Method for reverse verification of whether Cyclocarya paliurus tea has been withered based on characteristic factors

Abstract

The present invention discloses a method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic elements, which is characterized in that according to the transformation and fixation phenomenon of the substances contained in Cyclocarya paliurus tea before and after the withering process is performed under rapid heat transfer, the characteristic element is selected as a single compound of (2E)-2-tetradecene aldehyde, including comparing the content of the characteristic element components under two process states of withering and non-withering of Cyclocarya paliurus tea from different origins, and determining the withering process characteristics of the Cyclocarya paliurus tea to be tested. By analyzing the components of this characteristic element in Cyclocarya paliurus tea, it is determined whether the Cyclocarya paliurus tea has been processed by the withering process, and the identification is directional and qualitative, and accurate; by supercritical extraction, all components of the product to be tested can be retained in the extract, the extraction speed is fast, the sensitivity to volatile substances is high, the repeatability is good, and it has a wide range of application prospects.

Description

Technical Field

[0001] The invention relates to a quality detection technology for Cyclocarya paliurus tea, in particular to a method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic elements. Background Art

[0002] Cyclocarya paliurus is a relic tree species that survived the Ice Age and is unique to my country. Its leaves contain a variety of physiologically active substances that are beneficial to the human body, and are often used to make tea. The tea is golden in color and sweet in taste, and is called "sweet tea". It has high medicinal and health-care effects.

[0003] In the public technology, there are also some identification methods for whether it is a Cyclocarya paliurus tea. For example, the patent publication number CN109884257A provides a method for identifying Cyclocarya paliurus tea. This method first crushes the Cyclocarya paliurus tea and soaks it in boiling water to obtain a sample to be tested. Then, an electronic nose and an electronic tongue are used to detect the collected sample, and the test results are analyzed by PCA and DFA. At the same time, GC-TOFMS mass spectrometry technology is combined to comprehensively identify the authenticity, counterfeit, adulterated products of Cyclocarya paliurus tea and the origin of Cyclocarya paliurus tea. Although this method has a certain effect on distinguishing true and false Cyclocarya paliurus tea, it cannot determine whether the real Cyclocarya paliurus tea has undergone the withering process.

[0004] Killing the green leaves is one of the key processes in tea making technology. Killing the green leaves is to take high-temperature measures to quickly heat up the fresh leaves in a very short time, passivate the activity of enzymes in the fresh leaves, prevent the enzymatic browning of polyphenols, retain the polyphenols in the tea leaves, and quickly transform the contents in the fresh leaves, which can significantly improve the sensory quality of the tea. At present, the processing of Cyclocarya paliurus tea is mainly based on independent processing by farmers or cooperatives, and no standardized industry standards have been formed. Since the killing green processing technology requires professional equipment, the cost is relatively high, but the product quality is good. However, there are teas that are made in the existing market by simple processing methods such as drying and air-drying, which are inferior and cause confusion in the market. Therefore, it is particularly important to standardize the processing of Cyclocarya paliurus tea and to test and identify the product quality. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problem that the prior art lacks a method for identifying whether the finished product of Cyclocarya paliurus tea has been subjected to the withering process, and to provide a method for reversely verifying whether the Cyclocarya paliurus tea has been withered based on characteristic factors, which has the characteristics of reliable accuracy, fast extraction speed, high sensitivity to volatile substance detection, good repeatability, etc.

[0006] The above technical problem of the present invention is mainly solved by the following technical scheme: a method for reversely verifying whether the Cyclocarya paliurus tea has been withered based on characteristic elements, characterized in that: according to the transformation and fixation phenomenon of the substances contained in the Cyclocarya paliurus tea under rapid heat transfer before and after the withering process, the characteristic element is selected as a single compound of (2E)-2-tetradecene aldehyde, including the following contents:

[0007] (I) Comparison of the content of characteristic elements in Cyclocarya paliurus tea from different origins under the two processing conditions of withering and not withering:

[0008] (1) Collect samples, group them, classify them and number them.

[0009] (2) A portion of the original leaves of Cyclocarya paliurus tea are directly dried at 80°C to produce un-withered Cyclocarya paliurus tea, and the other portion is withered once by an infrared machine at a temperature of 170-180°C for 2-3 min, and then dried at 80°C to produce withered Cyclocarya paliurus tea.

[0010] (3) Collect the extracted products and perform GC-MS analysis.

