Microwave drying is particularly recommended for thermosensitive products such as food products in order to preserve all their properties. During drying, some fruits tend to oxidize and brown, losing flavor and vitamins A and C. To reduce oxidation and preserve the quality of the dried product, a pretreatment by placing the fruit in an acid solution (citric or ascorbic) is recommended. On the other hand, blanching, freezing and electric field treatment alters the cell structure, allowing moisture to escape more easily and products to rehydrate more quickly.

An experimental study was conducted to see the effect of different pretreatment methods on the kinetics and quality of microwave-dried apple samples. For drying kinetics, no significant effect is observed for the blanched and electric field treated samples. However, a reduction in drying time by a value of 14.6–20.3% is observed for frozen samples. In other hand, the best quality (lowest ΔE, lowest BI, and highest WI) is observed for the sample blanched in 5% citric acid at 60 °C. Finally, the effect of the different pretreatment methods on the quality of the surface structure of the dried samples was studied by scanning the surface structure using Scanning Electron Microscope (SEM).

微波干燥特别推荐用于食品等热敏产品，以保持其所有特性。在干燥过程中，一些水果容易氧化和变褐，失去风味和维生素 A 和 C。为了减少氧化并保持干燥产品的质量，建议将水果放入酸溶液（柠檬酸或抗坏血酸）中进行预处理。另一方面，热烫、冷冻和电场处理会改变细胞结构，使水分更容易逸出，产品更快地再水合。

进行了一项实验研究，以了解不同预处理方法对微波干燥苹果样品的动力学和质量的影响。对于干燥动力学，对于热烫和电场处理的样品没有观察到显着影响。然而，冷冻样品的干燥时间减少了 14.6-20.3%。另一方面，在 60 °C 下在 5% 柠檬酸中热烫的样品观察到最佳质量（最低 ΔE、最低 BI 和最高 WI）。最后，通过使用扫描电子显微镜（SEM）扫描表面结构，研究了不同预处理方法对干燥样品表面结构质量的影响。