Microbial succession and changes of nutritional components, volatile compounds of Chouguiyu, traditional Chinese...

In this study, the 3^rd sequencing technology was done to investigate microbial succession during mandarin fish fermentation, and dynamic changes in nutrients and volatile compounds were explored. It was found that the contents of basic nutritional components, including moisture, ash, crude fat, and crude protein displayed diverse trends, with the crude fat content decreasing rapidly. During the fermentation, the contents of hydrolyzed amino acids, free amino acids and unsaturated fatty acids showed an overall trend of increasing and then decreasing. However, by the end of fermentation, the free amino acids content was still 1.42 times higher than that of fresh fish. In addition, Vibrio natriegens and Clostridium tarantellae were the dominant bacteria in the early and late stages of fermentation, respectively, and Aeromonas hydrophila was abundant on the fourth day of fermentation. Correlation analysis revealed that dominant bacteria, including V. natriegens, C. tarantellae, and A. hydrophila, were closely associated to the formation of volatile compounds. We speculated that they might be primarily participate in the metabolism of amino acids such as methionine (Met), leucine (Leu), and valine (Val), as well as unsaturated fatty acids, and converted them into a variety of volatile compounds included tetrahydrothiophene, dipropyl disulfide, 3-methyl-1-butanol, (E)-2-undecenal, 2-octanone, (2,6)-dimethylpyrazine, ethyl heptanoate and methyl octanoate, etc.