What are the drying methods for dehydrated vegetables?

Drying is an important operation link in the production process of dehydrated vegetables. The water content of fresh vegetables is generally about 70%-90%, and the water content of vegetables after drying is 6%-8%. The drying methods for dehydrated vegetables include hot air drying, far infrared drying, microwave drying, freeze vacuum drying and puffing drying.

Dehydrated vegetable dryer have the characteristics of low investment, low cost, simple operation, convenient maintenance, good economic benefits, etc., and are widely used.

The through-flow drying layer has a large thickness, short drying time, fast speed and high production efficiency. Multi-layer and single-layer mesh belt dehydrated vegetable dryer both use the through-flow drying process and are ideal dehydrated vegetable drying equipment.

Far infrared drying and microwave drying

The production of dehydrated vegetables using far infrared drying and microwave drying technology is faster than hot air convection drying, has better product quality and is easy to realize automatic control, but the power consumption is too large. Under the current power shortage in my country, it is unconditionally adopted in large quantities.

Puffing drying and freeze vacuum drying

Puffing drying can improve production efficiency by more than double that of hot air drying, and the product has good rehydration, but it is limited to some varieties.

Freeze vacuum drying is to quickly freeze the cut materials in a closed container, then reduce the pressure in the container, so that the quick-frozen materials are in a vacuum state, and then heat the ice crystals inside the materials to sublimate directly into water vapor and discharge, and the materials are dehydrated and dried at low temperatures. After drying, the nutritional content, color, taste, shape, etc. of the products change very little, and the product quality is relatively high. However, freeze vacuum drying equipment requires large investment and high operating costs. It is more suitable for drying materials with good benefits, high economic value, strict requirements, and small output, such as ginseng, wolfberry, Huangshi, etc. At present, freeze vacuum drying is less used in the processing of dehydrated vegetables in China.