Optimisation of spray drying parameters using mixed flow in whey powder production using response surface methodology (RSM)

This work explored the impact of mixed flow spray drying on the physical and functional properties of whey powder without any subsequently added drying agent to increase whey utilisation. Spray drying was performed on a pilot scale using a mixed flow spray dryer. The effects of the inlet air temperature (150- 210 8C) and feed flow rate (2-7 L h-1) on several responses such as moisture content, yield, dispersibility, bulk density, and outlet air temperature were investigated using response surface methodology. In addition, with the optimised parameters, Carr index, Hausner ratio, solubility, wettability, hygroscopicity, degree of caking, crystallinity, and morphology of the obtained whey powder were determined. The investigation revealed that feed flow rate is the main parameter influencing all responses. The inlet air temperature significantly affected the bulk, tapped density, and outlet air temperature. The optimal inlet air temperature and feed flow rate for the production of whey powder were 182 8C and 3.2 L h-1, respectively. Under these parameters the moisture content, yield, bulk density, hygroscopicity, and degree of caking of the obtained product were 28.6, 1.80%, 0.24 g cm -3, 16.10 g H2O/g powder, and 85.56%, respectively.