[0011] (4) The test results were compared to obtain a comparison table of the peak areas of characteristic elements of Cyclocarya paliurus tea produced from different origins under two different process conditions.

[0012] (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process:

[0013] (1) Weigh the Cyclocarya paliurus tea and put it into a 50 mL supercritical carbon dioxide extraction kettle, extract it under set temperature and pressure conditions, and collect extract A.

[0014] (2) Weigh the extract A collected in step (1), dissolve it in dichloromethane, add anhydrous sodium sulfate for dehydration, and then filter it through a 0.45 μm organic filter membrane for GC-MS analysis and identification.

[0015] (3) If the peak area of ​​the characteristic element in the gas-mass spectrum in the test result is obvious, it is the Cyclocarya paliurus tea that has not been processed by the withering process; if the peak area of ​​the characteristic element in the gas-mass spectrum is below the detection limit and there is no data, it is the Cyclocarya paliurus tea that has been obtained by the withering process.

[0016] In the aforementioned method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic factors, preferably, the extraction and GC-MS chromatography conditions in content (I) and content (II) are the same.

[0017] In the aforementioned method for reversely verifying whether the Cyclocarya paliurus tea has been withered based on characteristic factors, as a preferred embodiment, in content (ii) (1), the supercritical carbon dioxide extraction temperature is 30-50°C, the extraction pressure is 25-35MPa, and the extraction time is 1.5-3h.

[0018] In the aforementioned method for reversely verifying whether the greening of Cyclocarya paliurus tea has been completed based on characteristic factors, preferably, in content (ii) (2), the mass volume ratio of extract A to dichloromethane is (0.01-0.05):1 (g / mL), and the mass volume ratio of anhydrous sodium sulfate to dichloromethane is (0.05-0.2):1 (g / mL).

[0019] In the aforementioned method for reversely verifying whether the green leaves of Cyclocarya paliurus tea have been withered based on characteristic factors, as a preferred method, the chromatographic conditions are: DB-5MS capillary column 30m×0.25mm×0.25μm, the carrier gas is high-purity helium, the constant flow rate is 1.2mL / min, the injection port temperature is 250°C, non-split injection, and the solvent delay is 3.5min; programmed temperature rise: 40°C for 3.5min, increase to 100°C at 10°C / min, then increase to 180°C at 7°C / min, and finally increase to 280°C at 25°C / min, and maintain for 5min.

[0020] In the aforementioned method of reversely verifying whether the Cyclocarya paliurus tea has been withered based on characteristic factors, as a preferred method, the mass spectrometry conditions are: electron bombardment ion source, ion source temperature 230°C, quadrupole temperature 150°C, mass spectrometry interface temperature 280°C, electron energy 70eV, scanning mode is selected ion detection mode, and qualitative and quantitative ion precise scanning.

[0021] In the aforementioned method for reversely verifying whether the Cyclocarya paliurus tea has been withered based on characteristic elements, preferably, the relative content of (2E)-2-tetradecenal in the sample is calculated based on the peak area of ​​the characteristic element (2E)-2-tetradecenal.

[0022] Due to the instantaneous heat transfer during the withering process, it can affect the transformation of some internal substances of Cyclocarya paliurus tea, especially it can effectively emit its own grassy smell, and significantly increase the content of characteristic aroma components, thereby improving the color, taste, aroma and other qualities of the finished tea.

[0023] There is a transformation of the substances contained in Cyclocarya paliurus tea before and after the withering process. This characteristic odor component has a direct impact on the quality indicators of the finished tea, and this odor component is specific and identifiable. This characteristic odor is the grassy astringency in the original tea or the characteristics of the strips, color, wholeness, purity, aroma, taste, soup color, and leaf bottom in the finished product. Among them: strips are the shape of tea leaves; color is the sensory color of tea leaves; wholeness is the degree of completeness; purity is the degree of cleanliness; aroma is the smell of tea leaves; taste is the actual feeling of tea leaves; soup color is the color of tea soup; and leaf bottom is the sensory indicator of tea bottom.

[0024] In this embodiment, the characteristic odor component and the identifiable attribute substance is (2E)-2-tetradecenal.

[0025] This technical solution uses experiments to analyze the components of the characteristic element (2E)-2-tetradecene aldehyde in the finished product of Cyclocarya paliurus tea. The results show that the finished product of Cyclocarya paliurus tea without the withering process contains the characteristic element (2E)-2-tetradecene aldehyde, and the content is relatively stable. The peak area in the mass spectrum can reach 11800-13000, while the Cyclocarya paliurus tea prepared by the withering process has this component below the detection limit. Using this feature, this method takes samples for testing, reversely judges whether the Cyclocarya paliurus tea is made by the withering process, and thus identifies the quality of the tea.

