Response surface methodology (RSM), based on multivariate non-linear model, was applied to study the interactions and optimization of the immobilization parameters for cell entrapment, namely alginate concentration, cell loading and bead diameter using Erwinia rhapontici NCPPB 1578 that produced palatinose. ANOVA analysis and statistical parameters calculations showed that RSM could be used effectively to model and improve a complex system like cell immobilization. Palatinose yield was increased by 40%. The maximum yield of 140 mg/ml was achieved in a batch of I h at alginate concentration of 5% w/v, cell loading of g l(-1) and 2.25 turn bead diameter. Thus, the E. rhapontici NCPPB 1578 immobilization in alginate bead and subsequent palatinose yield was successfully improved by application of RSM technique. (C) 2006 Elsevier Ltd. All rights reserved.