Process white tea characteristic marker and application thereof

Abstract

This invention discloses a characteristic marker for processed white tea and its application, belonging to the technical field of tea quality control and chemical marker identification. This invention is the first to screen and identify characteristic markers for processed white tea from tea leaves, and then uses liquid chromatography-mass spectrometry (LC-MS) for stable identification of white tea. Using the characteristic markers for processed white tea of ​​this invention for identification offers high accuracy and repeatability, making it suitable for standardized and batch analysis; it can also effectively distinguish white tea from non-white tea; and it can be widely applied in research institutions, testing institutions, tea companies, and market supervision for white tea quality control and classification evaluation.

Description

Technical Field

[0001] This invention relates to a characteristic marker for processed white tea and its application, belonging to the technical field of tea quality control and chemical marker identification. Background Technology

[0002] Based on different processing techniques and quality characteristics, tea can be divided into six major categories: green tea, black tea, white tea, yellow tea, dark tea, and oolong tea. Among them, white tea is a lightly fermented tea, and according to the tenderness of the fresh leaves picked, it can be divided into different varieties such as Silver Needle (single bud), White Peony (one bud and one or two leaves), Shoumei, and Gongmei (one bud and three or more leaves or only leaves). It is highly favored by consumers for its unique "fragrant and honey-like" quality and good health benefits. With the expansion of the white tea consumption market, the demand for identifying the authenticity of white tea products, determining their tea category, and evaluating their quality is increasing.

[0003] Currently, the main methods for identifying white tea include sensory evaluation, routine physicochemical index testing, and multivariate statistical analysis. Sensory evaluation relies primarily on the sensory assessment of professional evaluators, involving qualitative judgment based on observation of tea appearance, liquor color, infused leaves, and aroma. However, this method is inherently subjective and lacks repeatability, being significantly influenced by factors such as evaluator experience, environmental humidity, and olfactory fatigue, making it difficult to provide objective and quantifiable criteria. Routine physicochemical indicators, such as total polyphenols, amino acids, and caffeine, overlap to some extent among different tea types, making it difficult to meet the requirements for accurate identification. While multivariate statistical analysis (principal component analysis, HCA, discriminant analysis, etc.) can improve classification capabilities, it often relies on complex models and large sample training, hindering the development of simple, stable, and easily scalable technical solutions.

[0004] Current technologies primarily focus on differentiating processing techniques within the same tea variety and determining the origin and aging years of white tea. There is currently a lack of a highly specific, easy-to-use, and reliable method for distinguishing white tea from other tea types. In particular, the potential of characteristic secondary metabolites present in white tea as diagnostic markers has not been fully explored.

[0005] Therefore, developing a technical solution that can achieve rapid identification based on a single or a few characteristic compounds without complex modeling has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] [Technical Issues] The chemical identification of white tea lacks specific markers.

[0007] [Technical Solution] To address the aforementioned problems, this invention provides a characteristic marker for processed white tea and its application. Specifically, this invention is the first to screen and identify characteristic markers for processed white tea from tea leaves, and then uses liquid chromatography-mass spectrometry (LC-MS) for detection to achieve stable identification of white tea. Using the characteristic markers for processed white tea of ​​this invention for identification offers high accuracy and repeatability, making it suitable for standardized and batch analysis; it can effectively distinguish white tea from non-white tea; and it can be widely applied in research institutions, testing institutions, tea companies, and market supervision for quality control and classification evaluation.

[0008] The first objective of this invention is to provide a characteristic marker for processed white tea, which has the following characteristics in liquid chromatography-mass spectrometry analysis: (1) The precursor ion [M+H]+ was detected at 485.10724 in the primary mass spectrometer; (2) The secondary mass spectrometer contains at least one or more characteristic fragments of m / z 139, 153, 165, and 177; (3) The molecular formula of the marker is C 24 H 20 O 11 .

