Method for identifying the origin of early-maturing pear based on GC-IMS analysis of characteristic odor substances

Abstract

The application discloses a method for identifying the origin of early mature sand pear based on GC-IMS analysis of characteristic odor substances. The application analyzes sand pear samples from different origins based on GC-IMS technology, obtains characteristic volatile markers for determining sand pear samples from different regions according to the differences in the types and relative contents of volatile components, combines the VIP value and the ROAV value, and identifies the origin of early mature sand pear according to the indexes of the characteristic volatile markers. The application collects and analyzes complex aroma substances in sand pear samples from different origins by using the GC-IMS technology, provides characteristic volatile markers for sand pear samples from different origins, and realizes the origin tracing of sand pear according to the indexes of the characteristic volatile markers of sand pear samples from different origins.

Description

Technical Field

[0001] This invention relates to a method for rapidly identifying the origin of early-maturing sand pears based on gas chromatography-ion mobility spectrometry (GC-IMS) analysis of characteristic volatile odor substances, belonging to the field of fruit traceability and detection technology. Background Technology

[0002] Pears are an important fruit crop in my country, and their flavor, quality, and market price are often closely linked to specific production areas. Early-maturing pears in my country are harvested annually from June to July. Early-maturing sandy pears are scarce and command high prices, but problems such as variety confusion and falsified origins exist in the sales chain, harming consumer rights and brand reputation while disrupting market order. Therefore, establishing reliable pear origin identification techniques is beneficial for protecting production areas, enhancing consumer confidence in the products, and has significant economic and legal implications.

[0003] Aroma is one of the most important sensory attributes of fruit. Its composition and content are influenced by multiple factors, including variety, local ecological environment (climate, soil), and cultivation, forming a unique "origin flavor fingerprint." Flavor analysis technology, through qualitative and quantitative analysis of volatile substances, forms aroma fingerprints and flavor profiles, providing accurate and intuitive information for tracing the origin of fruits. However, existing sensory evaluation or conventional chromatographic methods are insufficient for quickly capturing and analyzing the overall differences in this complex volatile aroma.

[0004] GC-IMS is a newly emerging technology for the detection of volatile organic compounds (VOCs) in recent years. It is widely used in environmental monitoring, medical diagnostics, and food odor determination, offering advantages such as high sensitivity and simple sample processing. However, existing methods primarily target the aroma fingerprint and flavor profile of single pear varieties, failing to systematically screen specific volatile markers with stable correlations to origin from a large number of characteristic peaks. This results in limited generalization ability of the discrimination results. Furthermore, the lack of quantitative or semi-quantitative discrimination models based on characteristic markers and the absence of clear origin discrimination thresholds mean that practical applications rely on subjective interpretation of spectra by operators, hindering the standardization and automation of origin traceability. Therefore, there is an urgent need to develop an origin traceability method for early-maturing sand pears, based on GC-IMS technology and combined with specific volatile marker screening and sensory verification, to address the shortcomings in the accuracy, stability, and practicality of existing technologies. Summary of the Invention

[0005] Objective of the Invention: To address the aforementioned problems, this application provides a method for identifying the origin of early-maturing sand pears based on GC-IMS analysis of characteristic odor substances. This method establishes a unique volatile odor substance profile for pears from different origins, screening for characteristic volatile organic compounds. Based on these characteristic volatile organic compounds, the content of four components—butyraldehyde monomer, hexanal dimer, 2-methylbutyraldehyde monomer, and 2-methylbutyraldehyde dimer—can be obtained, enabling rapid identification of the origin of early-maturing sand pears.

[0006] Technical Solution: The present invention provides a method for identifying the origin of early-maturing sand pears based on GC-IMS analysis of characteristic odor substances, characterized by comprising the following steps:

[0007] (A1) GC-IMS analysis was performed on early-maturing sand pear samples from different origins to obtain volatile organic compound (VOC) detection data in early-maturing sand pears;

[0008] (A2) Analyze the differences in volatile organic compound content, VIP value, and ROAV value to screen characteristic volatile biomarkers;

[0009] (A3) Determine the relative content threshold of characteristic volatile markers as the identification standard based on their relative content;

[0010] (A4) The place of origin is confirmed by comparing the relative content values ​​of characteristic volatile markers in the early-maturing sand pear sample with the relative content threshold obtained in step (A3).

