Quality fingerprint of black tea hydrolat and construction method and identification application thereof

Abstract

The application discloses a quality fingerprint of black tea hydrolat and a construction method and application thereof, and belongs to the technical field of tea deep processing and quality evaluation. The method comprises the following steps: collecting Meizhan black tea hydrolat samples; preparing a test sample solution; adopting gas chromatography-mass spectrometry technology analysis to obtain a total ion flow chromatogram; identifying and calibrating 15-25 common characteristic peaks, selecting gerianol as a reference peak; calculating the relative retention time and relative peak area of each characteristic peak; establishing a standard fingerprint based on multiple batches of samples; verifying the methodology; and performing quality identification based on similarity evaluation. The application firstly constructs a characteristic aroma fingerprint of Meizhan black tea hydrolat, and establishes a quality identification method based on similarity evaluation, comprehensively reflects the variety characteristics of the Meizhan black tea hydrolat, such as flower and fruit aroma, sweet and mellow fruit honey aroma, and can effectively distinguish products with different processes, thereby providing a scientific basis for quality control, process optimization and high-value utilization of the Meizhan black tea hydrolat.

Description

Technical Field

[0001] This invention relates to the field of tea processing and quality evaluation technology, specifically to a method for constructing a quality fingerprint spectrum for black tea hydrosol products and its application in quality identification based on the fingerprint spectrum. This invention establishes a fingerprint spectrum of characteristic aroma components of Meizhan black tea hydrosol using gas chromatography-mass spectrometry combined with chemometrics analysis, enabling variety identification, quality evaluation, and process monitoring of Meizhan black tea hydrosol. Background Technology

[0002] Meizhan black tea is a distinctive type of tea with unique varietal aromas (orchid and fruity aromas). Meizhan black tea hydrosol, prepared by steam distillation from its raw materials, is rich in characteristic aroma components such as geraniol, linalool, and nerol. It has an elegant floral and fruity aroma and excellent antioxidant activity, and has broad application prospects in cosmetics, functional foods, and aromatherapy.

[0003] Existing technologies have reported methods for preparing black tea hydrosol. By controlling parameters such as distillation temperature, material-liquid ratio, and time, black tea hydrosol products with pure aroma and high antioxidant activity can be obtained.

[0004] However, in the tea processing industry, the following technical deficiencies still exist in the quality evaluation of new deep-processed tea products such as Meizhan black tea hydrosol: Deficiency 1: Lack of quality evaluation methods specifically for the varietal characteristics of Meizhan black tea hydrosol In existing technologies, the quality control of tea hydrosols mainly focuses on conventional physicochemical indicators (pH value, relative density) and microbiological indicators, and no systematic quality evaluation method specifically for the varietal characteristics of Meizhan black tea hydrosol has been found. The unique "floral and fruity aroma, sweet and mellow fruit and honey aroma" of Meizhan black tea hydrosol cannot be quantitatively characterized by conventional physicochemical indicators, resulting in high-quality products being unable to be effectively distinguished from ordinary products.

[0005] Defect 2: The evaluation index is too simplistic and cannot fully reflect the aroma and quality of Meizhan black tea hydrosol. Current technologies often use a single component (such as geraniol content) as a quality control indicator for tea hydrosols. However, the aroma quality of Meizhan black tea hydrosol is the result of the synergistic effect of multiple characteristic aroma components, and a single indicator cannot comprehensively evaluate its overall aroma quality. Studies have shown that Meizhan black tea hydrosol exhibits the highest total ionic strength of aroma components and a rich variety of aroma components, with higher levels of characteristic aroma substances (geraniol, nerol, linalool, etc.), all of which cannot be reflected by a single indicator.

[0006] Defect 3: Lack of methods for distinguishing products from different processing conditions Studies have shown that the aroma composition and sensory quality of Meizhan black tea hydrosols prepared at different extraction temperatures (0℃, 90℃, and 100℃) differ significantly: the product extracted at 90℃ has a rich floral and fruity aroma and the highest sensory score (9.2 points); the product extracted at 0℃ has a light aroma (6.5 points); and the product extracted at 100℃ has a slightly dull aroma (7.8 points). However, current technology lacks a quantitative evaluation method that can scientifically distinguish these differences.

[0007] Defect 4: Lack of effective monitoring methods for batch consistency Due to fluctuations in raw material batches and production process parameters, the aroma and quality of different batches of Meizhan black tea hydrosol may vary. Currently, the lack of effective scientific methods to monitor batch-to-batch consistency hinders the standardized production of the product.