[0009] In one embodiment of the present invention, its structure is analyzed based on mass spectrometry data, and its structural formula is obtained as follows:

[0010] The second objective of this invention is to provide a method for identifying white tea based on characteristic markers of processed white tea, comprising the following steps: (1) Extract the tea sample to be tested, centrifuge, and take the supernatant to obtain the sample solution to be tested; (2) The sample solution was detected by liquid chromatography-mass spectrometry to obtain primary mass spectrometry information and secondary mass spectrometry fragment information; (3) Extract the signal of the characteristic marker based on the mass spectrometry information and calculate the internal standard normalized response value of the characteristic marker; wherein, the internal standard normalized response value is the ratio of the peak area of ​​the characteristic marker to the peak area of ​​the internal standard. (4) Compare the test results. When the sample meets all of the following judgment conditions, the tea sample is judged to be white tea or has the characteristics of white tea: ① Primary mass spectrometry detected the precursor ion [M+H]. + 485.10724; ② At least one characteristic fragment with m / z 139, 153, 165, or 177 is present in the secondary mass spectrometer; ③ Compound C detected in the sample solution 24 H 20 O 11The internal standard normalized response value is not lower than a preset threshold; wherein, the preset threshold is set based on the known distribution of response values ​​of real white tea samples and non-white tea control samples, preferably more than 3 times the standard deviation of the mean response value of non-white tea control samples.

[0011] In one embodiment of the present invention, the tea sample to be tested in step (1) is one of the following: commercially available finished tea, loose tea, tea powder, tea extract, or tea-containing products.

[0012] In one embodiment of the present invention, the tea sample to be tested in step (1) is one or more of white tea, green tea, yellow tea, oolong tea, black tea and dark tea; white tea includes one or more of Baihao Yinzhen, Bai Mudan, Gongmei and Shoumei.

[0013] In one embodiment of the present invention, the tea sample to be tested in step (1) is a commercially available finished tea sample that has been freeze-dried and then ground into powder using a pulverizer.

[0014] In one embodiment of the present invention, the solvent used in step (1) is a mixed solution of a polar organic solvent and water, wherein the polar organic solvent is one or both of methanol and acetonitrile; preferably, the solvent used in the extraction is an aqueous methanol solution with a volume fraction of 50%-90%, and more preferably an aqueous methanol solution with a volume fraction of 70%.

[0015] In one embodiment of the present invention, the solvent used in step (1) needs to be pre-cooled; the pre-cooling temperature is 3-5°C.

[0016] In one embodiment of the present invention, the ratio of the amount of tea sample to be tested and the solvent used for extraction in step (1) is 50mg:600-1000μL, and more preferably 50mg:800μL.

[0017] In one embodiment of the present invention, the extraction in step (1) is carried out by vortexing at room temperature (15-35℃) for 20-40 seconds; ultrasonic extraction at 50-70Hz for 15-25 minutes; and vortexing once every 5-10 minutes.

[0018] In one embodiment of the present invention, the centrifugation in step (1) is performed at 3-5°C and 10,000-15,000g for 10-20 minutes; more preferably, it is performed at 4°C and 12,000g for 15 minutes.

[0019] In one embodiment of the present invention, the liquid chromatography-mass spectrometry technique in step (2) is ultra-high performance liquid chromatography-high resolution mass spectrometry; preferably, the liquid chromatography-mass spectrometry technique is UPLC-Q-Exactive high resolution combined mass spectrometry system Q-Exactive Focus Orbitrap System.

[0020] In one embodiment of the present invention, in step (2), the sample solution to be tested is diluted with an extraction reagent, then mixed with an internal standard, centrifuged, and the supernatant is placed into a sample vial.

[0021] In one embodiment of the present invention, the chromatography in step (2) uses a Hypersil Gold column; the mobile phase is: A is 0.075% formic acid water, and B is acetonitrile containing 0.075% formic acid; the gradient elution program is: 0-2 min, 5-40% B; 2-7 min, 40-80% B; 7-11 min, 80-95% B; 11-15 min, 95% B; the column temperature is 35℃, the flow rate is 0.3 mL / min, and the injection volume is 4 μL.

[0022] In one embodiment of the present invention, the mass spectrometer in step (2) uses a Q-Exactive Focus Orbitrap System; an electrospray ion source, positive ion detection mode, and a full scan mode for non-targeted analysis. The sheath gas flow rate is 45 arb, the auxiliary gas flow rate is 15 arb, the tail gas flow rate is 1 arb, the capillary temperature is 350℃, the capillary voltage is 3.8 kV, the lens RF energy level is 60%, the acquisition mass range is m / z: 50-1000, the resolution is 70000, and the fragmentation voltage is 20 V±50%.

