Application of the agglomeration process on spinach juice powders obtained using spray drying method

Abstract

In this study, wet agglomeration process was applied at selected conditions (at 60 °C air inlet temperature and 1.6 m/s air velocity) to improve the functional properties of the spinach juice powders produced by the spray drying technique and distilled water, maltodextrin, whey protein isolate, and gum Arabic solutions were used as the binder agents. The moisture content and the water activity values of the obtained spinach juice agglomerates were in the range of 6.44%–11.68% and 0.254–0.412, respectively. Further a decrease in lightness (L*) values and an increase in yellowness/blueness (b*) values were observed in the agglomeration process. The agglomeration process increased the mean particle diameters, and decreased the wettability and solubility times. The calculated bulk and tapped density values for spinach juice agglomerates are in the range of 380–510 and 490–618 kg/m3, respectively. The agglomeration process improved the values of cohesiveness, flowability, porosity, and hygroscopicity. Low friability and high solubility values were also obtained after agglomeration. The microstructure of powders changed depending on binder agents, and the glass transition temperature of the powders increased from 110.72 to 117.32–127.38 °C for the agglomerates. As a result, the agglomeration process of the spray dried spinach juice powders was successfully carried out in the fluidized bed. The moisture content and water activity values were in safe limits and their powder properties were improved.