Spouted bed drying of skimmed milk: Multivariable optimization of the conditions to improve physicochemical properties of the dried milk

In the present research, the influence of the inlet parameters of a laboratory spouted bed (inlet air temperature and milk flow rate) on the physical properties (moisture content, wettability, dispersibility, particle size and density), chemical properties (protein, cholesterol, and triglyceride content) and morphology of the milk powder was evaluated and compared with properties of the commercial spray dried powder. The effect of these two inlet parameters was significant on all of the physical and chemical properties. Particle morphology of the spouted bed dried samples (flat, solid, and irregular) was entirely different from commercial spray dried milk powder (spherical, and hollow). The optimum values of the inlet air temperature and milk flow rate, calculated by RSM, were obtained 80 °C and 2.8 ml/min, respectively. The small error between properties predicted by the models and the experimental data indicated that the performed optimization was satisfactory. © 2021 Elsevier Lt