[0011] Further, in step (A1), the headspace gas chromatography (GC) conditions are as follows: chromatographic separation is performed using an MXT-5 capillary column (15m × 0.53 mm, 1 μm), with an initial column temperature of 60℃. 2 ± 0.2 g of early-ripening sand pear sample is incubated at 40°C for 15 min. The injection temperature is 85℃, the injection volume is 0.5 mL, and high-purity nitrogen (purity ≥99.99%) is used as the carrier gas. The program is set as follows: 0–2 min, 2 mL / min. -1 ; 2–8 min, 10 mL·min -1 ; 8–20 min, 100 mL·min -1 Ion mobility spectrometry (IMS) conditions: high-purity nitrogen gas (purity ≥99.999%) was used for drift gas; the drift gas flow rate was 150 mL / min. -1 Detector temperature: 45 ℃; Drift tube length: 9.8 cm; Linear voltage inside the tube: 500 V·cm -1 The sample analysis time is 30 min.

[0012] Further, in step (1), the volatile organic compounds include (E)-2-heptenal, (E,E)-2,4-hexadienal, hexanal, 2-hexenal, 2-methylbutanal, butanal, octanal, pentanal, trans-2-pentenal, (Z)-3-hexenol acetate, ethyl acetate, ethyl 2-methylpropionate, ethyl propionate, hexyl acetate, (Z)-2-penten-1-ol, 1-hexanol, 1-pentanol, 1-penten-3-ol, 1-propanol, 2-hexanol, acetic acid, 3-pentanone, 1-penten-3-one, 3-hydroxy-2-butanone, and β-pinene, wherein hexanal, 2-hexenal, 2-methylbutanal, butanal, pentanal, ethyl acetate, ethyl 2-methylpropionate, ethyl propionate, hexyl acetate, 1-hexanol, 3-pentanone, and 1-penten-3-one comprise monomers and dimers.

[0013] Furthermore, in step (A2), the screening of volatile organic compounds includes the following steps:

[0014] (B1) One-way ANOVA was used to analyze the significance of the content difference (P).

[0015] (B2) Partial least squares discriminant analysis (PLS-DA) was used to calculate the variable importance projection values ​​(VIPs);

[0016] (B3) Calculate the relative aroma activity value (ROAV) by combining volatile organic compounds with the odor activity threshold;

[0017] (B4) Select volatile organic compounds that simultaneously meet the following criteria: content difference P < 0.05, VIP value > 1, and ROAV value > 1 as characteristic volatile markers.

[0018] Furthermore, the characteristic volatile organic compounds include 2-methylbutyraldehyde monomer, 2-methylbutyraldehyde dimer, hexanal dimer, and butyraldehyde monomer.

[0019] Furthermore, the different production areas include Zhenjiang, Suqian, Changzhou, Xiangyang, and Nantong.

[0020] Furthermore, the early-maturing sand pear is named 'Su Cui No. 1' or 'Cui Guan'.

[0021] Furthermore, the origin of the 'Su Cui No. 1' early-maturing sand pear is determined according to the following rules:

[0022] If the content of hexanal dimer is ≥33.0% and the content of 2-methylbutyral dimer is ≤0.5%, the place of origin is determined to be Nantong.

[0023] If the 2-methylbutyraldehyde dimer is ≥11.5% and the butyraldehyde monomer is ≥3.7%, the place of origin is determined to be Suqian.

[0024] If the 2-methylbutyraldehyde monomer content is ≥5.0% and the 2-methylbutyraldehyde dimer content is ≥9.5%, the place of origin is determined to be Xiangyang.

[0025] If the content of hexanal dimer is ≥31.0% and the content of 2-methylbutyraldehyde dimer is ≤7.0%, the place of origin is determined to be Zhenjiang.

[0026] Furthermore, the origin of the "Cuiguan" early-maturing sand pear is determined according to the following rules:

[0027] If the 2-methylbutyraldehyde dimer is ≥12.5% ​​and the butyraldehyde monomer is ≥4.0%, the place of origin is determined to be Xiangyang.

[0028] If the 2-methylbutyraldehyde monomer content is ≥5.8% and the hexanal dimer content is ≤28.0%, the place of origin is determined to be Changzhou.

[0029] If the content of hexanal dimer is ≥32.0% and the content of 2-methylbutyraldehyde dimer is ≥8.0%, the place of origin is determined to be Suqian.

[0030] If the 2-methylbutyraldehyde dimer is ≤2.5% and the butyraldehyde monomer is ≤1.5%, the place of origin is determined to be Zhenjiang.

