Metabolomics Based on UHPLC-Orbitrap-MS and Global Natural Product Social Molecular Networking Reveals Effects of Time Scale and Environment of Storage on the Metabolites and Taste Quality of Raw Pu-erh Tea

Abstract

Raw Pu-erh tea (RPT) needs ageing before drinking. However, the influence from environment and time of storage on chemical profile and flavor of RPT is unclear. In this study, the RPTs stored in wet-hot or dry-cold environment for 1−9 years were assessed using metabolomics based on UHPLC-Orbitrap-MS and global natural product social (GNPS) featurebased molecular networking as well as electronic tongue measurement. The results exhibited that the chemical profiles of RPTs were similar at an early stage but started to differentiate from each other at the 5th and the 7th year in wet-hot and dry-cold environments. The discriminating features including N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (flavoalkaloids), unsaturated fatty acids, lysophosphatidylcholines, flavan-3-ols, amino acids, and flavonol-O-glycosides among the three chemical profiles were discovered and analyzed by means of multivariate statistics, GNPS multilibraries matching, and SIRIUS calculation. The metabolomic data were consistent with the results obtained through electronic tongue measurement.

Pu-erh tea: Fermentative process as a potentialized of sensory aspects and bioactive profile – a review

“…The search for Pu-erh tea with high quality (aged) is intensified, which requires analysis of the products storage time, since they have higher prices when compared to freshly produced tea (Yang et al, 2021). Sensory techniques are applied to assess the effect of Pu-erh tea storage time through trained judges who explore the five sense organs to assess perceived attributes (Zhou et al, 2020b) in addition to the use of conventional detection methods such as chromatography (Xie et al, 2009;Xu et al, 2019) and near-infrared spectroscopy (NIR) (Liu et al, 2018). Xu et al (2019) studied studied the effect of the storage period in dry and cold, humid and hot environments through sensory analysis, determining that a large part of the flavoring compounds in Pu-erh tea leaves remain stable in dry and cold environments, claiming that this condition allows to maintain the original flavor of the product, when compared to those exposed to storage in humid and hot environments.…”

Quality chemical analysis of crush–tear–curl (CTC) black tea from different geographical regions based on UHPLC‐Orbitrap‐MS

“…At present, many detection techniques are applied to tea‐quality analysis, such as nuclear magnetic resonance (Lee et al., 2015), liquid chromatography‐mass spectrometry (Xu et al., 2015), and gas chromatography‐mass spectrometry (Wu et al., 2019). However, ultrahigh performance liquid chromatography‐Orbitrap‐mass spectroscopy (UHPLC‐Orbitrap‐MS) has the advantages of higher sensitivity, high flexibility, and a wide detection range (Xu et al., 2019). UHPLC‐Orbitrap‐MS is a critical technique for monitoring and identifying potential key markers of tea quality.…”

“…Moreover, taste characteristic is an important method for evaluating tea quality. Compared with traditional sensory evaluation methods and equivalent quantitative methods to detect the taste characteristics of tea (Yu et al., 2008), the electronic tongue (e‐tongue) has the advantages of being more scientific, fast, and repeatable (M. Xu et al., 2019; S. Xu et al., 2019). However, these methods have not been applied to the taste characteristic analysis of CTC black tea.…”

Rapid characterization of the volatile profiles in Pu‐erh tea by gas phase electronic nose and microchamber/thermal extractor combined with TD‐GC‐MS

“…The unique method of Pu-erh tea fermentation is involved microorganisms that enter the fermentation process as a natural flora (Lin et al, 2021). According to the fermentation level, Pu-erh tea is classified into two groups, including raw Pu-erh tea and ripened Pu-erh tea (S. Xu et al, 2019). In recent years, the ripened Pu-erh tea is being increasingly favored by consumers due to its multiple health-promoting properties, and therefore its market demand has been expanded greatly (H.-p. Lv et al, 2013).…”