Preparation method of cigarette holder aerogel and degradable cigarette filter stick with effects of reducing tar and harm
By preparing a composite of shiitake mushroom stem nanocellulose aerogel and potato acetylated starch, the problems of low capture efficiency and environmental pollution of cellulose acetate filter rods were solved, achieving a highly efficient, tar-reducing, and biodegradable tobacco filter rod.
Patent Information
- Application Number
- CN202610023642.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-08
- Publication Date
- 2026-03-06
AI Technical Summary
Existing cellulose acetate filter rods are inefficient at capturing small molecule harmful substances and are difficult to degrade, leading to environmental pollution. At the same time, the use of organic solvents in the production process may cause chemical pollution.
Using shiitake mushroom stems as raw material, nanocellulose aerogels were prepared through processes such as steam explosion, enzymatic hydrolysis, and freeze drying. Combined with potato acetylated starch, the high specific surface area and three-dimensional porous structure of nanocellulose were utilized to capture tar particles and polar harmful substances, achieving biodegradability.
It improves the capture efficiency of tar and polar harmful substances, reduces production costs, solves environmental pollution problems, and realizes the resource utilization of waste.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of filter rod material technology, and particularly relates to a method for preparing tobacco aerogel and a biodegradable tobacco filter rod with tar reduction and harm reduction effects. Background Technology
[0002] In the tobacco industry, reducing tar and harm is an important development direction, and as a crucial component of cigarettes, the performance of the filter material in cigarette filters is paramount. Currently, the mainstream filter material on the market is cellulose acetate filter rods.
[0003] The preparation of cellulose acetate filter rods uses wood pulp or cotton linters as raw materials, which undergo acetylation to produce cellulose diacetate, and then are spun into filaments; for details, see [link to process details]. Figure 1 Its core filtration mechanism relies on the physical interception of the three-dimensional network structure of fibers. Due to limitations in the spinning process, the fiber fineness and pore distribution uniformity are insufficient, which can only capture some larger tar particles. Its adsorption capacity for small molecule harmful substances is weak, directly resulting in limited filtration efficiency and an inability to fully reduce harmful substances in flue gas. At the same time, cellulose diacetate contains stable ester bonds, which are difficult to be degraded by microorganisms in the natural environment, causing long-term residues of discarded filter tips and resulting in serious environmental pollution. In addition, the raw materials rely on special plant resources, and the production process requires the use of organic solvents such as acetone, which not only increases costs but may also generate chemical pollution. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a method for preparing tobacco aerogel and a biodegradable tobacco filter rod with tar reduction and harm reduction effects. This method makes full use of mushroom stems, and the prepared aerogel can efficiently capture tar particles and polar harmful substances.
[0005] This invention provides a method for preparing cigarette holder aerogel, comprising the following steps:
[0006] The shiitake mushroom stems are crushed to 40-120 mesh, the moisture content is controlled at 15-55%, and steam is performed under pressure of 0.6-1.4 MPa for 30-150 seconds to obtain pretreated shiitake mushroom stems.
[0007] The pretreated shiitake mushroom stems were mixed with water, the pH was adjusted to 6.0, heat-stable α-amylase was added, the mixture was stirred, the pH was adjusted to 8.0, alkaline protease was added, the mixture was stirred again, the pH was adjusted to 5.5, amyloglucosidase was added, the mixture was shaken, the enzyme was inactivated after enzymatic hydrolysis, the mixture was centrifuged, and the precipitate was freeze-dried to obtain insoluble dietary fiber.
[0008] The insoluble dietary fiber, NaOH and H2O2 were mixed, stirred, and deionized water was added to terminate the reaction. After centrifugation, the mixture was washed with water until neutral and then freeze-dried to obtain shiitake mushroom stem cellulose.
[0009] The cellulose from the shiitake mushroom stems was dispersed in an acetate buffer solution, cellulase was added for enzymatic hydrolysis, followed by sonication, centrifugation, and washing to obtain a nanocellulose suspension.
[0010] The nanocellulose suspension and the gelatinized acetylated starch suspension were mixed and freeze-dried under vacuum to obtain a cigarette holder aerogel.
