Method for detecting polyol distribution in tobacco leaves based on stimulated raman and application thereof

Abstract

The application provides a method for detecting distribution of polyols in tobacco leaves based on stimulated Raman and application thereof, and the method comprises the following steps: performing stimulated Raman detection on the tobacco leaves to be detected, performing Lasso fitting and splitting on the detection results by using a standard atlas of polyols, and obtaining the distribution of polyols in the tobacco leaves to be detected. The method has the advantages of high sensitivity, high spatial resolution, fast imaging and nondestructive detection, and establishes a qualitative analysis and semi-quantitative detection method for polyols outside tobacco leaves.

Description

Technical Field

[0001] This invention belongs to the field of tobacco detection and analysis technology, specifically relating to a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy and its application. Background Technology

[0002] Polyols (such as propylene glycol and glycerol) in tobacco leaf liquor are important additives in tobacco products, affecting the moisture retention, sensory quality, and smoke release of cigarettes. Their spatial distribution uniformity directly determines the flavor stability and process controllability of tobacco products. Currently, the detection techniques for polyols in tobacco leaves include gas chromatography, gas chromatography-mass spectrometry, and liquid chromatography to determine the content of polyols, or nuclear magnetic resonance (NMR) to characterize the distribution of polyols. However, these existing detection methods require pretreatment of tobacco leaf samples, such as grinding and extraction, which destroys their original structure and fails to preserve the spatial distribution information of polyols. Furthermore, most require the preparation of a series of standard solutions to achieve accurate quantification, making the measurement process cumbersome and time-consuming, and unable to meet the needs of rapid detection.

[0003] CN223426555U discloses a detector for glycerol content in reconstituted tobacco leaves for heated cigarettes and a heated cigarette processing device. The detector includes a housing and a microwave detection unit. The use of the detector involves introducing reconstituted tobacco leaves for manufacturing heated cigarettes into a gap channel through a tobacco sheet detection inlet for microwave detection. By pre-adjusting the position of the guide strip on the tobacco sheet detection inlet, the guide strip above the detection inlet can act as a limiting strip to restrict the tobacco sheet. Working in conjunction with the guide strip below the detection inlet, it can effectively guide the tobacco sheet into the gap channel. As the tobacco sheet passes through the microwave detection unit, the upper and lower parts of the microwave detection body will produce different responses due to the different glycerol content inside the tobacco sheet. This eliminates the need for pre-processing of the tobacco sheet sample, solving the problems of most existing glycerol content measuring instruments damaging the heated cigarette sheet when detecting tobacco components and the slow feedback speed of the detection results.

[0004] CN101718758A discloses a method for determining the uniformity of liquid application in the cigarette additive process. The method uses 1,2-propanediol in the liquid as a marker, and utilizes the 1,2-propanediol content in the tobacco sheet after additive application to represent the distribution of the liquid content in the tobacco sheet. The uniformity of additive application is determined through detection, calculation, and statistical analysis. This invention provides a complete and objective method for quantitatively evaluating the uniformity of liquid application in the cigarette additive process. The adoption of this method is of great significance for improving additive equipment and processes, and enhancing the quality and stability of cigarette products.

[0005] However, the aforementioned methods still suffer from damage to tobacco samples or fail to achieve effective distribution detection. Therefore, finding a detection method that can simultaneously identify polyols, their spatial distribution, and measure their content, while being simple, rapid, and providing accurate and reliable results, has become an urgent problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy and its applications. The method provided by this invention has the advantages of high sensitivity, high spatial resolution, rapid imaging, and non-destructive testing, establishing a qualitative and semi-quantitative detection method for added polyols in tobacco leaves.

[0007] To achieve this objective, the present invention adopts the following technical solution: On one hand, the present invention provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, the method comprising the following steps: Stimulated Raman spectroscopy was performed on the tobacco leaves to be tested, and the results were analyzed by Lasso fitting and splitting of the polyol standard spectrum to obtain the distribution of polyols in the tobacco leaves.

[0008] The above method is based on stimulated Raman spectroscopy, which can specifically enhance the Raman signal of polyol molecules. It has the advantages of high sensitivity, high spatial resolution (enabling submicron imaging), rapid imaging, and non-destructive testing. A qualitative and semi-quantitative detection method for added polyols in tobacco leaves has been established.

[0009] Preferably, the polyol includes propylene glycol and / or glycerol.

[0010] Preferably, the tobacco to be tested includes flue-cured tobacco, aromatic tobacco, burley tobacco, cigar tobacco, or sun-cured tobacco.

