Detection system and method for flavor substances in yeast for making hard liquor

Abstract

The invention provides a system and a method for detecting flavor substances in yeast for making hard liquor, and relates to the field of flavor analysis of fermented foods. The system comprises a sample treatment device, a three-stage cold trap device and a gas chromatograph-mass spectrometer, the sample treatment device comprises a sample container and a thermal power unit, and the thermal power unit pretreats a solid-phase sample in the closed sample container until the solid-phase sample is in a thermal fluidization state and keeps the thermal fluidization state for a preset time period; the volatile components in the solid-phase sample are fully volatilized; the three-stage cold trap device collects a gas phase sample formed by sufficient volatilization of the solid phase sample, the gas phase sample is subjected to impurity removal and enrichment through a three-stage cold trap in the three-stage cold trap device, and then the gas phase sample is fed into a gas chromatograph-mass spectrometer according to a preset volume for gas chromatography-mass spectrometry. According to the invention, the solid-phase sample is subjected to thermal fluidization and trace components in the solid-phase sample are fully volatilized, and the fully volatilized trace components are concentrated and enriched in cooperation with the multi-stage cold trap device, so that the detection rate of the trace components is remarkably improved, and the composition of the solid-phase sample can be comprehensively known without being limited by instruments.

Description

Technical Field

[0001] This invention relates to the field of flavor analysis technology for fermented foods, specifically to a system and method for detecting flavor substances in daqu (a type of starter culture). Background Technology

[0002] Traditional fermented foods refer to foods made from plant and animal raw materials through a fermentation process under natural or artificially controlled conditions, using microorganisms (such as bacteria, yeast, and mold) or enzymes. Their flavor is a comprehensive expression of various volatile and non-volatile compounds, mainly including organic acids, alcohols, esters, aldehydes, ketones, and sulfur-containing compounds. These substances collectively constitute the unique aroma, taste, and texture of fermented foods, giving them regional characteristics and functional value.

[0003] The brewing industry is a vital pillar of the light and food industries and a traditional advantageous food product in my country. Daqu, as the saccharification and fermentation agent in traditional Baijiu (Chinese white liquor), is a crucial source of the typical aroma characteristics of Baijiu. It contains abundant microbial systems, enzyme systems, and complex aroma substances, playing a decisive role in the style and quality of Baijiu. Rapid and comprehensive evaluation of the flavor, material basis, and variation patterns of Daqu is of great significance for studying Baijiu aroma and improving the quality of base liquor.

[0004] Currently, methods for detecting the flavor of Daqu (a type of Chinese koji) are mainly divided into two categories: sensory evaluation and instrumental analysis. These methods differ significantly in accuracy, efficiency, and application scope. Sensory evaluation primarily involves professional evaluators describing and scoring the aroma, taste, and other attributes of Daqu. It can comprehensively assess the overall harmony of the flavor, but it struggles to quantify specific flavor compounds and cannot analyze the relationship between chemical components and sensory attributes. Instrumental analysis, such as electronic noses, only provides a "fingerprint" and cannot identify specific compounds. Furthermore, the sensors are susceptible to temperature and humidity interference, resulting in poor long-term stability. High-performance liquid chromatography (HPLC) cannot analyze volatile aroma components, has long separation times, and consumes large amounts of solvent. Gas chromatography-mass spectrometry (GC-MS) is the most commonly used instrumental method for analyzing volatile substances in Daqu, but its pretreatment is complex, and different pretreatment methods lead to significant differences in results.

[0005] HS-SPME-GC-MS (Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry) is currently a widely used technique for the detection of volatile substances, offering advantages such as high sensitivity and selectivity, simple sample pretreatment, and high-throughput analysis capabilities. However, this method also has significant drawbacks, including limited fiber coating selection, matrix (moisture, etc.) interference, semi-quantitative limitations, and material loss. When applied to the flavor detection of Daqu (a type of starter culture), the limited concentration of flavor substances by headspace solid phase microextraction and the difficulty in eliminating certain impurities adsorbed on the extraction head mean that, apart from some high-content and well-known flavor substances, this method can only detect a portion of low-content flavor substances. Although existing technologies have successfully identified various volatile components in Daqu, the identification of flavor substances in specific Daqu samples, especially trace flavor substances with low thresholds, remains challenging. This incomplete understanding of the flavor substances in Daqu hinders the optimization of fermentation engineering processes and the construction of standardized production systems.

