Quality Characteristics of Oolong Tea Products in Different Regions and the Contribution of Thirteen Phytochemical Components to Its Taste

Abstract

Regionality is a term used in the tea industry to describe the particular style of tea produced by a growing region. Determining the characteristics of the tea of specific regions can help growers predict tea plant quality before harvesting and eventually production. As such, in this study, we collected representative Oolong tea samples from 15 regions in 8 countries. Quantitative description analysis (QDA) and a flavor wheel were used to analyze their sensory characteristics. Chemometrics was used to screen the phytochemical components that significantly contribute to the taste of Oolong tea. We preliminarily obtained 35 sensory characteristic descriptors and constructed a flavor wheel for Oolong tea. We found that Oolong tea in each region has unique sensory quality characteristics. The content of thirteen phytochemical components of Oolong tea in different regions widely varied, and the average coefficient of variation was 45.56%. Among of them, we found the largest difference in free amino acids. We identified the relationship between taste sub-attributes, and the thirteen phytochemical components was found through correlation analysis. Finally, we selected phytochemical components with significant effects on five taste sub-attributes that were selected from the thirteen detected phytochemical components. The construction of the Oolong tea flavor wheel can help realize the qualitative and quantitative sensory evaluation of Oolong tea from different origins and contribute to the quality identification and directional improvement of Oolong tea products.

Untargeted Metabolomics and Transcriptomics Reveal the Mechanism of Metabolite Differences in Spring Tender Shoots of Tea Plants of Different Ages

“…Flavonoids belong to phenols, which are mainly bitter and astringent, while free amino acids are mainly umami and sweet [ 10 ]. Therefore, within a moderate range, a low content of flavonoids and other phenolic compounds and a high content of free amino acids in tea tender shoots are the material basis for making high-quality tea [ 14 ]. According to the results of the biochemical components analysis and total metabolic spectrum, GC-40 was found to still have the material basis for making high-quality tea because the contents of flavonoids and free amino acids were upregulated.…”

“…The quality-related metabolites in the tender shoots of tea plants mainly include catechins, flavonoids and their glycosides, amino acids, alkaloids, nucleotides, saccharides, and organic acids [ 12 , 13 ]. Catechins, flavonoids and their glycosides, and alkaloids are mainly bitter and astringent, while amino acids, nucleotides, and saccharides are mainly umami and sweet [ 14 ]. If the content of metabolites with umami and sweet tastes in the tender shoots is high and the content of metabolites with bitter and astringent tastes is low, higher-quality tea products can be made with these raw materials [ 8 , 15 ].…”

Widely Targeted Metabolomics Analysis Reveals the Differences of Nonvolatile Compounds in Oolong Tea in Different Production Areas

“…Southern Fujian’s Oolong tea is mainly Tieguanyin, Northern Fujian’s Oolong tea is mainly Wuyi rock tea, and Guangdong’s Oolong tea is mainly Fenghuang Dancong tea [ 3 ]. Previous studies on the quality characteristics of Oolong tea from these three producing areas found that each had its own characteristics, but there was no quantitative evaluation of taste [ 6 , 23 ]. In this study, the quantitative taste evaluation was carried out to further clarify the taste differences of Oolong tea in the three production areas.…”

“…[ 5 ]. The flavor formation of Oolong tea is affected by the variety, producing areas, processing technology, season, and picking method [ 6 ]. For example, different Oolong tea cultivars have different “cultivar fragrances” [ 3 ].…”

Differential characterization of volatile components and aroma sensory properties of different types of Hehong tea (Congou black tea)

“…OPLS‐DA provides a supervised classification that can be used to distinguish between different sample species and extract differential information 27 . To investigate the differences in the volatile components among the three types of Hehong tea and distinguish them, OPLS‐DA modelling analysis was conducted on all detected compounds, and we found that the model effectively divided the three types of Hehong tea (Figure 2A).…”