# Effect of Leaf Grade on Taste and Aroma of Shaken Hunan Black Tea
## 3 Results
### Analysis of Main Taste Compounds
Additionally, phenylalanine and leucine, classified as bitter amino acids, significantly contribute to tea bitterness. Conversely, theanine, glutamic acid, and threonine, categorized as sweet amino acids, act as inhibitors of the bitter and astringent taste in tea [19]. The present study observed a decrease in the bitter, astringent, and acidic tastes of shaken Hunan black tea as the fresh leaf maturity increased, which aligns with the findings of the sensory evaluation. \begin{table}
\begin{tabular}{c c c c c} \hline
**Components** & **First Grade** & **Second Grade** & **Third Grade** & **Fourth Grade** \\ \hline Polyphenol & 16.15 \(\pm\) 0.25 & 15.67 \(\pm\) 0.16 & 11.1 \(\pm\) 0.69 & 10.51 \(\pm\) 0.55 \\ Theobromine & 0.47 \(\pm\) 0.00 & 0.28 \(\pm\) 0.00 & 0.11 \(\pm\) 0.00 & 0.1 \(\pm\) 0.00 \\ Gallic acid & 0.68 \(\pm\) 0.01 & 0.56 \(\pm\) 0.02 & 0.4 \(\pm\) 0.04 & 0.37 \(\pm\) 0.02 \\ CAF & 4.67 \(\pm\) 0.07 & 3.96 \(\pm\) 0.09 & 3.07 \(\pm\) 0.12 & 3.18 \(\pm\) 0.12 \\ EGC & 0.15 \(\pm\) 0.00 & 0.16 \(\pm\) 0.00 & 0.12 \(\pm\) 0.01 & 0.12 \(\pm\) 0.00 \\ D, L-C & 0.09 \(\pm\) 0.00 & 0.07 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 \\ EC & 0.21 \(\pm\) 0.00 & 0.2 \(\pm\) 0.01 & 0.15 \(\pm\) 0.00 & 0.13 \(\pm\) 0.00 \\ EGCG & 1.09 \(\pm\) 0.08 & 0.99 \(\pm\) 0.04 & 0.65 \(\pm\) 0.02 & 0.65 \(\pm\) 0.02 \\ GCG & 0.13 \(\pm\) 0.00 & 0.12 \(\pm\) 0.00 & 0.13 \(\pm\) 0.00 & 0.1 \(\pm\) 0.00 \\ ECG & 0.4 \(\pm\) 0.03 & 0.36 \(\pm\) 0.01 & 0.17 \(\pm\) 0.00 & 0.15 \(\pm\) 0.00 \\ Asp & 0.24 \(\pm\) 0.02 & 0.18 \(\pm\) 0.00 & 0.15 \(\pm\) 0.00 & 0.19 \(\pm\) 0.01 \\ Ser & 0.08 \(\pm\) 0.00 & 0.11 \(\pm\) 0.01 & 0.09 \(\pm\) 0.00 & 0.11 \(\pm\) 0.00 \\ Glu & 0.21 \(\pm\) 0.02 & 0.15 \(\pm\) 0.01 & 0.17 \(\pm\) 0.00 & 0.26 \(\pm\) 0.01 \\ Gly & 0 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 \\ His & 0.06 \(\pm\) 0.00 & 0.06 \(\pm\) 0.00 & 0.06 \(\pm\) 0.00 & 0.1 \(\pm\) 0.00 \\ Arg & 0 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 \\ Thr & 0.03 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 \\ Ala & 0.03 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 \\ Pro & 0.07 \(\pm\) 0.00 & 0.05 \(\pm\) 0.00 & 0.06 \(\pm\) 0.00 & 0.07 \(\pm\) 0.00 \\ Theamine & 0.63 \(\pm\) 0.02 & 0.69 \(\pm\) 0.04 & 0.92 \(\pm\) 0.00 & 1.14 \(\pm\) 0.04 \\ Cys & 0.01 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 & 0.05 \(\pm\) 0.02 & 0.01 \(\pm\) 0.00 \\ Tyr & 0.04 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.11 \(\pm\) 0.05 & 0.02 \(\pm\) 0.00 \\ Val & 0.02 \(\pm\) 0.00 & 0.01 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 \\ Met & 0.06 \(\pm\) 0.00 & 0.06 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 \\ Lys & 0.05 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 \\ Ile & 0.02 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 \\ Leu & 0.05 \(\pm\) 0.00 & 0.04 \(\pm\) 0.01 & 0.03 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 \\ Phe & 0.04 \(\pm\) 0.00 & 0.04 \(\pm\) 0.00 & 0.03 \(\pm\) 0.00 & 0.02 \(\pm\) 0.00 \\ \hline \end{tabular}
\end{table} 
Table 2: Table of the content of the main taste components (%).