[0031] If the hexanal dimer is 29.5%~31.5% and the 2-methylbutyraldehyde dimer is 5.5%~6.5%, the place of origin is determined to be Nantong.

[0032] Furthermore, the relative content (%) is the percentage of the peak area of ​​each volatile organic compound to the total peak area, and the preset threshold of the origin discrimination rule is determined based on the mean ± standard deviation of three parallel samples from each origin.

[0033] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0034] This invention, based on GC-IMS technology, features simple sample pretreatment and rapid analysis, obtaining volatile organic compound fingerprints within 30 minutes, enabling rapid and efficient screening of batch samples. By constructing differential spectral mapping and chemometric models, it allows for intuitive comparison of flavor differences between samples from different origins, ensuring accurate, objective, quantifiable, and reproducible results. This invention directly analyzes volatile substances related to sensory flavor, organically combining origin identification with quality evaluation. It can be widely applied to the traceability of high-value early-maturing sand pears, providing a powerful technical tool for protecting geographical indication products and combating counterfeiting. Attached Figure Description

[0035] Figure 1 GC-IMS 3D images of early-maturing sand pears from different origins;

[0036] Figure 2 A graph showing the significant differences in volatile aroma compounds of early-maturing sand pears from different production areas;

[0037] Figure 3 VIP diagram of volatile aroma compounds in early-maturing sand pears from different origins. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments.

[0040] The early-maturing sand pear varieties 'Su Cui No. 1' and 'Cui Guan' mentioned in the examples are both commercially available varieties.

[0041] Example 1

[0042] I. Collection of Early-maturing Sand Pear Samples from Different Origins and Analysis of Volatile Aroma Components

[0043] 1. Instrument: FlavorSpec® Gas Chromatography-Ion Mobility Spectrometer (GC-IMS);

[0044] 2. Pear fruit sample collection and pretreatment: From June to August 2024, five sampling points were set up in each orchard of 'Sucui No. 1' and 'Cuiguan' pears from five production areas in Jiangsu Province (Zhenjiang, Suqian, Changzhou, Nantong) and Sichuan Province (Xiangyang). Pears of the same growth stage were selected, and six fruits were randomly selected from different parts (top, middle, bottom) of each pear tree, for a total of 30 fruits as a batch. The fruits were immediately placed in a foam box with ice packs for preservation and brought back to the laboratory. Undamaged pears with similar color and size were selected, then cored, cut into pieces, flash-frozen in liquid nitrogen, and stored in a -80 ℃ freezer for testing.

[0045] 3. Determination of volatile aroma components: Weigh 2 g of pear fruit sample preserved in liquid nitrogen, grind it, and place it in a 20 mL headspace vial. Incubate at 40 ℃ for 15 min at a rotation speed of 500 r·min. -1 The headspace injection needle temperature was 85 ℃; the injection volume was 500 µL. Gas chromatography (GC) conditions: Chromatographic separation was performed using an MXT-5 capillary column (15 m × 0.53 mm, 1 μm), with an initial column temperature of 60 ℃. 2 ± 0.2 g of early-ripening sand pear sample was incubated at 40°C for 15 min. The injection temperature was 85 ℃, and the injection volume was 0.5 mL. High-purity nitrogen (purity ≥99.99%) was used as the carrier gas. The program was set as follows: 0–2 min, 2 mL / min. -1 ; 2–8 min, 10 mL·min -1 ; 8–20 min, 100 mL·min -1Ion mobility spectrometry (IMS) conditions: high-purity nitrogen gas (purity ≥99.999%) was used for drift gas; the drift gas flow rate was 150 mL / min. -1 Detector temperature: 45 ℃; Drift tube length: 9.8 cm; Linear voltage inside the tube: 500 V·cm -1 The analysis time for the samples was 30 min. Calibration curves for retention time (RT) and retention index (RI) were established using a mixture of C4-C9 normal ketone standards (butanone, pentanone, hexanone, heptanone, octanone, and nonanone).

