Influence of spray drying process conditions on the physicochemical, functional and microstructural properties of Date palm syrup (phoenix dactylifera L.) powders

The aim of this study was to evaluate the influence of various parameters such as inlet air temperature and Arabic gum concentration on production efficiency, physicochemical, flowability and morphological properties of date syrup powder dried using pilot-scale spray drying. Process variables were: Inlet air temperature (140-180°C) and Arabic gum concentration (20:80 to 60:40 drying aid ratio to wet weight of date syrup). Maximum yield (55.74%) has been obtained for 50:50 Arabic gum ratio at 160°C. The product yield of the samples decreased, when inlet air temperature was increased from 160°C to 180°C and higher Arabic gum concentrations. Other Physicochemical properties such as moisture content, water activity, bulk density and tapped density of the powders reduced with increasing inlet temperature and carrier concentration. These properties were varied from 2.12-3.38%, 0.142-0.23, 0.5-0.72 and 0.56-0.87 g/ml, respectively.􀀃On the other hands, flowability behavior of samples was improved, when inlet air temperature and Arabic gum concentrations were increased, except for 60:40 Arabic gum ratios. Also, Hygroscopicity, solubility and wettability were significantly affected by the process variables. The results of scanning electron micrographs indicated that with increasing inlet air temperature and Arabic gum concentration, powder particles from fairly spherical, smooth surfaces and semi sticky state (in low carrier concentration) to individual and shrinkage particles (higher Arabic gum concentration in same temperature) were changed. Crakes in some particles didn’t observed when drying temperature was increased from 140 to 180°C.