Spray dried spinach juice: powder properties

The aim of this study is to determine the effect of the inlet and outlet air temperatures of the drying air and the addition of different types of drying agents (maltodextrin, whey powder, and gum Arabic) on the energy efficiency of the spray dryer, and the physical and powder properties of the spray dried spinach powders (SPs). In addition, the changes in the same properties of the SPs were determined during storage (5 months), at three different temperatures (4 +/- 2, 20 +/- 2, and 30 +/- 2 A degrees C). A pilot scale spray dryer was used at three different inlet/outlet air temperatures (160-200 A degrees C/80-100 A degrees C) where the outlet air temperature was controlled by regulating the feed flow rate. The total soluble solid content of the spinach juice (SJ) was measured to be as 3.2 +/- 0.2 A degrees Brix (A degrees Bx) and adjusted to 5.0 +/- 0.2 A degrees Bx before the drying operation by adding the appropriate amounts of the drying agents. The results showed that acceptable production efficiencies were obtained (67.32-85.15%) with the present equipment. The increase of outlet air temperatures, with a constant inlet air temperature, resulted in a significant decrease in the specific moisture extraction rate and the moisture extraction rate values and a significant increase in the specific energy consumption value (P < 0.05). The moisture content, water activity, flowability, and cohesiveness values of the SP significantly decreased and the average wettability and solubility times and hygroscopicity values of the SP significantly increased with the addition of different drying agents (P < 0.05). The wettability and solubility times and the bulk and tapped density values of the SPs changed during first or second months (P < 0.05) and stayed constant during storage (P > 0.05). The flow diagram of drying of spinach juice. [GRAPHICS] .