Application of microwave drying technology in food industry (1)

Microwave drying of food, such as using microwave heating method to dry vegetables with moisture content less than 20%, can be more than ten times higher than the traditional method. This method is not only suitable for vegetable drying

The moisture content of food is usually 30% ~ 97%. Microwave drying or microwave strengthening drying has broad application prospects.

(1) Microwave drying of food, such as using microwave heating method to dry vegetables with moisture content less than 20%, can be more than ten times higher than the traditional method. This method is not only suitable for vegetable drying, but also suitable for seaweed drying. Under the microscope, it can be found that the tissue of microwave dried vegetables is close to the fresh vegetables, but the drying time is shorter than that of freeze-drying products. Microwave can also be used for final drying of fried products, not only saving oil, but also obtaining light and delicious food with low oil content.

It takes 5-8 hours to dry the dough with hot air to avoid crusting or cracking. Microwave drying only takes 1-2 hours. The initial moisture content is dried to 20%, and the moisture content is removed by hot air. The energy saving is 25%. Microwave drying can also reduce bacterial pollution, such as drying garlic with hot air and microwave. Hot air can dry garlic from 80% to 10% (wet basis), and then microwave drying to 5%. The total number of bacteria is reduced by 90%, and energy saving is 30%.

Under vacuum condition, microwave can deal with materials that will deteriorate or degrade when the temperature is higher than 40 ℃ (sometimes even 15 ℃). The vacuum drying oven can only conduct heat conduction without convection heating, and the drying time is very long. The products of microwave vacuum drying include fruit juice, tea powder, enzyme, vegetables (mushrooms, garlic, soybeans, etc.). The cost of operation is between spray and freeze-drying. In these systems, the material is usually paste material, which is laid on the conveyor belt and passes through the specially made tunnel (vacuum degree is 133.3 ~ 2666pa) to form bubbles with good rehydration performance.