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The advantages of Litopenaeus vannameifarming in saline–alkali water have gradually attracted attention, but few studies have focused on its flavor. In this study, L. vannameicultured in saline–alkali water (SS) and ordinary seawater (CS) (both have a breeding time of 120 days) were selected for analysis (n= 5). High-performance liquid chromatography (HPLC) was used to measure free amino acids and flavoring nucleotides in the muscles of L. vannamei, while the taste activity value (TAV) and equivalent umami concentration (EUC) were used to analyze the degree of umami. The total essential amino acids (TEAA) in the SS group were 238.41 ± 46.24 mg/mL, significantly higher than that in the CS group (107.06 ± 15.65 mg/mL). The total amount of flavor nucleotides in the SS group was 2948.51 ± 233.66 μg/mL, significantly higher than those in the CS group (2530.37 ± 114.67 μg/mL). The content and TAV of some free amino acids (Glu, Cys-s) in the SS group were significantly higher. Meanwhile, due to the significant increase in IMP, the synergistic effect of free amino acids and flavored nucleotides leads to higher EUC. The significant separation of SS and CS samples in principal component analysis (PCA) indicates a significant difference between the two groups. Our results indicate that shrimp cultured in saline–alkali water has a stronger umami. This study enriches the basic theories related to the flavor of salt–alkali water crustaceans.

In this study, the best domestication time for mud crabs (Scylla paramamosain) that were domesticated in the same region was explored. MC crabs (Mang Cai City, Vietnam), TS crabs (Taishan City, Guangdong Province, China), and NB crabs (Ningbo City, Zhejiang Province, China) were used as experiment groups, which were all domesticated in the Sanmen area for 28 days. Then, free amino acids and flavor nucleotides in muscles and hepatopancreas were determined. In MC and NB crabs, flavor amino acids in hepatopancreas and equivalent umami concentration (EUC) of flavor nucleotides in the hepatopancreas and muscles were lower than those of CK1 and CK3 crabs before domestication (0 day). There was no significant difference between MC and CK1 and between NB and CK3 crabs after 28 days of domestication. The content of umami amino acids, the total content of flavor nucleotides, and EUC in the hepatopancreas in TS crabs were lower than those in CK2 crabs and were still lower than those in CK2 crabs after 28 days of domestication. Therefore, it takes at least a month to domesticate mud crabs. The theoretical basis and technical reference for the directional cultivation of the flavor quality of mud crabs were provided in this study..

Salinity affects the growth and development of crustaceans by affecting their physiological functions such as respiration, metabolism, osmotic regulation and immune defense. Gill is the most important organ of osmotic regulation. The adaptation of Scylla paramamosainto low salt is a process of oxygen consumption and energy consumption, and the mitochondria in the cells are considered to be the synthesis site of energy. Therefore, in this study, GC-MS technology was used to conduct non-targeted metabolomics studies on the posterior gill mitochondria of S. paramamosainunder acute hyposaline stress, revealing the key role of mitochondria in gill response to acute low salinity stress. We identified 196 metabolites, 21 of which were differentially expressed. Differential metabolite KEGG enrichment analysis identified 16 metabolic pathways. The results of this study suggest that mitochondria may maintain osmotic homeostasis by increasing the utilization of monosaccharides, and decreasing the synthesis of amino acids in crabs under acute low salt stress when they are in a state of oxygen and energy depletion. In addition, carbohydrates and organic acid metabolites may also play an important role. For the first time, we analyzed the metabolic mechanism of posterior gill mitochondria in response to acute low salt, aiming to provide effective technical support and theoretical reference for the cultivation of S. paramamosain.

