Immobilization of <i>Rhizomucor miehei</i> lipase in Biopolymer-Based organogels for green esterification

This study investigates the immobilization of <i>Rhizomucor miehei</i> lipase in organogel systems formulated with gelatin, chitosan, or alginate, incorporating different surfactants and organic solvents, both with and without glutaraldehyde activation. Among the systems tested, gelatin/SDS combinations demonstrated superior thermal stability, whereas chitosan-based matrices exhibited the highest catalytic performance, achieving up to 80% conversion in the esterification of oleic acid at a 1:1 molar ratio. When applied to the esterification of pequi and buriti oils, the biocatalyst performance was influenced by the oils' viscosity and lipid composition. The presence of sago starch in the reaction medium enhanced conversion rates, likely due to its role in modulating the interfacial environment and reducing water activity. This effect was less evident with pequi oil, possibly owing to its sensitivity to ethanol. Catalytic assays confirmed high initial activity, whereas reusability and operational stability tests revealed significant mass loss and limited activity retention during long-term operation, mainly due to physical disintegration of the chitosan-SDS matrix. Despite this limitation, the study provides mechanistic insight into the instability of ionically assembled organogels under real oil conditions. Overall, the findings highlight the complex interplay between support, solvent, substrate, and reaction conditions.