Modelling the production of ethyl butyrate catalysed by Candida rugosa lipase immobilised in polyurethane foams

• Published in: Biochemical engineering journal Vol. 33; no. 2; pp. 148 - 158
• Main Authors: Pires-Cabral, P., da Fonseca, M.M.R., Ferreira-Dias, S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.02.2007; Amsterdam Elsevier Science; New York, NY
• Subjects: Biological and medical sciences; Biotechnology; Ethyl butyrate; Fundamental and applied biological sciences. Psychology; Immobilised enzymes; Lipase; Modelling; Optimisation; Polyurethane foam; Optimisation; Immobilised enzymes; Modelling; Ethyl butyrate; Lipase; CCRD; RSM; Polyurethane foam; Yeast; Enzyme; Immobilization; Triacylglycerol lipase; Esterases; Modeling; Optimization; Carboxylic ester hydrolases; Butyrate; Fungi; Polyurethane; Production; Hydrolases; Fungi Imperfecti; Immobilized enzyme; Candida rugosa; Thallophyta
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2006.10.015

Response surface methodology was used to model and optimise the esterification of ethanol with butyric acid in n-hexane, catalysed by Candida rugosa lipase immobilised in two hydrophilic polyurethane foams (“FHP 2002™” and “FHP 5000™”). Experiments were carried out following central composite rotatable designs (CCRD), as a function of the initial water activity of the biocatalyst ( a w ), initial butyric acid concentration ( A) and ethanol:acid molar ratio (MR) in the organic medium. Ester production increased with increasing a w of the biocatalysts, probably due to the hydrophilicity of both substrates in contrast with the hydrophobicity of the product, which is released to the bulk medium. Thus, for each biocatalyst ( a w = 0.98 ) another CCRD was performed as a function of A and MR. With both preparations, higher conversions (>95%) were observed for low A values. For the “FHP 2002™” system, a maximum ester production of 0.23 M is expected, after 18-h reaction, at initial 0.35 M A and 1.51 MR, corresponding to a w of 0.95 and 0.84 M A and 1.65 M ethanol in lipase microenvironment. With “FHP 5000™” system, predicted initial conditions of 0.54 M A and 0.75 MR (0.32 M A; 0.75 M ethanol in microenvironment; a w of 0.95), will lead to the maximum ester production of 0.27 M. These maxima were experimentally confirmed.