Preparation of 1, 3‐dioleoyl‐2‐palmitoylglycerol‐rich structured lipids from basa catfish oil: Combination of fractionation and enzymatic acidolysis

1,3‐dioleoyl‐2‐palmitoylglycerol (OPO)‐rich structured lipids were successfully prepared from basa catfish oil by a two‐step process, namely, fractionation to enrich triacylglycerol (TAG) fractions with high content of sn‐2 palmitic acid and Lipozyme RM IM‐catalyzed acidolysis of the fractionated products with free fatty acids from high oleic acid sunflower oil to increase the content of OPO. In the first step, the content of sn‐2 palmitic acid of solid fraction was increased from 49.34 to 60.42% after programmed temperature treatment of basa catfish oil at 60°C for 30 min followed by 30°C for 12 h. In the second step, the solid fraction was used for transesterification with the fatty acids from high oleic acid sunflower oil and the conditions selected for acidolysis reactions were as follows: substrate molar ratio, 1:6 (fatty acids/solid fat); enzyme load, 12 wt%; reaction temperature, 50°C; and reaction time, 2 h. Under these conditions, the contents of sn‐2 plamitic acid and sn‐1, 3 oleic acid were 57.80 and 79.21%, respectively, and the content of POO was increased from 20.13% in the basa catfish oil to 43.80% in the enzymatic product, which indicated high content of OPO. Practical applications: Basa catfish oil is a type of newly discovered oil occurring in nature with similar fatty acid composition and distribution to human milk fat. Preparation of OPO‐rich structured lipids from basa catfish oil is a new method which is important for development of human milk fat substitutes. This process for OPO‐rich structured lipid preparation practically developed by combination of dry fractionation and enzymatic acidolysis has great potential for use in infant formula industry. Basa catfish oil was found to have similar triacylglycerol (TAG) structure to that of human milk fat. The oil was used to produce OPO‐rich structured lipids via a two‐step approach. The first step is to enrich TAG fractions with palmitic acid (PA) at sn‐2 position by low‐temperature fractionation, and the second step is to incorporate more oleic acid (OA) in sn‐1, 3 positions of triacylglycerols by Lipozyme RM IM‐catalyzed acidolysis. The final product had 22.29% total PA, 58.43% PA at sn‐2 position, 80.16% OA at sn‐1, 3 positions, and the content of POO was 43.80%, which indicated high content of OPO.