Rice flower carp (Cyprinus carpio rubrofuscus) has high economic value because of its tender meat. However, a comprehensive scientific evaluation of the meat quality and nutritional value of rice flower carp is still needed. At the same time, because of its fast growth and strong disease resistance, rice flower carp is widely popularized in rice field culture but without any research comparing its quality with the pond culture method. Although rice farming has high ecological value, the fish yield is low and its specifications are abnormal, which cannot guarantee the stability and safety of the commercial fish supply and limit the potential rice flower carp industrial benefits. In addition, some studies have shown that fish muscle quality can be affected by environmental conditions. This study aimed to comprehensively evaluate the muscle quality and nutritional value of the rice flower carp and investigate the relationships between the nutritional values and its culture conditions, providing data to increase the rice flower carp yield, economic efficiency, and farmed varieties available. Therefore, 6 000 Quanzhou rice flower carp (2.35±0.08 g) were randomly divided into ponds and rice field groups for the experiment (three replicates per group, with a density of 15 000/hm2). The pond culture group was fed with 3% of the commercially established everyday food per fish weight, while the rice field group was not fed. After 12 weeks, the fish were submitted to a 24 h period without food and anesthetized using MS-222 (USA, Sigma). The length and weight of 100 fish were measured for each treatment. For the rice field group and pond group, respectively, the lengths were (13.56±0.49) cm and (14.10±0.23) cm, and the weights were (73.19±7.02) g and (101.20±4.57) g. The muscle quality of 30 fish from each treatment was measured, including basic nutritional components, texture characteristics, and amino acid and fatty acid compositions. The nutritional level was compared between the pond and rice field groups using the FAO/WHO amino acid score, whole egg protein comparison, protein amino acid score (AAS), chemical score (CS), and essential amino acid index (EAAI). Moreover, no significant differences between the two culture methods were observed in relation to the total ash (P > 0.05). The crude protein and crude fat contents in the rice field group were significantly lower than in the pond group (P < 0.05), while moisture was significantly higher (P < 0.05). The viscosity of the rice field group was significantly lower than that of the pond group (P < 0.05), but the cohesion and shear force were significantly higher than those of the pond group (P < 0.05). There was no significant difference in the other texture indexes (P > 0.05). Essential amino acids (EAA) in both groups met the FAO/WHO standard. Among the 18 amino acids measured, the total amino acids (TAA), delicious amino acids (DAA), essential and nonessential amino acids (NEAA) were significantly lower in rice field conditions than in pond (P < 0.05), while the EAA/TAA and EAA/NEAA ratios were significantly lower in the pond group (P < 0.05). According to the amino acid score (AAS) and chemical score (CS), glutamic acid (Glu) was the most common amino acid in both groups, while the first and second limiting amino acids were tryptophan (Trp) and valine (Val). Among the 22 fatty acids observed, the contents of tridecanoic, pentadecanoic, palmitoleic, heptadecanoic, and docosatetraenoic acids were not significantly different between the two groups (P > 0.05). In contrast, the contents of linoleic, linolenic, and arachidonic acids in the pond group were significantly higher than those in the rice field group (P < 0.05), while 14 other fatty acids showed significantly lower contents in the pond group (P < 0.05). The monounsaturated fatty acid (MUFA) contents in the pond group were significantly higher (P < 0.05), while the EPA+DHA and n-3PUFA/n-6PUFA were significantly lower than those in the rice field group (P < 0.05). Overall, the contents of four main flavor amino acids (glutamic acid, glycine, alanine, and aspartic acid) in the rice field group were significantly lower than those in the pond group (P < 0.05). In conclusion, rice flower carp reared in both pond and rice field is a high-quality protein source. However, different cultural environments significantly influence the rice flower carp muscle nutritional value and quality, wherein a higher nutrient composition and amino acid score were observed in the pond environment. Concerning the fatty acids content, the muscle of rice flower carp reared in rice fields had higher EPA+DHA content and N-3/N-6 polyunsaturated fatty acid ratio, which is more suitable for people with hyperlipidemia and cardiovascular diseases. In addition, in terms of texture, the muscle of rice flower carp is chewier under the rice field rearing condition. Nevertheless, N-3PUFA shortages were observed in both culture conditions. Besides, fish in the pond group had better muscle nutrition than the rice field group. Different culture conditions can change rice flower carp's fatty acid composition and content to a certain extent, but none of the two conditions tested here could completely allay the lower N-3PUFA problem. Therefore, increasing the N-3PUFA content of rice flower carp is the key to improving its nutritional value, and pond culture conditions make this process easier to be manually controlled.

稻田和池塘养殖禾花鲤肌肉营养与品质分析