Abstract: Naturally fermented Jiaosu of Cudrania tricuspidata green fruits were prepared by the same method as that for traditional fermented Jiaosu with different fermentation periods,and they were investigated for changes in protein content and amino acid composition during the fermentation.In addition to the contents of protein and amino acids,ratio of amino acids (RAA),ratio coefficents of amino acids (RC) and score of ratio coefficients (SRC) were also analyzed.The results showed that the content of protein showed a gradual upward trend，a total of 16 kinds of amino acids were measured in the naturally fermented Jiaosu of Cudrania tricuspidata green fruits,the contents of different amino acids were extremely different in the fermentation.The total amino acid (T),human essential amino acid (E) and γ-aminobutyric acid content were increased at first and then decreased,The first two reached 2407.9,766.7 mg/L at 270^th day and the latter reached 211.5 mg/L on the 170^th day.Based on analysis of RAA,RC and SRC,the SRC reached the highest value of 59.52 on day 270^th of fermentation.With the progress of fermentation,the amino acid nutrition of the Jiaosu of Cudrania tricuspidata green fruits is more and more balanced,but the lack of Tyr and Cys+Met affects the nutritional value of the whole Jiaosu.The contents of different taste-active amino acids were in the order of umami amino acid > sweet amino acid > bitter amino acid > tasteless amino acid.

Key words: Jiaosu;amino acid, nutrition evaluation, cluster analysis, taste-active amino acids