A method for detecting flavor ingredients of baked foods by gas chromatography-mass spectrometry based on modified composite extraction layer

Abstract

This application relates to the technical field of food testing, specifically disclosing a gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer. The modified composite extraction layer disclosed in this application comprises the following components: modified activated carbon, PDMS prepolymer, polyethylene glycol, a functionalized metal composition, a curing agent, a solvent, a dispersant, and a photoinitiator. The modified activated carbon is prepared by immersing it in an ethanol solution of a silane coupling agent, ultrasonically treating it, drying it, and then treating it with argon plasma. The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles with a particle size of 20-80 nm. The composite extraction layer and detection method disclosed in this application solve the problems of low accuracy in flavor detection under high moisture and high matrix interference conditions in baked goods, easy decomposition of heat-sensitive flavors, and weak anti-contamination ability of the extraction layer. It can achieve efficient, accurate, and stable detection of multiple flavor components in baked goods.

Description

Technical Field

[0001] This application relates to the technical field of food testing, specifically to a gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer. Background Technology

[0002] Flavoring components in baked goods are the core elements that determine their flavor. These include natural plant flavorings (such as vanillin, citral, and linalool) and artificial flavorings (such as ethyl acetate, ethyl butyrate, and maltol). Their types and contents must comply with the standards for the use of food additives. Therefore, accurate detection of flavoring components in baked goods is of great significance for product quality control and food safety supervision.

[0003] Gas chromatography-mass spectrometry (GC-MS) is the mainstream technique for the detection of volatile components in food flavorings. Solid phase microextraction (SPME) is used as a sample pretreatment method combined with GC-MS. Its working principle is as follows: after the volatile components in the sample reach thermal equilibrium in a closed container, they are adsorbed and enriched using fused silica fibers coated with a stationary phase. The fiber tip is then inserted into the vaporization chamber of the gas chromatograph injection port for desorption, followed by GC-MS analysis. Because it requires no organic solvents and is simple to operate, this method is widely used for the analysis of volatile components in flavorings. In the existing technology, there are SPME-GC-MS detection methods for candles, daily chemical products and other fields. The stationary phase is activated carbon-polydimethylsiloxane (PDMS) composite extraction layer. However, when this method is directly applied to the detection of flavorings in baked goods, there are many compatibility problems, as follows: (1) Large matrix interference in baked goods: Baked goods contain high moisture, sugar, starch and protein. During headspace extraction, moisture is easy to evaporate excessively and combine with the extraction layer, blocking the adsorption sites. The pyrolysis products of sugar and starch will contaminate the extraction layer and GC inlet, resulting in drift of the detection signal. (2) Poor flavoring adsorption selectivity: Baked goods flavorings are mainly esters, aldehydes and terpenes. The existing composite extraction layer has insufficient targeted adsorption capacity for such polar / weakly polar flavorings. The response of low concentration flavoring components is poor and the quantitative accuracy is low. (3) Insufficient adaptability of extraction parameters: The extraction temperature (75-85℃), time and other parameters of the existing detection methods are designed for candle matrix. (4) When used directly for baked goods, high temperature can easily cause some heat-sensitive flavorings (such as maltol and vanillin) to decompose, resulting in distorted detection results. (5) Weak anti-contamination ability of existing extraction layers: Macromolecular matrix impurities in the headspace of baked goods are easily adsorbed on the surface of the extraction layer and are difficult to desorb, resulting in poor reusability of the extraction layer and high detection cost.

[0004] To address the aforementioned issues, there is currently no SPME-GC-MS method specifically adapted to the matrix of baked goods for flavor detection. There is an urgent need to directionally modify the existing composite extraction layer and optimize the detection process parameters to develop a precise detection method for flavor components in baked goods. Summary of the Invention

[0005] To address the aforementioned technical issues, this application provides a gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer.

