Effects of Rehydration Methods on the Quality and Water Mobility in Rehydrated Dried Tremella fuciformis

This study systematically investigated the effects of different rehydration methods on the quality characteristics and water mobility in rehydrated dried Tremella fuciformis. Dried T. fuciformis was subjected to four rehydration methods: hot water rehydration (HWR) at 70 and 100 ℃, and ultrasound hot water rehydration (US-HWR) at 70 and 100 ℃ with treatment times of 3, 4 and 5 min. Quality evaluation was by measuring rehydration ratio, color, texture properties (hardness and viscosity), polysaccharide content, and sensory scores. Low-field nuclear magnetic resonance (LF-NMR) was used to analyze the mobility of water during the rehydration process. The results showed that ultrasound-assisted rehydration (US-HWR) significantly increased the water absorption rate of T. fuciformis and accelerated water migration. However, it also led to a decrease in hardness, an increase in viscosity, and a reduction in polysaccharide content. Overall, the optimal rehydration process was US-HWR at 100 ℃ for 3 min. Under these conditions, the rehydration ratio was 12.79 ± 0.78, the hardness was (69.36 ± 3.13) g, the viscosity was (0.030 ± 0.002) g·s, and the sensory score reached the highest value of 82.50 ± 2.55. LF-NMR analysis revealed that the water in rehydrated T. fuciformis was mainly composed of four components (T_2b, T₂₁, T₂₂, and T₂₃). Both extended rehydration time and ultrasound treatment significantly increased the mobility of water in T. fuciformis and promoted water migration. US-HWR at 100 ℃ for 3 min is an efficient and high-quality rehydration technology. It can produce a product with excellent sensory and physicochemical quality in the shortest time, making it an ideal rehydration method for industrial production of ready-to-eat cold T. fuciformi dishes.