Organic Phase Synthesis of Ethyl Oleate Using Lipases Produced by Solid-state Fermentation

• Published in: Applied biochemistry and biotechnology 2008-12, Vol.151 (2-3), p.393-401
• Main Authors: Martinez-Ruiz, Antonio, Garcia, Hugo Sergio, Saucedo-Castaneda, Gerardo, Favela-Torres, Ernesto
• Format: Article
• Language: English
• Subjects: Batch reactors; Biochemistry; Biosynthesis; Biotechnology; catalysts; Chemistry; Chemistry and Materials Science; Enzyme Stability; Enzymes; esterification; Esters - chemical synthesis; Ethanol; Ethanol - metabolism; ethyl oleate; Fermentation; Lipase - metabolism; Mass transfer; Olea; oleic acid; Oleic Acid - metabolism; Oleic Acids - biosynthesis; Olive oil; Perlite; Rhizopus; Rhizopus - enzymology; solid state fermentation; Solvents; storage; Temperature; triacylglycerol lipase
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-008-8207-2

This paper reports a study of the enzymatic esterification of oleic acid and ethanol. The reaction was catalyzed by lipases produced by solid-state fermentation with Rhizopus sp. Olive oil and perlite were used as an inducer and inert support, respectively. Synthesis of ethyl oleate was carried out in a 10-mL batch reactor with magnetic stirring. The effects of substrate ratios, biocatalyst concentration, and temperature on the reaction rate and conversion efficiency were evaluated. The highest reaction rate (1.64 mmol/L min) was reached with an oleic acid/ethanol mol ratio of 1:5 (oleic acid 50 mM:ethanol 250 mM) and 1 g of biocatalyst. Conversions approaching 100% were obtained after 60 min of reaction at 45 °C with n-hexane as a solvent. The initial reaction rate increased proportionally with respect to biocatalyst concentration, which suggests that the reaction rate was not controlled by mass transfer. The biocatalyst retained more than 80% of its catalytic activity after 7 months of storage at 4 °C. The results demonstrate that the biocatalyst produced by Rhizopus sp. in solid-state fermentation can be successfully used for ethyl oleate synthesis over short reaction periods under conditions when ethanol is in excess.