Application of group of volatile compounds in identification of Pingquan shiitake mushrooms and method for identifying Pingquan shiitake mushrooms

Abstract

The invention belongs to the technical field of analytical chemistry, and particularly relates to application of a group of volatile compounds in identification of Pingquan shiitake mushrooms and a method for identifying the Pingquan shiitake mushrooms. The volatile compounds include 2, 2, 4, 6, 6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2, 3, 5-trithiahexane, and tris (methylthio) methane. By analyzing the content of volatile compounds in shiitake mushroom products with different geographical indications, the content of the volatile compounds in the Pingquan shiitake mushroom is obviously higher than that of the volatile compounds in shiitake mushroom products with other geographical indications, and 2, 3, 5-trithiahexane is determined as the biomarker of the Pingquan shiitake mushroom, so that whether the shiitake mushroom is the Pingquan shiitake mushroom or not can be accurately and quickly identified; technical means are provided for defining geographically indicated product sources and ensuring public clear consumption. The method for identifying the Pingquan shiitake mushrooms is provided for the first time, the Pingquan shiitake mushrooms can be accurately distinguished from other shiitake mushrooms, and technical support is provided for mining and identifying characteristic components of fungus geographical indication products.

Description

Technical Field

[0001] The invention belongs to the technical field of analytical chemistry, and particularly relates to application of a group of volatile compounds in identifying Hiraizumi shiitake mushrooms and a method for identifying Hiraizumi shiitake mushrooms. Background Art

[0002] Shiitake mushrooms (Lentinula edodes) are commercially cultivated edible fungi rich in carbohydrates, iron, calcium, manganese, phosphorus, and vitamins, offering both edible and medicinal value. my country has a history of over 800 years of cultivated shiitake mushrooms, resulting in several designated geographical indication production areas, including Pingquan in Hebei, Xixia in Henan, Qingyuan in Zhejiang, Suizhou in Hubei, and Shangluo in Shaanxi.

[0003] Due to differences in microclimate, cultivation methods, growing media, and water sources, each shiitake mushroom-producing region typically has its own unique quality characteristics. Uncovering the unique qualities of each region's shiitake mushrooms and tracing their origins have become key areas of focus for brand building. Current research on the origin traceability of shiitake mushrooms with geographical indications focuses on digital management of the entire supply chain through the integration of multiple technologies. The core approach is to achieve full transparency in the production process through blockchain, the Internet of Things, and big data platforms. Finding the identification markers for geographical indication products provides direct evidence for origin traceability, so there is an urgent need to identify intrinsic compounds in shiitake mushrooms to distinguish their origins, particularly to verify whether the tested mushrooms are Pingquan mushrooms. Summary of the Invention

[0004] In light of this, the present invention aims to provide a method for identifying Hiraizumi shiitake mushrooms using a set of volatile compounds. This method accurately and rapidly determines whether a shiitake mushroom sample is Hiraizumi shiitake mushroom based on the types of volatile compounds detected and the 2,3,5-trithiahexane content.

[0005] The invention provides an application of a group of volatile compounds in identifying Hiraizumi shiitake mushrooms. The volatile compounds include 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane.

[0006] The present invention provides a method for identifying Hiraizumi shiitake mushrooms, comprising the following steps:

[0007] Mixing the tested mushrooms with a saturated sodium chloride solution and performing headspace gas chromatography-mass spectrometry to obtain the content of volatile compounds in the tested mushrooms;

[0008] If 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane are detected in the shiitake mushroom to be tested, and the content of 2,3,5-trithiahexane is above 21.6 μg / kg, the shiitake mushroom to be tested is Hiraizumi shiitake;

[0009] The headspace gas chromatography conditions for the headspace gas chromatography-mass spectrometry detection include:

[0010] Headspace extraction temperature: 40-60°C; polar column; temperature program: initial temperature 40°C and hold for 2 min, then increase to 130°C at a rate of 2°C / min, then increase to 220°C at a rate of 5°C / min and hold for 5 min; carrier gas: helium, flow rate: 0.8-1.2 mL / min; injection port temperature: 240-260°C; splitless injection;

[0011] The mass spectrometry conditions of the headspace gas chromatography-mass spectrometry detection include:

[0012] Transfer line temperature: 230-250°C; ion source temperature: 220-240°C; quadrupole temperature: 140-160°C; ionization mode: EI; ionization energy: 70 eV; scanning mode: full scan, scanning range: 30-350 amu.

