Progress in Fishery Sciences (Feb 2024)
Effect of Simulated Express Transportation Period on Vigor and Meat Quality of Female Chinese Mitten Crab (Eriocheir sinensis)
Abstract
Chinese mitten crab (Eriocheir sinensis) is an important freshwater aquaculture species in China, favored by consumers for its unique flavor and high nutritional and economic value. Chinese mitten crabs are sold live and their production areas are mainly located in the eastern part of China. Live crabs need to be transported over various distances to be sold nation- and worldwide. In recent years, with the rapid development of the internet and e-commerce, an increasing number of Chinese mitten crab products have moved online, and e-commerce sales are gradually taking over the dominant position of sales. Since the Chinese mitten crab is able to survive for a longer period of time out of water, e-commerce transportation mainly adopts the method of air-exposure transportation for crabs. In the process of air-exposure transportation, factors such as temperature, humidity, oxygen, and mechanical vibration can affect the survival rate and metabolism of crustaceans. To guarantee the safety and high quality of the crab after transportation, increase the survival rate, and prolong the transportation time, Chinese mitten crabs are transported using styrofoam boxes to reduce vibration, in which ice bags or ice bottles as cooling media are added to reduce the temperature of the environment during express transportation. Conditioned transportation allows them to have a weakened metabolism and be semi-dormant or completely dormant, thus reducing the adverse effects of low-oxygen, stress, and other factors during transportation. However, the transportation time varies due to different geographical locations, and the transportation time of e-commerce sales is generally 24–72 h. The e-commerce storage and distribution mode of Chinese mitten crabs is highly developed, and there is an urgent need to clarify the changes in biochemical characteristics and flavor quality during the live logistics transportation process.In this study, the e-commerce transportation conditions of Chinese mitten crabs were simulated by placing female crabs in sealed styrofoam boxes containing ice packs. The temperature and relative humidity inside the box were monitored in real time during the simulated transportation. The vigor of E. sinensis was counted and evaluated for 24 h, 48 h, and 72 h during the simulated express transportation. The changes in the biochemical characteristics of the meat of E. sinensis were analyzed in terms of lactate, total volatile basic nitrogen (TVB-N) and pH, while the changes in the taste quality of the meat were assessed in terms of free amino acids, taste nucleotides, and sensory evaluation. In addition, correlation analysis was carried out on the vigor, biochemical characteristics, and taste quality of female E. sinensis during the simulated express transportation. The results showed that with the increase of transportation time, the temperature in the box during the simulated express transportation showed a trend of first falling and then rising, and the relative humidity inside the box increased with the increase of the simulated transportation time. The mortality rate of female E. sinensis was 0 and vigorous under the 24 h simulated transportation, and the lactate and TVB-N in meat were not significantly different from the 0 h group, and the bitter amino acid content in meat was the lowest in the 24 h group, confirming the importance of same-day delivery of live E. sinensis. After more than 24 h, the vigor of E. sinensis decreased significantly (P < 0.05) and the mortality rate increased at 3.33% after 48 h and 40.00% after 72 h of simulated transportation. The lactate, TVB-N, and pH in meat also increased significantly (P < 0.05) after 24 h. With the extension of transportation time, the umami, sweet and bitter free amino acid contents in the meat of female E. sinensis showed a trend of first decreasing and then increasing, with the lowest content of bitter amino acids in the crab meat of the 24 h group being 105.10 mg/100 g. In contrast, after 72 h of simulated transport, the content of 5ʹ-inosine monophosphate increased significantly to 97.47 mg/100 g, and the content of guanosine 5'-monophosphate plummeted to 6.49 mg/100 g. After simulated transportation, the equivalent umami concentration of female E. sinensis meat decreased and tended to decrease and then increase with the extension of transportation time. The sensory results showed that the umami intensity of female E. sinensis meat decreased after the simulated transportation. Correlation analysis of vigor, biochemical characteristics and taste quality showed that the vigor of female E. sinensis was significantly positively correlated with moisture content in meat (R=0.68), negatively correlated with TVB-N (R=–0.66) and highly significantly negatively correlated with IMP (R=–0.76).In conclusion, the mortality rate of female E. sinensis increased, vigor decreased, and biochemical characteristics and taste quality changed significantly as transportation time increased, indicating that the optimal transportation time for E. sinensis under the current e-commerce transportation conditions is 0–24 h. This study could provide a reference for the quality changes of Chinese mitten crab during marketing and transportation, as well as a theoretical basis for subsequent research and practice on the optimization of transportation conditions and quality control.
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