[0046] 4. Volatile Aroma Component Analysis: The Reporter module built into the GC-IMS software VOCal was used to plot the three-dimensional ion migration spectra of volatile aroma components in the five early-maturing sand pear samples from different origins. Figure 1 As shown, the x-axis, y-axis, and z-axis represent migration time, retention time, and ion peak intensity, respectively, with red indicating relatively high signal peak intensity. The 'Su Cui 1' ions from the five producing areas of Zhenjiang, Suqian, Changzhou, Nantong, and Xiangyang, Sichuan, are designated ZJ-1, SQ-1, CZ-1, NT-1, and XY-1, respectively; the 'Cui Guan' ions from the same five producing areas are designated ZJ-2, SQ-2, CZ-2, NT-2, and XY-2, respectively. Figure 1 It can be seen that the volatile aroma components of the five early-maturing sand pear samples 'Su Cui No. 1' and 'Cui Guan' from different origins vary greatly in terms of composition and content.

[0047] 5. Qualitative Analysis of Volatile Aroma Components: The volatile aroma components were qualitatively analyzed using the NIST and IMS databases built into the GC-IMS software VOCal, based on RI values ​​and drift times. A total of 39 volatile aroma components were identified in 'Su Cui No. 1' and 'Cui Guan Pear' from the aforementioned five origins, as detailed in Table 1. Among these, some compounds with high proton affinity formed dimers when ions passed through the drift cell. The monomers and dimers of these compounds are represented by M / D, where M represents the monomer and D represents the dimer.

[0048] Table 1. Main volatile aroma components in early-maturing sand pears from different origins

[0049]

[0050]

[0051] II. Screening of characteristic aroma markers for early-maturing sand pears from different origins

[0052] 1. Analysis of significant differences in volatile aroma components among different production areas: The original peak area data of each volatile aroma component in Table 1 were summed and normalized. One-way ANOVA was used to compare the differences in volatile content of 'Su Cui No. 1' and 'Cui Guan Pear' from the five production areas, with P < 0.05 as the significance standard. The results are as follows: Figure 2 As shown, the 39 volatile aroma components in 'Su Cui No. 1' showed significant differences across different production areas, and the 38 volatile aroma components in 'Cui Guan Pear', excluding hexyl acetate dimer, also showed significant differences across different production areas.

[0053] 2. Screening of characteristic aroma markers for early-maturing sand pears from different origins based on VIP values: Partial least squares discriminant analysis (PLS-DA) was performed using the MetaboAnalyst online platform to establish an origin prediction model based on the relative content of volatile aroma components, and the Variable Importance in Projection (VIP) values ​​of each volatile compound in Table 1 were calculated. The VIP value reflects the contribution of each volatile compound to the classification model; a higher VIP value indicates a greater contribution. Volatile compounds with a VIP value > 1 were selected as having significant contributions to origin identification. (Settlement details follow.) Figure 3 As shown, 'Su Cui No. 1' contains 6 volatile aroma components with VIP > 1, namely 2-methylbutyraldehyde dimer, 2-hexenal, ethyl acetate dimer, 2-methylbutyraldehyde monomer, hexenal dimer, and butyraldehyde monomer; 'Cui Guan' contains 7 volatile aroma components with VIP > 1, namely hexenal dimer, acetoin, 2-methylbutyraldehyde dimer, 2-methylbutyraldehyde monomer, butyraldehyde monomer, 2-hexenal monomer, and 1-hexanol monomer.

[0054] 3. Screening of characteristic aroma markers for early-maturing sand pears from different origins based on relative aroma activity values: Relative Aroma Activity Value (ROAV) is a physical quantity used to calculate the contribution of aroma compounds, representing the contribution of a single aroma component to the overall aroma. Aroma components with ROAV > 1 are generally considered to have a significant direct impact on the overall flavor. The volatile aroma components in Table 1 were combined with odor activity thresholds to calculate ROAV, which was used to assess the contribution of volatile aroma components to the overall flavor. ROAV is calculated according to the following formula:

[0055]

[0056] In the formula:

[0057] E-ROAV value;

[0058] 100—Relative Odor Activity Value (ROAV) coefficient, which defines the ROAV of the compound that has the most significant impact on the overall flavor of the sample as 100;

[0059] C i —Relative content of compounds in the sample, %; C m —The relative content of the component that contributes most to the overall flavor of the sample, %

[0060] T i —Odor threshold of compounds in the sample, μg·kg -1 ;

[0061] T m —Odor threshold of the component that contributes most to the overall flavor of the sample, μg·kg -1 .