[0023] In one embodiment of the present invention, the acquisition of secondary mass spectrometry fragment information in step (2) is performed using Fullscan-ddMS2 scanning mode with a fragmentation voltage of 30 V.

[0024] In one embodiment of the present invention, the preset threshold in step (4) is above 0.05, preferably 0.05.

[0025] The third objective of this invention is to apply the characteristic markers of processed white tea and the method for identifying white tea based on these characteristic markers to the distinction between white tea and non-white tea, the determination of the authenticity of white tea, the screening of white tea raw materials, the quality control of white tea products, the classification and evaluation of white tea, the construction of a database of tea metabolic markers, or the fields of tea market supervision and product traceability.

[0026] [Beneficial Effects] (1) This invention is the first to discover a characteristic compound that is significantly enriched in white tea and proves that it has stable differences among different types of tea; (2) This invention can accurately distinguish between white tea and non-white tea based on a single marker, without relying on complex statistical models; (3) The determination method proposed in this invention has good repeatability and cross-laboratory comparability; (4) The characteristic markers of the present invention have unexpected distribution characteristics and do not have the same discrimination ability in structurally similar objects; (5) Compared with existing detection methods that rely on standard comparison, the method of the present invention can distinguish white tea without the need for standard. It can complete the identification by relying only on mass spectrometry feature information and response value, which reduces the detection cost and improves the practicality and scalability of the method. Attached Figure Description

[0027] Figure 1 The structural analytical formula for the characteristic markers of processed white tea.

[0028] Figure 2 This is a secondary mass spectrometry image of characteristic markers for processed white tea.

[0029] Figure 3 This is a distribution map showing the content of characteristic markers of processed white tea in white tea and non-white tea. Detailed Implementation

[0030] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0031] Internal standard normalization method: In this invention, a fixed concentration of internal standard (DL-4-chlorophenylalanine, 0.3 mg / mL) was added to all sample detections, and the response values ​​of the characteristic markers were normalized with the peak area of ​​the internal standard.

[0032] The calculation formula is: Normalized response value of internal standard = Peak area of ​​characteristic marker / Peak area of ​​internal standard Internal standard normalization can effectively correct batch-to-batch fluctuations in sample pretreatment, injection volume, and instrument response, ensuring the reliability and repeatability of test results from different batches and at different times.

[0033] Raw materials used in the examples: All tea leaves used in the examples and comparative examples were commercially available.

[0034] Room temperature refers to 15-35℃.

[0035] Example 1: Discovery and structural identification of characteristic markers (1) Sample collection: A total of 126 samples of the six major tea categories (green tea, black tea, white tea, yellow tea, dark tea, and oolong tea) from different regions and grades were collected from the market, including some foreign tea samples. Among them, 40 samples were collected in 2017 and 86 samples were collected in 2018. The oolong tea samples included tea samples with different processing methods from northern and southern Fujian, and the yellow tea samples included yellow bud tea and yellow large tea. (2) Sample pretreatment After vacuum freeze-drying, the tea sample was ground into powder using a pulverizer. 50 mg ± 1 mg was accurately weighed into a centrifuge tube, and 800 μL of a 70% methanol aqueous solution pre-cooled to 4°C was added. The mixture was vortexed for 30 seconds. The sample was then extracted using ultrasonication at 60 Hz for 20 minutes, vortexing every 10 minutes. Afterward, the sample was centrifuged at 12000 g for 15 minutes at 4°C, and the supernatant was collected to obtain the test solution. (3) Detection method Take 50 μL of the sample solution to be tested, add 950 μL of 70% methanol aqueous solution pre-cooled to 4℃ for dilution, then add 10 μL of internal standard solution (DL-4-chlorophenylalanine methanol solution, concentration 0.3 mg / mL), vortex to mix, and centrifuge at 4℃ and 12000g for 15 min. Take 200 μL of the diluted solution into the sample vial.

[0036] Detection was performed using a liquid chromatography-high resolution mass spectrometry (LC-MS) system.

