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. 2024 Dec 24;14(1):4.
doi: 10.3390/foods14010004.

Differences in the Quality Components of Wuyi Rock Tea and Huizhou Rock Tea

Zhaobao Wu  1 , Weiwen Liao  1 , Hongbo Zhao  1 , Zihao Qiu  1 , Peng Zheng  1 , Yuxuan Liu  1 , Xinyuan Lin  1 , Jiyuan Yao  1 , Ansheng Li  1 , Xindong Tan  1 , Binmei Sun  1 , Hui Meng  1 , Shaoqun Liu  1
Affiliations

Differences in the Quality Components of Wuyi Rock Tea and Huizhou Rock Tea

Zhaobao Wu et al. Foods. .

Abstract

Different origins and qualities can lead to differences in the taste and aroma of tea; however, the impacts of origin and quality on the taste and aroma characteristics of Wuyi rock tea and Huizhou rock tea have rarely been studied. In this study, high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and sensory evaluation methods were used to compare the quality components of Wuyi rock tea and Huizhou rock tea. The sensory evaluation showed that they each have their own characteristics, but the overall acceptability of Wuyi rock tea is ahead of Huizhou rock tea (p < 0.01). Biochemical experiments showed that HT was the highest in water leachables, about 43.12%; WT was the highest in tea polyphenols, about 14.91%; WR was the highest in free amino acids, about 3.38%; and the six rock teas had different health benefits. High-performance liquid chromatography showed that the theanine contents of WS and WR were 0.183% and 0.103%, respectively, which were much higher than those of other varieties. The OPLS-DA model predicted the factors that caused their different tastes, in order of contribution: CG > ECG > caffeine > EGCG > theanine. Ten volatile substances with OAV ≥ 1 and VIP > 1 were also found, indicating that they contributed greatly to the aroma characteristics, especially hexanoic acid, hexyl ester, and benzyl nitrile. The results of the correlation analysis showed that theanine was significantly correlated with taste (p < 0.05), and hexanoic acid, hexyl ester, and benzyl nitrile were significantly correlated with smell (p < 0.05). Substances such as theanine, hexanoic acid, hexyl ester, and benzyl nitrile give them their unique characteristics. Analysis of the differences in the quality components of the six rock teas can provide reference value for the cultivation and processing of rock teas.

Keywords: GC–MS; HPLC; OAV; components; quality; rock tea.

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Conflict of interest statement

There is no conflict of interest to declare.

Figures

Figure 1
Figure 1
Production process flow chart for 6 kinds of rock tea.
Figure 2
Figure 2
Basic biochemical experiments determined the content of six indicators of six types of rock tea, and the content is expressed as the average value (%) ± standard deviation (n = 3). Significant differences are marked according to one-way ANOVA and Tukey’s post hoc test (* p < 0.05; ** p < 0.01). (A-1) Water content of 6 kinds of rock tea. (A-2) Water leachables content of 6 kinds of rock tea. (A-3) Soluble sugars content of 6 kinds of rock tea. (A-4) Free amino acids content of 6 kinds of rock tea. (A-5) Tea polyphenols content of 6 kinds of rock tea. (A-6) Phenol-to-amino acid ratio of 6 kinds of rock tea.
Figure 3
Figure 3
The contents of caffeine, theanine, catechins, and their monomers in the six rock teas were determined using high-performance liquid chromatography (HPLC), and the content is expressed as the mean value (%) ± standard deviation (n = 3). Significant differences are marked according to one-way ANOVA and Tukey’s post hoc test (* p < 0.05; ** p < 0.01). (A-1) Caffeine content of 6 kinds of rock tea. (A-2) Theanine content of 6 kinds of rock tea. (A-3) Catechins content of 6 kinds of rock tea. (A-4) GA content of 6 kinds of rock tea. (A-5) GC content of 6 kinds of rock tea. (A-6) EGC content of 6 kinds of rock tea. (A-7) C content of 6 kinds of rock tea. (A-8) EC content of 6 kinds of rock tea. (A-9) EGCG content of 6 kinds of rock tea. (A-10) GCG content of 6 kinds of rock tea. (A-11) ECG content of 6 kinds of rock tea. (A-12) CG content of 6 kinds of rock tea.
Figure 4
Figure 4
(A) OPLS-DA score plot. (B) Cross-validation model: 200-fold cross-validation model results: R2 = 0.26, Q2 = −1.04, indicating that the OPLS-DA discriminant model is not overfitted and the model is relatively reliable. (C) VIP score plot; yellow bars represent non-volatile compounds with VIP > 1; purple bars represent non-volatile compounds with VIP < 1.
Figure 5
Figure 5
(A) Volatile substance stacking chart of 6 rock teas. (B) Volatile substance Venn diagram of 6 rock teas. (C) Heat map of 23 common volatile substances.
Figure 6
Figure 6
(A) OPLS-DA score plot. (B) Cross-validation model: 200-fold cross-validation model results: R2 = 0.398, Q2 = −0.935, indicating that the OPLS-DA discriminant model is not overfitted and the model is relatively reliable. (C) VIP score plot, with yellow bars representing volatile compounds with VIP > 1 and purple bars representing volatile compounds with VIP < 1. (D) Heat map of the 10 important volatile compounds.
Figure 7
Figure 7
(A) Radar chart of the sensory evaluation results of 6 rock teas; (B) overall acceptability chart of the sensory evaluation of 6 rock teas (** p < 0.01); (C) tea infusion chart of 6 rock teas.
Figure 8
Figure 8
(A) Correlation analysis chart of the taste of the six rock teas and key non-volatile substances. (B) Correlation analysis chart of the odor of the six rock teas and key volatile substances (* p < 0.05; ** p < 0.01).
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