Ways to dry agricultural products

In order to prevent the growth of microorganisms after fruits are harvested, agricultural products drying has become a necessary process.

The dehydration and drying of fruits and vegetables is the process of removing a large amount of free water and part of colloidal bound water contained in their cells. This article will introduce several methods of drying agricultural products in industrial manufacturing.

The major technologies used in industrial production are hot air drying, heat pump drying and freeze drying. Rotary dehumidifier drying is also applied widely.

Hot air drying is low-cost and easy to operate. Firstly, it gasifies moisture on the surface and diffuses it into surrounding hot air. Then, it gradually transfers moisture inside the cells to the surface and repeats the former process until the water content of the products is down to a certain extent.

However, the relatively high heating temperature and the long time consuming make it easy to cause the loss of nutrients inside the products. And its dehumidification capacity is also limited.

The heating technology of heat pump drying is similar to that of hot air drying, except that its heat source is different. In recent years, heat pump technology has been gradually popular in fruit and vegetable drying process.

The quality of finished product dried by heat pump is better than those of hot air drying, and the whole process is pollution-free.

Freeze drying is a technology that quickly cools and condenses the moisture of into ice in a low-temperature environment, and then directly sublimates the ice to remove moisture.

The loss of nutrients in materials of this technology is less than that of hot air drying technology. However, freeze-drying consumes a lot of energy and is generally only applied in large-scale enterprises.

Rotary dehumidifier drying adopts a chemical adsorption medium to control the humidity. Humid air enters process area on rotor, the moisture will be adsorbed by the adsorbent. Then rotor rotates to regeneration area to dry the adsorbent. Study has shown that desiccant rotor drying has exceptional dehumidification performance.

Regarding the concern about the loss of nutrition of agricultural products, Puresci has developed the low-temperature drying series rotor, PSL series. The PSL rotor is designed to solve a series of material dehumidification and drying problems existing in heat pump drying. PSL series can help heat pump drying improve efficiency, reduce energy consumption and improve material quality, especially for heat-sensitive materials.