Ovarian fullness affects biochemical composition and nutritional quality of female swimming crab Portunus trituberculatus

Difference in nutritional status and food sources for hard- and soft-shell crabs (Portunus trituberculatus) using amino acids and isotopic tracers

The swimming crab, Portunus trituberculatus, supports the world's largest crab fishery. Hard-shell crabs have fully developed exoskeletons and are rich in meat, while soft-shell crabs, which have recently molted, contain less meat. To determine their nutritional status and feeding behavior, we measured amino acids (AAs), organic carbon (OC), δ13C, δ15N, and 210Po in the muscle of hard- and soft-shell crabs collected from the eastern Yellow Sea in May 2024. The concentrations of total AAs (TAAs) and OC were approximately 1.4 and 1.3 times higher, respectively, in hard-shell crabs than in soft-shell crabs. A significant positive correlation between TAAs and OC (r2 = 0.74, p < 0.05) suggests that hard-shell crabs have a better nutritional status, due to the consumption of higher-quality food. Hard-shell crabs also exhibited significantly higher δ13C values and 210Po activities than soft-shell crabs, whereas δ15N values showed no significant difference between the two groups. These results indicate that hard-shell crabs primarily consume higher trophic-level prey compared with soft-shell crabs, despite both occupying the same trophic position. Thus, this difference in food sources may be influenced by post-molt hiding behavior in soft-shell crabs, which limits access to high-trophic prey, or alternatively, by competition for food in coastal waters.

Comprehensive quality evaluation for oysters of geographical indication from Rushan in China: Characteristic profile of nutrition and flavor components

To reveal the differences in nutritional quality among diploid, triploid, and fattening oysters, nutrient and taste-contributing compounds were analyzed. The results demonstrate that diploid oysters exhibited significantly higher meat yield (22.88 %), protein (48.27 ± 2.50 g/100 g), total fatty acids (3032.52 ± 518.16 mg/100 g), vitamin B, mineral and flavor compounds than triploid and fattening oyster (P < 0.05). In contrast, triploid oysters exhibited higher lipid (10.02 ± 0.60 mg/100 g) and fat-soluble vitamin, and fattening oysters have higher EAA content (12.31 ± 0.69 mg/100 g) (P < 0.05). The edible quality of the three oyster types was evaluated using PCA and their nutrition value was assessed based on the NRF index score. The consistent rank results of the above two evaluation methods were diploid > triploid > fattening. The research results will provide data for oyster grading evaluation standards, thereby promoting the nutritional and health-oriented transformation of the oyster industry.

Cholesterol Modifies Nutritional Values and Flavor Qualities in Female Swimming Crab (Portunus trituberculatus)

The quality of crustacean aquatic products is affected by feed. Cholesterol (CHO), an essential element for crustacean growth, has been widely supplemented in diet, but its food quality regulation remains unclear. The study aimed to investigate the effects of different dietary CHO levels (0.12%, 1.00%, and 2.50%) on the nutritional value and flavor quality in the edible parts of female swimming crabs (Portunus trituberculatus). Results showed that dietary CHO levels significantly increased lipid content in the hepatopancreas and promoted the accumulation of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in the hepatopancreas and muscle by activating the gene expression related to biosynthesis pathways. However, with dietary CHO levels increased, protein content in muscle decreased significantly. This may be related to dietary CHO supplementation (especially 2.50% CHO level) suppressed amino acid accumulation in the hepatopancreas and muscle by downregulating the target of the rapamycin pathway and upregulating amino acid catabolism-related genes. Moreover, 1.00% CHO treatment had higher relative levels of volatiles, producing grassy, fruity, and fatty odors in muscle, which may be due to the upregulation of the branched-chain amino acid transaminase (bcat) expression level. Dietary CHO weakened nucleotide and free amino acid accumulation in hepatopancreas and muscle. Overall, this study suggests that dietary 1.00% CHO level had higher LC-PUFA and pleasing flavor substances in muscle but was not conducive to hepatopancreatic protein and flavor nucleotide deposition of swimming crab.