| Pearl gentian grouper(♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatus)is mainly distributed in the southeast coast of China with the warm water,belongs to large and medium-sized high-grade rare ocean fish.It is fast growth,rich nutrition,delicious taste,which is one of the main varieties of grouper breeding along the coast of south China at present,deeply favored by consumers.In order to meet the needs of China’s inland city consumers,Pearl gentian grouper is mainly sold in fresh form,fresh pearls gentian grouper land keep alive from long distances transport,which mainly adopts carry water with rich oxygen and replace the sea wateron the way,but the traditional insurance will live transportation mode for water quality deterioration,stress,lack of oxygen,vibration and other unfavorable factors lead to the deaths of fish,there is a low survival rate,the sex ratio(fewer loading capacity,high transport costs),change of the quality of the live fish,such as the loss of nutrient loss is big,flavour compounds)and fish narcotic drug residues security issues,etc.,So,it is particularly important to study the green,environment-friendly and safe way of live transportation of gentian grouper.Cryogenic dormancy preservation transportation is a kind of method with low cost,high survival rate,low quality change,more green and safe than other preservation technologies.This study mainly discusses the application of low temperature dormancy preservation technology in the survival transportation of grouper of gentiana paliana.The main research contents and results are as follows:(1)Effect of pre-shipment temporary feeding on preservation and transportation of pearl gentian grouper:through the grouper pre-shipmentpause temporarily raise research results show that the temporarily keep 24~48 h can effectively alleviate the stress reaction caused by fishing,transportation,and avoid the stress of hunger,and had no significant effect of basic nutrition of muscle,the serum biochemical indicators show the fish keep basic health.After 72 hours,the body weight loss rate increased significantly,reaching 7.49%,with no significant difference in water content.The crude protein and crude fat content decreased significantly,respectively1.44%and 0.53%.Therefore,temporary incubation of 24~48h before transport is beneficial to relieve stress,and the decrease of energy substance is not significant.(2)Optimization of low temperature induced dormancy and water conservation conditions for pearl gentian grouper:Through single factor and orthogonal experiment,the optimal survival condition was determined to be:temperature 15℃,the density of fish100 kg/m~3,gradient cooling mode,the survival time under the condition of can reach(168±8)h,keep alive after 72 h water total ammonia nitrogen concentration(7.28±0.06 mg/L.In serum biochemical indexes,blood glucose,glutamate transaminase activity and globulin content were significantly increased(p<0.05),while there were no significant changes in cortisol,triglyceride,urea nitrogen content,aspartate aminotransferase and lactate dehydrogenase activity,and the fish was in good health.The results show that the condition is suitable for the long-distance live transport of the grouper with gentian.(3)Pearl gentian grouper main nutritional components change in the simulation of transport process:compared with just catch fresh fish,grouper after 16 h simulating transportation group of crude protein,crude fat,muscle glycogen content was reduced by 0.10%,0.13%and 9.74%,respectively,and the lactic acid content decreased by33.33%;the content of crude protein,crude fat and muscle glycogen of the grouper in the actual production and transportation group(the method of preserving transportation widely adopted in the aquatic wholesale market of xiashan,Zhanjiang)decreased by 0.51%,0.31%and 24.73%respectively,while the content of lactic acid increased by 10.53%.By comparison,the loss of crude protein,crude fat and muscle glycogen in the simulated transport group decreased by 80.3%,58.0%and 60.6%,respectively.The lactate content decreased by 131.59%.It can be seen that the energy and material metabolism of fish during the simulated transport process is slow compared with the actual production transport group.(4)The fish presented the change of taste components in the simulation process:the research results showed that the amino acid of sweet and umami were the main flavor component in the free amino acid of the grouper,accounting for more than 70%of the total free amino acid.After 16 h,the amino acids in the simulated transport group and the actualproduction transport group increased by 13.71%and 18.67%,respectively,and the amino acids in the bitterness transport group increased by17.85%and 47.85%,respectively.Although the amino acids in the simulated transport group increased by 4.14%less than those in the actual production transport group,the amino acids in the bitterness transport group increased by 29.18%less than those in the actual production transport group.After 16 h,the IMP content of strong flavor substances increased by 9.92%and 0.56%respectively,and the bitter Hx content decreased by 38.68%and 4.31%respectively.Compared with the actual production and transport IMP content,simulated transport increased by 9.36%and Hx content decreased by 34.37%.After 72h,the amino acid content of sweet and umami in the simulated transport group was not significantly different from the initial value of fresh grouper,and the amino acid content of bitter taste increased by 256.1%.The content of IMP in ATP linked compounds was always at a high level,increasing by 14%after72h,while the bitter Hx content decreased by 12.29%.Citric acid content decreased by3.39%,succinic acid increased by 105.6%,while lactic acid content was close to the initial value and inorganic ion content changed little.The results showed that the taste components of the grouper could be well preserved in the simulated transport process. |
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