| Lateolabrax maculatus is one of the most common marine economic fishes because of its delicious meat and higher nutritional value than those of freshwater bass.Flower perch was selected as the research object in this study.In recent years,with the increasing demand for fresh fish from consumers,the study on the technologies of preservation transportation has become more and more hot.The fish decreases the respiration and metabolism,maintains the "hibernation" state and facilitate water-free transportation with low temperature.Waterless transportation technology is a new type of cold-chain living logistics technology,which is green,environmental-friendly,safe and efficient.The key technologies of fish ecological ice temperature and anhydrous transport include the determination of ecological ice temperature,gradient cooling,storage and transportation environment,and awakening.The main objection of this study was to determine the ecological ice temperature of perch.On the premise that the survival rate of the transportation time 8h is 100%,The optimum technology of ecological ice temperature and anhydrous transportation of perch was obtained via determining the key technological methods such as temporary culture time,cooling rate,packing oxygen concentration,awake and the concentration of preservative solution.And then the molecular biological changes of perch were studied,which provided a good basis for further study of functional genes related to anhydrous migration of perch.Finally,we explore the effect of ecological ice-temperature and anhydrous transportation technology on the nutritional composition and flavor of perch meat.In this study,by refining the oxygen concentration of the package,the water-free keep-alive effect of the perch is stabilized by using the protective liquid,the keep-alive rate is improved,the transportation efficiency is high,and the method has a strong economic value.1.Effects of different temporary incubation time and cooling rate on simulated anhydrous transport of Lateolabrax maculatusLateolabrax maculatus was temporarily firmed for 6h and 12 h,then were treated with different cooling rates of 11?/h,3?/h and 5?/h.After 8h anhydrous transportation,the activities of caspase-3,fish proprotein convertase subtilisin/Kexin Type 9(PCSK-9),alanine aminotransferase(ALT)and glutamic oxalate transaminase(AST)and the content of malondialdehyde(MDA)in serum were measured to study the effects of anhydrous transportation on the liver tissue of flour bass.The results showed that at 0 h of transportation all investigated biochemical parameters in three treatment groups were higher than those in the control group.At 8 h of transportation,these five parameters in 3 ?/h cooling group were significantly lower than those of other two treatment groups but higher than those in the control group(P < 0.05).At 2h,serum PCSK-9 activity in 3 ?/h cooling group was significantly lower than that in the other treatment groups(P < 0.05).Liver MDA concentration and caspase-3activity in Chinese sea bass after arousal were decreased compared to those at 8 h but were still high.The effect of temporary feeding time on blood and liver tissue indexes was not obvious,but the mortality data after 6 h wakefulness were significantly lower than those at 12 h.Under different cooling rates,anhydrous transportation had a strong negative impact on liver metabolism and vitality of perch.Though temporary incubation time had no significant impact on the indicators,temporary incubation for6 hours had an advantage.The liver tissue damage of bass treated with anhydrous transportation at 3?/h was lower than that at other temperature.It was suggested that the temporary incubation time should be set at 6 h and the cooling rate should be set at 3?/h.2.Effects of simulated anhydrous transport with different oxygen concentration and wake-up rate on Lateolabrax maculatusLateolabrax maculatus was temporarily firmed for 6 hours.And then the water temperature in the temporary incubator was decreased from 22?23 ? to 4 ? by a chiller at a cooling rate of 3 ?/h.After being removed from the water,Lateolabraxmaculatus was packaged with oxygen concentration(60%,80%,98%)and was simulated to be transported in anhydrous living environment for 8 hours.After transporting,Lateolabrax maculatus was awakened by 1 ?/h,5 ?/h and direct room temperature.In order to improve the efficiency of auxiliary respiratory organs of fish,high concentration of oxygen was used to pack perch during anhydrous transportation.At this time,with the prolongation of transportation time,60% MDA content in packaging was lower in the three packing groups.The packing oxygen concentration of 80% SOD was at a high level throughout the transportation process.Comparing the data between 8 h and 8 h after transportation,it was found that the SOD value of 5?/h wake-up operation was high and the MDA value was lower.The mucus lysozyme on the surface of Lateolabrax maculatus was inhibited by transportation operation,and recovered better after 5?/ h wake-up operation.The surface of the gill was influenced by direct exposure to high concentration of oxygen,which showed that the content of mucus lysozyme(LSZ)was inhibited.The gill tissue morphology was also influenced by anhydrous transportation.At that situation,gill filaments were obviously swollen,fused and adhered,while gill surface was wrinkled unevenly due to anhydrous condition.The shape of round particles and sinusoidal gap was not abnormal.Mitochondria increased and was located to epidermis.The microcrest at the edge of epidermis became thicker.The results showed that 60% packing oxygen concentration could ensure the antioxidant ability of perch.Rising to room temperature from 5?