Distiller's yeast quality grade identification method based on thermal desorption-photoionization ion migration electronic nose system
Through the thermal desorption-photoionization ion migration electronic nose system and SVM algorithm, the problems of traditional koji evaluation methods relying on manual experience and high cost of high-throughput sequencing were solved, and rapid, accurate identification and standardized detection of koji quality grades were achieved.
Patent Information
- Application Number
- CN202511034264.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-09-23
AI Technical Summary
Traditional methods for evaluating the quality of koji have the problems of relying on manual experience, high cost, complex operation and difficulty in comprehensively characterizing the complex microbial metabolic network of koji. The promotion and application of existing high-throughput sequencing technology in small and medium-sized enterprises is limited.
A thermal desorption-photoionization ion migration electronic nose system was used, combined with a thermal desorption module to achieve volatile matter enrichment and water removal. The photoionization ion migration electronic nose was used for millisecond-level separation and detection, and a koji quality grade discrimination model was constructed using the SVM algorithm.
It achieves rapid and accurate identification of koji quality grades, reduces testing costs and operational complexity, and improves the standardization and repeatability of evaluation, making it suitable for small and medium-sized enterprises.
Smart Images
Figure CN120685756A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of food quality detection, and in particular to a method for identifying the quality grade of koji based on a thermal desorption-photoionization ion migration electronic nose system. Background Art
[0002] Yeast, the core fermentation medium in winemaking (known as the "backbone of wine"), is a solid-state fermentation agent formed by naturally fermenting microorganisms such as mold and yeast, using a grain matrix (wheat, rice, etc.) as a carrier. It performs a dual function in winemaking: first, it converts grain starch into fermentable sugars; second, through microbial metabolism, it produces alcohol and hundreds of flavor compounds, which directly determine the flavor profile and quality grade of the wine. Therefore, establishing a scientific quality evaluation system for yeast is crucial to ensuring the stability of the winemaking process.
[0003] Traditionally, koji (drinking yeast) quality assessment relies primarily on experienced technicians observing its color, mycelial distribution, and smelling it. While this method offers rapid results, it has significant limitations: its pungent odor can easily lead to olfactory fatigue, requiring years of specialized training for evaluators. Furthermore, with the discontinuation of traditional techniques, qualified technicians are increasingly scarce. Modern instrumental analysis has established an objective evaluation system based on physicochemical parameters. By measuring core parameters such as water activity, acidity, starch content, and enzyme activity, a quantifiable quality assessment model has been established. This method, through the establishment of a standardized testing process, produces highly reproducible quantitative data (RSD <5%). However, a single physicochemical indicator cannot fully characterize the complex microbial metabolic network within koji, nor can it elucidate the mechanisms underlying the formation of complex flavor compounds.
[0004] In recent years, high-throughput sequencing technology has seen rapid adoption in the field of koji (drinking yeast) quality assessment. This technology analyzes the microbial community structure of koji, constructs a database of characteristic microbial markers, and then establishes a correlation model between koji quality grade and microbial composition. While this method offers significant advantages in resolution and sensitivity (with a detection limit of 0.01%), its application is limited by the following: 1) the sheer volume of sequencing data requires high-performance computing clusters for bioinformatics analysis; 2) the overall cost per sample exceeds 2,000 yuan, making large-scale testing uneconomical; and 3) the method places extremely high demands on scientific experimental design and operational standards, requiring a professional bioinformatics team for data analysis. These technical barriers significantly restrict its widespread adoption in small and medium-sized enterprises. Summary of the Invention
[0005] To address these issues, the present invention discloses a method for identifying the quality grade of koji (drinking yeast) based on a thermal desorption-photoionization ion mobility electronic nose system. First, a thermal desorption module is used to enrich and concentrate koji volatiles and efficiently remove water. Next, a photoionization ion mobility electronic nose is used to separate and detect trace characteristic components at the millisecond level, achieving a ppb-level detection limit that accurately captures the characteristic fingerprint of the koji. Finally, an integrated support vector machine (SVM) algorithm is used to construct an accurate koji quality grade discrimination model, enabling intelligent classification of koji quality grades. Validated with actual samples, koji grade identification can be completed within three minutes, with high agreement with the evaluation results of industry sensory experts. This provides a new quality control paradigm for liquor production that integrates rapid detection, intelligent analysis, and process monitoring.
