Longanin, preparation method thereof and method for identifying longan honey

Abstract

This invention relates to the field of honey detection and technology, specifically to a longanin compound, its preparation method, and a method for identifying longan honey. The longanin compound has the structure shown in Formula 1. Through research on longan honey, this invention discovered a new compound, longanin. This invention also found that when the honey to be tested simultaneously contains trans-, trans-abscisic acid, longanin, and cis-, trans-abscisic acid, the honey can be identified as longan honey. This invention also provides a new method for distinguishing the origin of longan honey.

Description

Technical Field

[0001] This invention relates to the field of honey detection technology, specifically to a longan extract, its preparation method, and a method for identifying longan honey. Background Technology

[0002] Longan honey is made from the longan tree, which typically blooms from March to June. Longan honey is amber in color, fragrant, sweet, and does not easily crystallize. Longan originated in my country and has a long history of cultivation, making it a popular fruit. my country and Thailand are the world's leading producers of longan.

[0003] Longan honey has a high market value, but adulteration exists, which seriously affects the interests of consumers and beekeepers and restricts the development of the longan honey industry.

[0004] Therefore, it is both necessary and urgent to establish a method for identifying and distinguishing longan honey. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for identifying longan extract, its preparation method, and a method for distinguishing longan honey. This method can be used to determine the authenticity of longan honey.

[0006] In a first aspect, the present invention provides longan extract having the structure shown in Formula 1:

[0007] Formula 1

[0008] This invention, through research on longan honey, discovered a novel compound called longanin, which can serve as a characteristic plant compound marker for longan honey. In particular, this compound, when combined with trans-,trans-abscisic acid and cis-,trans-abscisic acid, can be used to accurately determine the authenticity of longan honey.

[0009] Secondly, the present invention also provides a method for preparing the longan extract, which is obtained by separating terpenoid components in honey by high performance liquid chromatography, wherein the honey includes longan honey.

[0010] Preferably, in the high-performance liquid chromatography separation, mobile phase A is an aqueous solution of acetic acid with a concentration of 0.18~0.22%, mobile phase B is an acetic acid methanol solution with a concentration of 0.18~0.22%; and / or, gradient elution is used; and / or, the chromatographic column is a Phenomenex Gemini C18 column.

[0011] Further optimization yields the following gradient elution procedure:

[0012] From 0 to 11 minutes, the percentage of mobile phase B increased from 9% to 14%.

[0013] Over 11-14 minutes, the percentage of mobile phase B increased from 14% to 15%.

[0014] 14-17 min, mobile phase B maintained at 15%;

[0015] Over 17–24 minutes, the percentage of mobile phase B increased from 15% to 16%.

[0016] Over 24–28 minutes, the percentage of mobile phase B increased from 16% to 17%.

[0017] Over 28–30 minutes, the percentage of mobile phase B increased from 17% to 22%.

[0018] Over 30–38 minutes, the percentage of mobile phase B increased from 22% to 25%.

[0019] From 38 to 41 minutes, the mobile phase B increased from 25% to 30%.

[0020] From 41 to 46 minutes, the mobile phase B increased from 30% to 33%;

[0021] 46-55 min, mobile phase B maintained at 33%;

[0022] At 55–60 min, the content of mobile phase B increased from 33% to 34%.

[0023] Over 60-70 minutes, the mobile phase B increased from 34% to 35%.

[0024] Over 70-80 minutes, the mobile phase B increased from 35% to 36%.

[0025] In 80-90 minutes, the mobile phase B increased from 36% to 45%;

[0026] In 90-100 minutes, the mobile phase B increased from 45% to 52%;

[0027] Over 100–110 minutes, the percentage of mobile phase B increased from 52% to 57%.

[0028] Over 110–120 minutes, the percentage of mobile phase B increased from 57% to 65%.

[0029] Over 120–130 minutes, the mobile phase B increased from 65% to 70%.

[0030] At 130–135 min, the mobile phase B increased from 70% to 80%;

[0031] The sum of the volumes of mobile phase A and mobile phase B is 100%. In this invention, the volume of mobile phase A varies with the volume of mobile phase B, and the sum of their volumes is 100%. Based on the aforementioned stationary and mobile phases, and especially in conjunction with specific elution procedures and conditions, the separation and enrichment effect is significantly improved in the longan honey separation system of this invention.

