Optimisation and economic assessment of lipase-catalysed production of monoesters using Rhizomucor miehei lipase in a solvent-free system

Abstract Enzymatic production of glycerin monolaurate (GML) was carried out by lipase catalysed esterification of lauric acid and glycerin in a solvent-free media. Response surface methodology (RSM), based on 5-level and 3-variable composite design, was employed to study the interactive effects of reaction temperature (48–60 °C), enzyme load (1–4% w/w), and glycerin to lauric acid molar ratio (1:1–4:1) on glycerin laurate yield. The optimum conditions obtained were a temperature of 60 °C, an enzyme load of 4%, and a glycerin to lauric acid molar ratio of 4:1. The maximum predicted and experimental conversion values were 92.26% and 93.23%, respectively. Utilisation of Lipozyme RM IM (Rhizomucor miehei lipase) allowed the formation of a mixture consisting of 50% monoglyceride, 34.6% diglyceride and 8.4% triglyceride, which fulfills the requirements established by the World Health Organization (WHO) for use as a food emulsifier. In addition, the Lipozyme RM IM maintained more than 90% of its original activity after being used for six cycles. Finally, an economic study was performed to interrogate the feasibility of the proposed enzymatic manufacturing process. The obtained results were compared with the traditional catalysed chemical process. The economic feasibility study revealed that the needed amount of Lipozyme RM IM was 2.5 kg/t of feedstock. The high conversion achieved in a short reaction time (1 h), as well as the proven operational stability of Lipozyme RM IM, revealed a promising potential for this green and sustainable route in practical applications.