[0011] Preferably, the mass ratio of the pretreated shiitake mushrooms to water is 1:28~32;
[0012] The amount of heat-stable α-amylase added is 4.5~5.5 wt% of the shiitake mushroom stem powder.
[0013] Preferably, the amount of alkaline protease added accounts for 3.8-4.2% of the shiitake mushroom stem powder;
[0014] The amount of amylase added is 9.5~10.5 wt% of the mushroom stem powder.
[0015] Preferably, the amount of cellulase added is 100 U / g to 250 U / g.
[0016] Preferably, the enzymatic hydrolysis with added cellulase is carried out at a temperature of 48℃~52℃ for 8~20h.
[0017] Preferably, the ultrasonic treatment has a power of 150W to 300W and a duration of 15 to 30 minutes.
[0018] Preferably, the shiitake mushroom stem nanocellulose is in the form of long filament bundles with a diameter of 10.96±1.14 nm and a length in the micrometer range.
[0019] Preferably, the mass fraction of the gelatinized acetylated starch suspension is 4.8~5.2% (w / v).
[0020] The mass fraction of the nanocellulose suspension was 0.95~1.05% (w / v);
[0021] The volume ratio of the cellulose suspension to the gelatinized acetylated starch suspension is 1:1.
[0022] Preferably, the freeze-drying is carried out under vacuum at 10~90 Pa / min.
[0023] This invention provides a biodegradable cigarette filter rod with tar reduction and harm reduction effects, comprising a cigarette mouthpiece aerogel prepared by the preparation method described above.
[0024] This invention provides a method for preparing a cigarette holder aerogel, comprising the following steps: pulverizing shiitake mushroom stems to 40-120 mesh, controlling the moisture content to 15-55%, and subjecting them to steam explosion under a pressure of 0.6-1.4 MPa for 30-150 seconds to obtain pretreated shiitake mushroom stems; mixing the pretreated shiitake mushroom stems with water, adjusting the pH to 6.0, adding heat-stable α-amylase, stirring, then adjusting the pH to 8.0, adding alkaline protease, stirring again, adjusting the pH to 5.5, adding amylase, shaking, and inactivating the enzyme after enzymatic hydrolysis. Centrifuge, freeze-dry the precipitate to obtain insoluble dietary fiber; mix the insoluble dietary fiber, NaOH and H2O2, stir, add deionized water to terminate the reaction, centrifuge, wash with water until neutral, and freeze-dry to obtain shiitake stem cellulose; disperse the shiitake stem cellulose in acetate buffer, add cellulase for enzymatic hydrolysis, then sonicate, centrifuge, wash to obtain nanocellulose suspension; mix the nanocellulose suspension with gelatinized acetylated starch suspension, freeze-dry under vacuum to obtain cigarette filter aerogel. This method uses naturally biodegradable shiitake mushroom stems and starch as raw materials. Their molecular structure is easily decomposed by microorganisms and can be naturally degraded after disposal. Aerogel is used as a section of the filter rod and combined with cellulose acetate to make a ternary composite filter rod. Aerogel is prepared by combining shiitake mushroom stem nanocellulose with potato acetylated starch. The high specific surface area and three-dimensional porous structure of nanocellulose, combined with van der Waals forces and hydrogen bonding, can efficiently capture tar particles and polar harmful substances, solving the problems of single filtration mechanism and low efficiency in existing technologies. By using shiitake mushroom stems, a by-product of shiitake mushroom processing, as raw materials, the resource utilization of waste is realized, and costs are reduced. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the existing technology for preparing cellulose acetate filter rods;
[0026] Figure 2 This is a schematic diagram of the steam explosion device used in this invention.
[0027] Figure 3 This is a schematic diagram of the biodegradable cigarette filter rod of the present invention;
[0028] Figure 4 This is a schematic diagram of the process for preparing cigarette holder aerogel in an embodiment of the present invention;
[0029] Figure 5 This is a graph showing the relationship between the mesh size of the raw materials and the yield of cellulose in shiitake mushroom stems in an embodiment of the present invention.
[0030] Figure 6 This is a graph showing the relationship between moisture content and cellulose yield in shiitake mushroom stems in an embodiment of the present invention.
[0031] Figure 7 This is a graph showing the relationship between steam explosion pressure and cellulose yield in shiitake mushroom stems in an embodiment of the present invention.
