Preparation of Highly Pure n‐3 PUFA‐Enriched Triacylglycerols by Two‐Step Enzymatic Reactions Combined with Molecular Distillation

Abstract

AbstractHighly pure n‐3 polyunsaturated fatty acids (PUFA)‐enriched triacylglycerols (TAG) have attracted considerable attention due to their nutritional benefits and pharmacological effects. In this study, an alternative approach to the conventional method for the synthesis of highly pure n‐3 PUFA‐enriched TAG by using a multi‐step process was reported. First, glyceride mixtures were synthesized through Novozym 435 [Novozymes A/S (Bagsvaerd, Denmark)] catalyzed esterification of n‐3 PUFA‐enriched FA and glycerol. Second, partial glycerides in the resulting glyceride mixtures were hydrolyzed to FA by immobilized partial glycerides‐selective lipase from Malassezia globosa. The purity of TAG reached 99.84% under the optimized conditions: buffer solution of pH 6.0, water content of 100% (w/w, with respect to the oil mass), enzyme loading of 120 U/g (U/w, with respect to oil mass) and reaction temperature of 30 °C. During hydrolysis, the immobilized SMG1‐F278N exhibited good reusability and TAG purity of over 94% was maintained after being used for six cycles. Subsequently, purification of TAG was accomplished by molecular distillation at low temperature (150 °C) and highly pure (99.85%) TAG with 88.73% n‐3 PUFA was obtained. The final glyceride mixtures with low acid, peroxide and anisidine value were promising products for medical and dietetic purposes. Compared with the conventional one‐step synthesis of n‐3 PUFA‐enriched TAG by enzymatic esterification or glycerolysis or the two‐step method by combined transesterification and ethanolysis, this improved process allows for higher purity of n‐3 PUFA‐enriched TAG and significant reduction in reaction time.