Study on the synthesis of pine sterol esters in solvent‐free systems catalyzed by Candida rugosa lipase immobilized on hydrophobic macroporous resin

Abstract BACKGROUND Pine sterol ester is a type of novel food source nutrient with great advantages in lowering blood cholesterol levels, inhibiting tumors, preventing prostate enlargement, and regulating immunity. Macroporous resins with large specific surface area, stable structures, and various functional groups (epoxy, amino, and octadecyl groups) have been selected for immobilization of Candida rugosa lipase (CRL) to improve its stability and efficiency in the synthesis of pine sterol esters. A solvent‐free strategy using oleic acid (substrate) as an esterification reaction medium is an important alternative for avoiding the use of organic solvents. RESULTS The immobilization conditions of CRL immobilized on several types of commercial macroporous resins were optimized. Fortunately, by adsorption (hydrophobic interaction), a high immobilization efficiency of CRL was obtained using macroporous resins with hydrophobic octadecyl groups with an immobilization efficiency of 86.5%, enzyme loading of 138.5 mg g −1 and enzyme activity of 34.7 U g −1 . The results showed that a 95.1% yield could be obtained with a molar ratio of oleic acid to pine sterol of 5:1, an enzyme amount of 6.0 U g −1 (relative to pine sterol mass) at 50 °C for 48 h. CONCLUSION The hydrophobic macroporous resin (ECR8806M) with a large specific surface area and abundant functional groups was used to achieve efficient immobilization of CRL. CRL@ECR8806M is an efficient catalyst for the synthesis of phytosterol esters and has the potential for further large‐scale applications. Therefore, this simple, green, and low‐cost strategy for lipase immobilization provides new possibilities for the high‐efficiency production of pine sterol esters and other food source nutrients. © 2023 Society of Chemical Industry.