Immobilization of Sustine® 131 onto Spent Coffee Grounds for Efficient Biosynthesis of Ethyl Hydrocinnamate

Ethyl hydrocinnamate is an ester with a sweet, fruity, honey-like scent commonly used as a flavor and fragrance agent. Due to its chemical structure, it can be easily obtained through enzymatic reactions without the need for harsh substances and processes. This study investigated the immobilization of the commercial lipase Sustine® 131 onto spent coffee grounds (SCG) as a low-cost support for the enzymatic synthesis of ethyl hydrocinnamate. Spent coffee grounds underwent pretreatment with water, hexane, and ethanol to serve as a lipase adsorption platform and extract valuable bioactive compounds such as polyphenols. The immobilized lipase displayed both hydrolytic and synthetic activities during 12 weeks of storage at room temperature. The optimal reaction conditions for the synthesis of ethyl hydrocinnamate were determined using a Box–Behnken plan. It was shown that the enzyme concentration and the temperature were crucial for achieving high yields of ethyl hydrocinnamate with a conversion rate above 92%. Specifically, at least 18% enzyme concentration and a temperature of 45 °C were necessary. This eco-friendly approach utilized abundant food waste residue as an inexpensive and renewable immobilization support, enabling efficient biocatalytic production of the high-value flavor ester ethyl hydrocinnamate.