A method for improving the quality of grass carp (Ctenopharyngodon idellus): A comprehensive evaluation of clear water depuration based on sensory and nutritional aspects

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This study investigates the effects of clear water depuration farming on grass carp muscle quality, nutrition, and flavor. Results show that clear water depuration significantly reduces off-flavor compounds while improving muscle texture and sensory traits. After three months, fish muscle hardness, chewiness, and whiteness increased, while drip and freezing loss decreased. Low-density farming better preserved essential amino acids and unsaturated fatty acids, enhancing nutritional value. Glycine, histidine, and alanine were the main free amino acids with elevated levels. Volatile analysis showed nonanal, hexanal, and 1-octen-3-ol levels declined with time, especially under low-density conditions. Muscle texture improvements correlated positively with monounsaturated fatty acids, protein, and collagen, and negatively with moisture, pH, and polyunsaturated fatty acids. Clear water depuration may also promote collagen synthesis. Overall, a three-month depuration under low-density conditions is optimal for improving grass carp's sensory and nutritional quality without negatively affecting texture and taste.