[0006] Therefore, existing technologies lack a detection system and method for trace components in solid-phase samples such as Daqu (a type of starter culture), which can more comprehensively detect trace flavor substances in fixed samples and cannot reflect the true flavor composition of Daqu. The detection system and method involved in this invention make up for this deficiency, improve the understanding of Daqu, provide new development ideas for optimizing brewing technology and improving the quality of Baijiu (Chinese liquor), and also provide a reference for the detection and analysis of flavor substances in other traditional fermented foods. Summary of the Invention

[0007] The purpose of this invention is to provide a system and method for detecting flavor substances in Daqu (a type of starter culture). By subjecting the solid sample to thermal fluidization, the volatile flavor substances contained therein are fully volatilized and then enriched for detection. Compared with the prior art, this method greatly improves the detection rate of flavor substances and enhances the understanding of solid samples.

[0008] To achieve the above objectives, the present invention proposes the following technical solution: Firstly, a detection system for flavor substances in Daqu (a type of Chinese starter culture) is proposed, comprising: a sample processing device, a three-stage cold trap device, and a gas chromatography-mass spectrometry (GC-MS) instrument connected in sequence. The sample processing device includes a sample container and a thermodynamic unit; the sample container is used to contain a solid sample, and the thermodynamic unit acts on the solid sample in the sample container to heat the solid sample and make it fluidized in the sample container. The three-stage cold trap device includes a sampling end and a sampling end; the sampling end extends into the sample container from the open end of the sample container to collect a gas sample, and the connection between the open end and the sampling end is sealed; the sampling end is connected to the gas chromatography-mass spectrometry (GC-MS) instrument, and the gas sample is injected into the capillary column of the GC-MS instrument at a preset volume after being purified, enriched, desorbed, and heated by the three-stage cold trap inside the three-stage cold trap device for gas chromatography-mass spectrometry analysis.

[0009] Furthermore, the thermodynamic unit includes a heating element and a power element; The heating unit is disposed around the sample container and is used to heat the sample container and the solid sample therein; the power unit includes a gas tank and a control outlet connected to the gas tank. The outlet extends into the sample container from the open end of the sample container. The connection between the outlet and the open end is sealed, and the end of the outlet extends into the solid sample. The power unit controls the fluidization volume of the solid sample in the sample container by regulating the gas flow rate and gas pressure output from the gas outlet.

[0010] Furthermore, it also includes a filtration unit, which is disposed inside the gas collection tube of the sample container or the sampling end, and the pore size of the filtration unit does not exceed 5μm.

[0011] Furthermore, the thermodynamic unit acts on the solid sample inside the sample container to raise the target temperature of the solid sample to 40~60℃.

[0012] Furthermore, the power unit controls the gas flow rate output from the outlet to be 50~100mL / min, and the power unit controls the gas pressure output from the outlet to be 0.05~0.2MPa.

[0013] Furthermore, the solid sample is a sample powder, and the particle size of the sample powder is such that it passes through a 40-100 mesh sieve.

[0014] Furthermore, the operating parameters of the gas chromatography-mass spectrometry system are as follows: injection volume 300~1200mL; splitless; column: DB-WAX flexible quartz fiber capillary column 60m x 0.25 mm, 0.25μm; temperature program: 35℃ for 5min, increase to 150℃ at a rate of 5℃ / min, hold for 7min, increase to 210℃ at a rate of 10℃ / min, hold for 4min; carrier gas: He, flow rate 1.0 mL / min; detector temperature: 250℃, inlet temperature: 250℃.

