Optimization of Microwave Vacuum Drying Technology for Radish Musk and Its Characteristics
Absrtact: In order to expand the development and utilization of radish reel resources, microwave vacuum drying technology was used to dry radish reel. On the basis of single factor experiments, the response surface methodology was used to optimize the microwave vacuum drying process parameters of radish reel, and compared with microwave drying equipment, hot air drying and vacuum drying methods, the effects of microwave vacuum drying on its quality characteristics were studied.
The results showed that the vacuum degree had a significant effect on the drying rate of radish reel, while the thickness of material layer had little effect. The optimum drying parameters were microwave power 438.92 W, vacuum degree 0.09 MPa, loading 151.57 g and material layer thickness 25.49 mm. By comparing the rehydration ratio, chlorophyll content and Vc content of the products under four drying methods, it was found that microwave vacuum drying had the best effect. Microwave vacuum drying is an effective drying technology for radish reel.
Key words: radish reel microwave drying; microwave vacuum drying; response surface analysis; rehydration ratio; chlorophyll content
The scientific name of radish leaves is "Raphanus Leaf" and the common name is "Radish Mu". Its taste is sweet and bitter, and it has the effect of "generating Jin and promoting Qi, removing dampness and intestines, curing diarrhea and dysentery, appetizing" (Xinshen Yinpian).
It is found that radish reel is rich in essential oils, vitamins and antiviral components (interferon inducer dsRNA). Its protein, vitamin and trace element contents are much higher than radish, especially its calcium content is 350 mg/100 g, ranking first among vegetables, which is very suitable for people lacking calcium.
However, the nutritional value of radish reel has not been paid enough attention for a long time, and its dark green color, high moisture content, easy yellowing, inconvenient storage, often abandoned, resulting in waste of resources.
The commonly used dehydration methods of sunshine are greatly influenced by weather and have low efficiency; vacuum freeze-drying has good quality but high investment cost; hot air drying has problems of low drying efficiency, low energy utilization rate and poor quality of dry products; microwave drying can easily lead to overheating and damage the quality of products, resulting in charring, gelatinization, surface hardening and other phenomena.
Microwave vacuum drying combines microwave with vacuum technology. It combines the advantages of microwave drying, such as fast drying, whole heating and vacuum drying, low temperature and fast dehumidification. It has low drying temperature, fast drying speed, low energy consumption and isolation from oxygen. It has obvious advantages in preserving the original nutrients, color and fragrance of dried materials. It has been successfully applied in the drying process of various fruits and vegetables. There is no report on microwave vacuum drying of radish reel.
In this paper, the chlorophyll content and rehydration ratio of radish reel were used as indexes, and the parameters of microwave power, vacuum degree, loading capacity and material layer thickness were optimized by response surface analysis method. The optimum microwave vacuum drying technology of radish reel was determined, and the microwave vacuum drying characteristics of radish reel were studied.
The effects of microwave power, vacuum degree and loading amount on water loss rate were discussed, and the dynamic model of microwave vacuum drying of radish reel was established in order to provide theoretical basis for optimization and control of microwave vacuum drying process of radish reel and solve the technical problems of storage and transportation of radish reel resources.