| Sea cucumber has attracted more and more people’s attention as a high protein, low fat, no cholesterol, high-quality nutritious ingredient. Fresh sea cucumber is very difficult to be stored, therefore, generally processed into dried sea cucumber. Dried sea cucumber is one of the most popular type of products. Dried sea cucumber is the most popular type of product. Water content of dried sea cucumber is required to be restored to that of fresh sea cucumber before cooked and eaten. The existing rehydration ways are diverse and time-costing, which results in quality varies. In this study, dried sea cucumbers from Shandong and Liaoning Fortuna Island were used to optimize rehydration process, and evaluated the effects of ultrasonic treatment on rehydration and quality of sea cucumbers. Based on these results, a convenient and functional food with nutritional value and good senses was obtained. Meanwhile, the shelf life of rehydrated sea cucumber under ice temperature was investigated. The conclusions were as follows:(1) The results showed that the number of poached and single boiled time were the most important factors. Response model of dry sea cucumber rehydration process were obtained by Box-Behnken test:Y=47.10-11.75A-5.16B-0.44C-2.33AB+0.12AC-0.23BC-3.32A2-1.87B2-2.24C2(2) Boiled twice, a single boiling time of 26 min and temperature of incubation at4℃ were the optimum conditions for dry sea cucumber rehydration process. Sensory evaluation value of theoretical level had a score of 35.93 and the actual score was 36.07.The theoretical value of water holding capacity was 62.71% and the actual yield of62.68%. The theoretical content of acid mucopolysaccharides was 0.6419 g/100 g dry weight and the actual yield was 0.6411 g/100 g dry weight. The model was accurate and reliable to predict water retention and acid mucopolysaccharide content.(3) When applied in light dry sea cucumber penetration rehydration process,ultrasound can significantly accelerate the mass transfer efficiency. Rehydration time was reduced by 6-10 h through ultrasonic wave, which greatly reduced the required time and provided scientific guidance for the industrial production of instant sea cucumber.(4) Ultrasonic 2 times, single ultrasonic time of 45 min, ultrasonic power 150 W,and 4.0% of complex aquasorb dosage were the optimal sonication conditions to sea cucumber rehydration. The theoretical yield of sensory evaluation value, water holding capacity and acid mucopolysaccharides content were 36.1, 74.98% and 0.6581 g/100 g dry weight under these conditions. Sensory evaluation value, the water holding capacity and acid mucopolysaccharide content were higher than the experimental group,especially the water holding capacity. Therefore, the orthogonal experiment results were credible.(5) Quality of the sea cucumber with two rehydration treatments were compared.The results showed that ultrasonic treatment with the use of complex aquasorb could effectively improve the quality of rehydrated sea cucumber. Ultrasonic treatment which shortened the rehydration time was a more efficient and favorable way of treatment.(6) Sensory evaluation value, water holding capacity and pH value were gradually decreased with the extension of time during storage; in contrast, TVB-N value, TBA value and the total number of colonies were increased. The deterioration of instant sea cucumbers was slowed down more effectively under-1℃compared to 4℃. An acceptable limit of shelf life reach to 56 d under 4℃and 84 d under ice storage temperature(-1℃). The physical and chemical indicators of sea cucumber under-1℃were in the normal range with exception of the total number of colonies. In addition,the sensory quality was almost the same as fresh rehydrated sea cucumber. These data suggested that the ice temperature storage has a better preservation effect to sea cucumber. |
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