苹果微波干燥的变温控制方法研究

Microwave Drying of Apples Based on Stage-changed High-temperature Treatment

摘要:

在苹果脱水处理中，微波干燥可以有效缩短干燥时间，提高干燥品质。试验采用6种设定温度下的恒温微波干燥方案、3种变温微波干燥方案，研究苹果在不同方案下的干燥特性及品质。试验结果表明：“恒温”干燥方案中，干燥速率在干燥中期缓慢降低,会造成制品的品质较低。“干燥速率控制”方案中，干燥速率在干燥中期控制为恒速，但在干燥初期控制存在缺陷；“线性温度控制”方案中，干燥速率在干燥中期基本保持恒速，并且干燥耗时、耗能合理，感官质量、色泽品质等均优于恒温干燥；“三段温度控制”方案中，简化了“线性温度控制”方案所用设备的复杂程度，虽制品品质指标略有下降，但设备简化，更利于工业应用。该研究为微波干燥技术应用于苹果的干燥理论提供了技术依据。

Abstract:

Microwave drying can shorten the drying time and improve the product quality of dehydrated apples. The drying characteristics of apple were investigated using six fixed-temperature and three stage-changed temperature microwave-drying strategies. The results showed that the drying rate with the fixed-temperature strategy slowly decreased in the middle stage, leading to reduction in the quality of dehydrated apple. The controlled drying-rate strategy showed a constant drying rate in the middle stage, but a defective initial stage. The drying rate for the linear-temperature strategy was nearly constant; drying time and energy consumption were acceptable, while sensory and color quality improved. To simplify the linear-temperature strategy, a three-step temperature strategy was used. The quality of the products decreased slightly, but the equipment used was greatly simplified so as to be more conducive for industrial applications. These results indicate a potential application of microwave drying techniques for apple processing.