[0008] Defect 5: The application of fingerprinting technology in the field of tea hydrosols is lacking. Although fingerprinting technology for traditional Chinese medicine has been widely used in the quality control of medicinal materials, its application in tea hydrosols, especially black tea hydrosols, is relatively limited. Existing fingerprinting studies on black tea mainly focus on the tea leaves themselves, and no methods for constructing fingerprint profiles for tea hydrosols, a novel deep-processed tea product, have been reported.

[0009] In conclusion, developing a fingerprinting method suitable for Meizhan black tea hydrosol that can comprehensively and scientifically evaluate its varietal characteristics and aroma quality is of significant theoretical and practical value for improving the deep processing technology of Meizhan black tea and promoting the high-value utilization of tea resources. Summary of the Invention

[0010] The purpose of this invention is to overcome the technical defects of existing technologies, such as the single quality evaluation index of Meizhan black tea hydrosol, the lack of variety-specific evaluation methods, and the inability to effectively distinguish products from different processes. This invention provides a method for constructing a quality fingerprint spectrum of black tea hydrosol based on gas chromatography-mass spectrometry. By identifying and labeling characteristic aroma components, a standard fingerprint spectrum is established to achieve variety identification, quality evaluation, and process monitoring of Meizhan black tea hydrosol.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: a method for constructing a quality fingerprint spectrum of black tea hydrosol, comprising the following steps: S1. Sample Collection and Preparation Samples of Meizhan black tea hydrosol prepared under different batches and processing conditions were collected. The Meizhan black tea hydrosol was prepared by steam distillation and sterilization filtration using Meizhan black tea as raw material. Three parallel samples were prepared for each sample and stored at 4°C for later use.

[0012] S2. Preparation of the test solution Take 10 mL of Meizhan black tea hydrosol sample, add 2 mL of dichloromethane or ethyl acetate, vortex for 2-5 minutes, sonicate for 10 minutes, centrifuge at 4000 rpm for 10 minutes, take the lower organic phase, filter through a 0.22 μm organic phase membrane to obtain the test solution.

[0013] S3. Chromatography-Mass Spectrometry Analysis The test solution was analyzed using gas chromatography-mass spectrometry to obtain a total ion chromatogram.

[0014] Chromatographic conditions: DB-Heavy Wax capillary column with dimensions of 30m × 250 μm × 0.5 μm was used; the injection port temperature was 250℃; the temperature program was as follows: initial temperature 50℃, hold for 2 minutes, increase to 240℃ at 5℃ / min, hold for 5 minutes; the carrier gas was high-purity helium at a flow rate of 1.0 mL / min; the injection volume was 1 μL, and the split ratio was 10:1.

[0015] Mass spectrometry conditions: ion source temperature 250℃; transfer line temperature 250℃; electron impact source 70 eV; scan range m / z 35-550; acquisition rate 10 spectra / s.

[0016] S4. Identification and Calibration of Characteristic Peaks Based on the total ion current chromatogram, qualitative analysis was performed using the NIST spectral library to identify and label 15-25 common characteristic peaks. The characteristic aroma components corresponding to these peaks include at least 15 of the following: geraniol, linalool, D-limonene, nerol, α-terpineol, β-myrcene, phenylacetaldehyde, 2,4-di-tert-butylphenol, 3-heptanone, 1-nonanol, and α,α,4-trimethylbenzyl alcohol.

[0017] S5. Selection of Reference Peak Geraniol, the most characteristic, stable, and well-shaped peak in Meizhan black tea hydrosol, was selected as the reference peak. The qualitative ions for geraniol were m / z 69, 93, and 123, with a retention time of 12.5 ± 0.2 minutes. Its relative retention time and relative peak area were set to 1.00.

[0018] S6. Calculation of relative retention time and relative peak area Calculate the relative retention time and relative peak area of ​​each characteristic peak and the reference peak: Relative retention time = Characteristic peak retention time / Reference peak retention time Relative peak area = Characteristic peak area / Reference peak area S7. Establishment of Standard Fingerprint Patterns Based on the measurement results of at least 10 batches of high-quality Meizhan black tea hydrosol samples, the mean relative retention time and relative peak area range of each characteristic peak were statistically analyzed to establish a standard fingerprint spectrum for Meizhan black tea hydrosol. The standard fingerprint spectrum contains 20 characteristic peaks, with geraniol as the reference peak. The relative retention time of each characteristic peak is within ±5% of the specified value, and the relative peak area is within the specified range.

