A method for bleaching tobacco samples

Abstract

The present invention relates to a method for bleaching a tobacco sample, comprising: (1) providing a mixture containing NaClO 2 Solution, NaClO 2 The concentration is 1-5wt% and the pH value is 2-4; (2) performing bleaching treatment on the tobacco sample to be bleached 1-3 times; the bleaching treatment comprises: soaking with the treatment solution at a treatment temperature of 70-80°C for a treatment time of 20-40min, separating the solid and the liquid after the treatment, and collecting the solid.

Description

Technical Field

[0001] The invention belongs to the field of tobacco, and in particular relates to a tobacco sample bleaching treatment method, and more particularly to a tobacco cellulose extraction and bleaching quantitative characterization method. Background Art

[0002] Cellulose is the main component of tobacco cell walls and the basic substance that constitutes tobacco leaf cell tissue and skeleton. Its combustion behavior has an important influence on the overall combustion behavior of tobacco. Determining the content of cellulose and hemicellulose in tobacco provides an important reference for evaluating the quality of tobacco. The chemical composition of tobacco is an intrinsic factor that determines the quality of tobacco and is the material basis for the quality and style of tobacco. The stability of the chemical composition of tobacco is the basis for the stability of cigarette quality. Quantitative analysis of cellulose components in tobacco not only guides tobacco production, but also has important significance for the supply of tobacco raw materials and improving the quality of cigarettes. Therefore, in order to evaluate the quality differences between tobacco leaves produced in different regions, tobacco leaves picked in different seasons, tobacco leaves picked at different growth stages, and tobacco leaves prepared by different baking processes, it is necessary to quantitatively determine the content of cellulose in these tobacco leaves, and obtain tobacco cellulose standard materials with good uniformity, good stability, and high tobacco cellulose content. The preparation of tobacco cellulose standard materials requires processes such as crushing, impurity removal, alkaline hydrolysis, bleaching, and quantification.

[0003] The bleaching process is a key step in obtaining tobacco cellulose standard material. Summary of the invention

[0004] The present invention proposes an innovative bleaching treatment method for tobacco samples. The bleached product obtained by the innovative bleaching treatment method has the advantages of low gray value, high cellulose yield and high cellulose content. In the process of optimizing the bleaching treatment method, the present invention innovatively uses ImageJ software to perform grayscale ratio quantitative analysis on tobacco cellulose sheet photos. Based on the use of the above software, the present invention realizes the quantitative analysis of bleaching degree (also called grayscale) for the first time, so that the parameters can be accurately adjusted so that the obtained bleached product has the best grayscale value.

[0005] In a first aspect, the present invention provides a method for bleaching a tobacco sample, comprising the following steps:

[0006] (1) providing a solution containing NaClO2, wherein the concentration of NaClO2 is 1-5wt%, and the pH value is 2-4;

[0007] (2) performing a bleaching treatment on the tobacco sample to be bleached 1-3 times;

[0008] The bleaching treatment comprises: soaking with the treatment solution, the treatment temperature is 70-80° C., the treatment time is 20-40 min, and after the treatment, the solid-liquid separation is performed and the solid is collected.

[0009] In some embodiments, in step (1), the concentration of NaClO2 is 2-4 wt%.

[0010] In some embodiments, in step (1), acetic acid is used to adjust the pH value.

[0011] In some embodiments, in step (1), the pH value of the treatment solution is 2.5-3.5.

[0012] In some embodiments, in steps (2) and (3), the treatment temperature is 73-77°C.

[0013] In some embodiments, in steps (2) and (3), the treatment time is 25-35 min.

[0014] In some embodiments, in steps (2) and (3), the bleaching treatment is performed 2-3 times.

[0015] In some embodiments, the sample to be bleached is a tobacco sample from which water-soluble impurities, lipid impurities, and hemicellulose have been removed.