[0006] The specific plan is as follows: A method for identifying the quality grade of koji based on a thermal desorption-photoionization ion migration electronic nose system comprises the following steps: Step 1: Accurately weigh 3.0 g of koji sample (accuracy 0.1 mg) and place it in a 60 mL headspace vial; after tightening the cap, incubate it in an 80°C incubator for 1 hour to collect the volatiles in the headspace of the koji; Step 2: Use a 20 mL borosilicate glass syringe to extract 40 mL of volatile gas from the headspace bottle in step 1 twice and inject it into the Tenax-TA adsorption tube for dynamic enrichment and concentration of the target compound; Step 3: Transfer the Tenax-TA adsorption tube prepared in step 2 to the sampling area of the thermal desorber and perform a secondary thermal desorption process to achieve desorption and transfer of adsorbed volatiles; Step 4: The desorption product of step 3 is introduced into a thermal desorption-photoionization ion transfer electronic nose system through a six-way injection valve to detect volatile substances in the koji; Step 5: After the test is completed, the response signal spectrum data is input into the SVM algorithm to establish a recognition model for koji samples of different quality grades; Step 6: re-test N blind samples with the photoionization ion mobility electronic nose according to Steps 1 to 4 above, and predict the quality level of the blind samples using the SVM model established in Step 5; Step 7: Calculate the prediction results. The prediction accuracy of the blind sample is: Accuracy=N1 / (N1+N2)=N1 / N×100% The number of samples predicted accurately is N1, and the number of samples predicted incorrectly is N2, N=N1+N2.
[0007] Furthermore, the secondary thermal desorption procedure is as follows: after placing the Tenax TA adsorption tube in the sampling area of the thermal desorber, (1) close the gas line valve and introduce high-purity nitrogen for 10 seconds to test the air tightness of the system; (2) reversely purge the Tenax TA adsorption tube with 40 mL / min of high-purity nitrogen for 20 seconds to remove organic impurities and moisture in the tube; (3) heat the Tenax TA adsorption tube to 300°C at a heating rate of 3000°C / min, and purge the analyte with high-purity nitrogen for 200 seconds; (4) the purged material is captured by a cold trap at -40°C; (5) the cold trap is instantly heated to 300°C, and the secondary thermal desorption is completed within 60 seconds.
[0008] Furthermore, the specific method of photoionization ion migration electronic nose detection is as follows: (1) acetone gas is ionized under 10.6 eV ultraviolet radiation to form reactive ions; (2) the secondary thermal desorption products of the koji are injected into the ionization region of the electronic nose and react with the reactive ions to generate product ions; (3) the product ions are injected into the migration region by the TPG ion gate (cycle 20 ms, gate pulse width 200 us); (4) under the action of 600 V / cm electric field and reverse drift gas, the product ions are separated according to the difference in ion reduced mobility K0 and collected by the Faraday disk at different migration times, forming a weak current signal in the range of 10-1000 nA; (5) after 109 V / A signal gain and A / D conversion, a two-dimensional fingerprint spectrum of ion signal intensity and migration time is generated.