[0006] In a first aspect, this application provides a modified composite extraction layer, specifically comprising the following components in parts by weight: 15-25 parts modified activated carbon, 50-60 parts PDMS prepolymer, 8-12 parts polyethylene glycol, 2-3 parts functionalized metal composition, 5-7 parts curing agent, 8-12 parts solvent, 0.8-1.5 parts dispersant, and 0.3-0.5 parts photoinitiator; The modified activated carbon is prepared by immersing activated carbon in an ethanol solution containing 1.2-1.8 wt% silane coupling agent, ultrasonically treating for 25-35 min, drying at 60-70℃, and then treating with argon plasma for 10-15 min to obtain the modified activated carbon. The performance parameters of the activated carbon are: particle size 1-10 μm, specific surface area 900-1300 m² / g. The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 3-7:1, with a particle size of 20-80 nm.

[0007] The purpose of this application is to overcome the shortcomings of existing technologies and provide a gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer. By modifying the activated carbon-PDMS composite extraction layer to adapt to the baking food matrix, adding hydrophilic functional components, and optimizing the ratio of functionalized metal compositions, this method solves problems such as low accuracy of flavor detection under high moisture and high matrix interference conditions in baked goods, easy decomposition of heat-sensitive flavors, and weak anti-contamination ability of the extraction layer. This enables efficient, accurate, and stable detection of multiple flavor components in baked goods.

[0008] In the modified composite extraction layer technology, activated carbon is first ultrasonically treated with a silane coupling agent, and then treated with argon plasma to introduce active groups on its surface, improving its interfacial compatibility with PDMS and PEG and reducing raw material agglomeration. The hydrophilic component of PEG-2000 not only achieves targeted adsorption of polar flavorings such as esters and aldehydes in baked goods, but also selectively adsorbs trace amounts of moisture in the headspace, preventing moisture from clogging the adsorption sites of activated carbon and solving the problem of interference from high-moisture matrices. The PDMS prepolymer, after being compounded with PEG, adjusts the polarity of the extraction layer to suit the adsorption of esters and aldehydes in baked goods. The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles, which can effectively improve the specific adsorption capacity for oxygen-containing flavorings (such as vanillin and maltol) in baked goods, while catalytically degrading the pyrolysis products of sugars in the matrix, reducing contamination of the extraction layer and GC inlet, and improving the reusability of the extraction layer.

[0009] Preferably, the modified composite extraction layer specifically comprises the following components in parts by weight: 17-22 parts modified activated carbon, 53-58 parts PDMS prepolymer, 9-11 parts polyethylene glycol, 2.2-2.8 parts functionalized metal composition, 5.5-6.5 parts curing agent, 9-11 parts solvent, 0.9-1.4 parts dispersant, and 0.35-0.45 parts photoinitiator.

[0010] Preferably, the performance parameters of the PDMS prepolymer are: viscosity 350-450 mPa·s, number average molecular weight 60,000-80,000 g / mol.

[0011] Preferably, the average molecular weight of the polyethylene glycol is 1000-4000.

[0012] In one specific implementation, the polyethylene glycol may be PEG-1000, PEG-2000, or PEG-4000.

[0013] Preferably, the functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 4-6:1.

[0014] In one specific embodiment, the weight ratio of zinc oxide nanoparticles to titanium dioxide nanoparticles in the functionalized metal composition can be 4:1, 5:1, or 6:1.

[0015] Experimental analysis shows that using zinc oxide nanoparticles and titanium dioxide nanoparticles in the above weight ratio as a functionalized metal composition can further improve the accuracy of the detection method.

[0016] Preferably, the curing agent is benzoyl peroxide; the solvent is xylene; the dispersant is BYK-163; and the photoinitiator is 1-hydroxycyclohexylphenyl ketone.

[0017] Preferably, the silane coupling agent is selected from one or more of KH-560 and KH-570.