[0016] In some embodiments, the tobacco sample to be bleached is obtained by the following method:

[0017] (a1) providing raw tobacco powder;

[0018] (a2) treating the raw tobacco powder with deionized water to remove water-soluble impurities, and drying in an oven at 60° C.;

[0019] (a3) treating the product of the previous step with a non-polar solvent in a Soxhlet extractor to remove lipid impurities;

[0020] (a4) treating the product from the previous step with a NaOH solution to remove hemicellulose;

[0021] (a4) washing, drying, and collecting tobacco samples to be bleached.

[0022] In a second aspect, the present application provides a method for bleaching a tobacco sample, comprising:

[0023] (i) providing tobacco powder;

[0024] (ii) treating the tobacco powder with deionized water at 65-75° C. to remove water-soluble impurities, and then filtering and drying to collect solids;

[0025] (iii) extracting the product from the previous step with an absolute ethanol solution in a Soxhlet extractor to remove lipid impurities;

[0026] (iv) treating the product of the previous step with 5-15% by mass NaOH at 75-85° C. to remove hemicellulose, and then washing and drying to obtain a pretreated tobacco sample;

[0027] (v) bleaching the pretreated tobacco sample with a 2-4% sodium chlorite solution having a pH of 2.5-3.5 at 70-80° C. for 25-35 minutes,

[0028] (vi) Repeat step (v) 1-2 more times to obtain bleached tobacco cellulose.

[0029] In some embodiments, the tobacco sample is a cut tobacco sample, such as a cut tobacco powder sample.

[0030] In some embodiments, the tobacco sample processing method is a method for preparing a tobacco cellulose standard material.

[0031] In some embodiments, the tobacco sample processing method includes one or more of the following operations: crushing, impurity removal, alkaline hydrolysis, bleaching, and quantification.

[0032] In some embodiments, the tobacco sample processing method comprises

[0033] The step of detecting the grayscale ratio of the sample after bleaching and the sample before bleaching, wherein the grayscale ratio is defined as follows:

[0034]

[0035] In some embodiments, the tobacco sample processing method includes the step of optimizing the bleaching parameters according to the grayscale ratio of the sample after bleaching to the sample before bleaching:

[0036]

[0037] In some embodiments, the gray value is the average gray value detected by Image J software. That is, the sum of the gray values ​​of all pixels in the selected area divided by the number of pixels

[0038] In some embodiments, the picture of the compressed tobacco cellulose is opened in the Image J analysis software, the "Image" option in the toolbar is clicked, and "8 bits" is selected to convert the picture into a grayscale picture. Then, "Light background" is checked in "Subtract background" to eliminate the influence of the picture background. Click the "Analysis" option in the toolbar, pull down and select "Measurement", and check the following in the pop-up dialog box: area, average gray value, maximum and minimum gray value, and comprehensive density. Finally, the picture of tobacco cellulose is converted into a bright color through "Convert" in "Edit", and the mean gray value (mean gray value) of tobacco cellulose can be calculated by clicking "Measurement".

[0039] In some embodiments, if the grayscale ratio is higher than a preset value, the bleaching number or bleaching time is increased.

[0040] In some embodiments, the reference sample is a white sample, such as a white paper sample.

[0041] In some embodiments, the grayscale value is measured by image processing software, such as Image J software.

[0042] Beneficial Effects

[0043] One or more solutions of the present disclosure have one or more of the following beneficial effects:

[0044] (1) After bleaching, the grayness of tobacco samples decreased significantly compared with that of unbleached samples;

[0045] (2) The cellulose content in the bleached product is high;

[0046] (3) The yield of cellulose in the bleached product is high.

[0047] Terminology

[0048] The grayscale of an image reflects the depth of the color. The so-called grayscale refers to pure white, pure black, and a series of transitional colors from black to white. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Shows the compressed sheets of tobacco cellulose at different bleaching heating temperatures.

[0050] Figure 2 The grayscale ratio of the photos of tobacco cellulose sheets at different bleaching heating temperatures is shown.

[0051] Figure 3 The yield and production of cut tobacco cellulose in experiments with different heating temperatures are shown.