[0009] Furthermore, the thermal desorption-photoionization ion migration electronic nose system includes a nitrogen cylinder, a triple purifier, a gas flow stabilizing valve, a mass flow meter, a dopant module, a vacuum ultraviolet lamp, a high-voltage power supply, a high-voltage pulse generator, an ion gate, a thermal desorber, an amplifier, a data acquisition card, a computer and a floating gas; wherein the triple purifier is connected to the nitrogen cylinder to remove organic impurities and moisture contained in the nitrogen; there are two gas flow stabilizing valves, both of which are connected to the triple purifier to stabilize the gas flow in the gas path; there are two mass flow meters, which are respectively connected to the two gas flow stabilizing valves to regulate the flow size of the gas path; the input end of the dopant module is connected to a mass flow meter, and the output end is connected to the first air inlet at the front end of the ion migration tube to provide acetone dopant and generate acetone gas molecules; the vacuum ultraviolet lamp is fixedly connected to the ion migration tube to provide energy photons; the high The piezoelectric power source is connected to the circuit board of the ion transfer tube to construct the electric field of the ion transfer tube; the input end of the high-voltage pulse generator is connected to the data acquisition card, and the output end is connected to the circuit board of the ion transfer tube to generate a high-voltage pulse electrical signal to control the opening and closing of the ion gate; the ion gate is used to control the ion flow generated in the ionization zone to enter the migration zone; the output port of the thermal desorber is connected to the second air inlet of the ion transfer tube to enrich and concentrate the volatile sample of the koji; the input end of the amplifier is connected to the detector of the ion transfer tube, and the output end is connected to the data acquisition card to amplify the weak current signal and convert the current to digital; the input end of the data acquisition card is connected to the amplifier, and the output end is connected to the computer for collecting digital signals; the drift gas is provided by the output of another mass flow meter and connected to the third gas inlet at the tail end of the ion transfer tube to keep the migration zone clean.
[0010] Furthermore, the nitrogen cylinder is used to provide high-purity nitrogen; the triple purifier is connected to the pressure reducing valve joint of the nitrogen cylinder through a polytetrafluoroethylene tube; the gas steady flow valve is connected to the triple purifier through a polytetrafluoroethylene tube; the mass flow meter is connected to the gas steady flow valve through a polytetrafluoroethylene tube; the input end of the dopant module is connected to the mass flow meter through a polytetrafluoroethylene tube, and the output end is connected to the first gas inlet at the front end of the ion migration tube through a polytetrafluoroethylene tube; the output port of the thermal desorber is connected to the second gas inlet of the ion migration tube through a polytetrafluoroethylene tube; and the drift gas is connected to the third gas inlet at the tail end of the ion migration tube through a polytetrafluoroethylene tube.
[0011] Furthermore, the vacuum ultraviolet lamp is an ionization source and provides energy photons of 10.6 eV, and is connected and fixed to the ion transfer tube via a threaded knob.
[0012] Furthermore, the high-voltage power supply outputs high voltage, which is connected to the circuit board of the ion transfer tube through a power line.
[0013] Furthermore, the input end of the high-voltage pulse generator is connected to the data acquisition card through an SMA signal line, and the output end is connected to the circuit board of the ion transfer tube through a power line; and the ion gate is a TPG ion gate.
[0014] Furthermore, the input end of the amplifier is connected to the detector of the ion transfer tube through an SMA signal line, and the output end is connected to the data acquisition card through an SMA signal line; the input end of the data acquisition card is connected to the amplifier through an SMA signal line, and the output end is connected to the computer through a USB line; the computer is responsible for the pre-processing of the digital signal and the pattern recognition algorithm.
[0015] The beneficial effects of the present invention are: 1. The present invention adopts thermal desorption technology as the sample pretreatment unit, which realizes the efficient removal of water in the koji sample, avoids the interference of water on the photoionization process, and improves the enrichment efficiency of volatile organic compounds.
[0016] 2. The present invention is based on a photoionization ion migration electronic nose, which can achieve millisecond-level separation and ppb-level detection of trace characteristic components of koji.
[0017] 3. This invention establishes an accurate model for identifying the quality grade of distiller's yeast by introducing the support vector machine (SVM) algorithm. This model is highly accurate and robust, and can accurately distinguish distiller's yeast of different quality grades.
[0018] 4. Compared with traditional sensory evaluation, chemical analysis instruments and high-throughput sequencing methods, the method of the present invention not only reduces the dependence on manual experience and reduces the complexity of instrument operation, but also greatly improves the standardization and repeatability of koji quality assessment, making koji quality assessment more simple, objective and comprehensive. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of the thermal desorption-photoionization ion transfer electronic nose system in this application.