[0019] S8. Methodological Validation Precision tests, repeatability tests, and stability tests were conducted to verify the reliability of the method.

[0020] Precision test: Take the same test solution and inject it 6 times consecutively. Calculate the relative standard deviation of the relative retention time and relative peak area of ​​each characteristic peak. The relative standard deviation of the relative retention time should be less than 0.5%, and the relative standard deviation of the relative peak area should be less than 3.0%.

[0021] Repeatability test: Take 6 samples of the same batch of Meizhan black tea hydrosol, prepare test solutions for each sample, and analyze them. Calculate the relative standard deviation of the relative peak area of ​​each characteristic peak. The relative standard deviation should be less than 5.0%.

[0022] Stability test: Take the same test solution and inject it at 0, 2, 4, 8, 12, and 24 hours for analysis. Calculate the relative standard deviation of the relative peak area of ​​each characteristic peak. The relative standard deviation should be less than 5.0%.

[0023] S9. Quality Identification Methods The similarity between the sample and the standard fingerprint spectrum is calculated using the cosine similarity method. The formula is as follows: , in, Xi is the relative peak area of ​​the i-th characteristic peak in the standard fingerprint spectrum. Yi is the relative peak area of ​​the i-th characteristic peak in the sample to be tested. n is the total number of feature peaks involved in the similarity calculation. The similarity between the sample to be tested and the standard fingerprint spectrum is denoted by a value ranging from 0 to 1. The closer the value is to 1, the higher the similarity. Judgment criteria: When the similarity is greater than or equal to 0.95, it is judged as high-quality Meizhan black tea hydrosol; when the similarity is greater than or equal to 0.90 and less than 0.95, it is judged as qualified Meizhan black tea hydrosol; when the similarity is less than 0.90, it is judged as unqualified product or non-Meizhan variety hydrosol.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. First construction of characteristic aroma fingerprint spectrum of Meizhan black tea hydrosol This invention, targeting the varietal characteristics of Meizhan black tea hydrosol, establishes for the first time a quality fingerprint spectrum based on 20 characteristic aroma components. Compared with existing technologies that use only a single component as a quality control indicator, the fingerprint spectrum of this invention can comprehensively reflect the aroma quality of Meizhan black tea hydrosol, embodying the varietal characteristics of "floral and fruity aroma, sweet and mellow fruity and honey aroma". Studies have shown that high-quality Meizhan black tea hydrosol extracted at 90℃ has characteristic peaks such as geraniol, nerol, and linalool with relative peak areas within the specified range, and the highest total ionic strength, which is highly consistent with the sensory evaluation results.

[0025] 2. Establish a standardized evaluation system based on geraniol as the reference peak. This invention selects geraniol, the most characteristic and stable component in Meizhan black tea hydrosol, as a reference peak, and establishes specified values ​​for the relative retention time and relative peak area range for each characteristic peak. The qualitative ions of geraniol are m / z 69, 93, and 123, with a retention time of 12.5 ± 0.2 minutes, exhibiting good peak shape and easy identification. Based on this, the relative standard deviation of the relative retention time is less than 0.5%, ensuring the comparability and reproducibility of the fingerprint spectra.

[0026] 3. To achieve scientific differentiation of products using different processes. This invention effectively distinguishes between Meizhan black tea hydrosols prepared at different extraction temperatures. Analysis of the relative peak areas of characteristic peaks revealed that the 90℃ extract had higher relative peak areas for geraniol and nerol, which highly aligns with the sensory evaluation result of "rich floral and fruity aroma, sensory score of 9.2 points." The 100℃ extract had a higher relative peak area for 2,4-di-tert-butylphenol, corresponding to the sensory characteristic of "slightly dull aroma." The 0℃ extract had a lower total ionic strength, corresponding to the sensory characteristic of "light aroma." This method provides a quantitative evaluation basis for process optimization.

[0027] 4. Establish quality grading standards for similarity evaluation. This invention establishes a similarity evaluation model based on the cosine similarity method, classifying Meizhan black tea hydrosol into three grades: high quality, qualified, and unqualified, thus achieving quality identification of Meizhan black tea hydrosol. Verification of multiple batches of high-quality products shows similarity scores above 0.95, indicating good differentiation, and providing a scientific quality grading standard for the tea processing industry.