[0026] The invention has the following beneficial effects: since (2E)-2-tetradecenal only exists in the finished product of Cyclocarya paliurus tea which has not undergone the withering process, and the content is relatively stable and is not affected by the place of origin, by analyzing the components of this characteristic element in the Cyclocarya paliurus tea, it is determined whether the Cyclocarya paliurus tea has undergone the withering process, and the identification is directional and qualitative, and accurate; by using the supercritical extraction method, all components of the product to be tested can be retained in the extract, the extraction speed is fast, the detection sensitivity of volatile substances is high, the repeatability is good, and the invention has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the mass spectrum of (2E)-2-tetradecenal (cas number: 51534-36-2) in the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below through embodiments and drawings.

[0029] According to the phenomenon that the substances contained in Cyclocarya paliurus tea are transformed and fixed under rapid heat transfer before and after the withering process, the specific identifiable properties of substances that affect the quality of the finished tea are obtained through the withering process.

[0030] Embodiment 1:

[0031] A method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic elements, wherein the selected characteristic element is a single compound of (2E)-2-tetradecene aldehyde, and includes the following contents:

[0032] (I) Comparison of the content of characteristic elements in Cyclocarya paliurus tea from different origins under the two processing conditions of withering and not withering:

[0033] (1) The Cyclocarya paliurus leaf samples collected from Zhejiang and Jiangxi were divided into 10 portions, and the sample numbers were Zhejiang 1# to 10# and Jiangxi 1# to 10#.

[0034] (2) Take a portion of the original leaves of the above-mentioned Zhejiang 1#-10# and Jiangxi 1#-10#, and directly dry them at 80°C to produce un-withered Cyclocarya paliurus tea.

[0035] (3) Take a portion of the original leaves of the above-mentioned Zhejiang 1#~10# and Jiangxi 1#~10#, respectively, and use infrared mechanical withering once, the withering temperature is 170-180℃, the time is 2-3min, and then dry at 80℃ to make the withered Cyclocarya paliurus tea.

[0036] (4) Weigh 15.000 g of the Cyclocarya paliurus tea prepared in the above steps (2) and (3) and add it into a 50 mL supercritical carbon dioxide extraction kettle at an extraction temperature of 40° C., an extraction pressure of 30 MPa, and an extraction time of 2 hours, and collect the extract A.

[0037] (5) Weigh 50 mg of the extract A- obtained in step (4) above, dissolve it in 2 mL of dichloromethane, add 0.200 g of anhydrous sodium sulfate for dehydration, filter through a 0.45 μm organic filter membrane, and perform GC-MS analysis.

[0038] GC-MS Chromatographic Conditions:

[0039] DB-5MS capillary column (30 m × 0.25 mm × 0.25 μm, Agilent J&W Scientific, Folsom, CA, USA); carrier gas was high-purity helium with a purity of not less than 99.999%, constant flow rate of 1.2 mL / min, injection port temperature of 250 °C, non-split injection; solvent delay of 3.5 min.

[0040] Temperature program: maintain at 40°C for 3.5 min, increase to 100°C at 10°C / min, increase to 180°C at 7°C / min, and finally increase to 280°C at 25°C / min and maintain for 5 min.

[0041] Mass spectrometry conditions: electron impact ion source (EI), ion source temperature 230 °C, quadrupole temperature 150 °C, mass spectrometer interface temperature 280 °C, electron energy 70 eV, scanning mode selected ion detection mode (SIM), qualitative and quantitative ion precise scanning (GB 23200.8-2016).

[0042] Whether the sample has undergone the withering process is verified by whether (2E)-2-tetradecenal is detected, and the relative content of (2E)-2-tetradecenal in the sample is calculated based on the peak area of ​​(2E)-2-tetradecenal.

[0043] (6) Comparison of test results, and a comparison table of characteristic element quality peak areas under two process conditions of Cyclocarya paliurus tea from two origins was obtained. The following is Table 1:

[0044] Table 1 Comparison of the gas chromatography-mass spectrometry peak areas of (2E)-2-tetradecene aldehyde in Cyclocarya paliurus tea from two origins

[0045]

[0046] Conclusion: (2E)-2-Tetradecenal was detected in all the un-withered Cyclocarya paliurus teas, but not in the Cyclocarya paliurus teas made with the withering process.

