Lipase-catalyzed acidolysis of canola oil with caprylic acid to produce medium-, long- and medium-chain-type structured lipids

► Six different sources lipases showed different acidolysis activity and the 1, 3-regiospecificity in canola oil and caprylic acid reaction system. And Lipozyeme RM IM from Rhizomucor miehei was preferred as a catalyst to produce the high purity MLM-type of structured lipids. ► We get the MLM-type structured lipids with triacylglycerol composition 6.09% MMM, 50.2% MLM, 41.5% MLL and 2.06% LLL. ► This paper has significant benefits to guide the lipase screening during designing the special structured lipids. Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids (SLs) containing medium-chain fatty acid (M) at position sn-1,3 and long-chain fatty acid (L) at the sn-2 position in a solvent-free system. Six commercial lipases from different sources were screened for their ability to incorporate caprylic acid into the canola oil. The sn-1,3 regiospecificity toward the glycerol backbone of canola oil of the lipases with relatively higher acidolysis activity was compared by investigating the fatty acid profiles of the products. The results showed that Lipozyme RM IM from Rhizomucor miehei resulted in the highest caprylic acid incorporation ability and the lowest acyl migration. The reaction parameters including substrate mole ratio, enzyme load, reaction time and temperature of Lipozyme RM IM were investigated. Incorporation of caprylic acid was higher when reactions were carried with 10% lipase of the total weight of substrates with a 1:4 mole ratio of oil and caprylic acid. The optimal time course and temperature for synthesis SLs were 15h and 50–60°C. Possible triacylglycerol species and physical properties of the SLs product obtained at relative optimal conditions were characterized.