[0020] Figure 2 Figure 2 is the SVM model diagram for three different quality grades of koji samples.
[0021] Figure 3 This is the prediction result diagram of the superior torsional blindness SVM model.
[0022] Figure 4 This is the prediction result diagram of the first-level tomographic blindness SVM model.
[0023] Figure 5 This is the prediction result diagram of the secondary tomographic blindness SVM model.
[0024] List of reference numerals: 1-Nitrogen cylinder, 2-Triple purifier, 3-Gas flow regulator, 4-Mass flow meter, 5-Dopant module, 6-Vacuum UV lamp, 7-High-voltage power supply, 8-High-voltage pulse generator, 9-Ion gate, 10-Thermal desorber, 11-Amplifier, 12-Data acquisition card, 13-Computer. DETAILED DESCRIPTION
[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.
[0026] The present invention provides a method for identifying the quality grade of koji based on a thermal desorption-photoionization ion migration electronic nose system, comprising the following steps: Step 1: Accurately weigh 3.0 g of koji sample (accuracy 0.1 mg) and place it in a 60 mL headspace vial; after tightening the cap, incubate it in an 80°C incubator for 1 hour to collect the volatiles in the headspace of the koji; Step 2: Use a 20 mL borosilicate glass syringe to extract 40 mL of volatile gas from the headspace bottle in step 1 twice and inject it into the Tenax-TA adsorption tube for dynamic enrichment and concentration of the target compound; Step 3: Transfer the Tenax-TA adsorption tube prepared in step 2 to the sampling area of the thermal desorber and perform a secondary thermal desorption process to achieve desorption and transfer of adsorbed volatiles; Step 4: The desorption product of step 3 is introduced into a thermal desorption-photoionization ion transfer electronic nose system through a six-way injection valve to detect volatile substances in the koji; Step 5: After the test is completed, the response signal spectrum data is input into the SVM algorithm to establish a recognition model for koji samples of different quality grades; Step 6: re-test N blind samples with the photoionization ion mobility electronic nose according to Steps 1 to 4 above, and predict the quality level of the blind samples using the SVM model established in Step 5; Step 7: Calculate the prediction results. The prediction accuracy of the blind sample is: Accuracy=N1 / (N1+N2)=N1 / N×100% The number of samples predicted accurately is N1, and the number of samples predicted incorrectly is N2, N=N1+N2.
[0027] In this embodiment, the secondary thermal desorption procedure is as follows: after placing the Tenax TA adsorption tube in the sampling area of the thermal desorber, (1) close the gas line valve and introduce high-purity nitrogen for 10 seconds to test the air tightness of the system; (2) reversely purge the Tenax TA adsorption tube with 40 mL / min of high-purity nitrogen for 20 seconds to remove organic impurities and moisture in the tube; (3) heat the Tenax TA adsorption tube to 300°C at a heating rate of 3000°C / min, and purge the analyte with high-purity nitrogen for 200 seconds; (4) the purged material is captured by a cold trap at -40°C; (5) the cold trap is instantly heated to 300°C, and the secondary thermal desorption is completed within 60 seconds.
[0028] In this embodiment, the specific method of photoionization ion migration electronic nose detection is as follows: (1) acetone gas is ionized under 10.6eV ultraviolet radiation to form reactive ions; (2) the secondary thermal desorption products of the koji are injected into the ionization region of the electronic nose and react with the reactive ions to generate product ions; (3) the product ions are injected into the migration region by the TPG ion gate (cycle 20ms, gate pulse width 200us); (4) under the action of 600V / cm electric field and reverse drift gas, the product ions are separated according to the difference in ion reduced mobility K0 and collected by the Faraday disk at different migration times, forming a weak current signal in the range of 10-1000nA; (5) after 109V / A signal gain and A / D conversion, a two-dimensional fingerprint spectrum of ion signal intensity and migration time is generated.