[0032] Preferably, a Phenomenex Gemini C18 column was used; the flow rate was 0.6~0.8 mL / min, the injection volume was 20±2 μL, the column temperature was 34~36 ℃, and the detection wavelength was 280±10 nm.

[0033] Further optimization involves using mobile phase A as a 0.2% aqueous solution of acetic acid and mobile phase B as a 0.2% methanolic solution of acetic acid; the flow rate is 0.7 mL / min and the column temperature is 35 °C.

[0034] Further preferably, the high-performance liquid chromatography method further includes a step of extracting terpenoid components from honey using a solid-phase extraction column before high-performance liquid chromatography separation; specifically, a Strata-XA solid-phase extraction column is used for extraction, with methanol as an activator, water as a balancing agent and eluent, and a methanol solution of formic acid with a concentration of 9-11% (preferably 10%) as the eluent. Finally, the obtained eluent is dried, reconstituted with methanol, and filtered to obtain the final product.

[0035] Further optimization is achieved by using a filter membrane with a pore size of 0.22 μm during filtration.

[0036] Further preferred, the eluent is a methanol solution of formic acid with a concentration of 10%.

[0037] In this invention, the above extraction method can effectively remove the interference of water and sugar in longan honey, and achieve effective enrichment of the target component longanin.

[0038] Preferably, before separating terpenoid components in honey by high-performance liquid chromatography, a honey pretreatment step is included, which preferably includes the following steps: mixing honey with water, adjusting the pH to 6.5-7, and then centrifuging at 8800-9200 rpm for 18-22 min, and collecting the supernatant. Preferably, the pH is adjusted to 6.8, and centrifuged at 9000 rpm for 20 min.

[0039] In this invention, the amount of water added during pretreatment should be sufficient to fully dissolve the honey and facilitate subsequent operations.

[0040] Preferably, after separating the terpenoid components in honey by high performance liquid chromatography, the eluent of the target peak is collected, and the retention time of the target peak is 67.45 min.

[0041] Thirdly, the present invention also provides the application of the longanin or the longanin prepared by the method of preparing the longanin in the identification of longan honey.

[0042] Fourthly, the present invention also provides a method for identifying longan honey, which uses high performance liquid chromatography to detect terpenoid components in the honey to be tested. When the terpenoid components simultaneously contain trans, trans abscisic acid, longanin, and cis, trans abscisic acid, the honey to be tested is determined to be longan honey; the longanin is as described above.

[0043] The method for detecting the honey to be tested using high-performance liquid chromatography in the identification method of the present invention is as described above.

[0044] The high-performance liquid chromatography method of the present invention can effectively separate trans, trans abscisic acid, longanin, and cis, trans abscisic acid in the honey to be tested, thereby achieving accurate determination of authenticity.

[0045] Preferably, when the content of trans-trans abscisic acid in the honey to be tested is greater than 4.08 mg / kg, the content of longanin is greater than 3.39 mg / kg, and the content of cis-trans abscisic acid is greater than 9.67 mg / kg, the honey to be tested is determined to be longan honey.

[0046] Further preferred, when the ratio of the content of longanin to the content of cis-trans abscisic acid in the honey to be tested is greater than 1.1, the honey to be tested is determined to be Thai longan honey.

[0047] Fifthly, this invention provides a fingerprint spectrum of longan honey, which is constructed by processing longan honey using high-performance liquid chromatography (HPLC). In the HPLC fingerprint spectrum of the longan honey, the retention time of the characteristic peak of longanin is 67.45 min, the retention time of the characteristic peaks of trans- and trans-abscisic acid is 60.32 min, and the retention time of the characteristic peaks of cis- and trans-abscisic acid is 68.84 min. The HPLC method is as described above. Specifically, it includes the above-mentioned honey pretreatment step, the step of extracting terpenoid components from honey using a solid-phase extraction column, and the step of HPLC detection.

