The effects of total protein/total solid ratio (TP/TS) and pHon the spray drying process and rehydration properties
of soy powderwere investigated. The results showed that a decrease in the pH of the feed from7 to 4 resulted in
an increase of particle size, wettability index (WI), dispersibility index (DI) and water content (WC) of soy powder.
In contrast, the solubility index (SI) and viscosity decreased, presumably due to a decrease of surface charges
near the isoelectric point of soy protein leading to the formation of insoluble complexes at pH 4.WCand DI of the
powder obtained by spray drying decreased as TP in the powder increased, regardless of the dextrose equivalent
(DE) of themaltodextrin (MD). The latest affects the DI and WC in the powder; with increasing DE,WC and the
energy cost to manufacture the powder decreased, whereas DI slightly increased