[0011] Preferably, the tobacco to be tested includes tobacco produced on a production line or tobacco obtained using the following steps: The tobacco samples were equilibrated, and then a polyol solution was applied to the surface of the tobacco samples and allowed to stand.

[0012] Preferably, the equilibrium temperature is 20-40℃, the relative humidity is 20-80%, and the time is at least 72 hours. The temperature can be 20℃, 25℃, 30℃, 35℃, or 40℃, etc., and the relative humidity can be 20%, 30%, 40%, 50%, 60%, 70%, or 80%, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0013] Preferably, the settling temperature is 20-40℃, the relative humidity is 20-80%, and the time is at least 72 hours. The temperature can be 20℃, 25℃, 30℃, 35℃, or 40℃, etc., and the relative humidity can be 20%, 30%, 40%, 50%, 60%, 70%, or 80%, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0014] Preferably, the polyol is glycerol, and the amount of polyol applied to the surface of the tobacco sample is 0.5-110% of the tobacco mass, such as 0.5%, 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or 110%, but not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0015] Preferably, the polyol is propylene glycol, and the amount of polyol applied to the surface of the tobacco sample is 1-60% of the tobacco mass, such as 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc., but not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0016] Preferably, in the stimulated Raman detection, the pump light wavelength is 800-810 nm, the Stokes light wavelength is 1025-1080 nm, and the fingerprint wavelength is 2750-3075 cm⁻¹. -1 The pump light wavelength can be 800 nm, 801 nm, 802 nm, 803 nm, 804 nm, 805 nm, 806 nm, 807 nm, 808 nm, 809 nm or 810 nm, etc., and the Stokes light wavelength can be 1025 nm, 1030 nm, 1035 nm, 1040 nm, 1045 nm, 1050 nm, 1055 nm, 1060 nm, 1065 nm, 1070 nm, 1075 nm or 1080 nm, etc., but is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0017] Preferably, in the stimulated Raman detection, the detection depth is from the tobacco surface to a depth of 40 μm, and the width is at least 390 nm.

[0018] On the other hand, the present invention also provides the application of the method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy as described above in tobacco production and / or tobacco research and development.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy. It can specifically enhance the Raman signal of polyol molecules and has the advantages of high sensitivity, high spatial resolution (enabling submicron imaging), rapid imaging, and non-destructive testing. It establishes a method for qualitative analysis and semi-quantitative detection of added polyols in tobacco leaves. Attached Figure Description

[0020] Figure 1 For propylene glycol at 2750-3075 cm⁻¹ -1 Extended stimulated Raman plot; Figure 2 Glycerol at 2750-3075 cm⁻¹ -1 Extended stimulated Raman plot; Figure 3 For tobacco, the range is 2750-3075 cm. -1 Extended stimulated Raman plot; Figure 4 Stimulated Raman spectroscopy, Lasso splitting, and overlay images of two locations on the surface of tobacco leaves under conditions where 110% glycerol by mass is added; Figure 5 The images show stimulated Raman spectroscopy, Lasso splitting, and overlay images of two locations on the surface of tobacco leaves under conditions where 60% propylene glycol by mass is added. Figure 6 Stimulated Raman spectroscopy, Lasso splitting, and overlay images of tobacco leaves with 60% propylene glycol by mass added to a depth of 20 micrometers below the surface. Figure 7 The images show two stimulated Raman spectroscopy, Lasso splitting, and overlay images of the surface of tobacco leaves after wetting with water under conditions of adding 60% propylene glycol by mass; Figure 8 Three stimulated Raman field images, Lasso split images, and overlay images are shown for tobacco leaves with an added 5% propylene glycol by mass. Figure 9 Three stimulated Raman field images, Lasso split images, and overlay images are shown for tobacco leaves with an added 4% propylene glycol by mass. Figure 10 Three stimulated Raman field images, Lasso split images, and overlay images are shown for tobacco leaves with an added 3% propylene glycol by mass. Figure 11 Three stimulated Raman field images, Lasso split images, and overlay images are shown for tobacco leaves with an added 2% propylene glycol by mass. Figure 12 Three stimulated Raman field images, Lasso split images, and overlay images were generated for tobacco leaves with an added 1% propylene glycol by mass. Figure 13This is a graph showing the correlation between the propylene glycol to tobacco leaf mass ratio and the average signal intensity percentage of propylene glycol in the field of view. Figure 14 For propylene glycol aqueous solutions of different concentrations at 2750-3075 cm⁻¹ -1 Extended stimulated Raman plot; Figure 15 Different concentrations of propylene glycol aqueous solutions were tested at 2888 cm⁻¹. -1 The following is a graph showing the relationship between average signal intensity and concentration; Figure 16 Millimeter-scale stimulated Raman field of view, Lasso split image, and overlay image of tobacco leaves with simultaneous addition of glycerol and propylene glycol. Detailed Implementation

[0021] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0022] In the following example, the Raman tester model is: UltraView from ZhenDian (Suzhou) Medical Co., Ltd.

