蔬菜和药草的干燥原理（中英文版）
发布时间：2022-11-21 10:35:39
干燥就是因食品内外水蒸气分压不同而使内部水分传递到周围空气中的过程。
Drying: because of different inside and outside partial pressure of food and water vapor ,make internal moisture transfer to the surrounding air.
在热风干燥中，有效工作温度范围在60—90℃，干燥果蔬的时间需要长达15h。在恒速的干燥过程中，干燥速率由能量传递到食品湿表面的速度决定。由于蒸发冷却，产品的温度要比后期干燥过程中的低。一旦表面已干燥，从内部到表面的传质速率就不足以维持表面的透水性。
During hot air drying process, effective working temperature range is 60~90℃,vegetables and herbs drying time is very long , sometimes even 15h. In the process of the constant speed drying, the drying rate is determined by the energy transfer to the speed of food wet surface.Because of the evaporative cooling, the temperature of the product will be lower than the later drying process,once the sruface is dried, from the inside to the surface of the mass transfer rate is not enough to keep the surface of the water permeability.
在降速干燥阶段，扩散速率决定了干燥速率，并随水分子的含量降低而降低。由于物料表面水分蒸发冷却效应的降低，从而导致表面温度升高。在热风干燥温度下，挥发性风味物质的组分会流失，结构发生变化，比如：硬化抑制了后干燥的进行，并且延长了干燥时间，从而导致了破坏维生素、颜色和风味物质的化学和酶促反应。
In the falling-rate drying stages, diffusion rate determines the drying rate, and decrease with the content of water molecules. Due to the material surface evaporation cooling effect is reduced, resulting in higher surface temperature.
Under the hot air drying temperature, volatile flavor substances group branch loss, structural changes,for example:Hardening inhibits after-drying process, and the drying time was prolonged, leading to the destruction of vitamins, color and flavor of chemical and enzymatic reaction.
微波干燥过程，是微波对物料内、外同时加热的过程。物料由于内、外同时升温，且物料表面是直接接触空气，所以物料内部温度会略高于表面温度。同时物料内的水分由内部向外部迁移，经物料表面，蒸发至空气当中。
Microwave drying process, is heating inside and outside at the same time.Due to internal and external temperature raise at the same time,and material surface is directly contact with air,so material internal temperature will be slightly higher than the surface temperature. At the same time, material internal moisture will migrate from inside to outside,throught material surface, evaporate into the air.
So, adopts microwave drying , drying speed is higher than other drying methods(like hot air dryer,steam dryer etc).
因此，采用微波干燥，干燥速度高于其他干燥方法。
微波在对水果、蔬菜和药草干燥的过程中，也可以较好地保持物料原有的外形、色泽、香味及营养成本，有效地提高了产品品质。
Microwave in the drying fruits,herbs and vegetables process,can better keep the original shape,colour and lustre,flavor and nutrition,effectively improved products quality.
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