Preparation of regioisomers of structured TAG consisting of one mole of CLA and two moles of caprylic acid

TAG (MLM) with medium‐chain FA (MCFA) at the 1,3‐positions and long‐chain FA (LCFA) at the 2‐position, and TAG (LMM) with LCFA at the 1(3)‐position and MCFA at 2,3(1)‐positions are a pair of TAG regioisomers. Large‐scale preparation of the two TAG regioisomers was attempted. A commercially available FFA mixture (FFA‐CLA) containing 9‐cis, 11‐trans (9c, 11t)‐ and 10t,12c‐CLA was selected as LCFA, and caprylic acid (C8FA) was selected as MCFA. The MLM isomer was synthesized by acidolysis of acyglycerols (AG) containing two CLA isomers with C8FA: A mixture of AG‐CLA/C8 FA (1∶10, mol/mol) and 4 wt% immobilized Rhizomucor miehei lipase was agitated at 30°C for 72 h. The ratio of MLM to total AG was 51.1 wt%. Meanwhile, LMM isomer was synthesized by acidolysis of tricaprylin with FFA‐CLA: A mixture of tricaprylin/FFA‐CLA (1∶2, mol/mol) and 4 wt% immobilized R. miehei lipase was agitated at 30°C for 24 h. The ratio of LMM to total AG was 51.8 wt%. MLM and LMM were purified from 1,968 and 813 g reaction mixtures by stepwise short‐path distillation, respectively. Consequently, MLM was purified to 92.3% with 49.1% recovery, and LMM was purified to 93.2% with 52.3% recovery. Regiospecific analyses of MLM and LMM indicated that the 2‐positions of MLM and LMM were 95.1 mol% LCFA and 98.3 mol% C8 FA, respectively. The results showed that a process comprising lipase reaction and short‐path distillation is effective for large‐scale preparation of high‐purity regiospecific TAG isomers.