Du_2026_Bioresour.Technol_455_134818

An immobilized Candida rugosa lipase on mesoporous silica functionalized with C18 alkyl chains (MS-C18) was employed to construct a non-aqueous selective esterification system for the resolution of conjugated linoleic acid (CLA) isomers. The effects of acyl acceptors with different hydrophobicities on esterification performance and isomer selectivity were investigated in isooctane. Under controlled reaction conditions (CLA-to-alcohol molar ratio 1:1, 40 degreesC), increasing acyl acceptor hydrophobicity enhanced both the esterification rate and the differentiation of reaction rates between c9,t11-CLA and t10,c12-CLA, with n-octanol identified as the optimal acyl acceptor. A two-step esterification strategy, involving initial separation of c9,t11-rich ester and t10,c12-rich free fatty acid fractions from commercial CLA mixtures, followed by secondary esterification of the respective free fatty acid substrates, enabled simultaneous preparation of both isomers with high relative purity (<=90%) and total recovery of 38.1%-52.4%. Kinetic analysis indicated that the reaction follows an alcohol-inhibited Ping-Pong Bi-Bi mechanism, and the observed selectivity is associated with differential substrate affinity and catalytic efficiency of CRL toward the two CLA isomers. The use of more hydrophobic acyl acceptors likely reduces substrate inhibition and enhances the differentiation of reaction rates between isomers, thereby improving separation efficiency. This study demonstrates that tuning acyl acceptor hydrophobicity provides an effective strategy to regulate selective esterification in non-aqueous systems, offering a feasible and scalable approach for high-purity CLA isomer preparation.