Abstract: In this study, fresh intact shiitake mushrooms (Lentinus edodes) were used to investigate effects of three drying methods (three-stage microwave vacuum freeze drying (TS-MVFD), freeze drying (FD), and hot air drying (HAD) on drying characteristics, nutrient composition and microstructure of dried mushrooms and sensory characteristics of rehydrated mushrooms determined by quantitative scale analysis. The results showed that TS-MVFD, FD and HAD took 5, 14 and 8 hours to dehydrate mushrooms to a moisture content of less than 13%, respectively. After 120 min of rehydration, the rehydration rate of TS-MVFD-dried mushrooms (7.1) was significantly higher than that of FD (6.0) and HAD (4.4) dried samples. The rehydration coefficient (91.40%), cap color, content of total sugar (60.21 g/100 g), crude polysaccharide (7.41 g/100 g) and free amino acid (3.44 g/100 g) of the TS-MVFD dried mushroom were no significant difference when compared with FD dried mushroom. The microstructure of TS-MVFD dried samples was similar to that of FD dried samples, except for slightly larger micropore diameter. The cross-sectional structure of HAD dried samples was stacked with the cell wall collapsing seriously. After rehydration and cooking, the flavor and taste of TS-MVFD dried mushroom samples were significantly better than those of HAD and FD dried products. Therefore, we believe that TS-MVFD will become a popular drying method for shiitake mushrooms.

Key words: shiitake mushroom, three-stage microwave vacuum freeze drying, freeze drying, hot air drying, quality, microstructure