[0029] like Figure 1As shown, the thermal desorption-photoionization ion migration electronic nose system includes a nitrogen cylinder 1, a triple purifier 2, a gas steady flow valve 3, a mass flow meter 4, a dopant module 5, a vacuum ultraviolet lamp 6, a high-voltage power supply 7, a high-voltage pulse generator 8, an ion gate 9, a thermal desorber 10, an amplifier 11, a data acquisition card 12, a computer 13 and a floating gas; wherein the triple purifier is connected to the nitrogen cylinder to remove organic impurities and moisture contained in the nitrogen; there are two gas steady flow valves, both of which are connected to the triple purifier to stabilize the gas flow in the gas path; there are two mass flow meters, which are respectively connected to the two gas steady flow valves to regulate the flow size of the gas path; the input end of the dopant module is connected to a mass flow meter, and the output end is connected to the first air inlet at the front end of the ion migration tube to provide acetone dopant and generate acetone gas molecules; the vacuum ultraviolet lamp is fixedly connected to the ion migration tube to provide Energy photons; the high-voltage power supply is connected to the circuit board of the ion transfer tube to construct the electric field of the ion transfer tube; the input end of the high-voltage pulse generator is connected to the data acquisition card, and the output end is connected to the circuit board of the ion transfer tube to generate a high-voltage pulse electrical signal to control the opening and closing of the ion gate; the ion gate is used to control the ion flow generated in the ionization zone to enter the migration zone; the output port of the thermal desorber is connected to the second air inlet of the ion transfer tube to enrich and concentrate the volatile sample of the koji; the input end of the amplifier is connected to the detector of the ion transfer tube, and the output end is connected to the data acquisition card to amplify the weak current signal and convert the current to digital; the input end of the data acquisition card is connected to the amplifier, and the output end is connected to the computer for collecting digital signals; the drift gas is provided by the output of another mass flow meter and connected to the third gas inlet at the tail end of the ion transfer tube to keep the migration zone clean.
[0030] In this embodiment, the nitrogen cylinder is used to provide high-purity nitrogen; the triple purifier is connected to the pressure reducing valve connector of the nitrogen cylinder through a polytetrafluoroethylene tube; the gas steady flow valve is connected to the triple purifier through a polytetrafluoroethylene tube; the mass flow meter is connected to the gas steady flow valve through a polytetrafluoroethylene tube; the input end of the dopant module is connected to the mass flow meter through a polytetrafluoroethylene tube, and the output end is connected to the first gas inlet at the front end of the ion migration tube through a polytetrafluoroethylene tube; the output port of the thermal desorber is connected to the second gas inlet of the ion migration tube through a polytetrafluoroethylene tube; and the drift gas is connected to the third gas inlet at the tail end of the ion migration tube through a polytetrafluoroethylene tube.
[0031] In this embodiment, the vacuum ultraviolet lamp is an ionization source and provides energy photons of 10.6 eV. It is connected and fixed to the ion transfer tube via a threaded knob.
[0032] In this embodiment, the high-voltage power supply outputs high voltage, which is connected to the circuit board of the ion transfer tube via a power line.
[0033] In this embodiment, the input end of the high-voltage pulse generator is connected to the data acquisition card through an SMA signal line, and the output end is connected to the circuit board of the ion transfer tube through a power line; the ion gate is a TPG ion gate.
[0034] In this embodiment, the input end of the amplifier is connected to the detector of the ion migration tube via an SMA signal line, and the output end is connected to the data acquisition card via an SMA signal line; the input end of the data acquisition card is connected to the amplifier via an SMA signal line, and the output end is connected to the computer via a USB line; the computer is responsible for the pre-processing of the digital signal and the pattern recognition algorithm.
