Study On Waterless Preservation And Controlled Freezing-point Storage Of Crucian Carp And Chinese White Shrimp (Fenneropenaeus Chinensis)

Aquatic product has become an irreplaceable componts in dietary nutrition and structure because of low fat and high protein. As the standard of living rise, fresh aquatic product is becoming more and more popular. In recent years, the research on preservation technology of aquatic product is highly attentioned.The aim of this study was to explore the artificial hibernation of crucian carp for waterless preservation and to characterize the quality and biochemical properties during and after the hibernation. Anesthetized crucian carp using eugenol were stored at8?with90%oxygen and95-100%relative humidity for38h, and then transferred to fresh water to recover. Liquid loss (LL) and cooking loss (CL) had no significant changes. The total volatile basic nitrogen (TVB-N) content and2-thiobarbituric acid (TBA) value in hibernated fish were significant higher than fresh and recovered groups. Serum cortisol, glutamic-oxaloacetic transaminase (GOT), alkaline phosphatase (AKP) and acid phosphatase (ACP) activities significantly increased during hibernation, while glutamic-pyruvic transaminase (GPT) had no significant change. Both ACP and AKP activities decreased upon the fish recovered, but only the ACP activity returned to normal. However, there were increased serum glucose concentration, GOT and GPT activities in recovered fish. The results indicated that muscle quality would not be influenced, and most of stress responses would disappear after hibernated fish recovered.Low temperature can induce the fish or shrimp enter the hibernation state, and then subject waterless preservation. Serum cortisol concentration, lysozyme activity and GOT activity significantly increased in hibernated crucian carp compared to fresh sample, and then return to normal level after arouseing. Serum AKP activity offered upgrade firstly then descending tendency latter during and after hibernation There was no significant difference for ACP and GPT activities under low temperature. The results suggested that stress response under low temperature would be terminated when crucian carp was transferred to freahwater. The cell damage would disapper and immune function would be restored after recovered.Serum H2O2content significantly decreased in the initiation of hibernation, while there was no significant difference compared to the fresh samples after arousal from hibernation. The O2-production rate had no significant changes among fresh, hibernated and aroused crucian carp. The total superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities of hibernated crucian carp significantly increased. CAT activity significantly decreased to normal, while SOD and POD activities had no significant changes after arousal compared to hibernated samples. However, glutathione peroxidase (GSH-Px) activity had no significant differences during and after the hibernation. The SOD?CAT and GSH-Px gene relative expression significantly increased in hibernated crucian carp serum, and then SOD?GSH-Px gene relative expression significantly decreased after recovered, but there was no significant difference for CAT gene relative expression. On the basis of these findings, the antioxidant defenses capacity was activated in response to the hibernation, which would be part of the adaptive mechanism for survival against the cold shock.Waterless preservation under low temperature has certain effect on metabolism in crucian carp. Serum glucose and lactic acid concentration increased in hibernated crucian carp, and then return to normal level after recover. LDH activity declined firstly in hibernated sample and then rised in aroused crucian carp, while the changes of PK activity was just the opposite. HK activity had been rising during and after hibernation, however, there was no significant change for PFK activity. The results indicated that low temperature reduced the respiratory rate of crucian carp, which lead to hypoxia and anaerobic metabolism in tissue. The crucian carp began to breathe normally and aerobic metabolism in aroused crucian carp after waterless preservation for38h.Comparative proteomic approach was used to identify the proteins that were changed in abundance during the waterless preservation of Chinese white shrimp (Fenneropenaeus chinensis). Approximately380-430protein spots were observed in the two dimensional protein electrophoresis (2-DE) gels. Among them,14altered proteins from hemolymph were excised and subjected to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis.11protein spots were successfully identified, including hemocyanin, hemolymph clottable protein, myosin light chain and sarcoplasmic calcium-binding protein. It could be speculated that the combined action of decreased hemocyanin, increased hemolymph clottable protein and myosin light chain forced Chinese white shrimp into a temporary state of hibernation under cold temperature and could keep the hibernated shrimps alive during the waterless preservation. Moreover, increased expression of sarcoplasmic calcium-binding protein ensured that hibernated shrimps could be aroused at warm temperature. The present study provides a possible application of waterless preservation of Chinese white shrimp.Incubation treatment with compound (5%NaCl,5%CaCl2and2.5%sorbitol) could effectively depress the freezing point and retard bacterial growth in the shrimps. There was little difference in microstructure between fresh and freezing-point depressed shrimps after storage at-2.0±0.2?, while a large amount of ice crystals were observed in the control shrimps. Significant high WHC, SSP, and Ca2+-ATPase activity were obtained in freezing-point depressed shrimps. An additional2days of shelf life at-2.0±0.2?was achieved in shrimps when the freezing-point was depressed from-1.3?to-2.5?considering TVC, TVB-N, TMA-N and sensory scores. Results suggested that controlled freezing-point storage may be a promising method of maintaining the freshness of Chinese white shrimp and extending shrimp post-mortem shelf-life.