title: Lipase-catalysed ester synthesis in solvent-free oil system: is it esterification or transesterification?
abstract: Ester synthesis was carried out in a solvent-free system of lipase, coconut oil and ethanol or fusel alcohols to ascertain the reaction mechanism. During ester formation, octanoic and decanoic acids increased initially and then decreased gradually, indicating that ester production was a two-step reaction consisting of hydrolysis and esterification, rather than alcoholysis. With ethanol as the alcohol substrate, added butyric acid inhibited ester synthesis. However, when fusel alcohols were used as the alcohol substrate, no significant inhibitory effect by butyric acid was observed. Added octanoic acid did not show any adverse effect on the synthesis of corresponding esters. The results suggest that polarity of the reactants determines lipase activity. This study provides the first evidence on the mechanism of immobilised lipase-catalysed ester synthesis in a solvent-free system involving both hydrolysis and esterification.
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, Singapore 117543, Singapore.
authors.forename: Jingcan
authors.initials: J
authors.lastname: Sun
authors.forename: Bin
authors.initials: B
authors.lastname: Yu
authors.forename: Philip
authors.initials: P
authors.lastname: Curran
authors.forename: Shao-Quan
authors.initials: SQ
authors.lastname: Liu
mesh_terms: D002384:Catalysis; D000074263:Coconut Oil; D004951:Esterification; D004952:Esters / Q000138:chemical synthesis*; D000431:Ethanol / Q000737:chemistry; D006868:Hydrolysis; D008049:Lipase / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry
chemical_list: D004952:Esters; D010938:Plant Oils; D000431:Ethanol; D008049:Lipase; D000074263:Coconut Oil
keywords: Coconut oil; Esterification; Lipase; Mechanism; Solvent-free; Transesterification