[0048] The beneficial effects of this invention are at least as follows: This invention discovers a new compound, longanin, which can serve as a characteristic plant compound marker for longan honey. When the honey to be tested simultaneously contains trans-, trans-abscisic acid, longanin, and cis-, trans-abscisic acid, the honey can be identified as longan honey. This invention establishes a solid-phase extraction and high-performance liquid chromatography (HPLC) separation and detection method for terpenoid compounds in longan honey. Using the HPLC-QTOF method, four representative plant compounds in longan honey were identified: trans-, trans-abscisic acid, longanin, cis-, trans-abscisic acid, and a low-content 3-carbonyl-ionone. The obtained HPLC chromatograms of longan honey terpenoid compounds were imported into a traditional Chinese medicine chromatographic fingerprint similarity evaluation system, and a representative standard fingerprint chromatogram for longan honey was initially generated. Furthermore, this invention, through HPLC chromatogram comparison with three monofloral honeys—Vitex honey, Acacia honey, and Linden honey—and analysis of plant compounds in other niche honeys such as Safflower honey, Gallnut honey, Goji Berry honey, Motherwort honey, and Nine Dragon Vine honey, found that trans-, trans-abscisic acid, longanin, and cis-, trans-abscisic acid were not simultaneously detected in any monofloral honey other than longan honey. This demonstrates that these three components can serve as characteristic plant compound markers for longan honey and can be applied to the authenticity and quality evaluation of longan honey, which has significant practical implications for protecting the legitimate rights and interests of honey consumers and maintaining the healthy development of the honey consumption industry. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a first-order mass spectrum of longanin obtained by liquid chromatography-mass spectrometry in Example 1 of the present invention;

[0051] Figure 2 This is a secondary mass spectrometry (LC-MS) spectrum of longanin in Example 1 of the present invention;

[0052] Figure 3 The nuclear magnetic resonance spectrum of longanin in Example 1 of this invention;

[0053] Figure 4 This is a chromatogram of terpenoid components in longan honey from Example 1 of the present invention;

[0054] Figure 5This is an HPLC overlay chromatogram of longan raw honey from twenty different origins in Example 2 of the present invention; wherein, R represents the standard fingerprint chromatogram generated based on the longan raw honey from twenty different origins, and S1-S20 represent the longan raw honey from twenty different origins. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product manual. Instruments and other equipment whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are all obtainable from publicly available commercial sources.

[0057] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0058] Example 1

[0059] This embodiment provides a method for preparing longan extract and establishing a fingerprint spectrum of characteristic components of longan honey, as described below:

[0060] 1. Preparation of longan honey solution: Accurately weigh 20.0g of longan honey into a beaker, add 80mL of deionized water, stir with a glass rod until the honey is fully dissolved, add 5% ammonia solution, adjust the pH value to about 6.8, centrifuge at 9000rpm for 20min, and take the supernatant for later use.

[0061] 2. Extraction and enrichment of terpenoids in longan honey: Terpenoids in honey were extracted using a Strata-XA solid-phase extraction column. The column was first activated with 3 mL of methanol and equilibrated with 3 mL of deionized water. The supernatant was then added, followed by rinsing with deionized water. Finally, the eluent was eluted with a 10% formic acid-methanol solution, and the eluent was collected. The eluent was dried under nitrogen, reconstituted with 2.0 mL of methanol, and filtered through a 0.22 μm filter membrane for later use.

