Abstract
The quality of tea is presently evaluated by the sensory assessment of professional tea tasters, however, this approach is both inconsistent and inaccurate. A more standardized and efficient method is urgently needed to objectively evaluate tea quality. In this study, the chemical fingerprint of 7 different Dayi Pu-erh tea brands and 3 different Ya'an tea brands on the market were analyzed using fully automatic headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS). A total of 78 volatiles were separated, among 75 volatiles were identified by GC–MS in seven Dayi Pu-erh teas, and the major chemical components included methoxyphenolic compounds, hydrocarbons, and alcohol compounds, such as 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, 2,6,10,14-tetramethyl-pentadecane, linalool and its oxides, α-terpineol, and phytol. The overlapping ratio of peaks (ORP) of the chromatogram in the seven Dayi Pu-erh tea samples was greater than 89.55%, whereas the ORP of Ya'an tea samples was less than 79.10%. The similarity and differences of the Dayi Pu-erh tea samples were also characterized using correlation coefficient similarity and principal component analysis (PCA). The results showed that the correlation coefficient of similarity of the seven Dayi Pu-erh tea samples was greater than 0.820 and was gathered in a specific area, which showed that samples from different brands were basically the same, despite have some slightly differences of chemical indexes was found. These results showed that the GC-MS fingerprint combined with the PCA approach can be used as an effective tool for the quality assessment and control of Pu-erh tea.
Highlights
Tea (Camellia sinensis) is a popular drink consumed by two-thirds of the world’s population
The results showed that similarities of all D1 samples were more than 0.989, and the relative standard deviation (RSD) values of the relative retention times and relative peak areas of volatile constituents were less than 0.2% and 8%, indicating a satisfactory repeatability of the developed method
With the same extraction conditions, the stability was determined by performing headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrometry (GC–MS) experiments on the same D1 sample at 0, 4, 8, 16, 24, 48 h, respectively
Summary
Tea (Camellia sinensis) is a popular drink consumed by two-thirds of the world’s population. The classification and evaluation of tea quality are mainly performed by trained experts who have developed a unique language to describe the various quality attributes of a tea infusion This evaluation method is inconsistent in differentiating tea quality due to various factors, including individual variability and decreased sensitivity due to prolonged exposure, fatigue, stress, etc. The taste and aroma of tea infusion are affected by many factors, such as production area, variety, cultivation techniques, picking seasons, manufacturing processes, and storage conditions [5, 6]. These factors make it very difficult for manufacturers to maintain consistent tea quality. With the recent development of the tea industry, determining a method to overcome these challenges has become more urgent than ever
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