[0037] Chromatographic conditions: Hypersil Gold column; Mobile phase: A is an aqueous solution of formic acid with a volume fraction of 0.075%, and B is acetonitrile containing formic acid, with the volume fraction of formic acid in the acetonitrile being 0.075%. Gradient elution program: 0-2 min, 5-40% B; 2-7 min, 40-80% B; 7-11 min, 80-95% B; 11-15 min, 95% B; Column temperature: 35℃; Flow rate: 0.3 mL / min; Injection volume: 4 μL; Mass spectrometry conditions: Q-Exactive Focus Orbitrap System was used; Electrospray ionization source, positive ion detection mode, full scan mode for non-targeted analysis, sheath gas flow rate 45 arb, auxiliary gas flow rate 15 arb, tail gas flow rate 1 arb, capillary temperature 350℃, capillary voltage 3.8 kV, lens RF energy level 60%, acquisition quality range m / z: 50-1000, resolution 70000, fragmentation voltage 20 V ± 50%; Acquisition of fragmentation information by secondary mass spectrometry: Full scan-ddMS2 mode was used with a fragmentation voltage of 30 V.

[0038] Before testing each batch of samples, a quality control sample (QC) is inserted to examine the stability and repeatability of the system.

[0039] (4) Data processing and biomarker screening Import the collected raw data (.raw format) into Compound Discoverer 2.0 software for processing.

[0040] Parameter settings: Quality deviation < 5 ppm, retention time deviation < 0.2 min, signal-to-noise ratio ≥ 3.

[0041] By comparing mass spectrometry data of different types of tea, a compound peak was found that was prevalent and had a high response intensity in white tea samples, but had a very low or undetectable response in other types of tea samples. The precise mass-to-charge ratio of this compound was 485.10724.

[0042] (5) Structural analysis: The secondary mass spectrometry information of this compound was extracted, imported into software for analysis, and the results showed that the molecular formula of the compound is C2. 24 H 20 O 11 The isotope peak shapes showed good matching. The main fragment ions in the secondary mass spectrometry included m / z 139, 153, 165, and 177.

[0043] The structural analysis of this compound is based on the following: Precise molecular weight: Measured value [M+H]+ 485.10724, compared with theoretical value C 24 H 20 O 11 The [M+H]+ error of 485.1084 is <2.5ppm; secondary fragments: m / z 139, 153, 165, 177, consistent with the theoretical fragmentation mode; Based on the above mass spectrometry information, its structural formula is as follows:

[0044] Example 2 A method for identifying white tea based on characteristic markers of processed white tea includes the following steps: (1) Sample pretreatment After vacuum freeze-drying, the tea sample was ground into powder using a pulverizer. 50 mg ± 1 mg was accurately weighed into a centrifuge tube, and 800 μL of a 70% methanol aqueous solution pre-cooled to 4°C was added. The mixture was vortexed for 30 seconds. The sample was then extracted using ultrasonication at 60 Hz for 20 minutes, vortexing every 10 minutes. Afterward, the sample was centrifuged at 12000 g for 15 minutes at 4°C, and the supernatant was collected to obtain the test solution. (2) Detection method Take 50 μL of the sample solution to be tested, add 950 μL of 70% methanol aqueous solution pre-cooled to 4℃ for dilution, then add 10 μL of internal standard solution (DL-4-chlorophenylalanine methanol solution, concentration 0.3 mg / mL), vortex to mix, and centrifuge at 4℃ and 12000g for 15 min. Take 200 μL of the diluted solution into the sample vial.

[0045] Detection was performed using a liquid chromatography-high resolution mass spectrometry (LC-MS) system.

[0046] Chromatographic conditions: Hypersil Gold column; Detection was performed using a liquid chromatography-high resolution mass spectrometry (LC-MS) system.

[0047] Chromatographic conditions: Hypersil Gold column; Mobile phase: A is an aqueous solution of formic acid with a volume fraction of 0.075%, and B is acetonitrile containing formic acid, with the volume fraction of formic acid in the acetonitrile being 0.075%. Gradient elution program: 0-2 min, 5-40% B; 2-7 min, 40-80% B; 7-11 min, 80-95% B; 11-15 min, 95% B; Column temperature: 35℃; Flow rate: 0.3 mL / min; Injection volume: 4 μL; Mass spectrometry conditions: Q-Exactive Focus Orbitrap System was used; Electrospray ionization source, positive ion detection mode, full scan mode for non-targeted analysis, sheath gas flow rate 45 arb, auxiliary gas flow rate 15 arb, tail gas flow rate 1 arb, capillary temperature 350℃, capillary voltage 3.8 kV, lens RF energy level 60%, acquisition quality range m / z: 50-1000, resolution 70000, fragmentation voltage 20 V ± 50%; Acquisition of fragmentation information by secondary mass spectrometry: Full scan-ddMS2 mode was used with a fragmentation voltage of 30 V.

