Production of n-3 polyunsaturated fatty acid concentrate from sardine oil by immobilized Candida rugosa lipase

ABSTRACT:  This study was conducted to develop an immobilized-enzyme system to entrap lipase in chitosan-alginate-CaCl₂ beads for the purpose of concentrating n-3 polyunsaturated fatty acids (n-3 PUFAs) from sardine oil. Lipase was immobilized by an ionotropic gelatin method analyzed for characteristics. Optimum pH of immobilized lipase shifted from pH 7.0 to 6.0 and immobilized lipase showed higher stability against pH and temperature changes. Original sardine oil contained 38.1% n-3 PUFAs (25.2% 20:5n3 and 7.20% 22:6n3), and the concentration was significantly increased to 65.3% (40.2% 20:5n3 and 15.5% 22:6n3) with free lipase and to 64.8% (39.6% 20:5n3 and 15.3% 22:6n3) with immobilized lipase after 90 min of repeated hydrolysis. Fatty acid content of the free fatty acid (FFA) fraction of hydrolyzed oil showed that lipase preferably hydrolyzed 16:0, 16:1n7 and 18:0 accounting for 76.6% and 69.5% of total FFAs (after 1st and 2nd hydrolysis, respectively). This study shows that use of immobilized lipase systems for increasing n-3 PUFA concentration in sardine oil provides new processing opportunities for the industry.