Enzymatic production of a solvent-free menthyl butyrate via response surface methodology catalyzed by a novel thermostable lipase from Geobacillus zalihae

Abstract

Most substrate for esterification has the inherent problem of low miscibility which requires addition of solvents into the reaction media. In this contribution, we would like to present an alternative and feasible option for an efficient solvent-free synthesis of menthyl butyrate using a novel thermostable crude T1 lipase. We investigated the effects of incubation time, temperature, enzyme loading and substrate molar ratio and determined the optimum conditions. The high conversion of menthyl butyrate catalyzed by crude T1 lipase in a solvent-free system is greatly affected by temperature and time of the reaction media. The highest yield of menthyl butyrate was 99.3% under optimized conditions of 60 °C, incubation time of 13.15 h, 2.53 mg, 0.43% (w/w) enzyme to substrate ratio and at molar ratio of butyric anhydride/menthol 2.7:1. Hence, the investigation revealed that the thermostable crude T1 lipase successfully catalyzed the high-yield production of menthyl butyrate in a solvent-free system. The finding suggests that the crude T1 lipase was a promising alternative to overcome shortcomings associated with solvent-assisted enzymatic reactions.

Keywords:

• T1 lipase
• esterification
• Geobacillus zalihae
• central composite rotatable design

Acknowledgements

We would like to acknowledge valuable help and suggestions provided by the researchers at the Enzyme and Microbial Technology Research Centre, Universiti Putra Malaysia.

Additional information

Funding

This project was funded by the Ministry of Science and Technology and Innovation, Malaysia [grant number 5487729]; the Ministry of Education, the Exploratory Research grant scheme [grant number 4L132].