[0018] Secondly, this application provides a method for preparing the modified composite extraction layer, comprising the following steps: Modified activated carbon and functionalized metal composition were added to a dispersant and ball-milled to obtain a uniform dispersion. Add solvent, PDMS prepolymer, polyethylene glycol, curing agent, and photoinitiator to the dispersion, and stir at 400-600 rpm for 25-35 min to form a coating solution; The coating solution was spin-coated onto the surface of the quartz fiber probe at a spin speed of 700-900 rpm for 30-60 s, with a thickness of 8-15 μm. Then, it was cured under ultraviolet light to obtain the modified composite extraction layer.

[0019] In the preparation method of the modified composite extraction layer, the ultraviolet light rapid curing process is used to replace the traditional high temperature curing, which shortens the preparation cycle of the extraction layer, avoids the high temperature decomposition of raw materials, and controls the thickness of the extraction layer to 8-15μm, which is suitable for the rapid desorption requirements of spices in baked goods.

[0020] Thirdly, this application provides a gas chromatography-mass spectrometry (GC-MS) method for detecting flavoring components in baked goods based on a modified composite extraction layer, utilizing the modified composite extraction layer for detection; including the following steps: Sample pretreatment: Place the crushed baked food sample in a headspace vial with a PTFE septum and seal it; Headspace solid-phase microextraction: Place the sample vial in a metal bath and equilibrate at 60-70℃ for 10-15 min; insert the modified composite extraction layer into the septum of the sample vial, and extend the extraction head to a distance of 2-4 mm from the septum, so that the extraction layer is fully exposed to the headspace region, and extract at 60-70℃ for 30-40 min; after extraction, immediately retract the extraction head and pull out the modified composite extraction layer; GC-MS detection: Insert the modified composite extraction layer into the GC inlet and perform thermal desorption at 240-260℃ for 2-4 min to completely desorb the fragrance analytes in the extraction layer and allow them to enter the chromatographic column. Then, retract the extraction head and extract the probe; start the GC-MS instrument for qualitative and quantitative detection.

[0021] Preferably, the process parameters for GC-MS detection are: Chromatographic column: HP-INNOWax capillary column or DB-FFAP capillary column; Column temperature program: 35-45℃ for 2-5 min, increase to 220-240℃ at 2-10℃ / min, and hold for 25-35 min; Carrier gas: High-purity helium with a purity ≥99.999%, flow rate 0.8-1.2 mL / min, constant flow mode; Mass spectrometry conditions: EI ion source, electron energy 70 eV, ion source temperature 220-240℃, quadrupole temperature 140-160℃, scan range 30-450 u, qualitative analysis was performed using the NIST mass spectrum library, and quantitative analysis was performed using the external standard method.

[0022] In the gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods, this application further ensures the accuracy and stability of the detection method by adjusting the headspace extraction and GC-MS detection parameters. Specifically, an extraction temperature of 60-70℃ ensures sufficient volatilization of flavorings in baked goods while avoiding excessive moisture evaporation and decomposition of heat-sensitive flavorings; an extraction time of 30-40 min is adapted to the adsorption rate of the modified extraction layer, achieving sufficient enrichment of flavoring components. The use of a weakly polar chromatographic column enables efficient separation of various polar / weakly polar flavoring components in baked goods.

[0023] In summary, the technical solution of this application has the following effects: This application presents a gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer. This method is specifically innovative for baked goods, which are characterized by high moisture content, high matrix interference, and the presence of heat-sensitive flavorings. Compared to existing technologies, it offers the following significant advantages: (1) High detection accuracy: The modified composite extraction layer adds PEG hydrophilic components and optimizes the ratio of functional metal composition to achieve targeted adsorption of esters, aldehydes and terpenes in baked goods. The responsiveness of low-concentration flavor components is improved, the total deviation of standard sample detection is ≤10%, and the qualitative and quantitative results are accurate.

