蔬菜和藥草的干燥原理（中英文版）
發(fā)布時間：2022-11-21 10:35:39
干燥就是因食品內外水蒸氣分壓不同而使內部水分傳遞到周圍空氣中的過程。
Drying: because of different inside and outside partial pressure of food and water vapor ,make internal moisture transfer to the surrounding air.
在熱風干燥中，有效工作溫度范圍在60—90℃，干燥果蔬的時間需要長達15h。在恒速的干燥過程中，干燥速率由能量傳遞到食品濕表面的速度決定。由于蒸發(fā)冷卻，產品的溫度要比后期干燥過程中的低。一旦表面已干燥，從內部到表面的傳質速率就不足以維持表面的透水性。
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.
在降速干燥階段，擴散速率決定了干燥速率，并隨水分子的含量降低而降低。由于物料表面水分蒸發(fā)冷卻效應的降低，從而導致表面溫度升高。在熱風干燥溫度下，揮發(fā)性風味物質的組分會流失，結構發(fā)生變化，比如：硬化抑制了后干燥的進行，并且延長了干燥時間，從而導致了破壞維生素、顏色和風味物質的化學和酶促反應。
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.
微波干燥過程，是微波對物料內、外同時加熱的過程。物料由于內、外同時升溫，且物料表面是直接接觸空氣，所以物料內部溫度會略高于表面溫度。同時物料內的水分由內部向外部遷移，經(jīng)物料表面，蒸發(fā)至空氣當中。
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。
微波在對水果、蔬菜和藥草干燥的過程中，也可以較好地保持物料原有的外形、色澤、香味及營養(yǎng)成本，有效地提高了產品品質。
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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