To reveal the impact of different feeding modes on the flavor quality of female Chinese mitten crab (Eriocheir sinensis) this study was conducted to compare the sensory evaluation scores, flavor compounds in meat and hepatopancreas of female E. sinensis fed with 3 feeding modes, that is, natural diets (NDs), traditional diets (TDs), and formulated diets (FDs). The result showed that crabs fed with ND had significantly lower sensory scores than the other 2 feeding modes in both edible tissues. The odor and taste profiles were evaluated by Electronic nose (E-nose) and tongue (E-tongue) techniques, respectively; results of perchloric acid showed each edible tissue had significant differences among the 3 modes. Contents of volatile compounds were measured by Headspace-solid phase micro extraction combined with gas chromatography-mass spectrometer. A total of 35 and 44 volatile compounds were identified in meat and hepatopancreas, respectively. ND mode of meat had the highest relative odor activity value (ROAV) summation among the 3 diet modes. TD mode of hepatopancreas had significantly higher ROAV summations. Based on the analysis of free amino acids and 5'-nucleotides, nonvolatile compounds were evaluated by equivalent umami concentration (EUC) and taste active values (TAVs) methods. For both meat and hepatopancreas, TD had the highest contents of umami amino acid, as for the 5'-nucleotide, FD had the highest 5'-inosin monophosphate concentrations. Overall, the EUC and TAVs of TD were higher than that of FD, whereas ND mode had the lowest values in the 2 edible tissues. In conclusion, TD mode had the best performance in terms of sensory evaluation, ROAVs of aroma-active compounds, and nonvolatile active compounds.

As a catadromous species, salinity is a key parameter that affects gonadal development of Chinese mitten crab Eriocheir sinensis during reproductive migration. It is however unclear the effects of salinity on the gonadal development of male E. sinensis as well as their physiological responses to salinity during reproductive migration. This study investigated the effects of four salinities (0 ‰, 6 ‰, 12 ‰ and 18 ‰) on gonadal development, osmoregulation and metabolism of adult male E. sinensis over a 40-day period. The results showed that elevating salinity promote gonadal development, increase hemolymph osmolality and K+ and Mg2+ concentrations (P < 0.05). The 12 ‰ salinity resulted in the highest contents of taurine and arginine in the hemolymph while the highest contents of threonine, phenylalanine, lysine, ß-alanine, tryptophan, ornithine and total free amino acids were found for 0 ‰ treatment (P < 0.05). A decreasing trend was detected for the Na+/K+-ATPase activity and its mRNA expression level in the posterior gills with salinity (P < 0.05). Total saturated fatty acids in the anterior gills decreased with increasing salinity (P < 0.05); the 0 ‰ treatment had the highest total polyunsaturated fatty acids in the posterior gills while total n-6 polyunsaturated fatty acids increased with salinity (P < 0.05). The hemolymph glucose and uric acid showed a decreasing trend as salinity while an increasing trend was found for the hemolymph triglyceride and high-density lipoprotein cholesterol (P < 0.05). The 12 ‰ treatment had the highest levels of hemolymph malonaldehyde and hepatopancreatic γ-glutamyltranspeptidase (P < 0.05). In conclusion, these results suggested that the brackish water promote gonadal development of male E. sinensis, and increase osmolality and ionic concentrations in hemolymph while reduced the activity of Na+ /K+- ATPase and its mRNA expression in the posterior gills as well as metabolism.

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This study mainly investigated the composition of adult male Chinese mitten crab () from four grades/sizes (Grade I: 200-249 g; Grade II: 175-199 g; Grade III: 150-174 g; Grade IV: ≤ 150 g). The results showed that the grade III crabs had the largest gonadsomatic index (GSI), which was significantly higher than the grade I and grade II crabs, no significant difference was found with the grade IV crab. Significant differences in moisture and total lipid contents were observed among various edible parts from different grades of male . In particular, grade II crabs had the highest total lipid and dry matter content for hepatopancreas. A balanced amino acids composition and a high essential amino acids score (EAAS) were found in the muscle and gonads of grade III crabs. The levels of poly-unsaturated fatty acids (PUFA), n-3 PUFA, n-6 PUFA and docosahexaenoic acid (DHA) in the hepatopancreas, as well as the contents of PUFA, highly-unsaturated fatty acids (HUFA), n-3 PUFA, arachidonic acid (ARA), and eicosapentaenoic acid (EPA) in the gonads were significantly increased in the grade II crabs. Taken together, it can generally be concluded that adult male of 150-200 g (Grade II-III) weight have the highest nutritional quality even though they are not the largest crabs.