Lipase biocatalysis in the production of esters

Abstract

Lipase biocatatysis was investigated as a tool for the production of butyl oleate and rapeseed oil 2-ethy]-I -hexy[ ester by esterification and transesterification, respectively. We screened 25 commercially available [ipases and found that butyl oleate was produced at high yields from oleic acid and 1butanol by [ipases from Candida rugosa, Chromobacterium viscosum, Rhizomucor miehei, and Pseudomonas fluorescens. The initial water content of the system, lipase quantity, and the molar ratio of t-butanol to oleic acid were important factors in influencing the ester yield. In general, no ester was formed without the addition of water. The exception was Ch. viscosum lipase, which yielded 98% of ester in 12 h with t-butanol excess without additional water. The addition of 3.2% water increased the initial rate of reaction. With an oleic acid excess and only 0.3% lipase, C. rugosa and R. miehei lipases yielded 94 and 100% esters with initiaf water contents of 3.2 and 14%, respectively. Lipase-catatyzed alcoholysis of [ow-erucic acid rapeseed oil and 2-ethyl-I -hexanol without additional organic solvent also was studied in stirred batch reactors. In this case, C. rugosa lipase was the best biocatalyst with an optimal 2-ethyl-1 -hexanol to rapeseed oil molar ratio of 2.8, a minimum of 1.0% added water, and 37°C. An increase in temperature up to 55°C increased the rate of reaction but did not affect the final ester yield. The enzyme was inactivated at 60°C. Under optimal conditions, the ester yield increased from 88% in 7 h to nearly complete conversion in 1 h when the lipase content was increased from 0.3 to 14.6%. In a 2-kg small pilot scale, up to 90% conversion (97% of theoretical) was obtained in 8 h at 37°C with 3.4% lipase in the presence of Amberlite XAD-7 resin with 3% added water.

A review of the current state of biodiesel production using enzymatic transesterification

“…Optimal water activity for the enzymatic transesterification reaction system including substrates, enzymes, solvent and possibly also carrier material is specific for a given lipase, as seen from the results of Kaieda et al (2001), Linko et al (1995), Tan et al (2006), Zhang et al (2002Zhang et al ( , 2005, and Lu et al (2008). Kaieda et al (2001) tested free lipases from C. rugosa, P. cepacia, and P. fluorescens.…”

Ester synthesis in aqueous media in the presence of various lipases

“…Although most of the published studies of lipase-catalysed ester synthesis have been peIformed in non-aqueous media, some lipases have been shown to catalyse ester synthesis in aqueous media (Okumara et al 1979;Nishio et al, 1987;Briand et al, 1994: Boutur et al, 1994McNeill and Berger, 1995 ;Linko et al, 1995). In the presence of alcohol in the aqueous phase, esters can be produced by two mechanisms : a direct transfer of acyl groups fiom an acyl donor ester by alcoolysis, or the esterification of free fatty acids, eventually resulting from the hydrolysis of an acyl donor ester.…”

Transesterification of trimethylolpropane and rapeseed oil methyl ester to environmentally acceptable lubricants

“…Interest in the production of biodegradable, environmentally acceptable esters for biodiesel, lubricants, solvents, surface active agents, and the like by lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) biocatalysis from vegetable oils has increased markedly during the last few years (1,2). For example, butyl oleate (3) may be used as biodiesel additive, PVC plasticizer, water-resisting agent, and in hydraulic fluids.…”