Production of geranyl propionate by adsorption of Candida Rugosa lipase on acid functionalized multi-walled carbon nanotubes

Abstract

Geranyl propionate is an ester which is in high demand and usually synthesized chemically as a flavouring agent for use in the food and beverage industries. In view of the numerous undesirable effects of the chemical method can have on the environment and human health, efforts to finding alternative means to produce such ester merits scientific consideration. Hence, the biotechnological route to producing geranyl propionate by the biotechnological routeusing physically adsorbed Candida rugosa lipase (CRL) type VII onto acid-functionalized multi-walled carbon nanotubes (CRL-MWCNTs) is suggested. The properties and morphology of the developed CRL-MWCNTs were characterizedusing FTIR, FESEM and TGA showing was successful adsorption of CRL onto the surface of the functionalizedMWCNTs.The approach of one-variable-at-a-time (OVAT) based on four parameters viz. time, substrate molar ratio of geraniol to propionic acid and solvent log P were evaluated for comparative esterification reactions catalysed by both the free CRL and the CRL-MWCNTs. The findings revealed that the CRL-MWCNTs were catalytically more efficient than the free CL andafforded improved product conversion of 76.76% as compared to 40.40% in the free CRL under similar optimized reaction conditions of 8 h, substrate molar ratio 4:1 in hexane (log P 3.50) as solvent. Considering such outcome, it can be inferred that the improved biological activity demonstrated by theCRL-MWCNTs that surpassed that of the free CRL may have been attributed to the enhanced rigidity of the CRLprotein following immobilization on the acid functionalized MWCNTs.The outcomesadvocate that the RML/CS/MWCNTs biocatalyst developed here may be a promising alternative to overcome shortcomings associated with the chemically produced geranyl propionate.