[0048] Before testing each batch of samples, a quality control sample (QC) is inserted to examine the stability and repeatability of the system.

[0049] (3) Data processing The signals of characteristic markers are extracted based on mass spectrometry information, and the internal standard normalized response values ​​of the characteristic markers are calculated; where the internal standard normalized response value is the ratio of the peak area of ​​the characteristic marker to the peak area of ​​the internal standard. (4) Result determination The test results are compared, and the tea sample is determined to be white tea or have white tea characteristics when it meets all of the following criteria: ① Primary mass spectrometry detected the precursor ion [M+H]. + 485.10724; ② At least one characteristic fragment with m / z 139, 153, 165, or 177 is present in the secondary mass spectrometer; ③ Compound C detected in the sample solution 24 H 20 O 11 The internal standard normalized response value is not lower than the preset threshold (0.05).

[0050] Example 3: Verification of the identification method Representative samples of white tea, green tea, yellow tea, oolong tea, black tea, and dark tea were selected, and characteristic markers were detected according to the method described in Example 2. The internal standard normalized response values ​​are as follows: Table 1. Normalized response values ​​of characteristic compounds in different tea samples

[0051] Table 1 shows that the characteristic markers of processed white tea were generally detectable in white tea samples, exhibiting stable precursor ion signals and secondary characteristic fragments. However, in green tea, yellow tea, oolong tea, black tea, and dark tea, the response intensity of this compound was significantly lower, and it was not detected in some samples. Statistical analysis of the white tea group and the non-white tea group revealed that the normalized response value of this compound was significantly higher in the white tea group than in the non-white tea group. These results indicate that the characteristic markers of processed white tea of ​​the present invention are suitable for distinguishing white tea from other tea types.

[0052] Threshold setting basis: Based on the data in Table 1, the statistical analysis of the normalized response values ​​of the internal standard for non-white tea control samples (including green tea, yellow tea, black tea, oolong tea, and red tea) is as follows: The sample size N=10; the mean is 0.0197; the standard deviation is 0.0095; therefore, the threshold is set to 0.0482.

[0053] For ease of practical operation, the preset threshold is rounded to 0.05. This threshold is significantly lower than the lowest response value of white tea samples (1.0710), ensuring 100% discrimination accuracy. Furthermore, the setting of 3 times the standard deviation provides a reproducible threshold determination method for those skilled in the art: different laboratories can calculate the mean and standard deviation based on the response value distribution of non-white tea control samples under their own testing conditions, and thus determine the appropriate judgment threshold for their laboratory.

[0054] Comparative Example 1: Comparison of discriminative ability with structural analog EGC-C The molecular formula of the characteristic marker of the processed white tea used in Example 2 is C 24 H 20 O 11 [M+H] + 485.10724. The molecular formula of the compound EGC-C (epigallocatechin-3-O-caffeate) is known to be C. 24 H 20 O 10 [MH] - 467.1129. Both belong to hydroxycinnamoylated catechins, and the only structural difference is that the cinnamoyl group of the characteristic marker of processed white tea has an additional hydroxyl group.

[0055] Using EGC-C (epigallocatechin-3-O-caffeate) as a characteristic marker, the internal standard normalized response value of EGC-C was detected in the same batch of tea samples using the same detection method as in Example 2. Specifically as follows: Table 2 Normalized response values ​​of EGC-C in different tea samples

[0056] The EGC-C detection results are shown in Table 2. Table 2 shows that the response values ​​for black tea samples are 0.227-0.237, green tea is 0.058-0.064, oolong tea is 0.209-0.216, yellow tea is 0.037-0.040, dark tea is 0.091-0.095, and white tea is 0.230-0.241. Based on the distribution of response values ​​for non-white tea samples (mean 0.1275, standard deviation 0.0840), the threshold is calculated to be 0.379 (mean + 3 times the standard deviation).

