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

Feasible utilization of superheated steam spray drying at different inlet temperatures (160-200 degrees 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 mu m, 0.67-0.68 g/cm(3) and 192-226 s, while those of the air-dried powder were 29.03-31.02 mu m, 0.34-0.35 g/cm(3) 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.

Automated summary

The study shows that superheated steam spray drying may not be suitable for producing coffee powder, but has potential for producing color powder. The powder produced by superheated steam spray drying has smaller particle size, higher bulk density, and more wrinkled surfaces, leading to superior solubility.