Abstract/Summary

The aim of this study was to optimise the spray-drying process for low-phenylalanine (low-Phe) milk. Influence of inlet air temperature (100, 150 and 200 _C), feed flow rate (5, 10 and 15 mL min)1) and air flow rate (400, 600 and 800 L h)1) on the solubility, yield, water activity and moisture content (MC) of the milk powder were assessed using response surface methodology. The following optimum process parameters were determined: inlet air temperature of 160 _C, feed flow rate of 8 mL min)1 and air flow rate of 400 L h)1. The predicted values for the solubility, yield, water activity and MC were 98.77%, 88.08%, 0.263% and 5.48%, respectively. With the optimum parameters, the experimental values for the solubility, yield, water activity and MC were 97.56 ± 0.03%, 87.00 ± 0.10%, 0.26 ± 0.01% and 5.53 ± 0.08%, respectively. The similarity of the experimental results to the predicted values verified the models.