Short-term fasting and improvement the food quality of pond cultured grass carp(Ctenopharyngodon idella)

The demand for aquatic products has grown recently, and consumers are more concerned with the safety and quality of fish meat for consumption. This paper will explore the technical feasibility of short-term fasting to improve the food quality of pond cultured fish, commercial Ctenopharyngodon idella cultured in three adjacent ponds were taken as the objects and transferred to three cages in another pond for 21 days of short-term fasting. C. idella from three ponds were collected every seven days, and the fish body was divided into four body segments A, B, C and D muscle samples were collected for quantitative analysis of muscle moisture, crude protein, crude lipid and glycogen content. The results showed that the nutrient content of muscle of different body segments changed after fasting for 7 days, and the crude protein content and crude lipid content changed significantly after fasting for 14 days, and the crude protein content of tail (C and D segments) increased significantly; The crude lipid content of a segment of C. idella from No.10 pond was 22.60% and 17.07% lower than that of 0 d on 14 and 21 days, respectively. The crude lipid content of B and D segments was 7.50%, 19.41%, 12.61% and 28.83%, 36.68%, 13.49% lower than that of 0 d on 7, 14 and 21 days, respectively. The crude lipid content of A, C and D segments of C. idella from No.17 pond was significantly increased after 7 days. The crude lipid content of B segment was 26.76%, 58.41% and 62.90% lower than that of 0 d on 7, 14 and 21 days, respectively. The crude lipid content of D segment was 1.52% and 22.58% lower than that of 0 d on 7 and 14 days, respectively. The glycogen content (C, D segments) of C. idella muscle from three ponds showed a significant increase trend. The back muscle samples of C. idella were collected, and the water power, muscle texture characteristics and tissue sections of the muscle system were measured. It was found that there was no significant difference in the drip loss rate of the back muscle of C. idella from pond 10 on day 14, the drip loss rate of the back muscle of C. idella from pond 17 on day 14 was significantly higher than that of day 0, and the drip loss rate of the back muscle of C. idella from pond 18 on day 14 had a downward trend. With the extension of fasting time, the hardness of the B segment muscle of C. idella from three ponds decreased, and the muscle elasticity increased. Chewiness increased gradually before 14 days, while cohesion increased gradually. During fasting, the density of back muscle fibers (muscle cells) increased, the gap between muscle fibers decreased, and the muscle hardness gradually decreased with fasting time, while the elasticity and chewiness showed a gradual increase trend. The results showed that short-term fasting could change the eating quality of C. idella muscle, and the best experimental result was fasting for 14 days. The results of this study provide a scientific basis for improving the food quality of pond cultured fish.