The 1st aim of this study is to determine the influence of inlet and outlet air temperatures on the physical and chemical properties of obtained powders from spinach juice (SJ) with 3.2 ± 0.2 °Brix (°Bx). Second, the effect of 3 different drying agents (maltodextrin, whey powder, and gum Arabic) on the same properties was investigated for the selected inlet/outlet temperatures (160/100 °C) which gives the minimum moisture content and water activity values. For this purpose, the total soluble solid content of SJ was adjusted to 5.0 ± 0.2 °Bx with different drying agents. Finally, the effects of different storage conditions (4, 20, and 30 °C) on the physical and chemical properties of spinach powders (SPs) produced at selected conditions were examined. A pilot scale spray dryer was used at 3 different inlet/outlet air temperatures (160 to 200 °C/80 to 100 °C) where the outlet air temperature was controlled by regulating the feed flow rate. Results showed that the moisture content, water activity, browning index, total chlorophyll, and total phenolic contents of the SP significantly decreased and pH and total color change of the SP significantly increased by the addition of different drying agents (P < 0.05). In addition, the changes in the above‐mentioned properties were determined during the storage period, at 3 different temperatures. It was also observed that the vitamin C, β‐carotene, chlorophyll, and phenolic compounds retention showed first‐order degradation kinetic with activation energy of 32.6840, 10.2736, 27.7031, and 28.2634 kJ/K.mol, respectively.

中文翻译：

---

菠菜汁的喷雾干燥：表征，化学成分和储存

这项研究的第一个目的是确定进风温度和出风温度对从3.2±0.2°Brix（°Bx）的菠菜汁（SJ）获得的粉末的物理和化学性质的影响。其次，研究了三种不同的干燥剂（麦芽糊精，乳清粉和阿拉伯树胶）对所选进出口温度（160/100°C）的相同性能的影响，该温度给出了最低的水分含量和水活度值。为此，使用不同的干燥剂将SJ的总可溶性固形物含量调整为5.0±0.2°Bx。最后，研究了不同储存条件（4、20和30°C）对在选定条件下生产的菠菜粉（SP）的物理和化学性质的影响。在三个不同的进/出口空气温度（160至200°C / 80至100°C）下使用中试规模喷雾干燥机，通过调节进料流量控制出口空气温度。结果表明，通过添加不同的干燥剂，SP的水分含量，水分活度，褐变指数，总叶绿素和总酚含量显着降低，SP的pH和总颜色变化显着增加（P <0.05）。此外，上述特性的变化是在存储期间内在3个不同温度下确定的。还观察到维生素C，β-胡萝卜素，叶绿素和酚类化合物的保留表现出一级降解动力学，其活化能分别为32.6840、10.2736、27.7031和28.2634 kJ / K.mol。