A simplified kinetic model to describe the solvent-free enzymatic synthesis of wax esters

Abstract

BACKGROUND: The use of biotechnological processes at industrial scale is a promising tool to replace conventional synthesis as an efficient and eco-friendly technology. For that purpose, the kinetic modelling of an in-lab optimized enzymatic process prior to scaling-up is of great utility. RESULTS: In this work, a kinetic model for the solvent-free synthesis of cetyl laurate, myristate, palmitate and stearate using different commercial immobilized lipases has been developed. In order to describe the esterification process of the cetyl esters separately and as a mixture similar to natural spermaceti, a pseudo-first-order kinetic has been proposed and tested. A relation between the inverse values of the kinetic constant and the amount of biocatalyst has been observed. The effect of temperature on the reaction rate can be accurately described by the Arrhenius equation except for immobilized Thermomyces lanuginosus, which appears to be less resistant to temperatures above 70 °C. CONCLUSION: Low deviations between experimental and predicted values (R2 ≥ 0.99) indicate that this pseudo-first-order kinetic model can be considered valid for the data range studied. In addition, the reaction rate of spermaceti can be successfully predicted through a weighted average of the kinetic constants obtained during the synthesis of each cetyl ester. This simple but accurate kinetic model for describing the solvent-free enzymatic biosynthesis of wax esters from spermaceti may contribute to extending the application of lipases as industrial catalysts.