[0013] Preferably, the ratio of the shiitake mushroom to be tested to the saturated sodium chloride solution is 0.5 g: (4-6) mL.

[0014] Preferably, an internal standard is added when the shiitake mushroom to be tested is mixed with a saturated sodium chloride solution, and the internal standard is 1,2-dichlorobenzene.

[0015] Preferably, the shiitake mushrooms to be tested include one or more of Pingquan shiitake mushrooms, Xixia shiitake mushrooms, Qingyuan shiitake mushrooms, Suizhou shiitake mushrooms and Shangluo shiitake mushrooms.

[0016] Preferably, the shiitake mushroom to be tested is used in the form of powder, and the powder is the undersize portion of a 40-mesh sieve.

[0017] Preferably, the headspace extraction temperature is 45-55° C., and the time is 30-50 min.

[0018] Preferably, the desorption temperature after the headspace extraction is 240-260° C., and the desorption time is 0.5-1.5 min.

[0019] Preferably, the flow rate is 0.9-1.1 mL / min; the injection port temperature is 245-255°C.

[0020] Preferably, the polar chromatographic column is an HP-INNOWAX chromatographic column with a specification of 60m×0.25mm×0.25μm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides the use of a group of volatile compounds for identifying Hiraizumi shiitake mushrooms. These volatile compounds include 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane, and tris(methylthio)methane. Based on the types of volatile compounds detected in the shiitake mushroom samples and the content of the biomarker 2,3,5-trithiahexane, this method can accurately and rapidly identify whether a shiitake mushroom sample is Hiraizumi shiitake. This provides a technical means to reduce adulteration, clarify the source of geographical indication products, and ensure public understanding of consumption.

[0023] The present invention provides a method for identifying Pingquan shiitake mushrooms for the first time, which can accurately distinguish Pingquan shiitake mushrooms from other shiitake mushrooms (such as Xixia shiitake mushrooms, Suizhou shiitake mushrooms, Qingyuan shiitake mushrooms, and Shangluo shiitake mushrooms), providing technical support for the mining and identification of characteristic components of fungal geographical indication products. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a principal component analysis score graph of the GC-MS analysis data of five geographical indication shiitake mushroom products in the embodiment;

[0026] Figure 2 This is an orthogonal partial least squares discriminant analysis score graph of the GC-MS analysis data of the five geographical indication shiitake mushroom products in the embodiment;

[0027] Figure 3 This is an orthogonal partial least squares discriminant analysis permutation test diagram of the GC-MS analysis data of the five geographical indication shiitake mushroom products in the embodiment;

[0028] Figure 4 This is an S-plot scatter plot of the GC-MS data of the five geographical indication shiitake mushroom products in the embodiment based on OPLS-DA analysis;

[0029] Figures 5 to 8 : is a line graph showing the relative content distribution of seven characteristic volatile components in the Pingquan mushroom in the test samples in the embodiment, wherein Figure 5 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran and tris(methylthio)methane, Figure 6For dimethyl disulfide and dimethyl trisulfide, Figure 7 is 1,2,4-trithiocyclopentane, Figure 8 It is 2,3,5-trithiahexane;

[0030] Figure 9 This is a regional content distribution diagram of 2,3,5-trisulfide in five geographical indication shiitake mushroom samples in the example. DETAILED DESCRIPTION

[0031] The invention provides an application of a group of volatile compounds in identifying Hiraizumi shiitake mushrooms. The volatile compounds include 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane.

[0032] The present invention can accurately and quickly determine whether a shiitake mushroom sample to be tested is Hiraizumi shiitake mushroom according to whether 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane are detected in the shiitake mushroom to be tested, as well as the content of 2,3,5-trithiahexane.