[0024] (2) Strong matrix anti-interference ability: The modified activated carbon and functional metal composition work together to effectively degrade sugar and starch pyrolysis products in the headspace of baked food, avoiding contamination of the extraction layer and GC inlet. At the same time, PEG selectively adsorbs trace amounts of moisture, solving the interference of high moisture matrix on adsorption.

[0025] (3) Suitable for heat-sensitive flavorings: The optimized headspace extraction temperature (60-70℃) avoids the decomposition of heat-sensitive flavorings such as maltol and vanillin, ensuring the authenticity of the test results and making it suitable for flavoring detection in various baked goods.

[0026] (4) Excellent performance of the extraction layer: The extraction layer uses plasma composite modification of silane coupling agent and ultraviolet curing process. The raw materials are evenly dispersed and the structure is stable. It can be reused more than 17 times, which greatly reduces the cost of consumables and operation costs of detection.

[0027] (5) Easy to operate and highly versatile: The pretreatment steps of this application do not require organic solvents, the operation process is simple, the detection parameters are compatible with conventional GC-MS instruments, and it can be widely applied to the detection of flavor components in various baked foods such as cakes, bread, biscuits, and pastries. It can also be adapted to the formulation development for flavor improvement of baked foods. Detailed Implementation

[0028] The present application will be further described in detail below with reference to embodiments, comparative examples and performance test results. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0029] Example

[0030] Examples 1-3 Examples 1-3 respectively provide a modified composite extraction layer and its preparation method, and a gas chromatography-mass spectrometry method for detecting flavor components in baked goods based on the modified composite extraction layer.

[0031] The difference in the above embodiments is that the amount of each raw material component is different, as shown in Table 1.

[0032] (1) The specific preparation methods of the modified activated carbon in Examples 1-3 are as follows.

[0033] Modified activated carbon (particle size 5μm, specific surface area 1100m² / g) was soaked in an ethanol solution containing 1.5wt% silane coupling agent KH-560 at a solid-liquid ratio of 1:10, ultrasonically treated for 30 min at 200W, dried at 65℃, and then treated with argon plasma for 12 min to obtain modified activated carbon.

[0034] (2) The specific preparation methods of the modified composite extraction layer in Examples 1-3 are as follows.

[0035] Modified activated carbon and a functionalized metal composition (composed of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 5:1, with a particle size of 40 nm) were added to dispersant BYK-163 and dispersed by ball milling to obtain a uniform dispersion. The ball milling parameters were: alumina ball material, ball-to-material ratio of 8:1, rotation speed of 450 r / min, and a duration of 60 min.

[0036] Add xylene solvent, PDMS prepolymer (400 mPa·s, 70,000 g / mol), polyethylene glycol PEG-2000, benzoyl peroxide curing agent, and 1-hydroxycyclohexylphenyl ketone photoinitiator to the dispersion, and stir at 500 rpm for 30 min to form a coating solution.

[0037] The coating solution was spin-coated onto the surface of the quartz fiber probe at a spin speed of 800 rpm for 40 s, resulting in a thickness of 10 μm. The modified composite extraction layer was then cured by irradiation with ultraviolet light (wavelength 365 nm) for 6 min.

[0038] Table 1. Amounts of each raw material component in Examples 1-3

[0039] (3) A gas chromatography-mass spectrometry (GC-MS) method for detecting flavoring components in baked goods based on a modified composite extraction layer, comprising the following steps: Sample pretreatment: Cut the baked food sample (standard vanilla cake sample, with 5 ppm of baking flavoring added, the baking flavoring ingredients include vanillin, ethyl acetate, ethyl butyrate, citral, linalool, maltol, benzaldehyde, butyl acetate, geraniol, and ethyl maltol, each ingredient accounting for 10%) into 3 mm pieces, weigh 0.5 g and place it in a 20 mL headspace sample bottle with a PTFE septum, and seal it immediately to prevent the loss of volatile flavoring components.

