Abstract
Addressing global food waste challenges, this study investigated plant-based byproducts, spent coffee grounds, apple, and chokeberry pomaces, as sources of phenolic acids and biodegradable carriers for lipase immobilization. The goal was to enhance the lipophilicity and functionality of natural phenolics by enzymatic lipophilization. Microbial lipase from A. oryzae was immobilized on these materials, with native spent coffee grounds (NSCG) showing the highest activity (6.0 U/g hydrolytic; 1036 U/g synthetic). Chlorogenic acid (CGA), predominant in extracts, served as a model substrate. Using response-surface methodology, optimal conditions for butyl-CGA synthesis were determined. This is the first report of CGA lipophilization using food-waste-immobilized biocatalysts, where reaction yield for NSCG increased with alcohol chain length, peaking with dodecanol (34.06%). Among synthesized esters, butyl chlorogenate displayed the highest antioxidant activity, comparable to free CGA and BHT, and increased lipophilicity, though a “cut-off” effect appeared for longer chains. Medium-chain esters (C6, C8) showed selective antimicrobial activity against Gram-positive bacteria. While lipophilization of chokeberry pomace and spent coffee grounds extracts reduced antioxidant activity, short-chain esters (C4–C6) improved rapeseed oil stability. The findings highlight food waste as a sustainable source for developing biocatalysts and value-added bioactives with enhanced functional properties.