[0057] The results showed that the response values ​​of white tea samples (0.230-0.241) were below the threshold (0.379) and could not be classified as positive. Among non-white tea samples, the response values ​​of black tea (0.227-0.237) and white tea (0.230-0.241) completely overlapped and could not be distinguished. Therefore, EGC-C cannot set a threshold that can effectively distinguish between white tea and non-white tea.

[0058] The above results indicate that although the characteristic marker of the present invention is structurally similar to EGC-C, the additional hydroxyl substitution leads to a significant change in its metabolic accumulation pattern in tea plants. The response values ​​of EGC-C completely overlap between white tea and non-white tea, making effective differentiation impossible. In contrast, the characteristic marker of the present invention is specifically enriched in white tea and shows significant differences from non-white tea samples, achieving 100% accurate differentiation.

[0059] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A characteristic marker for identifying processed white tea, characterized in that, The aforementioned characteristic markers exhibit the following features in liquid chromatography-mass spectrometry analysis: (1) The precursor ion [M+H]+ was detected at 485.10724 in the primary mass spectrometer; (2) The secondary mass spectrometer contains at least one or more characteristic fragments of m / z 139, 153, 165, and 177; (3) The molecular formula of the marker is C 24 H 20 O 11 .

2. The characteristic marker according to claim 1, characterized in that, Based on the mass spectrometry data, its structure was analyzed, and its structural formula was obtained as follows: 。 3. A method for identifying white tea based on characteristic markers of processed white tea, characterized in that, Includes the following steps: (1) Extract the tea sample to be tested, centrifuge, and take the supernatant to obtain the sample solution to be tested; (2) The sample solution was detected by liquid chromatography-mass spectrometry to obtain primary mass spectrometry information and secondary mass spectrometry fragment information; (3) Extract the signal of the characteristic marker based on the mass spectrometry information and calculate the internal standard normalized response value of the characteristic marker; wherein, the internal standard normalized response value is the ratio of the peak area of ​​the characteristic marker to the peak area of ​​the internal standard. (4) Compare the test results. When the sample meets all of the following judgment conditions, the tea sample is judged to be white tea or has the characteristics of white tea: ① Primary mass spectrometry detected the precursor ion [M+H]. + 485.10724; ② At least one characteristic fragment with m / z 139, 153, 165, or 177 is present in the secondary mass spectrometer; ③ Compound C detected in the sample solution 24 H 20 O 11 The internal standard normalized response value is not lower than a preset threshold; wherein, the preset threshold is set based on the known distribution of response values ​​of real white tea samples and non-white tea control samples, preferably more than 3 times the standard deviation of the mean response value of non-white tea control samples.

4. The method according to claim 3, characterized in that, The solvent used in step (1) is a mixed solution of a polar organic solvent and water, wherein the polar organic solvent is one or both of methanol and acetonitrile; preferably, the solvent used in the extraction is an aqueous methanol solution with a volume fraction of 50%-90%, and more preferably an aqueous methanol solution with a volume fraction of 70%.

5. The method according to claim 3, characterized in that, In step (1), the ratio of the amount of tea sample to be tested to the amount of solvent used for extraction is 50mg:600-1000μL, and more preferably 50mg:800μL.

6. The method according to claim 3, characterized in that, In step (1), the tea sample to be tested is one of the following: finished tea, loose tea, tea powder, tea extract or tea-containing products available on the market.

7. The method according to claim 3, characterized in that, In step (2), the liquid chromatography-mass spectrometry technique is ultra-high performance liquid chromatography-high resolution mass spectrometry.

8. The method according to claim 3, characterized in that, In step (1), the extraction is performed by vortexing at room temperature for 20-40 seconds and then ultrasonically extracting at 50-70 Hz for 15-25 minutes.

9. The method according to claim 2, characterized in that, In step (4), the preset threshold is above 0.05, preferably 0.

05.

10. The application of the characteristic markers of processed white tea as described in claim 1 or 2, or the method for identifying white tea based on the characteristic markers of processed white tea as described in any one of claims 3-9, in the fields of distinguishing white tea from non-white tea, determining the authenticity of white tea, screening white tea raw materials, controlling the quality of white tea products, classifying and evaluating white tea, constructing a database of tea metabolic markers, or in the fields of tea market supervision and product traceability.

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