[0035] The advantages of the present invention are: 1. A thermal desorption-photoionization ion migration electronic nose system was proposed: an integrated system of thermal desorption module and photoionization ion migration electronic nose was constructed, and a secondary thermal desorption program (including 300℃ / 3000℃ / min gradient heating, 40mL / min nitrogen reverse purge, -40℃ cold trap capture and other parameters) was used to achieve efficient enrichment of koji volatiles and elimination of moisture interference.
[0036] 2. Designed a SVM model for the quality grade of koji: Based on the support vector machine (SVM), a multi-category discrimination model integrating ion migration time, signal intensity and migration spectrum morphology was constructed. Through kernel function optimization and hyperparameter adaptive adjustment, accurate classification of koji of different quality grades was achieved (e.g. Figure 2-5 The accuracy of blind sample verification reached 90.0%.
[0037] 3. A standardized rapid detection process was adopted: a complete method system was established from 3.0g sample headspace incubation, Tenax-TA dynamic enrichment, secondary thermal desorption transmission to electronic nose detection. The single sample detection time is ≤3 minutes and RSD is <5%, meeting the real-time quality control needs of the wine production line.
[0038] The technical means disclosed in the solutions of the present invention are not limited to those disclosed in the above-mentioned embodiments, but also include technical solutions composed of any combination of the above-mentioned technical features. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.
Claims
1. A method for identifying the quality grade of koji based on a thermal desorption-photoionization ion migration electronic nose system, characterized in that: The following steps are involved: Step 1: Accurately weigh 3.0 g of koji sample and place it in a 60 mL headspace bottle. After tightening the bottle cap, incubate it in an 80°C incubator for 1 hour to collect the volatiles in the headspace of the koji. Step 2: Use a 20 mL borosilicate glass syringe to extract 40 mL of volatile gas from the headspace bottle in step 1 twice and inject it into the Tenax-TA adsorption tube for dynamic enrichment and concentration of the target compound; Step 3: Transfer the Tenax-TA adsorption tube prepared in step 2 to the sampling area of the thermal desorber and perform a secondary thermal desorption process to achieve desorption and transfer of adsorbed volatiles; Step 4: The desorption product of step 3 is introduced into a thermal desorption-photoionization ion transfer electronic nose system through a six-way injection valve to detect volatile substances in the koji; Step 5: After the test is completed, the response signal spectrum data is input into the SVM algorithm to establish a recognition model for koji samples of different quality grades; Step 6: re-test N blind samples with the photoionization ion mobility electronic nose according to Steps 1 to 4 above, and predict the quality level of the blind samples using the SVM model established in Step 5; Step 7: Calculate the prediction results. The prediction accuracy of the blind sample is: Accuracy=N1 / (N1+N2)=N1 / N×100% The number of samples predicted accurately is N1, and the number of samples predicted incorrectly is N2, N=N1+N2.
2. The method according to claim 1, characterized in that The secondary thermal desorption procedure is as follows: after placing the Tenax TA adsorption tube in the sampling area of the thermal desorber, (1) close the gas line valve and introduce high-purity nitrogen for 10 seconds to test the air tightness of the system; (2) reversely purge the Tenax TA adsorption tube with 40 mL / min of high-purity nitrogen for 20 seconds to remove organic impurities and moisture in the tube; (3) heat the Tenax TA adsorption tube to 300°C at a heating rate of 3000°C / min, and purge the analyte with high-purity nitrogen for 200 seconds; (4) the purged material is captured by a cold trap at -40°C; (5) the cold trap is instantly heated to 300°C, and the secondary thermal desorption is completed within 60 seconds.
3. The method according to claim 1, characterized in that The specific method of photoionization ion migration electronic nose detection is as follows: (1) acetone gas is ionized under 10.6 eV ultraviolet radiation to form reactive ions; (2) the secondary thermal desorption products of the koji are injected into the ionization region of the electronic nose and react with the reactive ions to form product ions; (3) the product ions are injected into the migration region by the TPG ion gate; (4) under the action of a 600 V / cm electric field and reverse drift gas, the product ions are separated according to the difference in ion reduced mobility K0 and collected by the Faraday disk at different migration times, forming a weak current signal in the range of 10-1000 nA; (5) after a 109 V / A signal gain and A / D conversion, a two-dimensional fingerprint spectrum of ion signal intensity and migration time is generated.
