Application of drying technology in processing of dehydrated vegetables
Most of the dehydrated vegetables produced in China are made by sun drying and hot air drying. Because of the high temperature of sun drying and hot air drying, it is easy to produce quality problems such as color browning, loss of nutrients and poor rehydration performance. In China, a few enterprises adopt freeze-sublimation microwave drying machine technology, and the dehydrated vegetables processed are of good quality. microwave drying machine 1 principles and characteristics 2.1 fundamentals of microwave drying The water in vegetables exists in three different states: free water, colloidal bound water and combined water. Most of the free water and colloid bound water are removed during the drying process, and the hydrated water can not be removed by drying. The evaporation rate of moisture in vegetables is slower, not entirely depending on the temperature of dry air, but on the humidity saturation difference of air at this temperature, that is, the relativ
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