[0015] Furthermore, the operating parameters of the mass spectrometer in the gas chromatography-mass spectrometry system are as follows: EI ionization source, electron energy of 70 eV, electron multiplier voltage of 1610 V, ion source temperature of 200 °C, transfer line temperature of 250 °C, and mass scan range a / z of 35-500 amu.

[0016] Secondly, a method for detecting flavor substances in Daqu (a type of starter culture) is proposed, comprising the following steps: A thermodynamic unit is used to pretreat a solid sample in a sealed sample container until the solid sample is thermally fluidized in the sample container and maintained for a preset time period, so that the volatile components in the solid sample can be fully volatilized; wherein, the thermal fluidization is the solid sample exhibiting a fluidization effect in the sample container at a temperature not lower than 40~60℃. Collect a stable gaseous sample formed by the complete volatilization of the solid sample in the sample container; The gaseous sample is purified and enriched using a three-stage cold trap device to obtain an enriched sample; wherein the enrichment factor of the gaseous sample by the three-stage cold trap device is not less than 1000. The enriched sample was injected into a gas chromatography-mass spectrometry (GC-MS) system for analysis, and the analytical results of the enriched sample were output. The operating parameters of the GC-MS system were as follows: injection volume 300-1200 mL; splitless; column: DB-WAX flexible quartz fiber capillary column 60 m x 0.25 mm, 0.25 μm; temperature program: 35 °C for 5 min, then increased to 150 °C at a rate of 5 °C / min, and held for 7 min. The temperature was increased to 210℃ at a rate of 10℃ / min and held for 4 min; carrier gas: He, flow rate 1.0 mL / min; detector temperature: 250℃, inlet temperature: 250℃; the operating parameters of the mass spectrometer in the gas chromatography-mass spectrometry system were: EI ionization source, electron energy 70 eV, electron multiplier voltage 1610 V, ion source temperature 200℃, transfer line temperature 250℃, mass scan range a / z 35-500 amu.

[0017] Furthermore, the method also includes: Before performing gas chromatography-mass spectrometry analysis on the enriched sample, a gas purification unit was used to adsorb and filter CO2 in the enriched sample to obtain a filtered sample. The analysis results of the filtered sample were obtained by gas chromatography-mass spectrometry, and the analysis results of the filtered sample were compared with the analysis results of the enriched sample to determine the trace components in the enriched sample that were not detected under CO2 interference.

[0018] As can be seen from the above technical solutions, the technical solutions of the present invention have achieved the following beneficial effects: This invention discloses a system and method for detecting flavor substances in Daqu (a type of Chinese starter culture). The system includes a sample processing device, a three-stage cold trap device, and a gas chromatography-mass spectrometry (GC-MS) instrument. The sample processing device includes a sample container and a thermodynamic unit. The thermodynamic unit pre-treats the solid-phase sample in the sealed sample container until the solid-phase sample is in a thermally fluidized state and maintains this state for a preset time period to allow the volatile components in the solid-phase sample to fully volatilize. The three-stage cold trap device collects the component-stable gas phase sample formed by the fully volatilized solid-phase sample in the sealed sample container. After impurity removal and enrichment in the internal three-stage cold trap, the sample is injected into the GC-MS instrument at a preset volume for gas chromatography-mass spectrometry analysis. This invention, on the one hand, allows the solid-phase sample to be in a thermally fluidized state, enabling the full volatilization of its volatile trace components. On the other hand, it utilizes a multi-stage cold trap device to concentrate and enrich the fully volatilized trace components, making these trace components detectable and significantly improving the detection rate of trace components. This allows for a comprehensive understanding of the composition of solid-phase samples without instrument limitations, and has a wide range of applications.

[0019] Compared with the prior art, this invention proposes a detection system and method for trace components in solid-phase samples. When applied to Daqu (a type of starter culture), it increases the number of qualitative peaks by up to 52%. This shows that the system and method disclosed in this invention, when applied to solid-phase samples, can greatly improve detection quality and analytical capabilities, enhance the understanding of the components of solid-phase samples, and help optimize solid-phase samples, such as by improving the components of Daqu to optimize the brewing process.

