# Development of Assessment Criteria for Managing the Quality of Taishan Black Tea
## 4 Discussion  
Taste constitutes a crucial sensory attribute of tea, and is influenced by a multitude of chemical components and intricate interactions [13; 14; 15]. The divergence in various tea flavors stems from the distinct contributions of non-volatile components to the resultant tea flavor [16]. Our analysis of the flavor characteristics of Taishan black tea revealed that polyphenols and catechins played pivotal roles in shaping taste quality, followed by amino acids, water extracts, and caffeine (Table 4). Polyphenols exerted a significant influence on the taste quality, forming the basis for the heavy and strong and heavy and mellow taste profiles. They were mainly responsible for the astringency, brightness, color, and freshness of the black tea soup [17]. Catechins, known for their bitter and astringent properties, impacted the final quality and taste of the tea [18; 19]. The high contents of polyphenols and catechins in the Taishan black teas imparted characteristics of heavy and strong and heavy and mellow tastes, consistent with an earlier study [20]. By comparison, it was found that the average proportion of catechins in Taishan black tea was 8.16%, which was much higher than that of Anhui and Yunnan black tea, and the caffeine content of Taishan black tea was 2.3%, which was slightly higher than that of Anhui and Yunnan black tea [21]. \begin{table}
\begin{tabular}{c} **Accumulative** \\ **Contribution** \\ **Rate/\%** \\ \end{tabular} \\ \hline
1 & 11.58 & 27.57 & 27.57 & 6 & 3.09 & 7.35 & 86.29 \\
2 & 7.48 & 17.81 & 45.38 & 7 & 2.36 & 5.62 & 91.91 \\
3 & 5.25 & 12.50 & 57.88 & 8 & 2.04 & 4.87 & 96.78 \\
4 & 4.60 & 10.95 & 68.83 & 9 & 1.36 & 3.22 & 100 \\
5 & 4.25 & 10.11 & 78.94 & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Principal component characteristic values, contribution rates, and cumulative contribution rates of volatile components of the Taishan black tea. Figure 6: Relative contents of the key volatile components. Despite the elevated levels of phenolic compounds, the sensory evaluation in this study indicated that more tea samples exhibited heavy and mellow tastes, with only a few tea samples displaying bitterness. This observation can be attributed to two factors. Firstly, free amino acids played a role in enhancing the freshness, mellowness, and thickness of the tea [22]. Secondly, caffeine formed complexes with the polyphenols, amino acids, catechins, chlorogenic acid, and other substances in the tea infusion, enhancing the bitterness and astringency while improving the freshness [23]. Additionally, the color of the bottom of the leaves revealed that partially brewed Taishan black tea leaves retained a greenish hue, suggesting incomplete fermentation of the fresh tea leaves. The low content of thearbbigins in the incompletely fermented black tea leaves resulted in a light and astringent tea soup [20]. This issue was further corroborated by the content of water extracts (Table 2) and the aroma description (Table S1). Aroma, a critical parameter for evaluating the overall quality of black tea, constitutes a significant focus in black tea quality improvement research. Previous studies have found that the tea cultivars, processing techniques, and environmental conditions could influence the aroma of black tea [24]. For example, the Xinyang black tea has a sugary honey-like aroma [24], Keemun black tea has a distinct rose aroma/Keemun aroma [25], Sichuan black tea has a sweet and citrus-like aroma [26], Guangdong black tea has a sweet and floral aroma [27], and Jinxuan (Oolong tea cultivar) black tea possesses a higher floral aroma [28]. In this study, the aroma of Taishan black tea was mainly fruity, followed by a caramel, sweet aroma, with a strong and enduring fragrance. Due to the intricate nature of aromas, a single aromatic property falls short in adequately expressing the contribution of all components [29].