A preservation process for banana puree based on combined factors technology was optimized using response surface methodology to minimize banana colour changes during storage of the product for at least 4 months. A Box-Behnken design was adopted and second-order polynomials models were computed for each month of storage to relate some process variables (sodium bisulphite concentration, storage temperature and thermal treatment time after packaging) to a colour function (Brown Index). It was seen that storage temperature had a highly significant effect on colour changes affecting the free bisulphite level and the browning kinetics. The optimum values of the three process variables for minimal colour development were determined. (C) 1996 Elsevier Science Limited.