| Living storage and transportation have become the main trend in aquatic products storage and transportation especially for inland freshwater fish.Ice-temperature theory suggests that with the implication of cold acclimation fish and shellfish can survive and maintain a state of hibernation under ecological points even if the environment temperature is lower than zero.Respiration and metabolism is extremely low during hibernate,and fish and shellfish are able to live without water.With the lower temperature,respiration and metabolism is reduced,and reduced oxygen consumption at the same time,which induced the longer survival time out of water.As a heterothermic animal,fish is affected by temperature on their physiological activities such as reproduction,feeding and growth.The changes of enzyme activity are a mechanism to temperature adaptation of fish.Fish is adapted to temperature usually by enhance the acticity of metabolic enzymes,and by increasing the concentration of the enzyme,or by changing the structure of enzyme replacement to optimum thermal properties.There is aregulating mechanism when the body’s response to temperature change,and the change of enzyme activity can be used as a key indicator.Research on fish cryology is given priority to with long-term adaptation or cold shock,stress,and lack of physiological changes during the cooling process,and short of study during the period of short-term temporary about cooling rate,at the same time,the mechanism of low temperature effect on aquatic products need more research;Fish storage research focused on the change survival time along with the change of storage and transportation conditions,but the physiological indexes in the process of change and the storage and transportation conditions,and interactive relationship between various conditions and the physiological indexes indicated more detailed studies are needed.Based on the conditions affecting the water storage and transportation of crucian carp,this paper explains the relationship between temperature change and dormancy mode and various indexes of the body through the study of enzyme activity and physiological indexes,and reveals the physiological changes of crucian carp in the process of storage and transportation.Based on the regression model,the factors that affect the survival of fish storage.The following work has been carried out on this subject:1.Thermal properties of Brain,gill,hepatopancreas,muscle and blood of Carassius living in 8 ℃ were investigated by differential scanning calorimeter.Between 20 ℃～-40 ℃,blood showed lower specific heat capacity than other organs.It might help temperature equilibrium in organism.Blood and brain had higher freezing temperature.Brain showed the maximum water content but less freeze water while ventral muscle had the lowest water content but high freeze-able water.The blood has less calorific value,which is beneficial to rapid temperature regulation organizations,helps to balance the fish body temperature changes.At the same time,the greater the temperature difference between the phase change temperature and the lower the specific heat value of the tissue.The freezing temperature difference between different parts of carp fish is very different.0～-0.2℃ is the critical temperature for the living preservation of crucian carp,as an ecological ice temperature range.2.To investigate how juvenile Carassius coping with short time cooling,two cooling rates was set from 25℃ to 0℃:rapid and slow(1℃ or 5℃ per hour).The blood glucose showed a fluctuation above normal level in both groups,and liver glucogen was observed to be stable in rapid cooling group,and decreased under slow cooling.Meanwhile,muscle glycogen values cooling began to decrease under 1 ℃/h(P<0.05),then returned to normal.Juvenile Carassius was found all dead at 0℃subjected to 1℃/h cooling while survived subjected to 5℃/h cooling.It might be a result of the exhaustion of liver glycogen.In both treatments,the fluidity of brain mitochondrion membrane increased around 15℃,suggesting an increase of membrane bound enzymes activity;The level of free amino acid in dorsal muscle showed the same tend as the temperature cooling to 15℃ and might conduce to better nutrition and better flavor.It is suggested that the regulation of Carassius metabolism had a trigger did not depend on cooling rate as the temperature cooling.3.The impact of hyperthermia acclimation and storage temperature on waterless storage of live Crucian Carps was studied.Crucian Carp were put through hyperthermia acclimation at the speed of 5℃/h and 1 ℃/h,and then placed them for 24 hours at 4℃and 0℃ in waterless ice-temperature storage rooms to observe variations of metabolic enzyme and antioxidant enzyme.Results show that the temperature adaption set as 1℃/h has benefited activity of Lactate Dehydrogenase("LDH").Activity of isocitrate dehydrogenase("IDH")was also maintained comparatively better under such condition,while brain succinate dehydrogenas("SDH")stayed unchanged.Alaninetransaminase("ALT")activity was better maintained under 0 ℃ storage,and Malondialdehyde("MDA")accumulation was found under same condition.No obvious change was discovered in liver was caused by accumulated Catalase("CAT")in such low temperature storage.4.Technology of ice-temperature preservation for Carassiu kept alive without water was investigated.Physiological freezing point was defined from freezing point of organs;rigor mortis was considered as a index for vitality after leaving water;hydrolyzed and free amino acids was compared for fish preserved under ice-temperature preservation and refrigerated temperature(4℃)for nutrition absorption and flavor.Carassius survived 32 hours under ice-temperature preservation without water after 1℃/h cooling acclimation in water.Cold acclimation reduced rigor mortis after leaving water,and some hydrolyzed and free amino acids increased,suggesting elevated nutrition and taste.5.The impact of 3-Aminobenzoic acid ethyl ester methanesulfonate(MS-222),eugenol and live chilling induced metabolic inhibition of Crucian was investigated.Using 10,20,30 mg/L MS-222,eugenol and 0℃ as a way of anesthesia,analysis of crucian carp under the anesthetic effect of physiological changes,explore the inhibition effect of different anesthesia methods.Results indicate that high levels of drug effectively inhibit blood glucose,but no obvious inhibitory effect observed on cortisol levels;The brain Malondialdehyde(MDA)and liver CAT activity is related to breathing rate at 20 h.Brain MDA results show that of eugenol restrain lipid peroxidation level,and has good metabolic inhibition with the same concentration.The concentration of lactic acid in crucian carp increased rapidly and kept at a high level at ice temperature.Hypothermia induced dormancy leads to the accumulation of MDA in the brain.The MDA content in brain and CAT activity in liver were positively correlated with the respiratory rate of Carassius auratus after 20h,which was mainly determined by the level of MDA in brain.6.To explore the impact of dormancy and storage temperature on crucian carp in a waterless preservation.It is conducted by studying the influence of Eugenol anesthesia and cold acclimation on crucian carp,followed by having them preserved under waterless conditions at 0℃,4℃ and 8℃ to analyze their physiological state and damage degree of fish which were reflected by blood index and enzyme activity.The results showed that there was no significant change in serum cortisol level of crucian carp after anaesthesia;As the extension of time,the liver glycogen was gradually consumed,and the vitality of SDH increased,while the higher storage temperature led to the increase of MDA content in the brain,and the serum lactate content and CAT activity increased.The research findings reveal that different anesthetic methods on away from the water storage of crucian carp survivability has no apparent influence,the influencing factors of carp survivability for storage temperature,the higher 1℃ recovery time of crucian carp increased 1.42 times more likely to extend a level.Comparing with other two kinds of storage,Ice-temperature storage can greatly improve the carp from survival ability.The results indicated the protection of the physiological functions of crucian carp can further improve survival ability. |
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