Glycerolysis of glyceryl trioctanoate for the preparation of glyceryl monooctanoate and dioctanoate catalyzed by chitosan microsphere-immobilized Rhizomucor miehei lipase.

BACKGROUND: Lipase-catalyzed glycerolysis of triacylglycerols is an efficient approach for producing fatty acid-based food emulsifiers and functional lipids. However, free lipases suffer from poor reusability and difficult product separation. In this study, Rhizomucor miehei lipase (RML) was immobilized on chitosan microspheres (CS) to prepare a CS-supported catalyst (CS-G-R) for the glycerolysis of glyceryl trioctanoate (TCG) with glycerol (Gly) to produce glyceryl monooctanoate (MCG) and glyceryl dioctanoate (DCG).

RESULTS: Characterization confirmed the successful immobilization and high dispersion of RML on the CS support. The CS-G-R catalyst prepared with 600 μL of RML showed the best catalytic performance, achieving 76.72% TCG conversion with MCG and DCG selectivities of 38.73% and 37.26%, respectively. Molecular docking revealed strong binding between the open-form RML structure (4TGL) and TCG, whereas Gly interacted weakly outside the catalytic center. Molecular dynamics simulations further confirmed the stability of the 4TGL-TCG complex. Based on experimental and computational results, a glycerolysis mechanism involving acylation, deacylation, and a possible DCG-mediated pathway for MCG formation was proposed.

CONCLUSIONS: CS-G-R exhibited effective catalytic activity toward TCG glycerolysis, while molecular simulations provided insights into substrate recognition and catalytic pathways. This study offers an effective strategy for developing immobilized lipases for the production of food emulsifiers and functional lipids. © 2026 Society of Chemical Industry.