Recent development of microwave fluidization technology for drying of fresh fruits and vegetables

Background: With the mature of high-power magnetron production, microwave drying has been widely used as a clean and efficient method in the field of fruits and vegetables processing. Microwave fluidization drying (MFD) improves the uniformity and the moisture and heat dissipation efficiency of fruits and vegetables. In recent years, various types of MFD device have been developed, which have different strengths and weaknesses. Scope and approach: In this review the recent development of MFD device for the drying of fruits and vegetables such as microwave hot-air spouted drying (MASD), compressed-air pulse-spouted microwave vacuum drying (PMVD), microwave mechanical-vibration fluidization drying (MMFD) were analyzed. The working principle, drying quality, energy consumption, nutrition loss and son on have been discussed in detail. Key findings and conclusions: The drying uniformity of fruits and vegetables during MFD is improved in the case of uneven drying of microwave. Nutrition loss, drying efficiency is in advantage compared with hot air drying and static microwave drying. The drying quality and uniformity is good with puffing effect in PMVD and suitable for snacks. However, MASD and PMVD cannot achieve continuous production of dehydrated fruits and vegetables. The material is mixed evenly during MMFD with continues process, while the distribution and moving speed of the material in the fluidized bed need to be improved.