Effects of cold stress-induced dormancy methods on life characteristics and nutritional quality indexes of Patinopecten yessoensis during anhydrous living-preservation

Exploring the best method to induce the dormancy of scallops (Patinopecten yessoensis) before live transport can provide a theoretical basis for their survival and circulation. Referring to the actual industrial circulation, we treated the samples by three methods of natural cooling of crush ice, acute continuous cooling and gradient cooling, so as to explore the effects of different cooling and dormancy methods on the survival rate, life characteristics and nutritional quality of scallops during anhydrous living-preservation. The results show that the survival rate of the gradient cooling group was 93.33% after 3 d of keeping alive at 4 ℃, significantly higher than that of the acute and natural cooling groups. In the process of cooling dormancy, regular electrocardiogram could not be detected in the natural and acute cooling groups due to the sudden temperature change, and the heart rate in the gradient cooling group showed a regular slow decline. During the live transport, the heart rate in each group showed a decreasing trend. After 3 d of keeping alive, the irregular heart rate in the natural ice cooling group was no longer observed, while the irregular heart rate in the gradient and acute cooling groups was still observed. The edge mantle retraction ratio and the response time of all three cooling groups tended to increase gradually (Those of natural and acute cooling groups were significantly higher than those of gradient cooling groups), and the heart rate was negatively correlated with the response time of the mantle. The contents of water, crude protein, crude fat and muscle glycogen all showed a decreasing trend, and the consumption of glycogen was the largest. Less loss of nutrients before live transport was observed in the gradient cooling groups compared with the other groups. The microstructure also shows that the closed shell muscles in the gradient cooling group were closely arranged without an obvious fracture. This study indicates that inducing P. yessoensis to enter dormancy or semi-dormancy state by gradient cooling and then keeping them alive without water, is beneficial to improving the survival rate of living P. yessoensis, reducing the loss of nutrients during the live transport, and maintaining the vitality of living P. yessoensis, so it is more conducive to its anhydrous living-preservation.