[0028] 5. The methodology is thoroughly validated and highly reliable. In the precision test, the relative standard deviation of the retention time of each characteristic peak was less than 0.5%, and the relative standard deviation of the peak area was less than 3.0%. In the repeatability test, the relative standard deviation of the peak area of ​​each characteristic peak was less than 5.0%. In the stability test, the relative standard deviation of the peak area of ​​each characteristic peak was less than 5.0% within 24 hours. All methodological validation indicators met the requirements, indicating that the method has good accuracy, reliability, and operability.

[0029] 6. Provide technical support for the formulation of tea processing industry standards. This method provides a systematic technical solution for the quality evaluation of Meizhan black tea hydrosol, including a complete process such as sample pretreatment, GC-MS analysis, characteristic peak identification, relative parameter calculation, standard spectrum establishment, and similarity evaluation. It can serve as a reference for the formulation of tea processing industry standards and promote the standardized development of the tea hydrosol industry. Attached Figure Description

[0030] Figure 1 This is the total ion chromatogram of Meizhan black tea hydrosol (extracted at 90℃). The horizontal axis represents retention time, and the vertical axis represents ionic intensity. Twenty characteristic peaks are labeled, with peak 5 being the reference peak, geraniol.

[0031] Figure 2 This is a schematic diagram of the standard fingerprint spectrum of Meizhan black tea hydrosol. The figure shows the relative retention time positions and relative peak area ranges of 20 characteristic peaks in the form of a bar chart, with geraniol as a reference.

[0032] Figure 3 Principal component analysis score plots for Meizhan black tea hydrosol extracted at different temperatures. The plots show the clustering of products extracted at 0℃, 90℃, and 100℃. The 90℃ product clusters in a specific region, clearly separated from products extracted at other temperatures. Detailed Implementation

[0033] The following is in conjunction with the appendix Figures 1-3 The present invention provides a detailed description of the specific implementation of a quality fingerprint spectrum of black tea hydrosol, its construction method, and its identification application.

[0034] Example 1: Construction of Standard Fingerprint Spectrum of Meizhan Black Tea Hydrosol 1. Sample Source Ten batches of Meizhan black tea hydrosol samples were collected. Using Meizhan black tea as raw material, purified water was added at a material-to-liquid ratio of 1:20, and the mixture was steam distilled at 90℃ for 30 minutes. The distillate was collected and sterilized by filtration through a 0.22μm membrane. The samples were numbered MZ-01 to MZ-10.

[0035] 2. Preparation of the test solution Take 10 mL of each Meizhan black tea hydrosol sample, add 2 mL of dichloromethane, vortex for 3 minutes, sonicate for 10 minutes, centrifuge at 4000 rpm for 10 minutes, take the lower organic phase, filter through a 0.22 μm organic phase filter membrane to obtain the test solution.

[0036] 3. GC-MS Analysis The analysis was performed using a gas chromatography-mass spectrometry system, with the chromatographic and mass spectrometry conditions set as described in S3.

[0037] 4. Identification and calibration of characteristic peaks Qualitative analysis was performed using the NIST spectral library, and 20 common characteristic peaks were identified in the total ion chromatogram. The retention times and compound names of the main characteristic peaks are as follows: Peak 1 (9.2 min, D-limonene), Peak 2 (8.7 min, β-myrcene), Peak 3 (10.8 min, linalool), Peak 4 (11.9 min, α-terpineol), Peak 5 (12.5 min, geraniol), Peak 6 (13.1 min, nerol), Peak 7 (11.2 min, phenylacetaldehyde), Peak 8 (14.5 min, 2,4-di-tert-butylphenol), Peak 9 (7.5 min, 3-heptanone), Peak 10 (12.2 min, 1-nonanol), Peak 11 (13.8 min, α,α,4-trimethylbenzyl alcohol), Peak 12 (12.0 min, phenylethanol), Peak 13 (13.5 min, neraldehyde), Peak 14 (12.7 min, citronellol), Peak 15 (14.8 min, geraniol acetate), etc.

[0038] 5. Selection of reference peak and calculation of relative parameters Peak 5, geraniol, was selected as the reference peak, and the relative retention time and relative peak area of ​​each characteristic peak were calculated.

[0039] 6. Establishment of Standard Fingerprint Patterns Based on the measurement results of 10 batches of samples, the mean relative retention time and relative peak area range of each characteristic peak were statistically analyzed to establish a standard fingerprint spectrum for Meizhan black tea hydrosol.