[0023] Example 1: This embodiment provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, including the following steps: Under constant temperature and humidity conditions (30℃, 50% relative humidity), accurately weigh a 0.15g sample of well-formed leaves and let it stand for 3 days; immerse the tobacco leaves in glycerol solvent, absorb the glycerol from the surface, place them under vacuum for 3 days, and weigh the tobacco leaves after soaking in glycerol until the weight increases to 0.31g (the mass ratio of glycerol to tobacco is 1.1:1, defined as glycerol mass percentage of 110%). Perform stimulated Raman imaging on the sample. The stimulated Raman spectroscopy test conditions are: pump light 801 nm, 10mW; Stokes light 1027-1073 nm, 100 mW; 60x objective lens; NA 1.2; pixel count 400×400; single-point scan time 10μs; 0.39 μm / pixel; average scan count 1; hyperspectral scan step size 10 μm. The fingerprint wavelength of glycerol on the leaf surface at this concentration was obtained in the range of 2750-3075 cm⁻¹. -1 Stimulated Raman spectroscopy, using standard spectra of glycerol and tobacco leaves ( Figure 2-3 The glycerol and untreated tobacco were subjected to stimulated Raman spectroscopy under the above conditions, and the remaining standard spectra were obtained using the same method. Lasso fitting was then used to split the spectra to obtain the distribution map of glycerol in the leaves at that concentration. Figure 4 From left to right, the images are: original field of view, glycerol-resolved image, tobacco-resolved image, and glycerol and tobacco signal overlay (similar to the images below).

[0024] Example 2: This embodiment provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, including the following steps: Under constant temperature and humidity conditions (20℃, 20% relative humidity), accurately weigh a 0.15g sample of well-formed leaves and let it stand for 3 days; immerse the tobacco leaves in propylene glycol, absorb the surface polyols, and place them under vacuum for 3 days, weighing to obtain a weight gain of 0.24g after propylene glycol immersion (the mass ratio of propylene glycol to tobacco is 0.6:1, defined as 60% propylene glycol by mass). Perform stimulated Raman imaging on the sample. The stimulated Raman spectroscopy test conditions are: pump light 801 nm, 10mW; Stokes light 1027-1073 nm, 100 mW; 60x objective lens; NA 1.2; 400×400 pixels; single-point scan time 10 μs; 0.39 μm / pixel; average scan count 1; hyperspectral scan step size 10 μm. The fingerprint wavelength of propylene glycol on the leaf surface at this concentration was obtained in the range of 2750-3075 cm⁻¹. -1 Stimulated Raman spectroscopy, using standard spectra of propylene glycol and tobacco leaves ( Figure 1 and Figure 3 Lasso fitting was performed to split the data and obtain the distribution map of propylene glycol in the leaves at this concentration. Figure 5 By focusing on a point 20 μm below the leaf surface, a distribution map of propylene glycol at the 20 μm depth below the leaf can be obtained. Figure 6 The leaves were moistened with water, and propylene glycol partially dissolved in the water. The distribution of propylene glycol in the leaves under these conditions was then obtained (see diagram). Figure 7 ).