[0052] Figure 4 The photos show the compressed sheets of tobacco cellulose at different bleaching heating times.

[0053] Figure 5 The grayscale ratio of the tobacco cellulose sheet photographs at different bleaching heating times is shown.

[0054] Figure 6 The changes in tobacco cellulose yield and content at different bleaching heating times are shown.

[0055] Figure 7 Shows the compressed sheets of tobacco cellulose in different solution pH.

[0056] Figure 8 The grayscale ratio of the photos of tobacco cellulose sheets in different solution pH is shown.

[0057] Fig. 9 The changes in tobacco cellulose yield and content in different solution pH are shown.

[0058] Fig.10 Shown are photos of pressed sheets of tobacco cellulose at different bleaching times.

[0059] Fig.11 The grayscale ratio of the photographs of tobacco cellulose sheets at different bleaching times is shown.

[0060] Fig.12 The changes in cellulose yield and content of cut tobacco at different bleaching times are shown. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] 1 Materials and methods

[0063] 1.1 Experimental Materials and Instruments

[0064] Tobacco was provided by Fujian China Tobacco Industry Co., Ltd., and anhydrous ethanol, sodium chlorite, concentrated hydrochloric acid, 98% sulfuric acid, glacial acetic acid, sodium hydroxide, hexadecyltrimethylammonium bromide, and acetone were purchased from China National Pharmaceutical Group and were analytically pure or chemically pure.

[0065] DF-101S magnetic stirrer (Zhengzhou Great Wall Science & Technology Co., Ltd.); FW-5A infrared tablet press (Tianjin Botian Shengda Technology Development Co., Ltd.); Milli-Q water purifier (Merck, Germany); Nikon D 7000 digital camera (Nikon, Japan); SHB-III water multi-purpose vacuum pump (Zhengzhou Great Wall Science & Technology Co., Ltd.); Sartorius electronic balance BSA124S (sensitivity 0.0001 g, Sartorius, Germany).

[0066] 1.2 Experimental methods

[0067] 1.2.1 General method of tobacco cellulose bleaching process

[0068] Wash the tobacco raw materials with clean water, drain, dry in an oven at 70°C, grind in a universal grinder, pass through a 60-mesh sieve, and obtain powdered tobacco powder (PT).

[0069] Weigh 100g PT accurately, add 2L of deionized water, stir with a magnetic stirrer at a constant temperature of 70℃, filter to remove water-soluble impurities, dry in an oven at 60℃, then place in a Soxhlet extractor, extract with 500mL of anhydrous ethanol solution for 6h to remove impurities such as lipids. Mix evenly with 1000mL of 10% NaOH solution, place on a magnetic stirrer, heat to 80℃, stir at 600r / min for 2h to remove hemicellulose, wash with deionized water until neutral, place in an oven at 60℃ for 8h to obtain pretreated tobacco fiber (PT-a).

[0070] Accurately weigh 2.0 g of PT-a sample and add 60 mL of 3% sodium chlorite for bleaching. Use glacial acetic acid to adjust the appropriate pH value and heat in a water bath until the solid matter turns white. Remove the pigment and lignin, filter with a Buchner funnel, wash with deionized water until neutral, and dry in an oven at 60°C for 8 h to obtain tobacco cellulose (TC).

[0071] 1.2.2 Preparation of tobacco cellulose sheets

[0072] Accurately weigh 0.20g of tobacco cellulose (TC), put it into a clean cylindrical mold, compact it and make sure the middle is slightly higher than the surrounding area. Add the top column and gently rotate it to spread the sample evenly. Put the mold on the tablet press, adjust the pressure to 10Mpa, keep it for 10-20 seconds, release the pressure, and gently take the formed tobacco cellulose sheet out of the mold to prevent it from breaking. The thickness of the tobacco cellulose sheet is about 0.3-0.5mm.

