真空冷冻干燥（FD）产品的品质高、需求大，但高能耗、高成本限制了FD的应用。微波冷冻干燥（MFD）利用微波加热的整体性、高效性提高冷冻干燥的干燥效率、缩短干燥时间、节约能耗，同时保持产品的品质，但目前仅限于实验室研究，扩大应用存在着两大难题：高真空状态下的放电问题和干燥过程无法实时调控导致产品品质不稳定的问题。本项目以荔枝和白蘑菇为试材，采用太赫兹光谱技术实时监测物料的水分含量，探明微波冻干过程中物料的水分分布规律，进而阐明水分分布、微观细胞结构与电磁场耦合机制，揭示物料放电的机理；采用太赫兹呈像技术监测物料在MFD过程中的外观品质实时成像图谱，建立图谱与外观品质间的相关性，通过动态调整和控制微波冻干过程参数，获得高品质的MFD产品。该研究有望解决微波冷冻干燥技术所遭遇的瓶颈问题，从而推动果蔬冷冻干燥产业的发展。

Vacuum freeze-drying (FD) products retain high quality and therefore highly demanded, but high energy consumption of FD leads to high operation cost, which limits its application. In comparison, microwave freeze-drying (MFD) has several advantages, such as increased drying efficiency, short drying time, and reduced energy consumption while the quality of products is also maintained due to the integrity and high efficiency of microwave heating. However, MFD is currently limited to laboratory research only; its industrial application has two bottlenecks: the discharge under high vacuum and lack of real-time control over the drying process, which leads to unstable product quality. In this paper, litchi and white mushrooms were used as test materials, and their moisture contents were monitored in real time by terahertz spectroscopy. This research was aimed at exploring the law which governs the moisture distribution of materials during microwave freeze-drying process; the coupling mechanism between moisture distribution, cell microstructure, and the electromagnetic field was illustrated. The terahertz imaging technology was used to monitor the real-time image of the appearance quality of materials during the MFD process. The correlation between the image and appearance quality was established. High-quality MFD products can be obtained by dynamically adjusting and controlling the parameters of microwave freeze-drying process. Thus, the mechanism of material discharge was revealed. This research is expected to solve the problems in MFD technology, thus promoting its application in fruit and vegetable freeze-drying industry.