[0025] Example 3: This embodiment provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, including the following steps: Under constant temperature and humidity conditions (40℃, 80% relative humidity), accurately weigh 0.15g of well-formed leaves and let them stand for 3 days; prepare ethanol solutions of propylene glycol at different mass concentrations and spray them onto the tobacco leaves to obtain samples with propylene glycol / tobacco leaf mass ratios of 5%, 4%, 3%, 2%, and 1%, respectively; perform stimulated Raman imaging on the samples. The stimulated Raman spectroscopy test conditions are: pump light 801 nm, 10 mW; Stokes light 1027-1073 nm, 100 mW; 20x objective lens; NA 0.8; pixel count 400×400; single-point scan time 10 μs; 0.39 μm / pixel; average scan count 1; hyperspectral scan step size 10 μm. Stimulated Raman spectra of propylene glycol at 5 micrometers below the leaf surface were obtained at different concentrations, and compared with standard spectra of propylene glycol and tobacco leaves. Figure 1 and Figure 3Lasso fitting was performed to split the data and obtain the distribution map of propylene glycol in the leaves at this concentration. Figure 8-12 The average intensity of the signal in three fields of view was extracted for different mass ratios of propylene glycol to tobacco. A graph was plotted between the mass ratio of propylene glycol (i.e., the mass ratio of propylene glycol to tobacco) and the average signal intensity ratio of propylene glycol in the field of view (i.e., the ratio of the average signal intensity of propylene glycol to the sum of the average signal intensities of propylene glycol and tobacco). A linear relationship was observed. Figure 13 This is consistent with the linear relationship between propylene glycol aqueous solutions of different concentrations and stimulated Raman signals. Figure 14-15 This indicates that this method can be used for semi-quantitative evaluation and comparison of added propylene glycol in tobacco leaves.

[0026] Example 4: This embodiment provides a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, including the following steps: acquiring tobacco leaf samples with added glycerol and propylene glycol on the growth line, and performing stimulated Raman imaging on the samples. The stimulated Raman spectroscopy test conditions are: pump light 801 nm, 10 mW; Stokes light 1027-1073 nm, 100 mW; 20x objective lens; NA 0.8; pixel count 400×400; single-point scan time 10 μs; 0.39 μm / pixel; average scan count 1; hyperspectral scan step size 10 μm. Stimulated Raman spectra of glycerol and propylene glycol at 5 μm below the leaf surface are obtained, and the results are compared with standard spectra of glycerol, propylene glycol, and tobacco leaves (…). Figure 1-3 Lasso fitting was used to split the mixture, and the distribution maps of glycerol and propylene glycol in the leaves under mixed polyol conditions were obtained. Figure 16 The average intensity of glycerol, propylene glycol, and tobacco leaves was extracted from 12 fields of view, revealing that the contents of glycerol and propylene glycol were both low, consistent with actual conditions. Furthermore, using a 3×4 image stitching method, the distribution of polyols can be expanded from the micrometer scale to the millimeter scale.

[0027] The applicant declares that this invention illustrates the method and application of stimulated Raman spectroscopy for detecting polyol distribution in tobacco leaves through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

[0028] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0029] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy, characterized in that, The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy includes the following steps: Stimulated Raman spectroscopy was performed on the tobacco leaves to be tested, and the results were analyzed by Lasso fitting and splitting of the polyol standard spectrum to obtain the distribution of polyols in the tobacco leaves.

2. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to claim 1, characterized in that, The polyols include propylene glycol and / or glycerol.

3. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to claim 1 or 2, characterized in that, The tobacco to be tested includes flue-cured tobacco, aromatic tobacco, burley tobacco, cigar tobacco, or sun-cured tobacco.

4. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to any one of claims 1-3, characterized in that, The tobacco to be tested includes tobacco produced on the production line or tobacco obtained through the following steps: The tobacco samples were equilibrated, and then a polyol solution was applied to the surface of the tobacco samples and allowed to stand.

5. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to claim 4, characterized in that, The equilibrium temperature is 20-40℃, the relative humidity is 20-80%, and the time is at least 72 hours.

6. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to claim 4 or 5, characterized in that, The settling temperature is 20-40℃, the relative humidity is 20-80%, and the time is at least 72 hours.

7. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to any one of claims 4-6, characterized in that, The polyol is glycerol, and the amount of polyol applied to the surface of the tobacco sample is 0.5-110% of the tobacco mass. Preferably, the polyol is propylene glycol, and the amount of polyol applied to the surface of the tobacco sample is 1-60% of the tobacco mass.

8. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to any one of claims 1-7, characterized in that, In the stimulated Raman detection, the pump light wavelength is 800-810 nm, the Stokes light wavelength is 1025-1080 nm, and the fingerprint wavelength is 2750-3075 cm⁻¹. -1 .

9. The method for detecting polyol distribution in tobacco leaves based on stimulated Raman spectroscopy according to any one of claims 1-8, characterized in that, In the stimulated Raman detection, the detection depth is from the tobacco surface to a depth of 40 μm, and the width is at least 390 nm.

10. The application of a method for detecting the distribution of polyols in tobacco leaves based on stimulated Raman spectroscopy according to any one of claims 1-9 in tobacco leaf production and / or tobacco leaf research and development.

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