Comparative analysis of nutritional composition and energy density of muscle in three geographical populations of Megalobrama terminalis

In order to compare the nutritional composition and energy density of Megalobrama terminalis populations in Wangquan River, Moyang River and Xijiang River, we applied the biochemical analysis methods to determine the contents of moisture, crude protein, ash and crude fatty, as well as amino acid and fatty acid composition and energy density of the muscle of three M. terminalis populations. The results indicate that the Xijiang River population had the highest crude protein mass fraction (20.2±0.5)%, while Wangquan River population had the highest water mass fraction (79.0±0.5)%. The energy density of Xijiang River population was significantly higher than that of Wangquan and Moyang River populations (P<0.05). The essential amino acid index (EAAI) of Xijiang River population was higher than that of Wanquan and Moyang River populations. We had detected 23 kinds of common fatty acids in the muscle of three M. terminalis populations. The content of monounsaturated fatty acid (MUFA) in the muscle of Wanquan River population was the lowest, while the content of polyunsaturated fatty acids (PUFA) of Wanquan River populatin was the highest. The DHA content in muscle of Xijiang River population was much higher than that of Wanquan and Moyang populations. Potassium (K) and copper (Cu) had the highest and lowest contents among all the mineral elements in the muscle of three M. terminalis populations, respectively. The contents of ferrum (Fe) and manganese (Mn) of Xijiang River population were significantly higher than those of Moyang and Wanquan River populations, but the content of zinc (Zn) of Xijiang River population was much lower than that of Moyang River population.