[0073] 1.2.3 Photography of tobacco cellulose sheets

[0074] First, fix the Nikon D 7000 camera on the bracket, then place the prepared tobacco cellulose sheet directly under the camera, adjust the focus, and take pictures. Because the external light has a great influence on the photo image, the external light of each photo should be consistent during the photo shooting process, and each sample should be photographed three times in parallel to obtain the picture of the compressed tobacco cellulose.

[0075] 1.2.4 Image J grayscale analysis

[0076] Open the image of compressed tobacco cellulose in Image J analysis software, click the "Image" option in the toolbar, and select "8 bits" to convert the image into a grayscale image. Then check "Light background" in "Subtract background" to eliminate the influence of the image background. Click the "Analysis" option in the toolbar, pull down and select "Measurement value determination", and check the following in the pop-up dialog box: area, average gray value, maximum and minimum gray value and comprehensive density. Finally, convert the image of tobacco cellulose into light color through "Convert" in "Edit", and click "Measurement" to calculate the gray value (mean gray value) of tobacco cellulose.

[0077] Ordinary white 70g / m 2 A4 paper was subjected to Image J grayscale analysis, and the obtained grayscale value was used as the internal reference Ir value. The grayscale value of the compressed tobacco cellulose sample minus the Ir grayscale value was used as the measured grayscale value of the compressed sample, and the grayscale ratio of the unbleached tobacco fiber PT-a (Con) was defined as 100%. Each tobacco cellulose sample was measured three times in parallel, and the plotted values ​​were expressed as the average ± SD of the three experimental values. The calculation formula for the grayscale ratio (%) of tobacco cellulose is as follows:

[0078]

[0079] The smaller the grayscale ratio (%), the better the bleaching effect.

[0080] 1.2.5 Determination of the yield of tobacco cellulose

[0081] Accurately weigh M grams of bleached and dried tobacco fiber (PT-a), bleach with sodium chlorite, wash with deionized water until neutral, and dry in an oven at 60°C for 8 hours to obtain m grams of tobacco cellulose (TC). The calculation formula for the yield (%) of tobacco cellulose is as follows:

[0082]

[0083] 1.2.6 Determination of cellulose content in tobacco by Fan's method

[0084] Accurately weigh 1.00 g (about 1.00 g) of bleached and dried tobacco fiber (TC) sample into a 200 mL round-bottom beaker, and add 100 mL of acidic detergent (weigh 2 g of analytically pure hexadecyltrimethylammonium bromide and dissolve it in 100 mL of 0.5 mol / L sulfuric acid aqueous solution to obtain the acidic detergent). Put a condenser on the round-bottom beaker and place it on an electric furnace. Heat it to boiling within 5 to 10 minutes, and keep it slightly boiling for 60 minutes. While it is hot, filter it with a glass crucible that has been weighed and has a known weight, and repeatedly rinse the glass crucible and the residue with boiling water until the filtrate is neutral, and then rinse the residue with a small amount of acetone until the acetone liquid is colorless. Place the glass crucible in a 105°C oven and bake for 2 hours, then cool it in a desiccator for 30 minutes and weigh it. Repeat the operation twice until the glass crucible has a constant weight, which is recorded as G1 (g). Add 2 mL of 72% sulfuric acid to the acid-washed tobacco cellulose treated with the above acid washing solution, digest at 20°C for 3 hours, filter, and rinse to neutrality. Same as above, bake in an oven at 105°C to constant weight, recorded as G2 (g). The calculation formula for the content (%) of tobacco cellulose is as follows:

[0085]

[0086] 2 Results and discussion

[0087] This experiment explored the bleaching process of tobacco cellulose from four dimensions: heating temperature, heating time, solution pH and number of bleaching times, and examined the effects of these four dimensions on the bleaching effect, yield and content of tobacco cellulose. Image J analysis software was introduced to quantitatively analyze the grayscale ratio of tobacco cellulose pressed sheet photos.