[0047] (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process:

[0048] (1) Take a sample of Cyclocarya paliurus tea to be tested, weigh 15.000 g, add it into a 50 mL supercritical carbon dioxide extraction kettle, extract at 40° C., extract at 30 MPa, extract for 2 hours, and collect the extract A.

[0049] (2) Weigh 50 mg of the extract A- from step (1), dissolve it in 2 mL of dichloromethane, add 0.200 g of anhydrous sodium sulfate for dehydration, filter through a 0.45 μm organic filter membrane, and perform GC-MS analysis.

[0050] GC-MS Chromatographic Conditions:

[0051] Inlet: 250℃;

[0052] Injection volume: 1 μL, splitless injection;

[0053] Chromatographic column: HP-5MS 5% Phenyl Methyl Silox (30m×0.25mm, 0.25μm);

[0054] Carrier gas: high purity He, flow rate 1.2 mL / min;

[0055] The temperature was programmed as follows: 40°C for 3.5 min, then increased to 100°C at 10°C / min and held for 5 min, then increased to 180°C at 7°C / min, and finally increased to 280°C at 25°C / min and held for 5 min.

[0056] Mass spectrometer interface temperature: 280°C;

[0057] Mass spectrometry acquisition mode: full scan (scan), mass number 50.0-430, for qualitative analysis; selected ion scan (sim), mass number 189, dwell 40ms, mass number 286, dwell 100ms, mass number 271, dwell 40ms, for quantitative analysis;

[0058] Electron energy: 70eV

[0059] Solvent delay: 3.5min;

[0060] Ion source: 230℃;

[0061] MS quadrupole: 150 °C.

[0062] (3) If the peak area of ​​the characteristic element in the gas-mass spectrum in the test result is obvious, it is the Cyclocarya paliurus tea that has not been processed by the withering process; if the peak area of ​​the characteristic element in the gas-mass spectrum is below the detection limit and there is no data, it is the Cyclocarya paliurus tea that has been obtained by the withering process.

[0063] Test results, combined with Figure 1 The mass spectrum showed that the peak area of ​​the quantitative ion (70) was 11,000.

[0064] Conclusion: This batch of Cyclocarya paliurus tea was not produced through the withering process.

[0065] In this embodiment, the peak area of ​​the characteristic element (2E)-2-tetradecenal can also be used to calculate a standard curve to calculate the relative content of (2E)-2-tetradecenal in the sample.

[0066] Embodiment 2:

[0067] A method for reversely verifying whether Cyclocarya paliurus tea has adopted the withering process based on a single compound of (2E)-2-tetradecene aldehyde as a characteristic element is as follows:

[0068] (I) Comparison of the contents of characteristic elements in Cyclocarya paliurus teas from different origins under two process conditions: withering and not withering, using the same method as in Example 1.

[0069] (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process:

[0070] (1) Take a sample of Cyclocarya paliurus tea to be tested, weigh 15.000 g, add it into a 50 mL supercritical carbon dioxide extraction kettle, extract at 40° C., extract at 30 MPa, extract for 2 hours, and collect the extract A.

[0071] (2) Weigh 50 mg of the extract A- from step (1), dissolve it in 2 mL of dichloromethane, add 0.200 g of anhydrous sodium sulfate for dehydration, filter through a 0.45 μm organic filter membrane, and perform GC-MS analysis.

[0072] GC-MS Chromatographic Conditions:

[0073] Inlet: 250℃;

[0074] Injection volume: 1 μL, splitless injection;

[0075] Chromatographic column: HP-5MS 5% Phenyl Methyl Silox (30m×0.25mm, 0.25μm);

[0076] Carrier gas: high purity He, flow rate 1.2 mL / min;

[0077] The temperature was programmed as follows: 40°C for 3.5 min, then increased to 100°C at 10°C / min and held for 5 min, then increased to 180°C at 7°C / min, and finally increased to 280°C at 25°C / min and held for 5 min.

[0078] Mass spectrometer interface temperature: 280°C;

[0079] Mass spectrometry acquisition mode: full scan (scan), mass number 50.0-430, for qualitative analysis; selected ion scan (sim), mass number 189, dwell 40ms, mass number 286, dwell 100ms, mass number 271, dwell 40ms, for quantitative analysis;

[0080] Electron energy: 70eV

[0081] Solvent delay: 3.5min;

[0082] Ion source: 230℃;

[0083] MS quadrupole: 150 °C.