[0040] 7. Methodological Validation Precision test: Take the MZ-01 sample solution and inject it 6 times consecutively. The relative standard deviation of the relative retention time of each characteristic peak is 0.12%-0.35%, and the relative standard deviation of the relative peak area is 1.2%-2.8%, which meets the requirements.

[0041] Repeatability test: Take 6 portions of MZ-01 sample, prepare test solutions and measure them respectively. The relative standard deviation of the relative peak area of ​​each characteristic peak is 2.1%-4.5%, which meets the requirements.

[0042] Stability test: The MZ-01 sample solution was tested at 0, 2, 4, 8, 12 and 24 hours. The relative standard deviation of the relative peak area of ​​each characteristic peak was 1.8%-4.2%, which met the requirements.

[0043] Example 2: Comparison of fingerprint spectra of Meizhan black tea hydrosol extracted at different temperatures 1. Sample Preparation Using the same batch of Meizhan black tea as raw material, Meizhan black tea hydrosol samples were prepared by steam distillation at 0℃, 90℃ and 100℃ for 30 minutes at a material-to-liquid ratio of 1:20. Three parallel samples were prepared at each temperature.

[0044] 2. Fingerprint analysis Each sample was analyzed by GC-MS according to the method in Example 1, and the relative peak area of ​​each characteristic peak was calculated.

[0045] 3. Results Analysis The extracts obtained at 90℃ showed the highest relative peak areas for geraniol, nerol, and linalool, as well as the highest total ion intensity and the best match with the standard fingerprint spectrum. The extracts obtained at 100℃ showed a significant increase in the relative peak area of ​​2,4-di-tert-butylphenol and a decrease in the relative peak area of ​​geraniol. The extracts obtained at 0℃ showed a relatively high relative peak area for α,α,4-trimethylbenzyl alcohol and the lowest total ion intensity.

[0046] 4. Conclusion This method can effectively distinguish products extracted at different temperatures. 90℃ is the optimal extraction temperature, which is consistent with the sensory evaluation results and provides a quantitative basis for process optimization.

[0047] Example 3: Similarity Evaluation and Quality Grading Application 1. Sample to be tested Five batches of Meizhan black tea hydrosol samples (S1-S5) were selected, of which S1-S3 were products extracted at 90℃, S4 was products extracted at 100℃, and S5 was Yunnan black tea hydrosol.

[0048] 2. Similarity Calculation The relative peak areas of the characteristic peaks of each sample were obtained according to the method in Example 1, and the similarity with the standard fingerprint spectrum was calculated using the cosine of the included angle method.

[0049] 3. Results The similarity scores of S1, S2, and S3 to the standard fingerprint spectrum are 0.98, 0.96, and 0.95, respectively, all greater than 0.95, thus they are judged to be high-quality Meizhan black tea hydrosol. The similarity score of S4 is 0.88, less than 0.90, thus it is judged to be a substandard product. The similarity score of S5 is 0.75, less than 0.90, thus it is judged to be a non-Meizhan variety product.

[0050] 4. Conclusion This method can effectively identify different quality grades and varieties of black tea hydrosols. Products with a similarity of 0.95 or higher are high-quality Meizhan black tea hydrosols extracted at 90℃, while products with a similarity of less than 0.90 are products with poor processing or products that are not Meizhan varieties.

[0051] Example 4: Summary of Methodological Validation Results In the precision test, the relative standard deviation of the retention time of each characteristic peak was less than 0.5%, and the relative standard deviation of the peak area was less than 3.0%. In the repeatability test, the relative standard deviation of the peak area of ​​each characteristic peak was less than 5.0%. In the stability test, the relative standard deviation of the peak area of ​​each characteristic peak was less than 5.0%. All indicators met the requirements, indicating that this method has good accuracy, reliability, and operability.