[0062] 3. Separation and Detection of Terpenoids in Longan Honey: High-performance liquid chromatography (HPLC) was used to separate and detect the terpenoid components in the honey. A Phenomenex Gemini C18 column was used. Mobile phase A was an aqueous solution of 0.2% acetic acid, and mobile phase B was a methanol solution of 0.2% acetic acid. The gradient elution program was as follows: 0–11 min, mobile phase B increased from 9% to 14%; 11–14 min, mobile phase B increased from 14% to 15%; 14–17 min, mobile phase B remained at 15%; 17–24 min, mobile phase B increased from 15% to 16%; 24–28 min, mobile phase B increased from 16% to 17%; 28–30 min, mobile phase B increased from 17% to 22%; 30–38 min, mobile phase B increased from 22% to 25%; 38–41 min, mobile phase B increased from 25% to 30%; 41–46 min, mobile phase B increased from 41% to 46%; 42–46 min, mobile phase B increased from 25% to 30%; 41–46 min, mobile phase B increased from 25% to 30 ... At 46-55 min, mobile phase B increased from 30% to 33%; at 55-60 min, mobile phase B remained at 33%; at 60-70 min, it increased from 34% to 35%; at 70-80 min, it increased from 35% to 36%; at 80-90 min, it increased from 36% to 45%; at 90-100 min, it increased from 45% to 52%; at 100-110 min, it increased from 52% to 57%; at 110-120 min, it increased from 57% to 65%; at 120-130 min, it increased from 65% to 70%; and at 130-135 min, it increased from 70% to 80%. The injection volume was 20 μL, the column temperature was 35℃, and the detection wavelength was 280 nm. Perform detection and component separation according to the above conditions, and record the chromatogram. (See [reference needed]). Figure 4 Collect the eluent at each elution time and identify it.

[0063] Specifically, the above-mentioned methods of liquid chromatography with tandem diode array detector (HPLC-PDA) and liquid chromatography with tandem quadrupole / time-of-flight mass spectrometry (HPLC-QTOF) were used to classify the effectively separated and enriched terpenoid compounds.

[0064] The specific identification methods are detailed below:

[0065] 1. The structure of terpenoid components in longan honey after detection under the above liquid chromatography conditions was identified:

[0066] Liquid chromatography-mass spectrometry (LC-MS) analysis conditions: ion source was ESI (electrospray ionization), ion source injection voltage was 4 kV, outlet voltage was 130 V, heating temperature was 350 °C, nitrogen (N2) flow rate was 11 L / min, collision gas was helium, nebulizer gas flow rate was 80 kPa, nebulizer pressure was 40 psi, and mass scan range was m / z = 100-900 Da.

[0067] 2. Structural identification and analysis process and results of terpenoid compounds in longan honey:

[0068] (1) The structure of the compound in the eluent with a retention time of 60.32 min is analyzed as follows:

[0069] The primary mass spectrum showed a molecular ion peak of 265.1214 m / z for [M+H]+ and 287.1238 m / z for [M+Na]+, indicating a molecular weight of 264. Based on the retention time and maximum UV absorption wavelength of this compound obtained by high-performance liquid chromatography (HPLC), combined with the retention time and maximum UV absorption wavelength of the standard HPLC and the fracture pattern of the secondary mass spectrometry, this compound was identified as trans-trans abscisic acid.

[0070] (2) The structures of the compounds in the eluent with a retention time of 67.45 min are analyzed as follows:

[0071] The primary and secondary mass spectra in positive ion mode are shown. In the primary mass spectrum, there are molecular ion peaks at 205.1206 m / z for [M+H]+ and 227.1032 m / z for [M+Na]+, indicating a molecular weight of 204 for the compound. After collecting the fraction of this compound by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) analysis was performed, yielding the NMR spectrum of the compound, as shown below. Figure 3 As shown, the upper figure is the proton spectrum and the lower figure is the carbon spectrum; the chemical shifts are shown in Table 1.

[0072]

[0073] Table 1 Chemical shifts of compounds

[0074]

[0075] Its chemical formula is determined to be 4-(diene-3'-methyl ketone)-3,5,5-trimethyl-2-cyclohexenone, and it is named longanin. The structure of longanin is shown below:

[0076]

[0077] The fragmentation pathway of this compound under mass spectrometry is as follows:

[0078]

[0079] (3) The structures of the compounds in the eluent with a retention time of 68.84 min are analyzed as follows:

[0080] In the primary mass spectrum under positive ion mode, it has a value of 265.1256 m / z [M+H]. + The molecular ion peak, 287.1056 m / z [M+Na], is observed. + The molecular ion peak is 529.2435 m / z [2M+H]. + The molecular ion peak is 551.2239 m / z [2M+Na]. + The molecular ion peak indicates that the molecular weight of this compound is 264. The maximum UV absorbance of this compound is also 264. Verification with standards shows that the retention time and maximum UV absorbance of this compound are consistent with those of cis- and trans-abscisic acid standards. Therefore, this compound is identified as cis- and trans-abscisic acid.

