In this study, 39 tea tree varieties from the same plantation were employed, and their fresh spring and summer leaves were harvested and processed into broken black tea (BBT) using a standardized manufacturing process. The sensory quality and major physicochemical indicators were examined, and their correlations were analyzed. The quality differences between BBT produced from spring and summer raw materials from different varieties were clarified using multivariate statistical analysis. The results indicated that different varieties and seasons significantly impacted the quality of BBT. The sensory evaluation scores of BBT in spring (82.2-92.7 points, averaging 88 points) were generally higher than those in summer (81.1-91.2 points, averaging 87 points). The coefficients of variation for color, aroma, taste, and overall scores were higher in spring tea than in summer tea, indicating that the inter-varietal variation in BBT quality was greater in spring than in summer. Spring BBT exhibited higher average contents of tea polyphenols, theaflavins, thearubigins, and amino acids compared with summer BBT, while the opposite was observed for theabrownins and soluble sugars. Correlation analysis revealed that a significant positive correlation between tea polyphenol content and sensory quality was observed for both spring and summer tea. In contrast, the sensory quality of spring and summer BBT exhibited a negative correlation with the contents of soluble sugars and amino acids, respectively. A comprehensive evaluation system was developed using principal component analysis (PCA) and multiple regression analysis (MRA) to classify the tea varieties into three categories based on their BBT processing suitability: suitable for both spring and summer (e.g., Enchahong and Jiukengzao), season-dependent (e.g., Meizhan and Huangdan), and poorly suitable (e.g., Longjing 43, Baiye 1, and Fuyun 6). These findings provide a theoretical basis and practical guidance for variety selection and seasonal matching in BBT production.

To investigate the characteristics of quality formation of Simian tea, the non-volatile components, mineral elements and filamentary structure of fresh leaves from different positions of ‘Simian Tucha’ tea plants, endemic to Zigui, were analyzed using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), and scanning electron microscopy (SEM). The results showed that the non-volatile components were more abundant in the leaves with higher tenderness, with amino acids, alkaloids, catechins, and aroma glycosides being mainly concentrated in the first (L1) and second leaves (L2). Theanine, organic acids, and flavonoids were mainly concentrated in the third leaf (L3), while the content of non-volatile components in the older leaves was relatively lower. The accumulation of mineral elements greatly varied among tea leaves with different tenderness. The contents of nitrogen, phosphorus, potassium, zinc, and copper in L1 (32.41 mg/g, 4.53 mg/g, 15.65 mg/g, 45.45 μg/g, and 10.75 μg/g, respectively) and L2 (30.60 mg/g, 3.70 mg/g, 14.12 mg/g, 35.82 μg/g, 9.02 μg/g, respectively) were higher than those in older leaves. The contents of iron, manganese, and calcium were higher in mature leaves. Through SEM observation, it was found that the filamentary structure of Simian tea leaves consisted of two forms, triple-stranded coil and single-stranded coil, and was distributed in the internal thread or ringed vessels of the xylem in the vascular bundles in the midvein and lateral veins, and the number of filamentary structures was higher in the second, third and fourth leaves than that in buds and L1.

Matcha was prepared from 36 tea cultivars grown in the same tea garden according to the shading requirements for fresh leaves to be used for the production of matcha and its 11 quality indexes such as sensory quality, major physicochemical properties and chroma values were analyzed. In order to select tea cultivars suitable for the manufacturing of matcha, a comprehensive evaluation model of matcha quality was established by cluster analysis (CA), principal component analysis (PCA) and multiple linear regression analysis. The CA results showed that the 36 cultivars could be divided into three groups. Matcha from group Ⅰ had the best quality with green color, fresh and mellow taste, and low phenol/ammonia ratio. Matcha from group Ⅱ had high phenol/ammonia ratio and strong astringent taste. Matcha from Group Ⅲ, consisting of etiolated and albino cultivars, had poor color and aroma quality. The PCA results showed that the cumulative contribution rate of the first five principal components was 88.152%. Comprehensive evaluation of matcha using the evaluation function constructed based on the first five principal components showed that the top 10 cultivars were Zhongcha 102, Taicha 12, Zhongcha 108, Fuding Dahao, Meizhan, Fuding Dabai, Fuyun 6, Zi Mudan, Maolv and Yingshuang. The model describing the relationship between sensory quality and physicochemical properties established by multiple linear regression analysis was as follows: y = 3.167|a*| + 46.850 (R² = 0.710, P < 0.001). The scores of matcha cultivars evaluated by this model were highly consistent with the comprehensive evaluation results based on principal components, indicating that the a* value of dried tea could be used as a representative index to evaluate the quality of matcha. The results of this study can provide a reference for evaluating the suitability of tea cultivars for matcha manufacturing.

