Response Surface Methodology Approach for the Synthesis of Ethyl Butyrate

Vitor Cardoso Aragão, Maria Rita Alaniz Porto, Carlos André Veiga Burkert, Susana Juliano Kalil and Janaína Fernandes de Medeiros Burkert*

Department of Chemistry, Federal University Foundation of Rio Grande, P.O. Box 474, 96201-900, Rio Grande, RS, Brazil

Article history:
Received March 13, 2009
Accepted May 27, 2010

Key words:
ethyl butyrate, immobilized lipase, esterification, optimization, enzymatic synthesis

Summary:
Response surface methodology was used to determine optimum conditions for the esterification of ethanol and butyric acid to produce a flavour ester using immobilized lipase. Various reaction parameters including butyric acid concentration, enzyme concentration, temperature and ethanol/butyric acid molar ratio affecting ethyl butyrate production were investigated using a fractional factorial design 2^4–1. Based on the results from the first factorial design, all of the variables which were significant in the process were selected to be used in a 2⁴ central composite rotatable design (CCRD). The optimum conditions for the enzymatic reaction were obtained at a 90 mM butyric acid concentration using a 7.7 g/L enzyme concentration at 45 °C and the ethanol/butyric acid molar ratio of 1:1 for 3 h. The esterification percentage, under these conditions, was 87 %.

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