[0033] The present invention provides a method for identifying Hiraizumi shiitake mushrooms, comprising the following steps:

[0034] Mixing the tested mushrooms with a saturated sodium chloride solution and performing headspace gas chromatography-mass spectrometry to obtain the content of volatile compounds in the tested mushrooms;

[0035] If 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane are detected in the shiitake mushroom to be tested, and the content of 2,3,5-trithiahexane is above 21.6 μg / kg, the shiitake mushroom to be tested is Hiraizumi shiitake;

[0036] The headspace gas chromatography conditions for the headspace gas chromatography-mass spectrometry detection include:

[0037] Headspace extraction temperature: 40-60°C; polar column; temperature program: initial temperature 40°C and hold for 2 min, then increase to 130°C at a rate of 2°C / min, then increase to 220°C at a rate of 5°C / min and hold for 5 min; carrier gas: helium, flow rate: 0.8-1.2 mL / min; injection port temperature: 240-260°C; splitless injection;

[0038] The mass spectrometry conditions of the headspace gas chromatography-mass spectrometry detection include:

[0039] Transfer line temperature: 230-250°C; ion source temperature: 220-240°C; quadrupole temperature: 140-160°C; ionization mode: EI; ionization energy: 70 eV; scanning mode: full scan, scanning range: 30-350 amu.

[0040] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0041] The method comprises mixing a shiitake mushroom to be tested with a saturated sodium chloride solution and performing headspace gas chromatography-mass spectrometry detection to obtain the content of volatile compounds in the shiitake mushroom to be tested; the volatile compounds include 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane.

[0042] In the present invention, the shiitake mushrooms to be tested include one or more of Pingquan shiitake mushrooms, Xixia shiitake mushrooms, Qingyuan shiitake mushrooms, Suizhou shiitake mushrooms and Shangluo shiitake mushrooms.

[0043] In the present invention, the shiitake mushroom to be tested is preferably a dried shiitake mushroom fruiting body, and the shiitake mushroom to be tested is preferably used in the form of powder, and the powder is preferably the undersize portion of a 40-mesh sieve.

[0044] In the present invention, the ratio of the shiitake mushroom to be tested to the saturated sodium chloride solution is preferably 0.5 g:(4-6) mL, specifically 0.5 g:5 mL. The present invention utilizes the "salting-out effect" by adding the saturated sodium chloride solution to increase the concentration of volatile components in the headspace, thereby improving detection sensitivity.

[0045] In the present invention, an internal standard is preferably added when the shiitake mushroom to be tested is mixed with a saturated sodium chloride solution. The internal standard is preferably 1,2-dichlorobenzene. The 1,2-dichlorobenzene is preferably used in the form of a 1,2-dichlorobenzyl alcohol solution. The concentration of the 1,2-dichlorobenzyl alcohol solution is preferably 100 mg / L. The volume ratio of the internal standard solution to the saturated sodium chloride solution is preferably 0.01:5.

[0046] In the present invention, the headspace extraction preferably uses an SPME extraction head, and the SPME extraction head is preferably 50 / 30 μm DVB / CAR / PDMS, manufactured by Merck, Germany.

[0047] In the present invention, the headspace extraction temperature is preferably 45-55°C, specifically 50°C, and the time is preferably 30-50 min, specifically 40 min; the desorption temperature after the headspace extraction is preferably 240-260°C, specifically 250°C, and the desorption time is preferably 0.5-1.5 min, specifically 1 min.

[0048] In the present invention, the polar chromatographic column is preferably an HP-INNOWAX chromatographic column, and the specification is preferably 60m×0.25mm×0.25μm.

[0049] In the present invention, the flow rate is preferably 0.9-1.1 mL / min, specifically 1 mL / min; the injection port temperature is preferably 245-255° C., specifically 250° C. The headspace gas chromatography conditions preferably further include: a solvent delay of 3 min.

[0050] In the present invention, the transfer line temperature is preferably 240°C; the ion source temperature is preferably 230°C; and the quadrupole temperature is preferably 150°C.

[0051] The present invention has no particular requirements for the method for determining the content of volatile compounds in the tested shiitake mushrooms. Specifically, the internal standard method can be used to determine the relative content of the volatile compounds in the tested shiitake mushrooms by comparing the obtained peak area with the peak area of ​​the internal standard compound. In a specific embodiment of the present invention, 1,2-dichlorobenzene is used as the internal standard for quantitative analysis, and the relative content of the volatile compounds is calculated using the internal standard method according to the following formula:

[0052] Xj=(Ci×Vi×Sj / Si) / m

[0053] Where: Xj—relative content of volatile compounds (μg / kg); Ci—internal standard concentration (mg / L); Vi—internal standard volume (μL); Sj—volatile compound peak area; Si—internal standard peak area; m—sample weight (g).