Principal component analysis (PCA) and multiple linear regression analysis (MLRA) were used to analyze and investigate the suitability of green tea for tea tree varieties in different tea cultivars. The fresh leaves of 63 tea cultivars planted in the same garden were processed into roasted green tea by the same method. The sensory and major physicochemical qualities (tea polyphenols, free amino acids, water extracts and chlorophyll) and the color (L*, a* and b*) of green tea were analyzed. To evaluate the suitability of the tested cultivars for green tea processing and its major influential factors, the data obtained were analyzed by PCA and MLRA. The results showed that the coefficient of variation (CV) of chlorophyll content in different cultivars was the highest (26.7%), followed by tea a* value (22.2%), sensory score for tea infusion color (17.1%) and sensory score for tea color (16.2%). A significant correlation was found between the polyphenol content of green tea and its color, tea infusion color and the color of infused tea leaves; between the chlorophyll content, |a*| and b* values of green tea and its color; between the chlorophyll content and |a*| value of green tea and the color of infused tea leaves; and between the |a*| and b* values of green tea and tea infusion color (P < 0.01). The PCA results showed that the contribution rate of the first five principal components (PCs) was 76.895%, and that of the first principal component was 31.918%, mainly pointing to the color quality. According to the evaluation model constructed based on the first five PCs, the top 10 cultivars were Zhongcha 108, Wuniuzao, Pingyangtezao, Mengshan 9, Soubeizhong, Fudingdabai, Jiukeng 16, Fudingdahao, Maolv, and Longjing 43. Using MLRA, the regression function between overall sensory score (Y) and |a*| value (x) was obtained as Y = 68.668 + 5.174x (R² = 0.313) (P < 0.001). The top 10 varieties determined from this equation were highly consistent with the results of PCA, indicating that a* value is an important indicator for the evaluation of the suitability of tea cultivars for green tea processing.

To investigate the effects of tea varieties on the quality of Enshi Yulu tea, 10 main tea cultivars (Fuyun 6, Echa 1, Chunbolü, Zhenong 117, Longjing 43, Wuniuzao, Zhongcha 108, Echa 10, Zhuyeqi, and Fuding Dabai) grown in Enshi were processed into Yulu tea, which was then evaluated for sensory quality, major physicochemical quality components (tea polyphenols, free amino acids, water extracts, and chlorophylls), dry tea color parameters (L^*, a^*, and b^*), and volatile components. The results showed that Yulu teas made from different cultivars had their own characteristics. Among the 10 teas, Fuyun 6 had the highest sensory score for appearance with a tight and straight shape and a green color. Echa 1 and Chunbolü had the best mellow and fresh taste. Zhenong 117 had a high and long-lasting chestnut-like aroma with the highest sensory score for aroma. Chemical composition analysis showed that the phenolic/ammonia ratio of each tea was lower than 5, with Fuyun 6 having the lowest value, but not significantly different from Longjing 43. Wuniuzao had the highest soluble sugar content, while Fuyun 6 had the lowest value. Echa 1 had the highest total amount of catechins, followed by Echa 10 and Zhenong 117, while Zhongcha 108 and Wuniuzao had the lowest value. Chunbolü and Echa 1 had the highest ratio of lutein to chlorophyll a plus b, while Longjing 43 had the lowest level. Overall, Longjing 43, Chunbolü and Wuniuzao Yulu teas had better sensory and physicochemical qualities. A total of 98 aroma components were detected in the 10 Yulu teas using headspace solid-phase microextraction (HS-SPME), including 22 alcohols, 13 hydrocarbons, 15 aldehydes, 14 olefins, 16 esters, 6 ketones, 3 halogenated hydrocarbons, 2 phenolic compounds, 1 ether compound, and 6 heterocyclic compounds. Among them, alcohols were the most abundant. Analysis of relative odor activity values (rOAV) revealed that linalool, phenylethanol, geraniol, jasmine, trans-β-ionone and nonanal were the major contributors to the characteristic aroma of the 10 Yulu teas. Totally 17 key differential aroma components among these teas were identified, including benzyl alcohol, linalool, phenylethanol, geraniol, benzaldehyde and nonanal.

In order to diversify green brick tea products and integrate the health benefits of persimmon leaf tea and green brick tea, a high-vitamin C persimmon leaf green brick tea tablet was developed. This study used persimmon leaf tea extract and green brick tea extract as raw materials to investigate the effects of different extraction conditions on the components of persimmon leaf and the impact of various tablet formulations on the quality of tea tablets. The results showed that the optimal extraction conditions involved using distilled water at 70°C for 60 minutes with one extraction, yielding an extract with a vitamin C content of 3.56%, polyphenol content of 7.05%, and water extract content of 31.32% . The optimal blending ratio for the tablets was a 2:8 of green brick tea extract to persimmon leaf extract, resulting in a vitamin C content of 7.18 mg/g and a polyphenol content of 17.88 mg/g in the tablets.