Metabolomics of the hepatopancreas in Chinese mitten crabs (Eriocheir sinensis)

Chinese mitten crab (Eriocheir sinensis) is an important economic seafood in China, and the hepatopancreatic dim color and bitter taste of crabs significantly affects the consumer's acceptance. The crabs with brown hepatopancreas (BH) generally taste bitter, while the orange hepatopancreas (OH) does not taste bitter. While the metabolites perform their physiological functions, their metabolic relationship may directly affect the color and taste quality of the crab hepatopancreas. This study investigated the metabolic relationship of key metabolites related to the color and bitterness in the OH and BH of E. sinensis. The contents of total bile acids (BAs) (10.62 vs. 3.72 μg/g), bitter free amino acids (FAAs) (5.15 vs. 2.46 mg/g) and lutein (6.88 vs. 2.55 μg/g) in the BH group were significantly higher (P < 0.01) than those in the OH group, while β-carotene (314.47 vs. 478.52 μg/g) in the BH group was significantly lower (P < 0.05) than that in the OH group. In addition, BAs were positively correlated with lutein, saturated and monounsaturated fatty acids (SFA and MUFA) and bitter FAAs, and negatively correlated with color value, β-carotene and polyunsaturated fatty acids (PUFA). In conclusion, BAs and bitter FAAs may be the major contributors to the bitterness of BH, and the high content of BAs in the BH group may promote lipid catabolism, inhibit β-carotene absorption and enhance amino acid metabolism, leading to the hepatopancreas brown and bitter.