[0040] Headspace solid-phase microextraction: Place the sample vial in a metal bath and equilibrate at 65°C for 12 min; insert the modified composite extraction layer (probe) into the septum of the sample vial and extend the extraction head to a distance of 3 mm from the septum, so that the extraction layer is fully exposed to the headspace area, and extract at 65°C for 35 min; after extraction, immediately retract the extraction head and pull out the modified composite extraction layer.

[0041] GC-MS detection: Insert the above probe (i.e., the modified composite extraction layer) into the GC injection port and perform thermal desorption at 250℃ for 3 min to completely desorb the fragrance analytes in the extraction layer and enter the chromatographic column. Then, retract the extraction head and extract the probe; start the GC-MS instrument for qualitative and quantitative detection.

[0042] The GC-MS detection parameters were as follows: Column: Agilent HP-INNOWax capillary column, 60m × 0.25mm × 0.25μm; Column temperature program: initial temperature 60℃, hold for 3 min, increase to 240℃ at 4℃ / min, hold for 30 min; Carrier gas: high-purity helium gas with a purity ≥99.999%, flow rate 1mL / min, constant flow mode. Mass spectrometry conditions: EI ion source, electron energy 70eV, ion source temperature 230℃, quadrupole temperature 150℃, scan range 30-450u; qualitative analysis was performed using the NIST mass library, and quantitative analysis was performed using the external standard method.

[0043] Examples 4-5 Examples 4-5 respectively provide a modified composite extraction layer and its preparation method, and a gas chromatography-mass spectrometry method for detecting flavor components in baked goods based on the modified composite extraction layer.

[0044] The difference between the above embodiments and Embodiment 1 is that the preparation method of the modified activated carbon is different, as shown below.

[0045] In Example 4, the modified activated carbon was prepared by immersing activated carbon (particle size 5 μm, specific surface area 1100 m² / g) in an ethanol solution containing 1.2 wt% silane coupling agent KH-560 at a solid-liquid ratio of 1:10, ultrasonically treating it for 30 min at 200 W, drying it at 65 °C, and then treating it with argon plasma for 12 min to obtain the modified activated carbon.

[0046] In Example 5, the modified activated carbon was prepared by immersing activated carbon (particle size 5 μm, specific surface area 1100 m² / g) in an ethanol solution containing 1.8 wt% silane coupling agent KH-560 at a solid-liquid ratio of 1:10, ultrasonically treating it for 30 min at 200 W, drying it at 65 °C, and then treating it with argon plasma for 12 min to obtain the modified activated carbon.

[0047] All other process parameters in the above embodiments are the same as those in Embodiment 1.

[0048] Examples 6-9 Examples 6-9 respectively provide a modified composite extraction layer and its preparation method, and a gas chromatography-mass spectrometry method for detecting flavor components in baked goods based on the modified composite extraction layer.

[0049] The differences between the above embodiments and Embodiment 1 are as follows:

[0050] In Example 6: The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 3:1, with a particle size of 40 nm.

[0051] In Example 7: The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 7:1, with a particle size of 40 nm.

[0052] In Example 8, polyethylene glycol PEG-2000 was replaced with an equal amount of polyethylene glycol PEG-1000.

[0053] In Example 9, polyethylene glycol PEG-2000 was replaced with an equal amount of polyethylene glycol PEG-4000.

[0054] All other process parameters in the above embodiments are the same as those in Embodiment 1.

[0055] Comparative Example Comparative Examples 1-4 Comparative Examples 1-4 respectively provide a modified composite extraction layer and its preparation method, and a gas chromatography-mass spectrometry method for detecting flavor components in baked goods based on the modified composite extraction layer.

[0056] The differences between Comparative Examples 1-4 and Example 1 are as follows:

[0057] In Comparative Example 1: In the preparation method of the modified composite extraction layer, an equal amount of unmodified activated carbon was used to replace the modified activated carbon.

