Effects of Keep-Alive Methods on Vigor and Physiological Metabolism of Chinese Mitten Crab Eriocheir sinensis
In order to evaluate the effects of different preservation methods on vitality and physiological metabolism of Chinese mitten crab Eriocheir sinensis,female Chinese mitten crab with body weight of(149.89±6.82)g were bundled and placed in foam boxes of each 41 cm× 30 cm × 18 cm,with 15 individ-uals in each box,covered with completely soaked double-layer gauze,stored in constant temperature and humidity incubators at 16 ℃ and 5 ℃ for 72 h,and changed the gauze every 12 h.The crab in the control group was stored at 16 ℃ without moisturizing treatment.The changes in vitality,and contents of proxi-mate nutrients,glycogen,lactic acid and volatile basic nitrogen of Chinese mitten crab were measured at 0 h,24 h,48 h and 72 h after storage.The results showed that there was decrease in the survival rate and vigor with the extension of the storage time in the three groups of Chinese mitten crab,with decrease to 60.00%.At the end of the storage period,the survival rate and the vigor were also found to be decreased rapidly in the control group,while the survival rate of the two groups to be increased by 20.00 and 33.33 percentage points after moisturizing treatment with moistened gauze,and the vigor status was significantly improved(P<0.05).There were significantly higher moisture and content of crude protein in the two groups than those in the control group(P<0.05),with the decrease in glycogen content in the three groups,and the most rapid glycogen consumption rate in the control group,reduced by 9.59%-11.07%by moisturizing treatment.The Chinese mitten crab had an upward trend of lactic acid content and total volatile basic nitrogen content,with stable lactic acid accumulation in the low temperature moisturizing group after 24 h,and without exceeding the unacceptable limit of total volatile basic nitrogen of fishery products in the three groups,always maintaining lower level in low-temperature moisturizing group than in the other two groups.The down-trend first and up-trend later trend of pH value was observed in the three groups,with the range of 6.74-6.80 in the low temperature moisturizing group,which was close to the initial control(0 h)group.The adenylic energetic charge showed a decreasing trend,decreased by 4.56 percentage points in the control group after 72 h,with the disturbed energy homeostasis,Chinese mitten crabs in the low temperature moisturizing group remained at a high level.According to the compre-hensive changes of vigor status and physiological metabolism,it is believed that under the current circula-tion environment,the storage cycle is within 72 h of storage,the use of moisturizing storage medium and reducing the storage temperature are conducive to the better maintenance of vigor and the slowing down of energy and material consumption of Chinese mitten crab.The findings provide theoretical support and op-erational guidelines for optimizing the storage conditions and improving the quality of Chinese mitten crab.