Spray drying of stevia extract: evaluation of physicochemical, functional and microstructural properties

In this study, The effect of wall material (Arabic gum, maltodextrin and whey protein concentrate (WPC)) in different concentrations (10,20,30 w/v) on powder production yield, moisture content, Water activity, wettability, solubility, hygroscopicity, bulk, tapped and true density, colorimetric and flowability characteristics of stevia powders were investigated. Also, the microstructure of spray dried powder was evaluated by scanning electron microscopy. The results showed that increasing the maltodextrin ratio led to increasing in powder production yield. By increasing the carriers concentration, the amount of water activity, bulk, tapped, true density of samples, decreased, these properties were in the range of 0.08-0.33, 0.34-0.59 g / mL, 0.39 – 0.64 g/mL, 1.28 - 1.61 g/mL, respectively. The minimum flowability indexes (Hausner ratio, compressibility, angle of repose) obtained in 10 WPC sample. The maximum moisture content (5.03%), time of wettability (51.08 seconds), solubility (94.08%) and hygroscopicity (30.66%) were related to 10 WPC, 30 WPC, 10 MD, 10 GA samples, respectively. The evaluation of samples microstructure showed that the samples containing WPC had larger particles and deeper wrinkling surfaces.