Design Optimization Of A New-type Water Transport Device For Penaeus Vannamei And Study On Biochemical And Qualitative Stress Response Of The Shrimp Transported With The Device

1.Study on the design and operational effectiveness of a new type of water-retentive transport equipment for Penaeus vannameiIn order to optimise the transport system of Penaeus vannamei with water,a new transport device was designed,which is based on a split drawer structure,temperature control by circulating water in a chiller and oxygenation by spraying water,and which integrates the shrimp boxes in a single transport system,and a comparison of the transport effects of this device with traditional transport devices was carried out.Water quality indicators（temperature,dissolved oxygen,salinity,p H and harmful nitrogen compounds）as well as survival rates,reject rates and shelf life were compared between the different transport units at preset temperatures of 19.5°C,17.5°C and 14.5°C.The results showed that the water temperature stability of the new device was significantly higher than that of the conventional device at each preset temperature（P<0.05）,and the rate of warming of the conventional device was significantly higher at the preset 14.5°C（P<0.05）;the dissolved oxygen of both devices remained stable at>8mg/L,salinity at 8.0±0.2‰,p H at 8.34±0.05 and nitrite at The survival rate of the new device was higher than that of the traditional device at all preset temperatures,and the survival rate of the new device remained above 60%at the preset temperature of 14.5°C.The substandard rate of the new device was lower than that of the traditional device at all preset temperatures,and the substandard rate of the new device was lower than that of the traditional device at the preset temperature of 14.5°C.The substandard rate of the new device was higher than that of the traditional device at the preset temperature of 14.5°C.The substandard rate of the new device was higher than that of the traditional device at the preset temperature of14.5°C.The shelf life of the new device was significantly higher than that of the traditional device at all preset temperatures（P<0.05）,and at preset temperatures of19.5°C and 17.5°C,the shelf life of the new device was more than that of the traditional device（P<0.05）,and at preset temperatures of 19.5°C and 17.5°C,the shelf life of the new device was more than that of the traditional device（P<0.05）.The comparative tests demonstrated that the new device is more feasible for optimising the12-h water-retentive transport.2.Enhancement of the transport conditions of the new water-retentive transport device for Penaeus vannameiThe effects of pre-cooling temperature（pre-cooling phase）,transport temperature（transport phase）and water feeding method（transport phase）on recovery and transport effectiveness were investigated in order to improve the survival rate of Penaeus vannamei during transport with water in the new device and to increase the rate of rejects.The effect of pre-cooling temperature（21°C,19°C and 17°C）,transport temperature（19.5°C,17.5°C and 15.5°C）and water feeding method（drip feeding,spray feeding and tap feeding）on recovery and transport effectiveness was investigated in a single-factor test.The three water feeding methods had no significant effect on p H,temperature and survival rate in transport water quality（P≥0.05）,and the dissolved oxygen in the spray feeding method was higher than that in the drip feeding and tap feeding methods;the survival rate of Penaeus vannamei in transport changed significantly with the change of transport temperature（P<0.05）,and the survival rate of Penaeus vannamei showed a trend of increasing and then decreasing with the decrease of transport temperature,and the transport temperature of 17.5°C was significantly higher than that of the rest of the transport temperature groups（P<0.05）.The transport temperature of 17.5°C was significantly higher than the rest of the transport temperature groups（P<0.05）,and the transport survival rate at low temperature（15.5°C）decreased significantly to a lower level（P<0.05）.The results were used as the basis for the L₉（3⁴）orthogonal and validation tests.The results of the one-way test showed that the optimum pre-cooling temperature was 19°C,the optimum transport temperature was 17.5°C and the optimum water supply method was spray water.The results of the study demonstrate that the survival rate and the substandard rate of shrimps can be improved by adjusting the levels of the three factors:transport temperature,pre-cooling temperature and water feeding method,which provides a new idea for the survival of shrimps.3.Effect of transport density on survival and muscle quality transported with water of Penaeus vannameiIn order to meet the survival and quality needs of shrimp during transport,the above-mentioned new water-retaining transport device is used.to study the transport effects of different transport densities of Penaeus vannamei.A comparison of survival rates and changes in muscle quality and physiological stress indicators of shrimps before and after transport was carried out at shrimp-to-water ratios of 1:2（high density）,1:3（higher density）,1:4（medium density）,1:5（low density）and 1:7（lower density）.The results showed that the survival rate of Penaeus vannamei increased significantly（P<0.05）with increasing density and maintained the survival rate（≥80%）that met the requirements of commercial transportation at high density.The effects of high transport density on ROS scavenging,MDA accumulation,SOD and PO activation were significant（P<0.05）.The effects of stress on moisture,crude protein and crude fat content were not significant（P≥0.05）;the hardness and chewiness of shrimp muscles were significantly reduced after transport,and the effects of different transport densities on texture were not significant（P≥0.05）.The study showed that the Penaeus vannamei could be transported in water by means of a new preservation device（temperature fluctuation<1°C,dissolved oxygen>8 mg/L,survival rate≥80%during transport by the device）and that the device was highly feasible for high density transport（density greater than shrimp to water ratio 1:4）.