[0081] (4) The process of analyzing the structure of the compound in the eluent with a retention time of 76.15 min is as follows:

[0082] The first-order mass spectrum shows 207.1363 m / z [M+H]. + The molecular ion peak, 229.1181 m / z, is [M+Na]. + The separated sub-peak, 435.2482 m / z [2M +Na], is observed. + The molecular ion peak is observed. The molecular weight of this compound is 206. Based on the maximum UV absorption wavelength, retention time, and comparison with standards after verification, this compound is identified as 3-carbonyl-ionone. Its structure is shown below:

[0083]

[0084] The fragmentation pathway of this compound under mass spectrometry is as follows:

[0085]

[0086] Example 2

[0087] In this embodiment, the high performance liquid chromatography method of Example 1 was used to detect longan honey from ten bee farms, and the components of these longan honeys were quantitatively analyzed by external standard method.

[0088] Specific information on the source of the honey is shown in Table 2 below:

[0089] Table 2 Samples of Longan Raw Honey

[0090]

[0091] The superimposed chromatograms of longan honey from twenty different origins are shown in the figure. Figure 5.

[0092] In twenty longan honey samples, the average content of trans- and trans-abscisic acid was 14.29 mg / kg; the average content of longanin was 11.13 mg / kg; the average content of cis- and trans-abscisic acid was 34.41 mg / kg; and the average content of 3-carbonyl-ionone was 7.39 mg / kg. The results are shown in Table 3.

[0093] Table 3. Compound content in longan honey (mg / kg)

[0094]

[0095] Note: "—" indicates not detected.

[0096] Example 3

[0097] This embodiment uses the high-performance liquid chromatography (HPLC) method of Example 1 to analyze the components of Vitex honey, Acacia honey, Linden honey, Safflower honey, Gallnut honey, Goji berry honey, Motherwort honey, and Jiulongteng honey (specific raw material honey source information is shown in Table 4). The HPLC chromatograms of the above honeys are compared with those of longan honey from Example 1. The results show that the compounds trans-, trans-abscisic acid, longanin, and cis-, trans-abscisic acid were not simultaneously detected in any of the other monofloral honeys besides longan honey. Specific detection results are shown in Table 5.

[0098] Table 4 Information on Other Raw Honey Sources

[0099]

[0100]

[0101] Table 5 Information on whether other honeys contain marker compounds

[0102]

[0103]

[0104] Example 4

[0105] This embodiment uses the high-performance liquid chromatography (HPLC) method described in Example 1 to analyze 19 commercially available longan honey samples (from different brands on different sales platforms). These included 6 samples from Taiwan, 6 from mainland China, and 7 from Thailand. HPLC chromatographic analysis revealed the presence of trans- and trans-abscisic acid, longanin, cis- and trans-abscisic acid, and 3-carbonyl-ionone in all 19 brands, with average contents of 7.40 mg / kg, 5.97 mg / kg, 16.61 mg / kg, and 3.16 mg / kg, respectively. The ratio of longanin to cis-trans abscisic acid in Thai longan honey samples was significantly higher than that in longan honey from Taiwan and China. Therefore, Thai longan honey, Chinese longan honey, and Taiwanese longan honey can be distinguished by the ratio of longanin to cis-trans abscisic acid. When the ratio of longanin to cis-trans abscisic acid in the longan honey sample is greater than 1.1, it can be identified as Thai longan honey.

[0106] Table 6. Compound content (mg / kg) in commercial longan honey

[0107]

[0108]

