent ratio of 1: 2 under 4000 rpm of centrifugation speed. The acid value of 2.5720 mg KOH/ g fish oil and peroxide value of 11.2332 meq peroxide/ 1000 g fish oil indicated the fish oil produced were in good quality. Finally, there are saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids found in the fish oil undergone enrichment process.