[0054] In the present invention, when the shiitake mushroom to be tested is Hiraizumi shiitake mushroom, the content of 2,3,5-trithiahexane is preferably 21.6 to 75.4 μg / kg.

[0055] To further illustrate the present invention, the application of a group of volatile compounds provided by the present invention in identifying Hiraizumi shiitake mushrooms and the method for identifying Hiraizumi shiitake mushrooms are described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] 1. Sample processing

[0058] The dried shiitake mushroom fruiting bodies were provided by cooperatives in Pingquan, Xixia, Qingyuan, Suizhou, and Shangluo, respectively, with 15, 15, 10, 10, and 10 samples, for a total of 60 samples. The dried shiitake mushroom samples were crushed, passed through a 40-mesh sieve, and stored in a sealed container at room temperature until ready for use.

[0059] Headspace solid-phase microextraction (HSSPM) was used to extract the volatile components from Lentinus edodes. Weigh 0.50 g of Lentinus edodes powder into a 20 mL headspace vial. Then, add 10 μL of 1,2-dichlorobenzyl alcohol solution (100 mg / L) and 5 mL of saturated sodium chloride solution. The vial was sealed with a cap.

[0060] 2. Instrument detection

[0061] The instrument used was a gas chromatography-mass spectrometer (7890A-5975C, Agilent Technologies, Santa Clara, CA, USA) equipped with a polar chromatographic column (HP-INNOWAX, 60 m × 0.25 mm × 0.25 μm, Agilent). An SPME tip (50 / 30 μm DVB / CAR / PDMS, Merck, Germany) was inserted into the headspace vial containing the sample to be tested. Each sample was extracted at 50°C for 40 minutes. The tip was then inserted into the GC-MS inlet and desorbed at 250°C for 1 minute.

[0062] GC conditions: The initial temperature was set at 40°C and held for 2 minutes. The temperature was then increased at a rate of 2°C / min to 130°C, then increased to 220°C at a rate of 5°C / min and held for 5 minutes. 99.999% pure helium was used as the carrier gas at a flow rate of 1.00 mL / min, with a solvent delay of 3 minutes. Splitless mode was used for each injection.

[0063] MS conditions: electron impact (EI) mode, electron energy 70 eV, ion source temperature 230°C, transfer line temperature 240°C, full scan mode at a quadrupole temperature of 150°C, and a scan range of 30–350 amu.

[0064] 3. Qualitative and quantitative analysis

[0065] 1) Qualitative Analysis: First, the retention time and mass spectrum information were compared with the NIST17 database to preliminarily identify the volatile compounds. The retention index (RI) of the n-alkanes was then calculated using the following formula and compared with the RI in the LRI database (http: / / www.odour.org.uk / lriindex.html) for further qualitative analysis.

[0066] RI=100×(n+(Ti-Tn) / (T(n+1)-Tn),

[0067] Where: n—the number of carbon atoms in normal alkanes; Ti—the retention time of the detected compound in the sample; Tn and Tn+1—the retention time of alkanes around the target compound (Tn <Ti<Tn+1)。

[0068] 2) Quantitative analysis: Using 1,2-dichlorobenzene as the internal standard, the relative content of volatile compounds was calculated using the internal standard method according to the following formula:

[0069] Xj=(Ci×Vi×Sj / Si) / m,

[0070] Where: Xj—relative content of volatile compounds (μg / kg); Ci—internal standard concentration (mg / L); Vi—internal standard volume (μL); Sj—volatile compound peak area; Si—internal standard peak area; m—sample weight (g).

[0071] 4. Data processing

[0072] Data were imported into AntDAS-GCMS software for multi-sample analysis. Incomplete peaks were deleted using Microsoft Excel. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were performed using SIMCA 14.1 software.

[0073] 5. Results and Discussion

[0074] 1) Identification of volatile components

[0075] A total of 145 volatile compounds were identified from samples of five geographical indication Lentinus edodes (Pingquan, Xixia, Qingyuan, Suizhou, and Shangluo). These compounds included 25 alcohols, 27 aldehydes, 17 ketones, 19 esters, 32 sulfur-containing compounds and heterocyclic compounds, and 25 other compounds. Table 1 shows the qualitative and quantitative results of the 145 volatile compounds in Pingquan Lentinus edodes.

