As we all know, in the food processing, how to maintain the freshness of the material is the primary consideration, among them, shorten the drying time is very beneficial to maintain the color and flavor of food; Here, we introduce several examples of drying food by microwave + hot air, from which you can see the effect of this technology in practical applications.

1. Processing applications in noodles and seaweed drying, Japan.

Japan has used the combination of microwave and hot air (frequency of 915MHz, power of 125KW) to dry the egg noodles, noodles is processed 600kg per hour and the water content in noodles is decreased from 30% to 13%, meanwhile, in this process, the temperature of hot air is maintained at 80 ° C. To dry seaweed is another successful example, we use 12KW power microwave equipment that the speed is 6 PCS per second to process seaweed and the final moisture content in product is about 5%. In the past ten years, China has gradually adopted the microwave method to take place the traditional frying method in instant noodles dehydration drying process, and this method saves time, improves efficiency and product quality.

2. Processing applications in onion drying, United Kingdom.

In the United Kingdom, people use the combination of microwave and hot air heating equipment to dry onions and achieved remarkable results. We first use the conventional hot air to dry the onion and let its moisture content decrease from 80% to 10%, and then use microwave to reduce its water content from 10% to 5%. During this period of water content reduction, if we still use the conventional method, the drying process will be very long, which will greatly increase the energy cost. However, when we used microwave technology, it not only shortens the drying time, but also saves 30% of the energy costs, and the bacteria content will be reduced by 90%.

 

3. Processing applications in macaroni drying, United State.

One microwave drying company in the United States developed a macaroni dryer (915MHz / 60kw). The working process is that by use of hot air (71-82 ℃), this device in 35 minutes, do drying operation to macaroni and let its water content first dropped about 18%, and then use microwave heating method combined with hot air convection which temperature is of 82-93 ℃, and relative humidity is about 15% -20% to do further operation.

With the advantages of microwave rapid heating and hot air can quickly evaporate noodles surface moisture, in 12 minutes, the water content could be decreased to 13% or 13.5%, and finally we cool them.

The device can save 25% energy than the original equipment and the processing time shortened from 8 hours to 1 — 1.5 hours. Such equipment can also dry potato chips and other foods.

Conclusion

The quality of microwave drying products is between air-drying and freeze-drying, and the shortening of drying time is very useful for maintaining the color and fragrance of food.