[0088] 2.1 Investigating the effect of heating temperature on the bleaching effect, yield and content of tobacco cellulose

[0089] Weigh 4 groups of 2g PT-a tobacco cellulose, add 60mL 3% NaClO2, adjust the pH to 4 with glacial acetic acid, and heat in a water bath at 75℃, 60℃, 40℃ and 25℃ for 30min respectively. After heating, wash with deionized water until neutral to obtain bleached tobacco cellulose samples, and press the obtained tobacco cellulose samples and take pictures. The PT-a samples that have not been bleached are used as the control group (Con). The photographic results are shown in Figure 2. Figure 1 (Photographs of pressed tobacco cellulose sheets at different bleaching and heating temperatures). Figure 1 As can be seen from the photos, when bleached at room temperature of 25°C, the color of the tobacco cellulose becomes significantly lighter than that of the control group Con, but the sample is still yellowish brown. As the heating temperature increases, the yellowish brown color of the sample gradually fades, and the yellowish brown color is the lightest at 75°C.

[0090] The images of the compressed tobacco cellulose were analyzed and processed using Image J analysis software. The results of the analysis are shown in the figure. Figure 2 (Grayscale ratio of tobacco cellulose sheets at different bleaching heating temperatures) is shown in Figure 1. The grayscale ratio of the control group PT-a sample is defined as 100%. Figure 2 It can be seen that when the heating temperature rises from 25°C to 75°C, the grayscale ratio of the tobacco cellulose sheet photo gradually decreases from 39.19% to 22.14%. When the heating temperature reaches 75°C, its grayscale ratio is the smallest, that is, the bleaching effect is the best.

[0091] During the experiment, it was found that if the heating temperature was further increased to 90°C, a large amount of irritating gas would overflow, causing damage to the air and experimenters. Therefore, in this experiment, a heating temperature of 75°C was selected as the best. Figure 3 As shown, from Figure 3 It can be seen that the yield of tobacco cellulose at a heating temperature of 25°C is 82.35%, and the cellulose content of tobacco cellulose is only 79.79%. When the heating temperature rises to 75°C, the yield of tobacco cellulose drops to 70.36%, and the cellulose content of tobacco cellulose rises to 90.42%.

[0092] 2.2 Investigate the effect of heating time on tobacco cellulose bleaching effect, yield and content

[0093] Weigh 2 g of PT-a tobacco cellulose from three groups, add 60 mL of 3% NaClO2, adjust the pH to 4 with glacial acetic acid, and heat in a 75°C water bath for 10 min, 30 min, and 60 min, respectively. After heating, wash with deionized water until neutral to obtain bleached tobacco cellulose samples, and press and photograph the obtained tobacco cellulose samples. The PT-a samples that have not been bleached are used as the control group (Con). The photographic results are shown in FIG. Figure 4 As shown. Figure 4 As can be seen from the photos, when heated at 75℃ for 10 minutes for bleaching, the color of the tobacco cellulose becomes significantly lighter than that of the control group Con, and the sample is light yellow. When the bleaching time reaches 30 minutes or 60 minutes, the yellow color is no longer visible in the pictures of the samples, and they are close to white.

[0094] The images of the compressed tobacco cellulose were analyzed and processed using Image J analysis software. The results of the analysis are shown in the figure. Figure 5 The grayscale ratio of the control group PT-a sample is defined as 100%. Figure 5It can be seen that with the increase of heating time, the grayscale ratio of the tobacco cellulose sheet photo gradually decreases, but the grayscale ratios of the sample photos heated for 30 minutes and 60 minutes are 22.14% and 22.37% respectively, which is not much different and has little effect on the bleaching effect. Therefore, in this experiment, the heating time of 30 minutes is selected as the best. The yield and output of tobacco cellulose in the experiments with different heating times are shown in Figure 2. Figure 6 As shown, from Figure 6 It can be seen that when the heating time is 10, 30 and 60 minutes, the yields of tobacco cellulose are 76.80%, 70.36% and 67.40% respectively, and the contents of tobacco cellulose are 79.77%, 90.42% and 90.35% respectively.