[0020] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0021] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0022] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the detection system for flavor substances in Daqu (a type of starter culture) of the present invention; Figure 2 This is a flowchart of the method for detecting flavor substances in Daqu (a type of starter culture) of the present invention; Figure 3This is an overview diagram of the peak elution results in Examples 1-4 of the present invention; Figure 4 This is an overview diagram of the peak elution results of Embodiments 1 and 5-7 of the present invention; Figure 5 This is an overview diagram of the peak elution results of Embodiments 1 and 8-9 of the present invention; Figure 6 The total ion chromatograms of the samples from Example 1 and Comparative Example 1 of this invention were analyzed by GC-MS. Figure 7 This is a statistical chart showing the classification of flavor substances detected in Example 1 and Comparative Example 1 of the present invention.

[0023] The specific meanings of each mark in the diagram are as follows: 1-Sample container; 2-Heating unit; 3-Power unit; 4-Three-stage cold trap device; 5-Gas chromatography-mass spectrometry instrument; 6-Control unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0025] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0026] Since the flavor compounds in Daqu (a type of starter culture) directly affect the final flavor of Baijiu (Chinese liquor), it is necessary to analyze the components of Daqu. However, existing techniques for detecting trace components in solid-phase samples such as Daqu are limited by the special characteristics of solid-phase samples and the applicability of instruments, typically only detecting a portion of the trace components, resulting in poor analytical capabilities. Applying such methods to the detection of flavor compounds in Daqu only provides a partial understanding of its composition and cannot offer reliable suggestions for optimizing the brewing process. Therefore, this invention aims to propose a system and method for detecting trace components in solid-phase samples, specifically a system and method for detecting flavor compounds in Daqu. By enhancing the volatilization efficiency of trace components in solid-phase samples and combining component enrichment, this invention enables the detection of trace components that are undetectable by existing techniques, significantly improving detection quality and analytical capabilities.

[0027] Specifically, the detection system for flavor substances in Daqu (a type of Chinese liquor) disclosed in this invention includes: a sample processing device, a three-stage cold trap device 4, and a gas chromatography-mass spectrometry (GC-MS) instrument 5 connected in sequence. The sample processing device includes a sample container 1 and a thermodynamic unit. The sample container 1 contains a solid-phase sample, and the thermodynamic unit acts on the solid-phase sample within the sample container 1 to heat the sample and fluidize it within the container. The three-stage cold trap device 4 includes a sampling end and an outlet end. The sampling end extends into the sample container 1 from its open end to collect a gas sample, and the connection between the open end and the sampling end is sealed. The outlet end is connected to the GC-MS instrument 5. After impurity removal, enrichment, desorption, and heating within the three-stage cold trap device 4, the gas sample is injected at a preset volume into the capillary column of the GC-MS instrument 5 for gas chromatography-mass spectrometry analysis. In specific implementation, impurity removal in the three-stage cold trap device 4 mainly refers to moisture removal.

[0028] The purpose of the thermodynamic unit in the sample processing apparatus is to heat the solid sample in sample container 1 and fluidize it, thereby accelerating the volatilization of volatile trace components in the solid sample. In one embodiment, the thermodynamic unit includes a heating section 2 and a power section 3. Figure 1The installation diagram shows that the heating unit 2 is located around the sample container 1 and is used to heat the sample container 1 and the solid sample therein. The power unit 3 includes a gas tank and a control outlet connected to the gas tank. The outlet extends into the sample container 1 from the open end of the sample container 1. The connection between the outlet and the open end is sealed, and the end of the outlet extends into the solid sample. The power unit 3 controls the fluidized volume of the solid sample in the sample container 1 by adjusting the gas flow rate and gas pressure output from the outlet. In this embodiment, the solid sample is indirectly heated by heating the sample container 1 with the heating unit 2, and then the power unit 3 extends into the sample container 1 to form bottom blowing, which fluidizes the solid sample and accelerates its volatilization. Optionally, the thermodynamic unit further includes a control unit 6. A switch valve is provided on the gas outlet end of the gas tank, and the heating unit is an electric heating structure. The control unit 6 is connected to the switch valve and the electric heating structure, and is used to supply power to the switch valve and the electric heating structure and control their actions, such as opening the switch valve, adjusting the valve opening, starting heating, and controlling the temperature. In the embodiment shown in the figure, the heating unit 2 adopts a water bath heating pot, and the target temperature for heating the solid sample through the water bath heating pot is 40~60℃. Nitrogen gas is purged inside the gas tank, and the nitrogen gas flow rate output from the gas outlet end is 50~100mL / min, and the gas pressure is 0.05~0.2MPa.

