Feasibility study of the use of superheated steam spray drying to produce selected food powders

Abstract

Feasible utilization of superheated steam spray drying at different inlet temperatures (160–200 °C) and feed rates (3–15 mL/min) to produce instant coffee and sodium copper chlorophyllin (natural green colorant) powders was assessed. Yield, physical properties and morphology of the steam-dried powder were determined and compared with those of the air-dried one. Superheated steam spray drying might not be a proper method for producing coffee powder as at all test conditions coffee extract adhered and dried on the wall of the chamber. Superheated steam spray drying, on the other hand, has the potential to produce the color powder with smaller particle size, higher bulk density and more wrinkle surfaces, resulting in the superior solubility. Mean diameter (D[4,3]), bulk density and solubility time of the steam-dried powder were 15.53–15.97 µm, 0.67–0.68 g/cm3 and 192–226 s, while those of the air-dried powder were 29.03–31.02 µm, 0.34–0.35 g/cm3 and 244–283 s, respectively. In terms of yield and color, both of the powders and of the reconstituted solutions, no significant differences among the air-dried and steam-dried powders were observed.