Abstract:In order to investigate the effects of pulsed vacuum drying (PVD) on the rehydration kinetics and quality of dried sea cucumber after rehydration, the effects of different vacuum holding time (10 min and 20 min) on the rehydration kinetics, water retention, water state and distribution, microstructure, texture, polysaccharide and saponin of dried sea cucumber after rehydration were studied when PVD was held at atmospheric pressure for 5 min. Sea cucumbers dried by hot air (HAD) were used as control. The results showed that compared with the dried sea cucumber treated with HAD, the dried sea cucumber with PVD had higher rehydration ratio (improved by 3.24%-16.08%) and water holding capacity (improved by 5.06%-5.20%), and the dried sea cucumber with PVD vacuum holding time of 10 min had the highest rehydration ratio and water retention capacity, which were 8.95 and 63.00%, respectively. The sea cucumber dried by PVD had larger porous structure after rehydration, and the relaxation time of immobilized water was shorter. MRI images showed that the proton signal intensity of sea cucumber dried by PVD was higher after rehydration. The sea cucumber with PVD vacuum holding time of 10 min after rehydration had the lowest hardness (377.44 N), the highest polysaccharide and saponin contents (1.17 μg/g and 0.23 μg/g) and the highest amino acid contents (68.56 g/100 g). Compared with sea cucumbers dried by HAD, sea cucumbers dried by PVD had higher water rehydration ability by changing the tissue porous structure, and the dry sea cucumbers with PVD maintained higher nutrient content after rehydration. This study could help to elucidate the mechanisms by which PVD improved the rehydration characteristics and nutrient retention rates of sea cucumber, and provided a theoretical basis for finding suitable PVD conditions and obtaining high-quality rehydrated sea cucumber.