[0095] 2.3 Effect of solution pH on tobacco cellulose bleaching effect, yield and content

[0096] Weigh 2 g of PT-a tobacco cellulose from three groups, add 60 mL of 3% NaClO2, adjust the pH to 6, 4 and 3 with glacial acetic acid, and heat in a 75°C water bath for 30 min. After heating, wash with deionized water until neutral to obtain bleached tobacco cellulose samples. The obtained tobacco cellulose samples are pressed and photographed. The PT-a samples that have not been bleached are used as the control group (Con). The photographic results are shown in Figure 2. Figure 7 As shown. Figure 7 It can be seen from the photos that when the bleaching was carried out at pH = 6 or 4 and the temperature was 75℃ for 30min, the color of the tobacco cellulose became slightly lighter than that of the control group Con, and the bleaching effect of the sample was not good. Only when the pH dropped to 3, the sample picture no longer had yellow color and approached white, achieving the bleaching effect. This shows that the pH of the bleaching solution has a great influence on the bleaching effect of the tobacco cellulose sample. Under strong acidic conditions, high concentrations of H + The secondary bond forces of tobacco cellulose, such as van der Waals forces, hydrogen bonds and salt bonds, may be destroyed. In order not to destroy the microstructure of tobacco cellulose as much as possible, the pH value was no longer lowered in this experiment, and pH = 3 was selected as the best acid value of the bleaching solution.

[0097] The images of the compressed tobacco cellulose were analyzed and processed using Image J analysis software. The results of the analysis are shown in the figure. Figure 8 The grayscale ratio of the control group PT-a sample is defined as 100%. Figure 8 It can be seen that as the pH of the bleaching solution decreases, the grayscale ratio of the tobacco cellulose sheet photo gradually decreases. When pH = 3, the grayscale ratio of the sample is the smallest, which is 15.02%. However, a lower acid value is not conducive to maintaining the original structure of tobacco cellulose. Therefore, in this experiment, the bleaching solution with pH = 3 is selected as the best. The yield and output of tobacco cellulose in the experiments with different solution pH values ​​are shown in Figure 2. Fig. 9 As shown, from Fig. 9 It can be seen that the pH of the solution has a great influence on the yield of tobacco cellulose, and the yield of tobacco cellulose decreases from 87.95% at pH = 6 to 68.35% at pH = 3. When the solution acid value is adjusted from pH = 6 to pH = 3, most of the lignin in the tobacco cellulose is removed, and the decrease in the yield of tobacco cellulose is accompanied by a significant increase in the cellulose content of tobacco, from 72.04% at pH = 6 to 92.23% at pH = 3.

[0098] 2.4 Investigating the effect of bleaching times on the bleaching effect, yield and content of tobacco cellulose

[0099] Weigh 3g of PT-a tobacco cellulose, add 90mL of 3% NaClO2, adjust the pH to 3 with glacial acetic acid, and heat in a 75℃ water bath for 30min. After heating, wash with deionized water until neutral to obtain a bleached tobacco cellulose sample. Repeat the above experiment 3 times in the same way, and press and photograph the tobacco cellulose samples obtained each time. The PT-a sample that has not been bleached is used as the control group (Con). The photographic results are shown in Fig.10 As shown. Fig.10 As can be seen from the photos, after the first bleaching experiment, the color of the tobacco cellulose was already very white compared to the control group Con, and after the second and third bleaching, the bleaching effect of the sample did not change much.

[0100] The images of the compressed tobacco cellulose were analyzed and processed using Image J analysis software. The results of the analysis are shown in the figure. Fig.11 The grayscale ratio of the control group PT-a sample is defined as 100%. Fig.11 It can be seen that with the increase of bleaching times, the grayscale ratio of the tobacco cellulose sheet photo gradually decreases. The grayscale ratios of the samples bleached 2 times and 3 times are 9.97% and 8.13% respectively, which is not much different. Therefore, in this experiment, bleaching 2 times can achieve the best bleaching effect. The yield and output of tobacco cellulose after 1-3 times of bleaching are shown in Figure 2. Fig.12 As shown, from Fig.12 It can be seen that the yield of tobacco cellulose is between 63.11% and 68.35%, and the output is between 92.24% and 93.25%, and the experimental process changes slightly.