4. The method according to claim 1, wherein The thermal desorption-photoionization ion migration electronic nose system includes a nitrogen cylinder, a triple purifier, a gas flow stabilizing valve, a mass flow meter, a dopant module, a vacuum ultraviolet lamp, a high-voltage power supply, a high-voltage pulse generator, an ion gate, a thermal desorber, an amplifier, a data acquisition card, a computer and a floating gas; wherein the triple purifier is connected to the nitrogen cylinder and is used to remove organic impurities and moisture contained in the nitrogen; there are two gas flow stabilizing valves, both of which are connected to the triple purifier and are used to stabilize the gas flow in the gas path; there are two mass flow meters, which are respectively connected to the two gas flow stabilizing valves and are used to regulate the flow size of the gas path; the input end of the dopant module is connected to a mass flow meter, and the output end is connected to the first air inlet at the front end of the ion migration tube, which is used to provide acetone dopant and generate acetone gas molecules; the vacuum ultraviolet lamp is fixedly connected to the ion migration tube and is used to provide energy photons; the high-voltage power supply The thermal desorber is connected to the circuit board of the ion transfer tube to construct the electric field of the ion transfer tube; the input end of the high-voltage pulse generator is connected to the data acquisition card, and the output end is connected to the circuit board of the ion transfer tube to generate a high-voltage pulse electrical signal to control the opening and closing of the ion gate; the ion gate is used to control the ion flow generated in the ionization zone to enter the migration zone; the output port of the thermal desorber is connected to the second air inlet of the ion transfer tube to enrich and concentrate the volatile sample of the koji; the input end of the amplifier is connected to the detector of the ion transfer tube, and the output end is connected to the data acquisition card to amplify the weak current signal and convert the current to digital; the input end of the data acquisition card is connected to the amplifier, and the output end is connected to the computer to collect digital signals; the drift gas is provided by the output of another mass flow meter and connected to the third gas inlet at the tail end of the ion transfer tube to keep the migration zone clean.
5. The method according to claim 4, characterized in that The nitrogen cylinder is used to provide high-purity nitrogen; the triple purifier is connected to the pressure reducing valve joint of the nitrogen cylinder through a polytetrafluoroethylene tube; the gas steady flow valve is connected to the triple purifier through a polytetrafluoroethylene tube; the mass flow meter is connected to the gas steady flow valve through a polytetrafluoroethylene tube; the input end of the dopant module is connected to the mass flow meter through a polytetrafluoroethylene tube, and the output end is connected to the first gas inlet at the front end of the ion transfer tube through a polytetrafluoroethylene tube; the output port of the thermal desorber is connected to the second gas inlet of the ion transfer tube through a polytetrafluoroethylene tube; and the drift gas is connected to the third gas inlet at the rear end of the ion transfer tube through a polytetrafluoroethylene tube.
6. The method according to claim 4, characterized in that The vacuum ultraviolet lamp is an ionization source and provides energy photons of 10.6 eV. The vacuum ultraviolet lamp is connected and fixed to the ion transfer tube via a threaded knob.
7. The method according to claim 4, characterized in that The high-voltage power supply outputs high voltage, which is connected to the circuit board of the ion transfer tube through a power line.
8. The method according to claim 4, characterized in that The input end of the high-voltage pulse generator is connected to the data acquisition card through an SMA signal line, and the output end is connected to the circuit board of the ion transfer tube through a power line; the ion gate is a TPG ion gate.
9. The method according to claim 4, characterized in that The input end of the amplifier is connected to the detector of the ion migration tube through an SMA signal line, and the output end is connected to the data acquisition card through an SMA signal line; the input end of the data acquisition card is connected to the amplifier through an SMA signal line, and the output end is connected to the computer through a USB line; the computer is responsible for the pre-processing of digital signals and pattern recognition algorithms.