[0084] (3) Detection results: The peak area of ​​the characteristic element quantitative ion is lower than the detection limit. Figure 1 From the mass spectrum, we concluded that this batch of Cyclocarya paliurus tea was made through the withering process.

[0085] Embodiment three:

[0086] A method for reversely verifying whether Cyclocarya paliurus tea has been subjected to a withering process based on the characteristic elements of a single compound of (2E)-2-tetradecene aldehyde is as follows:

[0087] (I) Comparison of the contents of characteristic elements in Cyclocarya paliurus teas from different origins under two process conditions: withering and not withering, using the same method as in Example 1.

[0088] (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process:

[0089] (1) Take the sample of Cyclocarya paliurus tea to be tested, weigh 15.000 g, add it into a 50 mL supercritical carbon dioxide extraction kettle, extract at 30° C., extract at 35 MPa, extract for 3 hours, and collect the extract A.

[0090] (2) Weigh 50 mg of the extract A- in step (1), dissolve it in 2 mL of dichloromethane, add 0.300 g of anhydrous sodium sulfate for dehydration, filter through a 0.45 μm organic filter membrane, and perform GC-MS analysis.

[0091] GC-MS Chromatographic Conditions:

[0092] Inlet: 250℃;

[0093] Injection volume: 1 μL, splitless injection;

[0094] Chromatographic column: HP-5MS 5% Phenyl Methyl Silox (30m×0.25mm, 0.25μm);

[0095] Carrier gas: high purity He, flow rate 1.2 mL / min;

[0096] The temperature was programmed as follows: 40°C for 3.5 min, then increased to 100°C at 10°C / min and held for 5 min, then increased to 180°C at 7°C / min, and finally increased to 280°C at 25°C / min and held for 5 min.

[0097] Mass spectrometer interface temperature: 280°C;

[0098] Mass spectrometry acquisition mode: full scan (scan), mass number 50.0-430, for qualitative analysis; selected ion scan (sim), mass number 189, dwell 40ms, mass number 286, dwell 100ms, mass number 271, dwell 40ms, for quantitative analysis;

[0099] Electron energy: 70eV;

[0100] Solvent delay: 3.5min;

[0101] Ion source: 230℃;

[0102] MS quadrupole: 150 °C.

[0103] Test results, combined with Figure 1 The mass spectrum showed that the peak area of ​​the quantitative ion (83) was 6190.

[0104] Conclusion: This batch of Cyclocarya paliurus tea was not produced through the withering process.

[0105] Embodiment 4:

[0106] A method for reversely verifying whether Cyclocarya paliurus tea has been subjected to a withering process based on the characteristic elements of a single compound of (2E)-2-tetradecene aldehyde is as follows:

[0107] (I) Comparison of the contents of characteristic elements of Cyclocarya paliurus tea in different regions under two process conditions: withering and not withering, using the same method as in Example 1.

[0108] (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process:

[0109] (1) Take a sample of Cyclocarya paliurus tea to be tested, weigh 15.000 g, add it into a 50 mL supercritical carbon dioxide extraction kettle, extract at 50° C., extract at 25 MPa, extract for 1.5 hours, and collect the extract A.

[0110] (2) Weigh 50 mg of the extract A- from step (1), dissolve it in 2 mL of dichloromethane, add 0.150 g of anhydrous sodium sulfate for dehydration, filter through a 0.45 μm organic filter membrane, and perform GC-MS analysis.

[0111] GC-MS Chromatographic Conditions:

[0112] Inlet: 250℃;

[0113] Injection volume: 1 μL, splitless injection;

[0114] Chromatographic column: HP-5MS 5% Phenyl Methyl Silox (30m×0.25mm, 0.25μm);

[0115] Carrier gas: high purity He, flow rate 1.2 mL / min;

[0116] The temperature was programmed as follows: 40°C for 3.5 min, then increased to 100°C at 10°C / min and held for 5 min, then increased to 180°C at 7°C / min, and finally increased to 280°C at 25°C / min and held for 5 min.

[0117] Mass spectrometer interface temperature: 280°C;

[0118] Mass spectrometry acquisition mode: full scan (scan), mass number 50.0-430, for qualitative analysis; selected ion scan (sim), mass number 189, dwell 40ms, mass number 286, dwell 100ms, mass number 271, dwell 40ms, for quantitative analysis;

[0119] Electron energy: 70eV;

[0120] Solvent delay: 3.5min;

[0121] Ion source: 230℃;

[0122] MS quadrupole: 150 °C.

