Application of Taguchi Method in the Enzymatic Modification of Menhaden Oil to Incorporate Capric Acid

Abstract

Abstract Structured lipids (SL) were produced using menhaden oil and capric acid or ethyl caprate as the substrate. Enzymatic reaction conditions were optimized using the Taguchi method L9 orthogonal array with three substrate molar ratio levels of capric acid or ethyl caprate to menhaden oil (1:1, 2:1, and 3:1), three enzyme load levels (5, 10, and 15% [w/w]), three temperature levels (40, 50, and 60 °C), and three reaction times (12, 24, 36 hours). Recombinant lipase from Candida antarctica , Lipozyme ® 435, and sn‐ 1,3 specific Rhizomucor miehei lipase, Lipozyme ® RM IM (Novozymes North America, Inc., Franklinton, NC, USA), were used as biocatalysts in both acidolysis and interesterification reactions. Total and sn ‐2 fatty acid compositions, triacylglycerol (TAG) molecular species, thermal behavior, and oxidative stability were compared. Optimal conditions for all reactions were 3:1 substrate molar ratio, 10% [w/w] enzyme load, 60 °C, and 16 hours reaction time. Reactions with ethyl caprate incorporated significantly more C10:0, at 30.76 ± 1.15 and 28.63 ± 2.37 mol% versus 19.50 ± 1.06 and 9.81 ± 1.51 mol%, respectively, for both Lipozyme ® 435 and Lipozyme ® RM IM, respectively. Reactions with ethyl caprate as substrate and Lipozyme ® 435 as biocatalyst produced more of the desired medium‐long‐medium (MLM)‐type TAGs with polyunsaturated fatty acids (PUFA) at sn ‐2 and C10:0 at sn ‐1,3 positions.