Lipases from different yeast strains: Production and application for n-3 fatty acid enrichment of tuna eyeball oil

Abstract

Enrichment of n-3 polyunsaturated fatty acids (PUFA) in the glyceride fraction of skipjack tuna eyeballs oil (STEO) was investigated by using six extracellular and cell-bound lipases from three different yeast strains. Among all lipases tested, Candida rugosa extracellular lipase (Cr-ECL) showed promising enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in STEO. Firstly, various parameters including types of solvent, solvent to oil ratio, water to oil ratio, hydrolysis time, temperature, and lipase concentration were studied to select the major independent parameters. Finally, response surface methodology (RSM) was used to optimize the reaction conditions. Optimal condition included 450 U of Cr-ECL at water to oil ratio of 1:8 for 11.28 h, which resulted in 1.9-fold increase in DHA concentration in STEO. EPA was increased by 2.1-fold, when 191.35 U of Cr-ECL, water to oil ratio of 1:6 for 5.14 h was used. The Cr-ECL catalyzed hydrolysis was non-stereoselective, but had acyl chain specificity, and recognition of the whole triacyl-glycerol molecule as shown by 1H NMR and 13C NMR. Therefore, the established hydrolysis protocol for DHA and EPA enrichment was successful in converting fish oil from tuna waste to useful and healthy fish oil enriched with n-3 fatty acids. These findings pave the way for the future valorization of industrial marine waste oil.