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Shaken Hunan black tea is an innovative Hunan black tea processed by adding shaking to the traditional Hunan black tea. The quality of shaken black tea is influenced by leaf grades of different maturity. In this study, the taste and aroma quality of shaken Hunan black tea processed with different grades were analyzed by sensory evaluation (SP, HPLC, and HS-SPME/GC-MS). The results showed that shaken Hunan black tea processed with one bud and two leaves has the best quality, which has a sweet, mellow, and slightly floral taste, as well as a floral, honey, and sweet aroma. Moreover, caffeine and EGCG were identified as the most important bitter and astringent substances in shaken Hunan black. Combined with the analysis of GC-MS and OAV analysis, geraniol, jasmone, β-myrcene, citral, and trans-β-ocimene might be the most important components that affect the sweet aroma, while methyl jasmonate, indole, and nerolidol were the key components that affect the floral aroma of shaken Hunan black tea. This study lays a foundation for this study of the taste and aroma characteristics of shaken Hunan black tea and guides enterprises to improve shaken black tea processing technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shaking in the early withering stage is a key process effecting the floral aroma of Hunan black tea. • Volatile compounds of dry tea, tea infusion and infused leaf of Hunan black tea were systematically analyzed. • A total of 81 differentially volatile compounds were identified in Hunan black teas. • Indole and methyl jasmonate were identified as key floral aroma compounds in Shaking Hunan black tea. Shaking is a key process effecting the floral aroma of Hunan black tea (HBT). In this study, the aroma composition of HBTs shaken in the early withering stage (ES1, ES1 + LS1, and ES2), shaken in the late withering stage (LS1), and not shaken (NS), and the identification of main floral aroma compounds were analyzed using sensory evaluation combined with gas chromatography-mass spectrometry (GC–MS), gas chromatography–olfactometry (GC-O), and aroma recombination experiments. Sensory evaluation results showed that the floral aroma of HBT shaken in the early withering stage was with high intensity, whereas HBT shaken in the late withering stage had low-intensity floral aroma. GC–MS identified a total number of 81 differential volatile compounds in HBT, including 30 esters, 18 aldehydes, 15 alcohols, 12 terpenes, 4 ketones, and 2 nitrogen-containing compounds. Further screening of important floral aroma differential compounds was performed using sensory-guided, odor activity value (OAV), and GC-O analysis, which identified three critical floral aroma differential compounds. Eventually, absolute quantification analysis and aroma recombination experiments confirmed that indole and methyl jasmonate were the most critical compounds of HBT determining floral aroma intensity. The findings of this study provide valuable guidance for the production of HBT with rich floral aroma attributes. [ABSTRACT FROM AUTHOR]

Hunan black tea is well-known for its floral-honey aroma, but the volatile components responsible for the fragrance have not been elucidated yet. In this study, the volatile compounds in Hunan black tea were identified and quantified by the headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that 88 compounds were extracted and determined in Hunan black tea, including the dominant components Geraniol, phenethyl alcohol, phenylacetaldehyde, linalool, nonanal and other 5 aromatic compounds. Furthermore, the aroma-active compounds were identified by odor activity value (OAV). It was found that 24 aroma compounds, including geraniol with an OAV≥1 were regarded as the primary active aromatic compounds in Hunan black tea. Finally, partial least squares (PLS) regression analysis was employed and results revealed that Nonanal, trans -nerolidol, benzyl alcohol, and phenylethanol exhibit a positive correlation with the intensity of floral and sweet honey aromas. Overall, this study identified the volatile compounds responsible for the dominant floral-honey aroma in Hunan black tea. • Evaluation, screening, and ranking the floral-honey aroma in Hunan black teas by sensory analysis. • 88 compounds were extracted and determined in Hunan black tea. • Hunan black tea aroma dominated by 10 aromatic compounds. • 24 aroma substances were considered to be the primary active aromatic compounds. • Internal standards coupled with external standards were used to accurately quantify the content. [ABSTRACT FROM AUTHOR]