[0109] In summary, this invention, through comparative analysis of the plant compound components of longan honey and vitex honey, acacia honey, linden honey, safflower honey, gallnut honey, wolfberry honey, motherwort honey, and vine honey, found that the compounds trans, trans-abscisic acid, longanin, and cis, trans-abscisic acid were not simultaneously detected in any of these monofloral honeys other than longan honey. Therefore, trans, trans-abscisic acid, longanin, and cis, trans-abscisic acid can serve as characteristic plant compound markers for longan honey and can be applied to the authenticity and identification of longan honey.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing longan extract, characterized in that, Longan extract was obtained by separating terpenoid components in honey using high performance liquid chromatography; the honey is longan honey. The longanin has the structure shown in Formula 1: Formula 1 In the high-performance liquid chromatography (HPLC) separation, mobile phase A is an aqueous solution of acetic acid with a concentration of 0.18–0.22%, and mobile phase B is a methanolic solution of acetic acid with a concentration of 0.18–0.22%. Gradient elution is used, and a Phenomenex Gemini C18 column is employed. The gradient elution program is as follows: From 0 to 11 minutes, the percentage of mobile phase B increased from 9% to 14%. Over 11-14 minutes, the percentage of mobile phase B increased from 14% to 15%. 14-17 min, mobile phase B maintained at 15%; Over 17–24 minutes, the percentage of mobile phase B increased from 15% to 16%. Over 24–28 minutes, the percentage of mobile phase B increased from 16% to 17%. Over 28–30 minutes, the percentage of mobile phase B increased from 17% to 22%. Over 30–38 minutes, the percentage of mobile phase B increased from 22% to 25%. From 38 to 41 minutes, the mobile phase B increased from 25% to 30%. From 41 to 46 minutes, the mobile phase B increased from 30% to 33%; 46-55 min, mobile phase B maintained at 33%; At 55–60 min, the content of mobile phase B increased from 33% to 34%. Over 60-70 minutes, the mobile phase B increased from 34% to 35%. Over 70-80 minutes, the mobile phase B increased from 35% to 36%. In 80-90 minutes, the mobile phase B increased from 36% to 45%; In 90-100 minutes, the mobile phase B increased from 45% to 52%; Over 100–110 minutes, the percentage of mobile phase B increased from 52% to 57%. Over 110–120 minutes, the percentage of mobile phase B increased from 57% to 65%. Over 120–130 minutes, the mobile phase B increased from 65% to 70%. At 130–135 min, the mobile phase B increased from 70% to 80%; The sum of the volumes of mobile phase A and mobile phase B is 100%. Before separating terpenoid components in honey by high performance liquid chromatography, the honey pretreatment steps include: mixing honey with water, adjusting the pH to 6.5-7, centrifuging at 8800-9200 rpm for 18-22 min, and taking the supernatant. The high performance liquid chromatography method further includes the step of extracting terpenoid components in honey with a solid phase extraction column before high performance liquid chromatography separation; the extraction is performed using a Strata-XA solid phase extraction column, with methanol as an activator, water as a balancing agent and eluent, and a methanol solution of formic acid with a concentration of 9-11% as the eluent. The obtained eluent is dried, reconstituted with methanol, and then filtered. After separating the terpenoid components in honey by high performance liquid chromatography, the eluent of the target peak was collected, and the retention time of the target peak was 67.45 min.

2. A method for identifying longan honey, characterized in that, The terpenoid components in the honey were detected by high performance liquid chromatography. When the terpenoid components simultaneously contained trans-, trans-abscisic acid, longanin, and cis-, trans-abscisic acid, the honey was determined to be longan honey. The longanin has the structure shown in Formula 1. Formula 1.

3. The method for identifying longan honey according to claim 2, characterized in that, When the content of trans-trans abscisic acid in the honey to be tested is greater than 4.08 mg / kg, the content of longanin is greater than 3.39 mg / kg, and the content of cis-trans abscisic acid is greater than 9.67 mg / kg, the honey to be tested is determined to be longan honey.

4. The method for identifying longan honey according to claim 2 or 3, characterized in that, When the ratio of the content of longanin to the content of cis-trans abscisic acid in the honey to be tested is greater than 1.1, the honey to be tested is determined to be Thai longan honey.

5. A fingerprint spectrum of longan honey, characterized in that, The longan honey was prepared by high-performance liquid chromatography (HPLC). In the HPLC fingerprint of the longan honey, the retention time of the characteristic peak of longanin was 67.45 min, the retention time of the characteristic peaks of trans- and trans-abscisic acid was 60.32 min, and the retention time of the characteristic peaks of cis- and trans-abscisic acid was 68.84 min. The longanin has the structure shown in Formula 1. Formula 1.

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