[0058] In Comparative Example 2: The modified activated carbon was prepared by immersing activated carbon (particle size 5μm, specific surface area 1100m² / g) in an ethanol solution containing 1.5wt% silane coupling agent KH-560 at a solid-liquid ratio of 1:10, ultrasonically treating it for 30min at 200W, and drying it at 65℃ to obtain the modified activated carbon.

[0059] In Comparative Example 3: Activated carbon (particle size 5μm, specific surface area 1100m² / g) was soaked in an ethanol solution containing 2.2wt% silane coupling agent KH-560 at a solid-liquid ratio of 1:10, ultrasonically treated at 200W for 30min, dried at 65℃, and then treated with argon plasma for 12min to obtain modified activated carbon.

[0060] In Comparative Example 4: the functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 1:5, with a particle size of 40 nm.

[0061] All other process parameters in the above comparative examples are the same as those in Example 1.

[0062] Performance testing Detection indicators: The methods of the examples and comparative examples were used for detection. The difference between the detected proportion and the actual proportion of each fragrance (A vanillin, B ethyl acetate, C ethyl butyrate, D citral, E linalool, F maltol, G benzaldehyde, H butyl acetate, I geraniol, J ethyl maltol) was calculated. The total deviation value of the differences of the 10 fragrances was taken (the smaller the total deviation value, the higher the detection accuracy). At the same time, the number of times the extraction layer could be reused was counted (the pass standard was ≤10% for the total detection deviation value).

[0063] Test results are shown in Table 2.

[0064] Table 2 Performance test results of the detection methods in the examples and comparative examples

[0065] As can be seen from the test results in Table 2 above, by using the technical solution provided in this application and by adopting a modified composite extraction layer and matching detection parameters, the accuracy of flavoring detection in baked goods can be effectively improved, and the problems of matrix interference and decomposition of heat-sensitive flavorings can be solved. At the same time, the extraction layer can be reused ≥17 times, which is much higher than the comparative example, indicating that the anti-contamination ability of the modified composite extraction layer is significantly improved, and the detection cost is reduced.

[0066] By comparing the detection results of Examples 1, 4-5, and Comparative Examples 1-2, it can be seen that in Comparative Example 1, an equal amount of unmodified activated carbon was used instead of modified activated carbon; in Comparative Example 2, the modified activated carbon preparation method did not undergo argon plasma treatment after coupling agent treatment; and in Comparative Example 3, the modified activated carbon preparation method used a higher concentration of silane coupling agent to modify the activated carbon, resulting in a modified composite extraction layer. When used to detect flavor components in baked goods, the detection method was ineffective. In contrast, the present application first soaks the activated carbon in an ethanol solution of 1.2-1.8 wt% silane coupling agent, then ultrasonically treats it, dries it, and finally treats it with argon plasma. The resulting modified activated carbon is used to prepare a modified composite extraction layer, which can effectively improve the accuracy of the detection method when used to detect flavor components in baked goods.

[0067] By comparing the detection results of Examples 1, 6-7, and Comparative Example 4, it was found that Comparative Example 4, which used a functionalized metal composition consisting of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 1:5, showed poor performance in detecting flavoring components in baked goods. In contrast, this application uses a functionalized metal composition consisting of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 3-7:1, which can effectively improve the accuracy of the detection method.

[0068] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A modified composite extraction layer, characterized in that, Specifically, it includes the following components in parts by weight: 15-25 parts modified activated carbon, 50-60 parts PDMS prepolymer, 8-12 parts polyethylene glycol, 2-3 parts functionalized metal composition, 5-7 parts curing agent, 8-12 parts solvent, 0.8-1.5 parts dispersant, and 0.3-0.5 parts photoinitiator; The modified activated carbon is prepared by immersing activated carbon in an ethanol solution containing 1.2-1.8 wt% silane coupling agent, ultrasonically treating for 25-35 min, drying at 60-70℃, and then treating with argon plasma for 10-15 min to obtain the modified activated carbon. The performance parameters of the activated carbon are: particle size 1-10 μm, specific surface area 900-1300 m² / g. The functionalized metal composition consists of zinc oxide nanoparticles and titanium dioxide nanoparticles in a weight ratio of 3-7:1, with a particle size of 20-80 nm.