[0123] The test results show that the peak area of ​​the characteristic element quantitative ion is lower than the detection limit. Figure 1 From the mass spectrum, we concluded that this batch of Cyclocarya paliurus tea was made through the withering process.

[0124] The above embodiments are for explanation of the present invention, not for limitation of the present invention. Based on the spirit of the present invention, any method after simple transformation of the present invention by ordinary technicians in this field without departing from the principle of the present technical solution and without making creative work shall fall within the protection scope of the present invention.

Claims

1. A method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic factors, characterized in that: According to the transformation and fixation of the substances contained in Cyclocarya paliurus tea under rapid heat transfer before and after the withering process, the characteristic element was selected as a single compound of (2E)-2-tetradecene aldehyde, including the following:

1. Comparison of the content of characteristic elements in Cyclocarya paliurus tea from different origins under the two processing conditions of withering and not withering: (1) Collect samples, group them, classify them and number them; (2) A portion of the original leaves of Cyclocarya paliurus tea are directly dried at 80°C to produce un-withered Cyclocarya paliurus tea, and the other portion is withered once by an infrared machine at a temperature of 170-180°C for 2-3 min, and then dried at 80°C to produce withered Cyclocarya paliurus tea; (3) Collect the extracted products and perform GC-MS analysis; (4) Comparison of test results, obtaining a comparison table of the peak areas of characteristic elements of Cyclocarya paliurus tea from different origins under two processing conditions; (II) Determination of whether the Cyclocarya paliurus tea to be tested has been processed by the characteristics of the withering process: (1) Weigh Cyclocarya paliurus tea and put it into a 50 mL supercritical carbon dioxide extraction kettle, extract under set temperature and pressure conditions, and collect extract A; (2) Weigh the extract A collected in step (1), dissolve it in dichloromethane, add anhydrous sodium sulfate for dehydration, then filter it through a 0.45 μm organic filter membrane, and perform GC-MS analysis and identification; (3) If the peak area of ​​the characteristic element in the gas-mass spectrometry in the test results is obvious, it is Cyclocarya paliurus tea that has not been processed by the withering process; If the peak area of ​​the characteristic element mass spectrometry is lower than the detection limit and there is no data, then it is Cyclocarya paliurus tea obtained through the withering process.

2. The method for reversely verifying whether Cyclocarya paliurus tea has been finished based on characteristic elements according to claim 1, characterized in that: The extraction and GC-MS chromatographic conditions in Content (I) and Content (II) are the same.

3. The method for reversely verifying whether Cyclocarya paliurus tea has been finished based on characteristic elements according to claim 1 or 2, characterized in that: In content (ii) (1), the supercritical carbon dioxide extraction temperature is 30-50°C, the extraction pressure is 25-35MPa, and the extraction time is 1.5-3h.

4. The method for reversely verifying whether Cyclocarya paliurus tea has been finished based on characteristic elements according to claim 1 or 2, characterized in that: In content (ii) (2), the mass volume ratio of extract A to dichloromethane is (0.01-0.05) : 1 g / mL, and the mass volume ratio of anhydrous sodium sulfate to dichloromethane is (0.05-0.2) : 1 g / mL.

5. The method for reversely verifying whether the green tea of ​​Cyclocarya paliurus has been withered based on characteristic elements according to claim 2 is characterized in that the chromatographic conditions are: DB-5MS capillary column 30m×0.25mm×0.25μm, the carrier gas is high-purity helium, the constant flow rate is 1.2 mL / min, the injection port temperature is 250°C, non-split injection, and the solvent delay is 3.5 min; the programmed temperature is: 40°C for 3.5 min, increased to 100°C at 10°C / min, then increased to 180°C at 7°C / min, and finally increased to 280°C at 25°C / min, and maintained for 5 min.

6. The method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic elements according to claim 2, characterized in that: Mass spectrometry conditions: electron bombardment ion source, ion source temperature 230°C, quadrupole temperature 150°C, mass spectrometry interface temperature 280°C, electron energy 70eV, scanning mode is selected ion detection mode, qualitative and quantitative ion precise scanning.

7. The method for reversely verifying whether Cyclocarya paliurus tea has been withered based on characteristic elements according to claim 1, characterized in that: The relative content of (2E)-2-tetradecenal in the sample was calculated based on the peak area of ​​the characteristic element (2E)-2-tetradecenal.

Images