[0029] As another optional implementation, the thermodynamic unit directly induces thermal fluidization of the solid sample by introducing hot nitrogen gas at a temperature of 40-60°C into the sample container 1; for example, an auxiliary heating unit is installed at the gas outlet, and the nitrogen gas directly purges and fixes the sample after heat exchange with the auxiliary heating unit. Naturally, to accelerate the volatilization of volatile components in the solid sample, the solid sample is pre-ground into powder, and the particle size of the sample powder is such that it passes through a 40-100 mesh sieve.

[0030] In specific implementation, the sampling end of the three-stage cold trap device 4 extends directly into the sample container. Although the gas collection tube of the sampling end is placed near the opening of the sample container 1 during installation, the thermally fluidized sample powder may still be simultaneously drawn into the device, affecting the use of the device. Therefore, in this embodiment, the detection system for flavor substances in Daqu also includes a filtration unit. The filtration unit is set in the sample container 1 or the gas collection tube of the sampling end, and the pore size of the sieve of the filtration unit does not exceed 5 μm. Figure 1 The intermediate filtration unit uses a metal filter screen placed inside the gas collecting tube, and the pore size of the metal filter screen is 2μm. When the filtration unit is placed inside the sample container 1, the filtration unit is positioned outside the movement space when the fixed sample is transformed into a fluidized state.

[0031] In conjunction with the aforementioned detection system for flavor substances in Daqu (a type of starter culture), the present invention discloses a method for detecting flavor substances in Daqu, such as... Figure 2As shown, it includes the following steps: Step S102: The solid sample in the sealed sample container 1 is pretreated using a thermodynamic unit until it is thermally fluidized and maintained for a preset time period, so that the volatile components in the solid sample can be fully volatilized; wherein, the thermal fluidization means that the solid sample at a temperature not lower than 40~60℃ exhibits a fluidization effect in the sample container 1; in the embodiment, this is achieved by a combination of heating unit 2 and power unit 3; Step S104: A stable gaseous sample is collected from the solid sample in the sample container 1 after it has been fully volatilized; Step S106: The gaseous sample is purified and enriched using a three-stage cold trap device 4 to obtain an enriched sample; wherein, the enrichment factor of the gaseous sample by the three-stage cold trap device 4 is not less than 1000; Step S108: The enriched sample is injected into a gas chromatography-mass spectrometry (GC-MS) instrument 5 for gas chromatography-mass spectrometry analysis, and the analysis results of the enriched sample are output.

[0032] As an optional implementation, the above method further includes: before performing gas chromatography-mass spectrometry analysis on the enriched sample using a gas purification unit, such as a CO2 adsorption column, to adsorb and filter CO2 in the enriched sample to obtain a filtered sample; obtaining the analysis results of the filtered sample by the gas chromatography-mass spectrometry 5, and comparing and analyzing the analysis results of the filtered sample with the analysis results of the enriched sample to determine the trace components in the enriched sample that were not detected under CO2 interference.