[0076] Table 1 Volatile components in Shiitake mushroom identified by GC-MS

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] 2) Identification of different volatile components between Pingquan Shiitake mushroom and four other geographical indication Shiitake mushroom products

[0083] First, the principal component analysis method was used to confirm whether Pingquan mushrooms were different from the other four geographical indication mushroom products. Figure 1 The principal component analysis score diagram of the GC-MS analysis data of five geographical indication mushroom products. PQ, QY, SZ, XX, and SL represent the mushrooms from Pingquan, Qingyuan, Suizhou, Xixia, and Shangluo, respectively. Figure 1 It can be seen that Pingquan shiitake mushrooms (green dots in the red circle) can be effectively distinguished from other shiitake mushroom products. The variance contribution rates of the first and second principal components are 44.2% and 14.4%, respectively, indicating that Pingquan shiitake mushrooms have characteristic volatile substances that are different from shiitake mushrooms from other regions.

[0084] Then, orthogonal partial least squares discriminant analysis (OPLS-DA) was used to further analyze the characteristic volatile compounds of Shiitake mushroom samples. Figure 2 and Figure 3 The OPLS-DA analysis score diagram and permutation test result diagram of the GC-MS analysis data of 5 kinds of geographical indication mushroom products are shown in the figure. Figure 2 PQ represents the data of Pingquan shiitake mushroom, and OM represents the data of four other geographical indication shiitake mushroom products. It can be seen that the Pingquan shiitake mushroom sample data can be clearly distinguished from other geographical indication shiitake mushroom products. Figure 3 R2 represents the goodness of fit of the original model, Q2 represents the predictive ability of the original model, and the permutation test results show that the difference between the two is valid.

[0085] The OPLS-DA analysis data of the samples were displayed in an S-plot scatter plot, and the variables were screened based on the variable weight value (VIP>1), difference multiple (FC≥2 or ≤0.5), t-test (p<0.05), etc., to identify the characteristic volatile compounds in Pingquan mushrooms. Figure 4 This is an S-plot scatter plot of the GC-MS analysis data for five geographical indication shiitake mushroom products. All points in the scatter plot represent the 145 identified compounds. Negative values ​​on the horizontal axis correspond to compounds with higher concentrations in Pingquan shiitake mushroom, while positive values ​​correspond to compounds with higher concentrations in other geographical indication shiitake mushroom products. Points further to the sides indicate greater differences. Further analysis indicates that the characteristic volatile compounds of Pingquan shiitake mushrooms are marked with red dots on the left, while the characteristic volatile compounds of other geographical indication shiitake mushroom products compared to Pingquan shiitake mushrooms are represented by blue dots on the right. Green dots represent the remaining compounds with minimal differences. The characteristic volatile compounds of Pingquan shiitake mushrooms are organized separately, as shown in Table 2. These seven compounds are the characteristic volatile compounds of Pingquan shiitake mushrooms and can be used as basic indicators for constructing a fingerprint of Pingquan shiitake mushrooms and tracing their origin.

[0086] Table 2 Characteristic volatile components of Shiitake mushrooms

[0087]

[0088] A specific analysis of the contents of the seven compounds in Table 2 in the five geographical indication shiitake mushroom products showed that the contents of Pingquan shiitake mushroom were more than five times higher than those of other geographical indication shiitake mushroom products. Among these compounds, the contents of 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane, and tri(methylthio)methane all differed by more than 10 times. Among the five compounds with a content difference of more than 10 times, 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, and tri(methylthio)methane were present at levels of around 10 μg / kg and were also detected in other geographical indication shiitake mushroom products. Therefore, they should not be used as identification markers alone. The average contents of dimethyl disulfide and 2,3,5-trithiahexane were above 50 μg / kg. In particular, the average detection level of 2,3,5-trithiahexane in other geographical indication shiitake mushroom products was less than 0.1 μg / kg, making it suitable for use as a biomarker for Pingquan shiitake mushroom.