[0062] Fruit flavor depends not only on the relative content of each volatile aroma component but also on its odor activity threshold. To assess the contribution of each volatile aroma component to the overall aroma of pear fruit, a ROAV > 1 is typically used as the standard to screen volatiles that significantly contribute to origin identification. As shown in Table 2, 12 volatile aroma components had ROAV > 1 in the samples, including hexanal dimer, 2-hexenal dimer, 2-methylbutyraldehyde monomer, 2-methylbutyraldehyde dimer, butyraldehyde monomer, butyraldehyde dimer, octanal, pentanal monomer, ethyl 2-methylpropionate monomer, ethyl 2-methylpropionate dimer, 1-hexanol monomer, and 1-hexanol dimer.

[0063] Table 2. ROAV values ​​of volatile aroma components in early-maturing sand pears from different origins.

[0064]

[0065] The intersection of the three screening results (P < 0.05, VIP > 1, and ROAV > 1) yielded four characteristic volatile compounds as core markers for origin identification (characteristic volatile organic compounds): 2-methylbutyraldehyde monomer, 2-methylbutyraldehyde dimer, hexanal dimer, and butyraldehyde monomer. These four compounds simultaneously met the triple criteria of statistical significance (P < 0.05), high classification contribution (VIP > 1), and strong aroma activity (ROAV > 1).

[0066] III. Establishment of Origin Discrimination Thresholds for Early-maturing Sand Pears Based on Characteristic Aroma Markers

[0067] 1. Relative content of characteristic aroma markers and origin determination of early-maturing sand pear 'Sucui No. 1': The relative content of characteristic aroma markers of early-maturing sand pear 'Sucui No. 1' is shown in Table 3. Therefore, the origin determination threshold is established as follows:

[0068] If the content of hexanal dimer is ≥33.0% and the content of 2-methylbutyral dimer is ≤0.5%, the place of origin is determined to be Nantong.

[0069] If the 2-methylbutyraldehyde dimer is ≥11.5% and the butyraldehyde monomer is ≥3.7%, the place of origin is determined to be Suqian.

[0070] If the 2-methylbutyraldehyde monomer content is ≥5.0% and the 2-methylbutyraldehyde dimer content is ≥9.5%, the place of origin is determined to be Xiangyang.

[0071] If the content of hexanal dimer is ≥31.0% and the content of 2-methylbutyraldehyde dimer is ≤7.0%, the place of origin is determined to be Zhenjiang.

[0072] 2. Relative Content of Characteristic Aroma Markers and Origin Determination of Early-maturing Sand Pear 'Cuiguan': The relative content of characteristic aroma markers of early-maturing sand pear 'Cuiguan' (i.e., the percentage of each volatile organic compound peak area to the total volatile organic compound peak area) is shown in Table 3. Therefore, the origin determination threshold is established as follows:

[0073] If the 2-methylbutyraldehyde dimer is ≥12.5% ​​and the butyraldehyde monomer is ≥4.0%, the place of origin is determined to be Xiangyang.

[0074] If the 2-methylbutyraldehyde monomer content is ≥5.8% and the hexanal dimer content is ≤28.0%, the place of origin is determined to be Changzhou.

[0075] If the content of hexanal dimer is ≥32.0% and the content of 2-methylbutyraldehyde dimer is ≥8.0%, the place of origin is determined to be Suqian.

[0076] If the 2-methylbutyraldehyde dimer is ≤2.5% and the butyraldehyde monomer is ≤1.5%, the place of origin is determined to be Zhenjiang.

[0077] If the hexanal dimer is 29.5%~31.5% and the 2-methylbutyraldehyde dimer is 5.5%~6.5%, the place of origin is determined to be Nantong.

[0078] Table 3. Relative contents of characteristic aroma markers in early-maturing sand pears from different origins

[0079]

[0080] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for identifying the origin of early-maturing sand pears based on GC-IMS analysis of characteristic odor substances, characterized in that, Includes the following steps (A1) GC-IMS analysis was performed on early-maturing sand pear samples from different origins to obtain volatile organic compound (VOC) detection data in early-maturing sand pears; (A2) Analyze the differences in volatile organic compound content, VIP value, and ROAV value to screen characteristic volatile biomarkers; (A3) Determine the relative content threshold of characteristic volatile markers as the identification standard based on their relative content; (A4) The place of origin is confirmed by comparing the relative content values ​​of characteristic volatile markers in the early-maturing sand pear sample with the relative content threshold obtained in step (A3).