[0033] The following detailed description, in conjunction with specific embodiments, further illustrates the detection system and method for flavor substances in Daqu (a type of starter culture) disclosed in this invention. In the embodiments, the three-stage cold trap device 4 is a pre-concentrator operating on the principle of a three-stage cold trap; the solid sample is high-temperature Daqu blocks used in traditional Baijiu brewing, pulverized to pass through a 60-mesh sieve. Example 1

[0034] First, 100g of the powdered koji block was placed in a 500mL blue-capped bottle and heated at 55℃ using a water bath with nitrogen bottom blowing at a flow rate of 75mL / min and a gas pressure of 0.1MPa, maintaining thermal fluidization for 45min. Then, the pre-concentrator was used to start sampling, and after concentration and enrichment, the sample was injected into a gas chromatograph-mass spectrometer (GC-MS) 5 for gas chromatography-mass spectrometry (GC-MS) analysis. The standard samples selected for analysis by GC-MS 5 were a mixture of 1,4-difluorobenzene, bromochloromethane, chlorobenzene-D5, and p-bromofluorobenzene. The pre-concentrator uses a Suma tank for data collection, and its operating parameters are as follows: cooling temperature of the first-stage cold trap -30℃ and desorption temperature 40℃; cooling temperature of the second-stage cold trap -50℃ and desorption temperature 235℃; focusing temperature of the third-stage cold trap -165℃ and desorption injection pulse temperature 250℃. The operating parameters for gas chromatography-mass spectrometry (GC-MS) were as follows: injection volume 600 mL; splitless; column: DB-WAX flexible quartz fiber capillary column 60 m x 0.25 mm, 0.25 μm; temperature program: 35 °C for 5 min, ramp to 150 °C at 5 °C / min, hold for 7 min, ramp to 210 °C at 10 °C / min, hold for 4 min; carrier gas: He, flow rate 1.0 mL / min; detector temperature: 250 °C; inlet temperature: 250 °C. The operating parameters of the mass spectrometer in the gas chromatography-mass spectrometry system are as follows: EI ionization source, electron energy of 70 eV, electron multiplier voltage of 1610 V, ion source temperature of 200 ℃, transfer line temperature of 250 ℃, and mass scan range of a / z of 35-500 amu. Example 2

[0035] First, 100g of koji powder was placed in a 500mL blue-capped bottle and heated at 55℃ using a water bath for 45 minutes. Then, the pre-concentrator was used to start sampling. After concentration and enrichment, the sample was injected into a gas chromatograph-mass spectrometer for gas chromatography-mass spectrometry analysis. The analytical conditions and parameters were the same as in Example 1.

[0036] Example 3 differs from Example 1 in that the powder in the blue-capped bottle was fluidized by bottom-blowing with nitrogen at a flow rate of 75 mL / min and a pressure of 0.1 MPa. The sample was fluidized for 45 minutes before sampling; other analytical conditions remained unchanged. Example 4, compared to Example 1, involved directly placing the powder in the blue-capped bottle and maintaining it for 45 minutes before sampling, with other conditions unchanged. The analytical results comparing Examples 1 and Examples 2-4 are as follows. Figure 3 As shown.

[0037] The sample processing method combining water bath heating and purging in Example 1 yielded the highest number of flavor substances in the Daqu, with a peak count of 505; Example 2, with single water bath heating, yielded the second highest number of peaks, with a peak count of 432; Example 3, with a single purging phase, yielded a peak count of 207; and Example 4, with no processing and direct sample loading, yielded the fewest peaks, with a peak count of 187.

[0038] The only difference between Examples 5-7 and Example 1 is the injection volume of the flaked powder into the gas chromatography-mass spectrometry (GC-MS) instrument; the standard sample and other parameters remain the same. The compositional analysis results of the flaked powder are shown in Table 1 below. Figure 4 As shown.

[0039] Table 1. Effect of different injection volumes on component detection efficiency of powdered block samples.

[0040] Combining Table 1 and Figure 4 The injection volume of the powder block into the gas chromatography-mass spectrometry instrument is positively correlated with the CO2 content. When the injection volume is 900 mL and 1200 mL, the CO2 content interferes with the peak elution, and the peaks overlap. In terms of peak elution effect, the effect of different injection volumes is 600 mL > 300 mL > 900 mL > 1200 mL.