[0089] Figures 5 to 8 This line graph shows the relative content distribution of characteristic volatile components of Pingquan shiitake mushrooms in the tested samples. The vertical axis represents the average score, and the horizontal axis indicates the sample source and number. The sample difference distribution chart clearly shows that 2,3,5-trithiahexane was only detected in Pingquan shiitake samples; no significant quantitative values ​​were found for other geographical indication shiitake mushroom products. Figure 9 The results show the overall differences in 2,3,5-trithiazane levels among samples from different regions. The lowest 2,3,5-trithiazane level in Pingquan Shiitake mushroom samples was 6.0 μg / kg, and the highest was 220.0 μg / kg. The overall average level was 60.6 μg / kg, with a median of 39.5 μg / kg and a 25% to 75% confidence interval of 21.6 μg / kg to 75.4 μg / kg. The levels of other geographical indication Shiitake mushroom products were all zero. Therefore, the present invention further utilizes the detection and quantification of 2,3,5-trithiazane as a characteristic indicator for identifying Pingquan Shiitake mushrooms, which is more effective.

[0090] Although the above embodiments provide a detailed description of the present invention, they are only part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. Application of a group of volatile compounds in identifying Shiitake mushrooms, characterized in that: The volatile compounds include 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane, and tris(methylthio)methane.

2. A method for identifying Hiraizumi shiitake mushrooms, characterized in that: The following steps are involved: Mixing the tested mushrooms with a saturated sodium chloride solution and performing headspace gas chromatography-mass spectrometry to obtain the content of volatile compounds in the tested mushrooms; If 2,2,4,6,6-pentamethylheptane, 2-ethyl-5-methylfuran, dimethyl disulfide, 2,3,5-trithiahexane and tris(methylthio)methane are detected in the shiitake mushroom to be tested, and the content of 2,3,5-trithiahexane is above 21.6 μg / kg, the shiitake mushroom to be tested is Hiraizumi shiitake; The headspace gas chromatography conditions for the headspace gas chromatography-mass spectrometry detection include: Headspace extraction temperature: 40-60°C; polar column; temperature program: initial temperature 40°C and hold for 2 min, then increase to 130°C at a rate of 2°C / min, then increase to 220°C at a rate of 5°C / min and hold for 5 min; carrier gas: helium, flow rate: 0.8-1.2 mL / min; injection port temperature: 240-260°C; splitless injection; The mass spectrometry conditions of the headspace gas chromatography-mass spectrometry detection include: Transfer line temperature: 230-250°C; ion source temperature: 220-240°C; quadrupole temperature: 140-160°C; ionization mode: EI; ionization energy: 70 eV; scanning mode: full scan, scanning range: 30-350 amu.

3. The method for identifying Hiraizumi mushrooms according to claim 2, wherein: The dosage ratio of the shiitake mushroom to be tested to the saturated sodium chloride solution is 0.5 g: (4-6) mL.

4. The method for identifying Hiraizumi shiitake mushrooms according to claim 2 or 3, wherein: When the shiitake mushrooms to be tested are mixed with a saturated sodium chloride solution, an internal standard is added, and the internal standard is 1,2-dichlorobenzene.

5. The method for identifying Hiraizumi mushrooms according to claim 2, wherein: The shiitake mushrooms to be tested include one or more of Pingquan shiitake mushrooms, Xixia shiitake mushrooms, Qingyuan shiitake mushrooms, Suizhou shiitake mushrooms and Shangluo shiitake mushrooms.

6. The method for identifying Hiraizumi shiitake mushrooms according to claim 2 or 5, wherein: The shiitake mushrooms to be tested are used in the form of powder, which is the undersize portion of a 40-mesh sieve.

7. The method for identifying Hiraizumi shiitake mushrooms according to claim 2, wherein: The headspace extraction temperature is 45-55° C., and the time is 30-50 minutes.

8. The method for identifying Hiraizumi mushrooms according to claim 7, wherein: The desorption temperature after the headspace extraction is 240-260° C., and the desorption time is 0.5-1.5 min.

9. The method for identifying Hiraizumi shiitake mushrooms according to claim 2, wherein: The flow rate is 0.9-1.1 mL / min; the injection port temperature is 245-255°C.

10. The method for identifying Hiraizumi shiitake mushrooms according to claim 2, wherein: The polar chromatographic column is an HP-INNOWAX chromatographic column with a specification of 60m×0.25mm×0.25μm.

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