Effect of feed concentration and inlet air temperature on the properties of soymilk powder obtained by spray drying

In this study, soymilk powder was produced by spray drying. The inlet air temperature of spray dryer was varied from 200 to 280 degrees C and the feed concentration was varied from 15 to 25% (w/v). Response surface methodology was used to examine the effects of these independent variables on the detailed characteristics in terms of physical, structural, functional properties of powder. Overall, results show that rising the inlet air temperature caused a decrease in tapped and loose bulk density, true density, filling rate, water holding capacity, and water content of powder; and an increase in compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index. An increase in feed concentration led to an increase in true density, compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index; and a decrease in tapped and loose bulk density, filling rate, water holding capacity, and water content; whereas oil holding capacity might be increased or decreased and it depended almost solely on the feed concentration.