净化暂养及低温离水保活运输对虾夷扇贝品质的影响

Effects of purification, temporary rearing and low temperature waterless-keeping alive-transportation on quality characteristics of live Patinopecten yessoensis

为了分析在净化、暂养及低温离水运输对接过程中,活体虾夷扇贝品质随时间的变化。采用净化暂养循环水系统进行虾夷扇贝的净化暂养,并将虾夷扇贝分成3种不同前处理方式,组1净化56 h,组2净化32 h后梯度降温暂养24 h,组3无处理,将采用不同前处理的虾夷扇贝放入装有冰袋(250 m L)的聚乙烯保温箱(3 L)模拟低温离水运输条件。结果表明,水体在净化暂养过程中通过梯度降温方式,温度由净化阶段的(15±0.13)℃降至运输前4.76℃,盐度与pH值分别在32.47‰~33.00‰和8.29~8.44之间波动,溶解氧高于8.34 mg/L,保证了贝类存活环境的要求。试验过程中的虾夷扇贝,组1在64 h出现死亡,104 h全部死亡时细菌总数达到2 300 CFU/m L;而组2在104 h才出现死亡,在0~104 h细菌总数上升趋势较平缓,在120 h全部死亡时细菌总数仅为960 CFU/m L;组3在64 h全部死亡。组1和组2净化阶段细菌总数显著下降,组3细菌总数与组1和2有显著差异(P<0.05)。所有组的粗蛋白、粗脂肪及糖原随时间延长总体都呈现下降趋势,与组1、3相比,组2的逐级降温暂养环节延缓了糖原的消耗(P<0.05),因此可采用净化32 h及梯度降温暂养24 h的方法衔接活体虾夷扇贝的低温离水运输。研究结果为虾夷扇贝在净化暂养及低温离水过程中的品质提升提供参考。

During fishery transportation, the alive shellfish should be stored in favorable living conditions for longer survival time. Typically, the survival rate declines over time, affected by 3 steps, i.e. water purification, temporary rearing and low temperature waterless-transportation. In this paper, the analytical results were presented by using the Patinopecten yessoensis samples to explore the efficiencies of the above procedures. The recycled water system for purification and temporary rearing consists of the aquaculture rearing pool, water circulating device, oxygenation device, temperature control and disinfection device. The recycled water system for purification and temporary rearing was used to realize both purification and temporary rearing of Patinopecten yessoensis. In the experiment, certain parameters were monitored, including water temperature, salinity, pH value and dissolution oxygen level. The samples were divided into 3 groups based on 3 different procedures involved： Group 1 was purified for 56 h straight; Group 2 was first purified for 32 h and cooled for 24 h gradually afterward; Group 3 was directly kept in a polyethylene insulation box. Then Group 1 and Group 2 were transported in a 3 L polyethylene insulation box with ice packs （250 mL） to study the quality of transport based on the different pretreatment. The results showed that the temperature of water dropped from （15？0.13） ℃ in purification to 4.76 ℃ before low temperature waterless- transportation by gradient cooling during the purification and temporary rearing, the salinity of water fluctuated between 32.47‰ and 33.00‰, the pH value of water fluctuated between 8.29 and 8.44, and the dissolved oxygen in the water remained above 8.34 mg/L. It was demonstrated that the water environment was valid within the living condition requirements of the shellfish throughout the experiment. As a result, in Group 1, the first death was shown after 64 h, and all shellfishes died after 104 h with total bacteria density of 2 300 CFU/mL. In Group 2, the first death was shown after 104 h and the total number of bacteria was increasing steadily within 0-104 h. After 120 h, all shellfishes died with total bacteria density of 960 CFU/mL. In Group 3, all shellfishes died in 64 h. The total number of bacteria in Group 1 and 2 declined significantly in the purification. The bacteria number in Group 3 was significantly different from Group 1 and 2 （P〈0.05）. The crude protein, crude fat and glycogen of all groups declined over time. However, compared to Group 1 and 3, the consumption of glycogen in Group 2 was delayed by the gradual cooling procedure （P〈0.05）. The result proved that the purification and temporary rearing procedures improved the sterilization of the bacteria, and the survival rate was less sensitive to the temperature change, and got longer. Therefore the consumption of crude protein, crude fat and glycogen was delayed. With this experiment, the procedures of 32 h purification followed by 24 h gradient cooling are proved to be efficient for the low temperature waterless-transportation. The results provide sound references for the Patinopecten yessoensis’ quality studies with purification, temporary rearing and low temperature waterless-transportation technologies.