[0041] The only difference between Example 8 and Example 6 is that a CO2 adsorption column was added before injection into the gas chromatograph-mass spectrometer 5; the only difference between Example 9 and Example 8 is that the mass of the koji powder placed in the 500mL blue-capped bottle was 50g; the specific results are as follows. Figure 5 As shown, compared to Example 6, the addition of a CO2 adsorption column significantly reduced CO2 interference, but the number of peaks was also significantly lower than in Example 1 without a CO2 adsorption column; the number of peaks in Examples 8 and 9 were 290 and 264, respectively. Therefore, it is feasible to determine the trace components in the enriched sample that were not detected by CO2 interference by using a gas purification unit for CO2 adsorption filtration before performing gas chromatography-mass spectrometry (GC-MS) analysis on the enriched sample, and then comparing the results with the analysis results before filtration.

[0042] Comparative Example 1 Flavor compounds in koji powder were analyzed using a headspace solid-phase microextraction (HS-SPME) device combined with GC-MS. 2g of koji powder was extracted using a 20mL headspace vial in a 50℃ water bath for 45 minutes, followed by GC-MS analysis. The results are as follows: Figure 6 As shown in the figure; the total ion chromatogram clearly shows that compared to Example 1, which used a sample processing device with a pre-concentrator and produced 505 peaks, Comparative Example 1, which used headspace solid-phase microextraction, produced only 368 peaks. Qualitative analysis revealed that Example 1 could detect 265 flavor compounds in Daqu, while Comparative Example 1 could only detect 174 flavor compounds, representing a 52% increase in the number of qualitative peaks. The specific statistics for the number of various flavor compounds are shown below. Figure 7 As shown.

[0043] Compared with existing technologies, this invention proposes a detection system and method for trace components in solid-phase samples. Besides its application in detecting trace flavor substances in Daqu (a type of starter culture) as described in the example, it has universal applicability to the detection of trace components in various solid-phase samples. After application, it can not only detect more trace components in low concentrations, but also perform comprehensive analysis with trace components detected by existing methods, improving the overall understanding of sample composition, assisting in process optimization and updating, and proposing new directions for process development.

[0044] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A system for detecting flavor substances in Daqu, characterized in that, The application relates to a sample processing device, a three-stage cold trap device and a gas chromatograph-mass spectrometer. The sample processing device comprises a sample container and a thermal power unit; the sample container is used for containing a solid-phase sample; the thermal power unit acts on the solid-phase sample in the sample container, and is used for heating the solid-phase sample and making the solid-phase sample present in a fluidized state in the sample container. The three-stage cold trap device comprises a sampling end and a sample outlet end; the sampling end extends into the sample container from an opening end of the sample container to collect a gas sample, and the opening end is sealed with the sampling end; the sample outlet end is connected to the gas chromatograph-mass spectrometer; the gas sample is purified, enriched, desorbed and heated in the three-stage cold trap of the three-stage cold trap device, and then is injected into a capillary chromatographic column of the gas chromatograph-mass spectrometer according to a preset volume to perform gas chromatography-mass spectrometry. The thermal power unit comprises a heating part and a power part.

2. The system for detecting flavor substances in Daqu according to claim 1, characterized in that, The heating part is arranged at the periphery of the sample container and is used for heating the sample container and the solid-phase sample in the sample container; the power part comprises a gas tank and a gas outlet end connected to the gas tank; the gas outlet end extends into the sample container from an opening end of the sample container; the gas outlet end is sealed with the opening end; and the end of the gas outlet end extends into the solid-phase sample. The power part controls the fluidized volume of the solid-phase sample in the sample container by regulating the gas flow and gas pressure output by the gas outlet end. The filter unit is arranged in the sample container or a gas collecting pipe of the sampling end, and the pore size of the filter unit is not more than 5 mu m.