[0101] 3 Conclusion

[0102] In order to extract high-content tobacco cellulose from tobacco leaves, this research paper uses tobacco as the starting material, and obtains white tobacco cellulose through water washing, alcohol extraction, alkaline hydrolysis and bleaching. When optimizing the tobacco cellulose bleaching process, Image J analysis software was also introduced to quantitatively analyze the grayscale ratio of tobacco cellulose pressed sheet photos, and the optimal experimental results were obtained.

[0103] The experimental results show that the best bleaching process for tobacco cellulose is: 2g PT-a tobacco cellulose, add 60mL of 3% sodium chlorite bleaching solution with pH=3, heat in a 75℃ water bath for 30min, repeat the above experiment in the same way, a total of 2 times. The yield of tobacco cellulose obtained is 65.32%, the content is 93.25%, and the grayscale ratio of the tobacco cellulose sheet photo is only 9.97% of the control group (Con). In summary, the quantitative analysis results of the grayscale ratio of tobacco cellulose sheet photos by Image J analysis software are effective and feasible.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A bleaching method for a tobacco sample, comprising the following steps: (1) providing a solution containing NaClO2, wherein the concentration of NaClO2 is 1-5wt%, and the pH value is 2.5-3.5; (2) performing bleaching treatment on the tobacco sample to be bleached 1-3 times; The bleaching treatment comprises: soaking in the solution containing NaClO2 at a treatment temperature of 70-80°C for a treatment time of 25-40 minutes, and separating the solid and the liquid after the treatment to collect the solid.

2. The method according to claim 1, wherein in step (1), the concentration of NaClO2 is 2-4wt%.

3. The method according to claim 1, wherein in step (1), acetic acid is used to adjust the pH value.

4. The method according to claim 1, wherein in step (2), the treatment temperature is 73-77°C.

5. The method according to claim 1, wherein in step (2), the treatment time is 25-35 min.

6. The method according to claim 1, wherein in step (2), the bleaching treatment is performed 2-3 times.

7. The method according to claim 1, wherein the tobacco sample to be bleached is a tobacco sample from which water-soluble impurities, lipid impurities and hemicellulose have been removed.

8. The method according to claim 1, wherein the tobacco sample to be bleached is obtained by: (a1) providing raw tobacco powder; (a2) treating the raw tobacco powder with deionized water to remove water-soluble impurities, and drying in an oven at 60° C.; (a3) treating the product of the previous step with a non-polar solvent in a Soxhlet extractor to remove lipid impurities; (a4) treating the product of the previous step with a NaOH solution to remove hemicellulose; (a5) Washing, drying, and collecting tobacco samples to be bleached.

9. A method for bleaching a tobacco sample, comprising: (i) supplying tobacco powder; (ii) treating the tobacco powder with ionized water at 65-75° C. to remove water-soluble impurities, and then filtering and drying to collect solids; (iii) extracting the product from the previous step with anhydrous ethanol solution in a Soxhlet extractor to remove lipid impurities; (iv) treating the product of the previous step with 5-15% by mass NaOH at 75-85° C. to remove hemicellulose, and then washing and drying to obtain a pretreated tobacco sample; (v) bleaching the pretreated tobacco sample with a 2-4% sodium chlorite solution having a pH of 2.5-3.5 at 70-80° C. for 25-35 minutes, (vi) Repeat step (v) 1-2 more times to obtain bleached tobacco cellulose.

10. The method according to any one of claims 1 to 9, comprising The step of detecting the grayscale ratio of the sample after bleaching and the sample before bleaching, wherein the grayscale ratio is defined as follows: Grayscale ratio (%) = % .

Images