[0052] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. Any improvements and modifications made by those skilled in the art without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing a quality fingerprint spectrum of black tea hydrosol, characterized in that, Includes the following steps: (1) Sample collection and preparation: Meizhan black tea hydrosol samples prepared under different batches and different process conditions were collected; (2) Preparation of test solution: Take the Meizhan black tea hydrosol sample, and treat it by liquid-liquid extraction or solid phase extraction to obtain a volatile component enrichment solution, which is used as the test solution; (3) Chromatography-mass spectrometry analysis: Gas chromatography-mass spectrometry was used to analyze the test solution and obtain the total ion chromatogram; (4) Identification and labeling of characteristic peaks: Based on the total ion current chromatogram, 15-25 common characteristic peaks are identified and labeled, which correspond to the characteristic aroma components of Meizhan black tea hydrosol; (5) Selection of reference peak: Geraniol was selected as the reference peak, and its relative retention time was set to 1.00 and its relative peak area was set to 1.00; (6) Calculation of relative retention time and relative peak area: Calculate the relative retention time and relative peak area of ​​each characteristic peak and the reference peak; (7) Establishment of standard fingerprint spectrum: Based on the measurement results of multiple batches of samples, the mean relative retention time and relative peak area range of each characteristic peak were statistically analyzed to establish the standard fingerprint spectrum of Meizhan black tea hydrosol. (8) Method validation: Conduct precision tests, repeatability tests and stability tests to validate the reliability of the method.

2. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, In step (2), the liquid-liquid extraction uses dichloromethane or ethyl acetate as the extraction solvent, the sample to solvent volume ratio is 1:2, and the extraction time is 2-5 minutes.

3. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, The gas chromatography-mass spectrometry (GC-MS) analysis conditions described in step (3) are as follows: the chromatographic column is a DB-Heavy Wax capillary column with dimensions of 30m×250μm×0.5μm; the injection port temperature is 250℃; the temperature program is as follows: initial temperature 50℃, hold for 2 minutes, increase to 240℃ at 5℃ / min, hold for 5 minutes; the carrier gas is high-purity helium with a flow rate of 1.0mL / min; the injection volume is 1μL and the split ratio is 10:1; the mass spectrometry conditions are as follows: ion source temperature 250℃, transfer line temperature 250℃, electron impact source 70 eV, scan range m / z 35-550, and acquisition rate 10 spectra / s.

4. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, The characteristic aroma components corresponding to the characteristic peaks in step (4) include at least 15 of the following: geraniol, linalool, D-limonene, nerol, α-terpineol, β-myrcene, phenylacetaldehyde, 2,4-di-tert-butylphenol, 3-heptanone, 1-nonanol, and α,α,4-trimethylbenzyl alcohol.

5. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, The qualitative ions of the reference peak geraniol mentioned in step (5) are m / z 69, 93, 123, and the retention time is 12.5 ± 0.2 minutes.

6. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, The standard fingerprint spectrum described in step (7) contains 20 characteristic peaks, with geraniol as the reference peak. The relative retention time of each characteristic peak is within ±5% of the specified value, and the relative peak area is within the specified range.

7. The method for constructing a quality fingerprint spectrum of black tea hydrosol according to claim 1, characterized in that, The standard for method validation in step (8) is as follows: in the precision test, after six consecutive injections, the relative standard deviation of the retention time of each characteristic peak is less than 0.5%, and the relative standard deviation of the peak area is less than 3.0%; in the repeatability test, after six parallel samples are measured, the relative standard deviation of the peak area of ​​each characteristic peak is less than 5.0%; in the stability test, after the samples are measured within 24 hours, the relative standard deviation of the peak area of ​​each characteristic peak is less than 5.0%.

8. A standard fingerprint spectrum of black tea hydrosol constructed using the method described in any one of claims 1-7, characterized in that, The standard fingerprint spectrum consists of 20 characteristic peaks, with geraniol as the reference peak. The relative retention time of each characteristic peak is within ±5% of the specified value, and the relative peak area is within the specified range.

9. A method for quality identification of black tea hydrosol, characterized in that, The standard fingerprint spectrum constructed using the method described in any one of claims 1-7 is used to evaluate the similarity of the sample to be tested. When the similarity between the sample to be tested and the standard fingerprint spectrum is greater than or equal to 0.90, it is determined to be a qualified product; when the similarity is greater than or equal to 0.95, it is determined to be a high-quality product.

10. The method for quality identification of black tea hydrosol according to claim 9, characterized in that, The similarity calculation uses the cosine similarity method, and the calculation formula is as follows: ， in, X i This represents the relative peak area of ​​the i-th characteristic peak in the standard fingerprint spectrum. Y i Let be the relative peak area of ​​the i-th characteristic peak in the sample to be tested. n is the total number of feature peaks involved in the similarity calculation. The similarity between the sample to be tested and the standard fingerprint spectrum is denoted by a value ranging from 0 to 1. The closer the value is to 1, the higher the similarity.

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