2. The modified composite extraction layer according to claim 1, characterized in that, Specifically, it includes the following components in parts by weight: 17-22 parts modified activated carbon, 53-58 parts PDMS prepolymer, 9-11 parts polyethylene glycol, 2.2-2.8 parts functionalized metal composition, 5.5-6.5 parts curing agent, 9-11 parts solvent, 0.9-1.4 parts dispersant, and 0.35-0.45 parts photoinitiator.

3. The modified composite extraction layer according to claim 1, characterized in that, The performance parameters of the PDMS prepolymer are: viscosity 350-450 mPa·s, number average molecular weight 60,000-80,000 g / mol.

4. The modified composite extraction layer according to claim 1, characterized in that, The average molecular weight of the polyethylene glycol is 1000-4000.

5. The modified composite extraction layer according to claim 1, characterized in that, The curing agent is benzoyl peroxide; the solvent is xylene; the dispersant is BYK-163; and the photoinitiator is 1-hydroxycyclohexylphenyl ketone.

6. The modified composite extraction layer according to claim 1, characterized in that, The silane coupling agent is selected from one or more of KH-560 and KH-570.

7. The method for preparing the modified composite extraction layer according to any one of claims 1-6, characterized in that, Includes the following steps: Modified activated carbon and functionalized metal composition were added to a dispersant and ball-milled to obtain a uniform dispersion. Add solvent, PDMS prepolymer, polyethylene glycol, curing agent, and photoinitiator to the dispersion, and stir at 400-600 rpm for 25-35 min to form a coating solution; The coating solution was spin-coated onto the surface of the quartz fiber probe at a spin speed of 700-900 rpm for 30-60 s, with a thickness of 8-15 μm. Then, it was cured under ultraviolet light to obtain the modified composite extraction layer.

8. A gas chromatography-mass spectrometry (GC-MS) method for detecting flavoring components in baked goods based on a modified composite extraction layer, characterized in that, Detection is performed using the modified composite extraction layer according to any one of claims 1-6; including the following steps: Sample pretreatment: Place the crushed baked food sample in a headspace vial with a PTFE septum and seal it; Headspace solid-phase microextraction: Place the sample vial in a metal bath and equilibrate at 60-70℃ for 10-15 min; insert the modified composite extraction layer into the septum of the sample vial, and extend the extraction head to a distance of 2-4 mm from the septum, so that the extraction layer is fully exposed to the headspace region, and extract at 60-70℃ for 30-40 min; after extraction, immediately retract the extraction head and pull out the modified composite extraction layer; GC-MS detection: Insert the modified composite extraction layer into the GC inlet and perform thermal desorption at 240-260℃ for 2-4 min to completely desorb the fragrance analytes in the extraction layer and allow them to enter the chromatographic column. Then, retract the extraction head and extract the probe; start the GC-MS instrument for qualitative and quantitative detection.

9. The gas chromatography-mass spectrometry (GC-MS) method for detecting flavor components in baked goods based on a modified composite extraction layer according to claim 8, characterized in that, The process parameters for GC-MS detection are as follows: Chromatographic column: HP-INNOWax capillary column or DB-FFAP capillary column; Column temperature program: 35-45℃ for 2-5 min, increase to 220-240℃ at 2-10℃ / min, and hold for 25-35 min; Carrier gas: High-purity helium gas with a purity ≥99.999%, flow rate 0.8-1.2 mL / min, constant flow mode; Mass spectrometry conditions: EI ion source, electron energy 70 eV, ion source temperature 220-240℃, quadrupole temperature 140-160℃, scan range 30-450 u, qualitative analysis was performed using the NIST mass spectrum library, and quantitative analysis was performed using the external standard method.

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