Oxygenated storage alleviates autolysis of the sea cucumber Apostichopus japonicus during transport

This study aimed to examine the oxygenation effects on sea cucumber autolysis by comparing the condition between the oxygen-addition group and air-addition group during storage and transportation. Sea cucumbers were exposed to 0, 6.25, 12.5, 25, 50, and 100% oxygen addition for 6 days, and the levels of ammonia released were measured to monitor the status of the sea cucumbers. Results showed that a general decline in ammonia release from 0 to 25% oxygen, then an increase again from 25 to 100% oxygen. Hence, the oxygen level of 25% was found to be optimal in maintaining the sea cucumber health during storage. Subsequently, 25% oxygen and air treatments on sea cucumber were compared, and results showed sea cucumbers in the oxygen group exhibited better morphology, and got 1.23 times better sensory scores than that of the air-treated group. The body-wall hardness of the oxygen group was 2.17-fold higher than that of the air treatment group. The respiratory tree and intestine microstructure tests showed the air-treated sea cucumber group suffered from autolysis after storage, showing visible tissue atrophy and disintegration of surface villi. By contrast, the oxygen-treated group exhibited only slight autolysis with largely intact tissue structure. Various gene expression levels for key enzymes, including superoxide dismutase, glutathione peroxidase, acid phosphatase, alkaline phosphatase, lysozyme, succinate dehydrogenase, lactate dehydrogenase, Alpha-amylase, peptidase, trypsin, and heat shock protein 70 (Hsp70), were determined for oxygen and air treated sea cucumbers after 6-day storage. Results suggested that oxygen-treated sea cucumbers maintained good immune defense, oxidation resistance, and digestive capacity, while the air-treated sea cucumbers did not. HSP70 expression level in the oxygen-treated group was 13.5-fold higher than the fresh sea cucumber group, indicating that oxygen inhibited/delayed sea cucumber autolysis mainly by preventing protein denaturation via the improvement of HSP70 expression level.

Automated summary

This study examined the effects of oxygenation on sea cucumber autolysis. The results showed that 25% oxygen was optimal in maintaining sea cucumber health. Compared to the air-treated group, sea cucumbers in the oxygen group exhibited better morphology, sensory scores, body-wall hardness, and tissue structure. The oxygen-treated sea cucumbers also had higher expression levels of key enzymes related to immune defense, oxidation resistance, and digestive capacity.