Extraction and production of n-3 polyunsaturated fatty acid concentrate from Pacific sardines (Sardinops sagax)

Intrinsic characteristics of Pacific sardines were determined. The lipid content in sardines was initially low (6.79%) in the beginning of the season, increased to 22.95% in mid-August, and decreased slightly by the end of September. An inverse correlation (R2 = -0.90) was found between lipid and moisture content. Analysis showed that 20:5n3 was the most abundant fatty acid in sardine oil followed by 16:0 and 22:6n3.;Microbial lipases from Candida rugosa (CR), Candida cylindracea (CC), Mucor javanicus (MJ), and Aspergillus niger (AN) were used for enzymatic hydrolyses of sardine oil to concentrate n-3 polyunsaturated fatty acids (n-3 PUFAs). Hydrolysis with CR and CC lipases resulted in a two-fold increase of docosahexaenoic acid while MJ and AN were less effective in concentrating n-3 PUFAs. Thin layer chromatography analysis showed that triglycerides were the predominant fraction in the final products.;A new oil extraction method involving isoelectric point (pI) adjustment was compared with the heat processing method in terms of lipid recovery and quality. Oil extracted by adjusting pH to pI using tartaric acid and citric acid showed the highest oil recovery, followed by calcium tartarate (Ca-TA) and calcium citrate (Ca-CA). The oil extracted by heat contained the lowest total fatty acids and resulted in the lowest total n-3 PUFAs. Oil extracted by the heat process showed the highest TBA (value 12.24) on 0 day while the lowest thiobarbituric acid reactive substance values were found in the oil extracted with Ca-TA and Ca-CA.;A study was conducted to develop an immobilized-enzyme system to entrap CR lipase in chitosan-alginate-CaCl2 beads for the purpose of concentrating n-3 PUFA from sardine oil. Lipase was immobilized by an ionotropic gelatin method. Scanning electron microscopy analysis revealed that lipase had a strong influence on bead structure. Optimum pH of immobilized lipase shifted to pH 6.0 from that of free lipase (pH 7.0), and immobilized lipase showed higher stability against pH and temperature changes. Both free and immobilized lipases increased total n-3 PUFAs from 38.13% to 65.00% after 90 min of repeated hydrolysis. Among different lipid fractions, the diglyceride fraction contained the highest n-3 PUFAs.