Modelling and optimization of ethyl butyrate production catalysed by Rhizopus oryzae lipase Original Research Article

Response surface methodology was used to model and optimise the production of ethyl butyrate, catalysed by Rhizopus oryzae lipase immobilised in a hydrophilic polyurethane foam. Experiments were carried out following a central composite rotatable design, as a function of reaction temperature (T: 22–38 °C) initial butyric acid concentration (A: 0.031–0.619 M) and initial molar ratio ethanol/acid (MR; 0.257–2.443). After 48 h reaction time, the production of ethyl butyrate could be fitted to a surface described by a second-order polynomial model. A maximum ethyl butyrate concentration of 0.106 M, corresponding to 47% conversion into ester and a productivity of 2.21 μmole/mL h, is expected at initial reaction conditions of T, A and MR of 33 °C, 0.225 M and 1.637, respectively. This maximum was experimentally confirmed.