Comparison of Potent Odorants in Raw and Ripened Pu-Erh Tea Infusions Based on Odor Activity Value Calculation and Multivariate Analysis: Understanding the Role of Pile Fermentation

Abstract

Infusions prepared from raw pu-erh tea (RAPT) and ripened pu-erh tea (RIPT) showed remarkable aroma differences. Predominant odorants in RAPT and RIPT infusions were identified and compared by the combined use of gas chromatography–olfactometry, aroma extract dilution analysis, odor activity values (OAVs), and multivariate analysis. A total of 35 and 19 odorants (OAV > 1) were detected in RIPT and RAPT, respectively. Odorants in RAPT and RIPT are significantly different in both odor properties and aroma compound intensities. Overall, RAPT contained a complex variety of chemical classes with diverse odors and moderate odor intensities, while RIPT is dominated by structurally and organoleptically similar compounds with high potency. Specifically, stale and musty smelling methoxybenzenes contributed the most to RIPT, while floral-, sweet-, and woody-smelling terpene alcohols, terpene ketones, and phenolic compounds were the predominant odorants in RAPT. Orthogonal partial least squares discriminant analysis revealed that linalool, α-ionone, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxy-5-methylbenzene, 1,2,3,4-tetramethoxybenzene, and 1,2,3-trimethoxybenzene underwent remarkable changes during pile fermentation and could be used as potential odor-active markers for RIPT and RAPT discrimination. The comprehensive aroma characterization of pu-erh tea and determination of the effect of pile fermentation on odorant alteration herein will provide guidance for pu-erh tea flavor quality control and evaluation.

Identification of volatile components and analysis of aroma characteristics of Jiangxi Congou black tea

“…The roasted tea is generally formed, released and accumulated in the process of drying or enhancing aroma, which can improve the aroma quality of tea to a certain extent. [21] According to the analysis, in addition to the heterocyclic compounds that were furaneol and methyl-pyrazine, which were roasted, were positively correlated to roasted, the compounds with green or fresh, such as 1-hexanol, linalool, orcinol, ((Z)-2-penten-1-ol and (Z)-3-hexen-1-ol, were positively correlated with it. In the correlation analysis of sensory attributes of QDA (Table S2), it was also found that green and roasted, which were opposite to each other, appeared up in the same tea, and had a certain positive correlation.…”

“…It is common in flavor characteristics for dark tea, and rarely found in black tea. [20,21] In the sample of this study, No. 3, No.…”

Region identification of Xinyang Maojian tea using UHPLC‐Q‐TOF/MS‐based metabolomics coupled with multivariate statistical analyses

“…Recently, HPLC (Rahim et al., 2014; Zhang et al., 2013), LC‐MS (Zhao et al., 2019; Zhou et al., 2020), GC‐MS (Pang et al., 2019), electronic tongue (E‐tongue) (Hou et al., 2014), and electronic nose (E‐nose) (Yang et al., 2018) have been developed to determine nonvolatile and volatile components in tea, or carry out for the quality evaluation. Particularly, LC‐MS/MS metabolomics based on ultra‐high performance liquid chromatography‐quadrupole time of flight‐mass spectrometry (UHPLC‐Q‐TOF/MS) method coupled with multivariate statistical analyses, such as principal component analysis (PCA), orthogonal projection to latent structures discriminate analysis (OPLS‐DA), and hierarchical cluster analysis (HCA), have become a potent tool in distinguishing production place, storage environment and processing technologies of tea (Long et al., 2020; Ma et al, 2021; Wang et al., 2018; Zhou et al., 2019;).…”

Characterization and Quantitative Comparison of Key Aroma Volatiles in Fresh and 1-Year-Stored Keemun Black Tea Infusions: Insights to Aroma Transformation during Storage

“…In addition, (E)-2-nonenal, frequently detected in various teas through GC-O, contributed slightly to both KBT aromas, with OAVs of 2 and 1 in the FKBT and 1Y-KBT infusions, respectively. Although dihydroactinidiolide was reported to be an aroma volatile in several teas [ 3 , 25 , 26 ], we did not perceive its aroma. However, the concentration of dihydroactinidiolide in the FKBT infusion was only 60% of that in the 1Y-KBT infusion according to standard addition, supporting our previous conclusion that dihydroactinidiolide was a reliable indicator of storage duration.…”