/h was beneficial to preserve more lysozyme to resist adverse environment.The gill tissue morphology of perch packaged with 80% oxygen for 8h was similar to that of CK group,which was also economical.It was suggested that the packing oxygen concentration should be set at 60%-80% and the wake-up rate should be set at 5 ?/h.3.Effects of different concentrations of protective solution on anhydrous transportation of Lateolabrax maculatus during temporary raising and transportationBlood biochemical parameters,gill tissue Na+/K+-ATPase(NKA),serum lysozyme(LZM),immunoglobulin M(Ig M)levels of perch were studied when vitamin C(Vc)supplementation and different concentrations of protective solution were added to anhydrous transportation.The results showed that C2(30 mg/L,vitamin C)was added into the temporary culture water for 6 hours.The fish was immersed in the G2(lysozyme 0.09%+sorbitol 0.3%+ginger 0.08%)protective solution for 2-3 seconds before packaging after cold acclimation.At final,the fish were separately packed and transported without water.The best preservation effect was obtained with this procedure.Total protein and albumin in the blood of perch increased first and then decreased,while the contents of uric acid,creatinine,blood sugar and lactic acid increased significantly.Temporary water with Vc significantly influenced the concentration of Na+/K+-ATPase(NKA)in gill tissue,but had no significant influence to the immunoglobulin M(Ig M).Protective solution added with ginger solution significantly increased the activity of lysozyme in the serum of perch.Different doses of ginger solution in the protective solution can cause different changes in lysozyme activity.Adding protective liquid during temporary farming and transportation can enhance liver and kidney function and energy metabolism,maintain normal ion transport in gill tissue,and enhance cellular immune function and anti-infection ability.The mortality of perch can be reduced by 1-5% by using protective solution after transportation without water.4.Effects of anhydrous living transportation treatment on the differential expression of liver transcripts in Lateolabrax maculatusThe optimum technical conditions of ecological ice temperature and no water transportation of Lateolabrax maculatus selected from the first three chapters.Application of illumina HiSeq high flux sequencing technology CK,WL8 h,AW24h sequencing of liver tissue gene transcripts from Lateolabrax maculatus.The obtained Unigene was compared and analyzed in GO and KOG,KEGG database.A total of104942 Transcripts and 60206 Unigenes were obtained from the liver tissues of perch.The N50 of Transcript and Unigene were 1745 and 1372,respectively.GO database annotation,down-regulation of WL8 h symplast expression,which affects the intercellular tightness of liver tissue.The liver tissue detoxification function of WL8 h was lost and AW24 h was not recovered,which was one of the main reasons for the short survival time of Lateolabrax maculatus.KOG database comparison,WL8h division,down-regulation of recombinant and repair gene expression,no recovery of AW24 h,down-regulation of energy production and transformation expression.In KEGG database,carbohydrate metabolism and fat metabolism were the main ways of energy production,and the synthesis of secondary metabolites was the main way.The immune system genes were also fully mobilized.This study provided data for the changes of key genes in the process of ecological ice temperature and anhydrous transportation of Lateolabrax maculatus.5.The nutrition and flavor of Lateolabrax maculatus on the Influence of Anhydrous Living treatmentThe perch was farmed in 30 mg/L vitamin C,salinity 16‰?17‰,4-6 mg/L dissolved oxygen and pH 7.5-8.5 water for 6 hours.Then the temperature in the temporary incubator was decreased from 22?23 ? to 4 ? with 3?/h rate.After dormancy,the perch was immersed in protective solution which contained with lysozyme 0.09%,sorbitol 0.3%,ginger 0.8%,salinity 16‰?17‰,pH 7.5-8.5,and the remaining water for 2-3 seconds.After that,the perch was packaged independently and put on the shaking table which was used to simulate anhydrous transportation for 8 hours.At final,the temperature in the temporary incubator was increased to 22 ? 23 ? with 5?/h rate,while the fish survived for more than 24 hours.In this study,we used the low-temperature and anhydrous transportation technology to transport perch and explored the advantages of this technology in protecting the quality and flavor of perch meat.Under the stress of low temperature and transportation,the perch still maintained its energy demand by glycogen decomposition.Glycogen decomposition into glucose caused blood sugar increasing,while blood sugar continued to decompose into adenosine triphosphate(ATP)to provide energy for the body.The content of GMP and AMP in the muscle of perch were lower than 1.Anhydrous procedure resulted in the decrease of water,protein,fat and other basic nutrients in fish.The content of ATP in the muscle increased after 8hours of transportation.The decomposition of ATP resulted in the accumulation of flavored IMP and AMP.The content of IMP and AMP in the muscle of perch increased significantly,and IMP was the main flavor nucleotide in the muscle ofperch.24 hours after awakening,energy metabolism,basic nutrients,free amino acids and taste nucleotides in muscle of perch gradually returned to normal level. |
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