Mathematical modeling of enzymatic esterification process between essential oil from Cymbopogon winterianus and cinnamic acid

To explore esterification processes via enzymatic catalysis, mathematical models represent an innovative and indispensable tool. This study aims to investigate the esterification process of monoterpene alcohols, specifically geraniol and citronellol, which are key components of citronella essential oil (Cymbopogon winterianus). The focus lies in understanding the complex dynamics of their reaction with cinnamic acid within an organic solvent system, employing the immobilized commercial lipase NS 88011 as the biocatalyst. The independent variables investigated in this study were as follows: temperature (50, 60, and 70 °C), enzyme concentration (1, 5, 10, and 15 %), agitation speed (50, 125, and 200 rpm), and the molar ratio of cinnamic acid to alcohol (geraniol/citronellol) (1:2, 1:3, 1:6, 1:9, and 1:12). The optimized conditions were found to be 10 % catalyst concentration, 60 °C, 50 rpm agitation speed, and a molar ratio of 1:3 (acid:alcohol). Under these conditions, the production yielded 7845 mg/L (52.3 %) of citronellyl cinnamate and 15089 mg/L (48.3 %) of geranyl cinnamate within 120 h of the reaction time. The best-fitting model that accurately described the reaction kinetics was determined to be the Ping Pong bi bi model. This research underscores the critical importance of systematic parameter optimization and the selection of kinetic models to enhance the efficiency of enzymatic esterification processes, thereby making a substantial contribution to the progress of the field of enzymatic catalysis.