2. The method according to claim 1, characterized in that, In step (A1), the headspace gas chromatography conditions were as follows: chromatographic separation was performed using an MXT-5 capillary column with an initial column temperature of 60°C. 2 ± 0.2 g of early-ripening sand pear sample was incubated at 40°C for 15 min. The injection temperature was 85°C, and the injection volume was 0.5 mL. High-purity nitrogen was used as the carrier gas. The program was set to: 0–2 min, 2 mL / min. -1 ; 2–8 min, 10 mL·min -1 ; 8–20 min, 100 mL·min -1 .

3. The method according to claim 1, characterized in that, In step (A1), the ion mobility spectrometry conditions are as follows: the migrating gas is high-purity nitrogen; the drift gas flow rate is 150 mL·min. -1 Detector temperature: 45℃; Drift tube length: 9.8 cm; Intratube linear voltage: 500 V·cm -1 The sample analysis time is 30 min.

4. The method according to claim 1, characterized in that, In step (1), the volatile organic compounds include (E)-2-heptenal, (E,E)-2,4-hexadienal, hexanal, 2-hexenal, 2-methylbutanal, butanal, octanal, pentanal, trans-2-pentenal, (Z)-3-hexenol acetate, ethyl acetate, ethyl 2-methylpropionate, ethyl propionate, hexyl acetate, (Z)-2-penten-1-ol, 1-hexanol, 1-pentanol, 1-penten-3-ol, 1-propanol, 2-hexanol, acetic acid, 3-pentanone, 1-penten-3-one, 3-hydroxy-2-butanone, and β-pinene, wherein hexanal, 2-hexenal, 2-methylbutanal, butanal, pentanal, ethyl acetate, ethyl 2-methylpropionate, ethyl propionate, hexyl acetate, 1-hexanol, 3-pentanone, and 1-penten-3-one comprise monomers and dimers.

5. The method according to claim 1, characterized in that, In step (A2), the screening of volatile organic compounds includes the following steps: (B1) One-way ANOVA was used to perform significance analysis to obtain the content difference P; (B2) Partial least squares discriminant analysis was used to calculate the variable importance projection value (VIP). (B3) Calculate the relative aroma activity value (ROAV) by combining volatile organic compounds with the odor activity threshold; (B4) Select volatile organic compounds that simultaneously meet the following criteria: content difference P < 0.05, VIP value > 1, and ROAV value > 1 as characteristic volatile markers.

6. The method according to claim 5, characterized in that, Characteristic volatile organic compounds include 2-methylbutyraldehyde monomer, 2-methylbutyraldehyde dimer, hexanal dimer, and butyraldehyde monomer.

7. The method according to claim 1, characterized in that, Different production areas include Zhenjiang, Suqian, Changzhou, Xiangyang, and Nantong.

8. The method according to claim 7, characterized in that, Early-maturing sand pears are 'Su Cui No. 1' or 'Cui Guan'.

9. The method according to claim 8, characterized in that, The following rules apply to the determination of the origin of the 'Su Cui No. 1' early-maturing sand pear: If the content of hexanal dimer is ≥33.0% and the content of 2-methylbutyral dimer is ≤0.5%, the place of origin is determined to be Nantong. If the 2-methylbutyraldehyde dimer is ≥11.5% and the butyraldehyde monomer is ≥3.7%, the place of origin is determined to be Suqian. If the 2-methylbutyraldehyde monomer content is ≥5.0% and the 2-methylbutyraldehyde dimer content is ≥9.5%, the place of origin is determined to be Xiangyang. If the content of hexanal dimer is ≥31.0% and the content of 2-methylbutyraldehyde dimer is ≤7.0%, the place of origin is determined to be Zhenjiang.

10. The method according to claim 8, characterized in that, The following rules apply to determining the origin of the 'Cuiguan' early-maturing sand pear: If the 2-methylbutyraldehyde dimer is ≥12.5% ​​and the butyraldehyde monomer is ≥4.0%, the place of origin is determined to be Xiangyang. If the 2-methylbutyraldehyde monomer content is ≥5.8% and the hexanal dimer content is ≤28.0%, the place of origin is determined to be Changzhou. If the content of hexanal dimer is ≥32.0% and the content of 2-methylbutyraldehyde dimer is ≥8.0%, the place of origin is determined to be Suqian. If the 2-methylbutyraldehyde dimer is ≤2.5% and the butyraldehyde monomer is ≤1.5%, the place of origin is determined to be Zhenjiang. If the hexanal dimer is 29.5%~31.5% and the 2-methylbutyraldehyde dimer is 5.5%~6.5%, the place of origin is determined to be Nantong.

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