An efficient upgrading approach to produce n-3 polyunsaturated fatty acids-rich edible grade oil from high-acid squid visceral oil

Abstract

High-acid squid visceral oil is unsuitable for consumption owing to its high content of free fatty acids (FAs). In this study, an edible grade resource of n-3 polyunsaturated fatty acids (PUFA) was developed from high-acid squid visceral oil (HASVO) by converting free FAs and partial glycerides in HASVO to ethyl esters (EEs) using a partial glycerides-selective lipase from Malassezia globosa while leaving triacylglycerol (TAG) intact. FAs in HASVO decreased from 13.84% to 0.06% corresponding to a deacidification efficiency of 99.57% under the optimal conditions. After purification by molecular distillation at 130°C, a final product contained 99.41% TAG, 0.51% diacylglycerol, and 0.08% FA was obtained with a TAG recovery of 98.86%. The acid, peroxide and anisidine value of the final product fulfilled the demand of edible grade and the high n-3 PUFA content (36.34%) in the obtained glyceride mixtures was comparable to other kinds of marine fish oil, suggesting it could be used as an alternative resource of n-3 PUFA. Moreover, the resulting byproduct EEs with 46.29% n-3 PUFA could be used as substrates for the synthesis of n-3 PUFA-rich structured lipids. This is the first study for upgrading of HASVO to edible grade with the form of TAG.