Abstract: Contact dehydration sheet (CDS) is a new low-temperature dehydration technology for drying protein-containing foods such as aquatic products. In order to explore the effect and mechanism of low-temperature dehydration on improving rehydration characteristics of Penaeus vannamei, the structural changes of proteins in dried Penaeus vannamei dehydrated to different moisture contents (60%, 45% and 30%; on a wet basis) by using CDS, as well as rehydration ratio and water distribution during rehydration and water-holding capacity (WHC) at the end of rehydreation were analyzed and compared with those from hot air drying (HAD). The results showed that the rehydration ratio and WHC of dried shrimps prepared by CDS dehydration were higher than those of hot air dried shrimps (85.22% and 69.17% versus 62.55% and 65.73% when the moisture content was 30%, respectively). Low-field nuclear magnetic resonance (NMR) analysis demonstrated that the proportions of bound, immobile and free water in rehydrated shrimps dehydrated to a moisture content of 30% were closer to those in fresh shrimps compared with hot air dried shrimps. Surface hydrophobicity and protein secondary structure changed less in CDS-dehydrated shrimps than in HAD-dehydrated shrimps. Therefore, CDS-dehydrated shrimps could maintain the integrity of protein structure during the dehydration process, and have higher rehydration ratio and WHC, so that the product quality could be closer to fresh shrimp. CDS could be used as a new strategy for the dehydration of shrimps and other high-value aquatic products.

Key words: Penaeus vannamei; contact dehydration sheets; rehydration characteristics; water distribution; protein structure