# Development of Assessment Criteria for Managing the Quality of Taishan Black Tea
## 3 Results
### Quality and Composition Characteristics of Taishan Black Tea
#### 3.2.2 Comprehensive Evaluation of Taishan Black Tea Taste and Quality  
A principal component analysis (PCA) can illustrate the overall differences between groups and the degree of variability among samples within each group. Figure 3 presents the PCA results for black tea samples from different companies. Except for JQB, there were differences in taste quality among the black tea samples, although these distinctions were not significant. This finding indicates a high degree of similarity in taste and quality among Taishan black tea varieties.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Component** & **Concentration Range** & **Sample Frequency** & **Percentage/\%** & **Cumulate Percent/\%** \\ \hline \multirow{4}{*}{Water extracts/\%} & 36.32–38.65 & 7 & 15.56 & 15.56 \\  & 38.65–41.01 & 18 & 40 & 55.56 \\  & 41.01–43.35 & 18 & 40 & 95.56 \\  & 43.35–45.72 & 2 & 4.44 & 100 \\ \hline \multirow{4}{*}{Amino acids/\%} & 1.41–2.42 & 9 & 20 & 20 \\  & 2.42–3.45 & 22 & 48.89 & 68.89 \\  & 3.45–4.41 & 10 & 22.22 & 91.11 \\  & 4.41–5.43 & 4 & 8.89 & 100 \\ \hline \multirow{4}{*}{Tea polyphonies/\%} & 9.80–12.43 & 15 & 33.33 & 33.33 \\  & 12.43–15.05 & 22 & 48.89 & 82.22 \\  & 15.05–17.68 & 6 & 13.33 & 95.56 \\  & 17.68–20.31 & 2 & 4.44 & 100 \\ \hline \multirow{4}{*}{Catechin/\%} & 6.11–7.55 & 15 & 33.33 & 33.33 \\  & 7.55–9.03 & 22 & 48.89 & 82.22 \\  & 9.03–10.45 & 5 & 11.11 & 93.33 \\  & 10.45–11.91 & 3 & 6.67 & 100 \\ \hline \multirow{4}{*}{Caffeine/\%} & 1.18–1.65 & 4 & 8.89 & 8.89 \\  & 1.65–2.12 & 13 & 28.89 & 37.78 \\  & 2.12–2.58 & 17 & 37.78 & 75.56 \\  & 2.58–3.05 & 11 & 24.44 & 100 \\ \hline \multirow{4}{*}{Phenol–ammonia ratio} & 2.31–3.76 & 12 & 26.67 & 26.67 \\  & 3.76–5.21 & 18 & 40 & 66.67 \\ \cline{1-1}  & 5.21–6.65 & 10 & 22.22 & 88.89 \\ \cline{1-1}  & 6.65–8.10 & 5 & 11.11 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Distribution frequency of biochemical components of the Taishan black tea.  
Figure 3: Distribution map of the Taishan black tea samples based on PCA.  
As shown in Table 3, the cumulative contribution rate of the first three principal components reached 89.14%, which could explain most of the data of the samples. PC1 explained 51.16% of the total information, primarily synthesizing the data on catechins and tea polyphenols. These compounds are important factors influencing the taste intensity, bitterness, and freshness of Taishan black tea soup. PC2 encompassed 22.21% of the data, and its size was mainly determined by the amino acids and water extracts, crucial factors that impact the freshness, mellowness, and thickness of Taishan black tea soup. PC3 contained 15.77% of the data, and its size was mainly determined by caffeine. Caffeine, with its inherent bitter taste, contributes to both freshness and bitterness when combined with catechins and theaflavins. Consequently, caffeine emerged as a significant factor affecting the overall taste profile of the Taishan black tea soup. In summary, catechins and tea polyphenols emerged as crucial indicators influencing the taste quality of the Taishan black tea, followed by amino acids, water extracts, and caffeine.