Influence of alcohol: oil molar ratio on the production of ethyl esters by enzymatic transesterification of canola oil

Abstract

The influence of alcohol:oil molar ratio on the canola oil transesterification reaction in solvent-free medium using free lipase from Thermomyces lanuginosus and Burkholderia cepacia was studied. The experiments conducted in batch reactor for 72 h at 37°C in cosolvent-free reaction system with ethanol addition in three steps showed great potential for ester production. The stepwise addition of ethanol allowed increasing yield throughout the total period of the reaction, even if the course has limited reaction at times, minimizing possible deleterious effects of the alcohol on the enzyme structure. The highest yields were achieved with lipase from T. lanuginosus, despite presenting lower activity values than those of Burkholderia cepacia lipase, which proved to be less selective for ester production. In the reaction medium containing lipase from T. lanuginosus, 100 % yield was obtained using a molar ratio of 12:1. For B. cepacia lipase, the highest yield was 90.73% at a molar ratio of 6:1. In all cases studied, at least 92% of the triacylglycerols from canola oil were consumed.

Keywords: Free lipase, Thermomyces lanuginosus, Burkholderia cepacia, molar ratio, solvent-free medium, transesterification reaction, triacylglycerols, diacylglycerols, monoacylglycerols, ester.

Afr. J. Biotechnol Vol. 12 No. 50