Scylla paramamosainis an important mariculture animal. In the present study, we examined the physiological and biochemical characteristics of juvenile S. paramamosainunder hypoosmotic stress and further verified the function of ABCC1, a key transport protein in gill tissue. The results showed that Na+/K+-ATPase, Ca2+-ATPase, and Na+/K+/2Cl-cotransporter in gill tissues increased first and then decreased. In addition, SOD and CAT activities also began to gradually increase, protecting gill tissues from oxidative damage. The hemolymph osmolarity decreased rapidly from 792 mOsm/kg to 560 mOsm/kg within 6 h, and then rose to 626.25 mOsm/kg at 48 h, and then remained stable. At the same time, Na+, Cl-, K+, and Ca2+concentrations were decreased to varying degrees. There were significant changes in free amino acids such as aspartic acid, glutamic acid, and asparagine in hemolymph in response to acute salt depletion. By injection of ABCC1 inhibitor/activator, it was found that while ABCC1 transporter activity in the MK-571 group showed a decreasing trend at 9 h, Na+/K+-ATPase activity began to increase and reached a peak at 48 h. Compared with the control group, the levels of aspartic acid, glutamic acid, asparagine, glycine, arginine, alanine, lysine, and proline in the MK-571 group showed significant differences at 6 h; Significant differences in glutamate, asparagine, arginine, alanine, lysine, and proline appeared at 12 h in the Thiethylperazine group. These results suggested that the dynamic changes of gill ion transport enzymes, antioxidant enzymes, inorganic ions, and free amino acids in hemolymph occurred in S. paramamosainunder hypoosmotic stress, and the ABCC1 transporter played an important role in this regulatory process.

The mud crab (Scylla paramamosain) is an important species for seawater aquaculture, the utilization of saline-alkali water provides potential for the further development of the mud crab industry, but the adaptation mechanism of the antennal gland to chloride type low-salt saline-alkali water has not been fully studied. In this study, we evaluated the osmoregulatory enzyme activity (n=3) and metabolic changes (n=5) of the antennal gland in S. paramamosainafter a sudden drop in salinity from 23‰ of seawater to 2‰ of chloride type low-salt saline-alkali water. After the decrease in salinity, the activity of osmoregulatory enzymes in the antennal gland, including Na+/K+-ATPase, NKCC, carbonic anhydrase (CA), and V-ATPase showed a trend of first increasing and then decreasing. Through LC-MS technology, we identified 308 differential metabolites. In addition, KEGG enrichment analysis identified eight significant metabolic pathways (P<0.05), primarily related to amino acid metabolism, signaling pathways, and lipid metabolism. Among them, amino acid and energy metabolism occupy the majority, followed by lipid metabolism pathways. Our research results indicate that amino acids and energy metabolism are involved in the adaptation of the antennal gland of the mud crab to acute chloride type low-salt saline-alkali water stress, in which lipid metabolites play an important supportive role.

The red drum (Sciaenops ocellatus), a globally significant marine aquaculture species, boasts formidable osmoregulatory capabilities and remarkable adaptability to low salinity, making it an ideal candidate for commercial cultivation in inland low salinity saline-alkaline waters. However, studies on the fundamental nutritional composition and flavor quality of S. ocellatusin these inland low salinity saline-alkaline waters remain unreported. This study delves into the impact of inland low salinity saline-alkaline environments on the basic nutritional components and nonvolatile flavor substances (including free amino acids and free nucleotides) in the muscle tissue of S. ocellatus. The findings reveal that redfish cultivated in these conditions exhibit a significant increase in the crude fat, ash, and protein content in their dorsal muscle tissue, coupled with a decrease in moisture content (p< 0.05), indicating an enhancement in the nutritional value of the dorsal muscle tissue. Furthermore, this cultivation environment significantly elevates the content of free amino acids in the muscle tissue (p< 0.05), particularly those contributing to umami and sweet tastes, while reducing the relative content of bitter amino acids. Although the total content of free nucleotides decreased, the equivalent umami concentration (EUC) in the muscle tissue markedly increased (p< 0.05) due to the synergistic effect of umami amino acids and flavor nucleotides, enhancing the umami taste characteristics. Therefore, inland low salinity saline-alkaline aquaculture not only elevates the nutritional value of S. ocellatusmuscle tissue but also improves its umami flavor characteristics. This discovery opens new perspectives for further research into the impact of inland low salinity saline-alkaline environments on the flavor properties of marine animals.