In the vacuum drying process, the material to be dried […]
In the vacuum drying process, the material to be dried is placed in a closed drying chamber, and the vacuumed system of Freeze Dry Machine is used to continuously heat the material to be dried, so that the moisture inside the material diffuses to the surface through a pressure difference or a concentration difference, and water molecules are on the surface of the material. Obtaining sufficient kinetic energy to escape the low pressure space of the vacuum chamber after overcoming the mutual attraction between the molecules, thereby being pumped away by the vacuum pump. Vacuum drying facilitates of Freeze Dry Machine the recovery of useful and hazardous materials and provides good sealing. In the sense of environmental protection, some people call vacuum drying "green dry".
Under vacuum conditions, the boiling point of the material moisture is reduced and the vaporization process is accelerated, so it is particularly suitable for materials that are sensitive to temperature and easily decompose. Vacuum drying is mainly carried out in a low vacuum region. During the evaporation process, the boiling evaporation temperature of the grain is proportional to the ambient pressure.
The high-moisture grain is placed in a closed drying cylinder to form a drying cylinder and maintain a certain degree of vacuum. At the same time, the grain in the drying cylinder is continuously heated. The moisture inside the grain is diffused to the surface through the pressure difference, and is vaporized and then pumped away by the vacuum pump to continuously dehydrate and dry the high-moisture grain under the vacuum low temperature state.
Vacuum drying reduces the boiling evaporation temperature of water from 100 ° C to below 40 ° C. Since the evaporation temperature is lower than the gelatinization temperature of the starch, it does not damage the grain. It avoids the expansion and bursting of grain grains, and can guarantee the quality of the products after the grain is dried. It ensures that the original color, fragrance, taste, nutrient composition and quality of the material are basically unchanged after drying. It is a low-temperature drying in the true sense, which is completely different from the general hot air drying at low temperature.
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