3. The system for detecting flavor substances in Daqu according to claim 1, characterized in that, The target temperature for heating the solid-phase sample in the sample container by the thermal power unit is 40-60 DEG C.

4. The system for detecting flavor substances in Daqu according to claim 1, characterized in that, The gas flow output by the gas outlet end is regulated to be 50-100 mL / min, and the gas pressure output by the gas outlet end is regulated to be 0.05-0.2 MPa.

5. The system for detecting flavor substances in Daqu according to claim 2, characterized in that, The solid-phase sample is a sample powder, and the particle size of the sample powder is larger than 40-100 mesh.

6. The system for detecting flavor substances in Daqu according to claim 1, wherein, The working parameters of the gas chromatograph in the gas chromatograph-mass spectrometer are as follows: injection volume is 300-1200 mL; no split; chromatographic column is a DB-WAX elastic quartz fiber capillary column with a length of 60 m, a diameter of 0.25 mm and a thickness of 0.25 mu m; programmed temperature is 35 DEG C for 5 min, then the temperature is increased to 150 DEG C at a speed of 5 DEG C / min, and then the temperature is kept for 7 min, then the temperature is increased to 210 DEG C at a speed of 10 DEG C / min, and then the temperature is kept for 4 min; carrier gas is He, and the flow rate is 1.0 mL / min; detector temperature is 250 DEG C, and inlet temperature is 250 DEG C.

7. The system for detecting flavor substances in Daqu according to claim 1, wherein, The working parameters of the mass spectrometer in the gas chromatograph-mass spectrometer are as follows: EI ionization source, electron energy is 70 eV, electron multiplier voltage is 1610 V, ion source temperature is 200 DEG C, transmission line temperature is 250 DEG C, and mass scanning range a / z is 35-500 amu.

8. The system for detecting flavor substances in Daqu according to claim 1, characterized in that, The application further relates to a sample processing method.

9. A method for detecting flavor substances in Daqu, characterized in that, ​ The heat power unit is used to pretreat the solid phase sample in the sealed sample container to make the solid phase sample in the sample container in hot fluidization at a temperature of not less than 40-60℃ and keep for a preset time period to make the volatile components in the solid phase sample sufficiently volatilize; The component-stable gas phase sample formed by the sufficient volatilization of the solid phase sample in the sample container is collected; The three-stage cold trap device is used to remove impurities and enrich the gas phase sample to obtain the enriched sample; wherein the enrichment multiple of the three-stage cold trap device for the gas phase sample is not less than 1000; The enriched sample is injected into the gas chromatograph mass spectrometer for GC-MS analysis, and the analysis result of the enriched sample is output; wherein the working parameters of the gas chromatograph in the gas chromatograph mass spectrometer are as follows: injection volume 300-1200mL; no split; chromatographic column: DB-WAX elastic quartz fiber capillary column 60mx0.25mm, 0.25μm; programmed temperature: 35℃ for 5min, at a temperature rising rate of 5℃ / min to 150℃, keeping for 7min, at a temperature rising rate of 10℃ / min to 210℃, keeping for 4min; carrier gas: He, flow rate 1.0mL / min; detector temperature: 250℃, inlet temperature: 250℃; the working parameters of the mass spectrometer in the gas chromatograph mass spectrometer are as follows: EI ionization source, electron energy 70eV, electron multiplier voltage 1610V, ion source temperature 200℃, transmission line temperature 250℃, mass scan range a / z 35-500amu.

10. The method for detecting flavor substances in Daqu according to claim 9, characterized in that, Further comprising: Before the GC-MS analysis of the enriched sample by the gas chromatograph mass spectrometer, the CO2 in the enriched sample is adsorbed and filtered by the gas purification unit to obtain the filtered sample; The analysis result of the filtered sample by the gas chromatograph mass spectrometer is obtained, and the analysis result of the filtered sample and the analysis result of the enriched sample are compared and analyzed to determine the trace components not detected in the enriched sample under the interference of CO2.

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