[0032] Figure 8 This is a graph showing the relationship between the pressure time and the yield of cellulose in shiitake mushroom stems in an embodiment of the present invention.
[0033] Figure 9 This is a graph showing the relationship between the amount of cellulase added and the yield of shiitake mushroom stem nanocellulose in the embodiments of the present invention.
[0034] Figure 10 This is a graph showing the relationship between enzymatic hydrolysis time and the yield of shiitake mushroom stem nanocellulose in an embodiment of the present invention.
[0035] Figure 11 This is a graph showing the relationship between ultrasonic power and the yield of shiitake mushroom stem nanocellulose in an embodiment of the present invention.
[0036] Figure 12 This is a graph showing the relationship between ultrasonic time and the yield of shiitake mushroom stem nanocellulose in an embodiment of the present invention.
[0037] Figure 13 The images shown are scanning electron microscope (SEM) images of the aerogels prepared according to embodiments of the present invention. A is an SEM image of the aerogel lyophilized at a vacuum rate of 10 Pa / min; B is an SEM image of the aerogel lyophilized at a vacuum rate of 30 Pa / min; C is an SEM image of the aerogel lyophilized at a vacuum rate of 50 Pa / min; D is an SEM image of the aerogel lyophilized at a vacuum rate of 70 Pa / min; and E is an SEM image of the aerogel lyophilized at a vacuum rate of 90 Pa / min. Detailed Implementation
[0038] This invention provides a method for preparing cigarette holder aerogel, comprising the following steps:
[0039] The shiitake mushroom stems are crushed to 40-120 mesh, the moisture content is controlled at 15-55%, and steam is performed under pressure of 0.6-1.4 MPa for 30-150 seconds to obtain pretreated shiitake mushroom stems.
[0040] The pretreated shiitake mushroom stems were mixed with water, the pH was adjusted to 6.0, heat-stable α-amylase was added, the mixture was stirred, the pH was adjusted to 8.0, alkaline protease was added, the mixture was stirred again, the pH was adjusted to 5.5, amyloglucosidase was added, the mixture was shaken, the enzyme was inactivated after enzymatic hydrolysis, the mixture was centrifuged, and the precipitate was freeze-dried to obtain insoluble dietary fiber.
[0041] The insoluble dietary fiber, NaOH and H2O2 were mixed, stirred, and deionized water was added to terminate the reaction. After centrifugation, the mixture was washed with water until neutral and then freeze-dried to obtain shiitake mushroom stem cellulose.
[0042] The cellulose from the shiitake mushroom stems was dispersed in an acetate buffer solution, cellulase was added for enzymatic hydrolysis, followed by sonication, centrifugation, and washing to obtain a nanocellulose suspension.
[0043] The nanocellulose suspension and the gelatinized acetylated starch suspension were mixed and freeze-dried under vacuum to obtain a cigarette holder aerogel.
[0044] This invention prepares an aerogel by combining shiitake mushroom stem nanocellulose and potato acetylated starch. Utilizing the high specific surface area and three-dimensional porous structure of nanocellulose, combined with van der Waals forces and hydrogen bonds, it efficiently captures tar particles and polar harmful substances, solving the problems of single filtration mechanisms and low efficiency in existing technologies. This invention uses naturally biodegradable shiitake mushroom stems and starch as raw materials; their molecular structure is easily decomposed by microorganisms and can naturally degrade after disposal, thus solving the environmental pollution problem of cellulose acetate filter rods.
[0045] The present invention involves crushing shiitake mushroom stems to 40-120 mesh, controlling the moisture content to 15-55%, and steam-exploding them under a pressure of 0.6-1.4 MPa for 30-150 seconds to obtain pretreated shiitake mushroom stems.
[0046] This invention utilizes shiitake mushroom stems, a byproduct of shiitake mushroom processing, as raw materials to achieve resource utilization of waste and reduce costs. It also employs green processes such as ultrasonic-assisted enzymatic methods and freeze-drying to reduce chemical pollution and energy consumption, thereby promoting the coordinated development of agriculture and the tobacco industry.
[0047] The present invention pulverizes shiitake mushroom stems to 40-120 mesh, specifically 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh or 120 mesh; and controls the moisture content to 15-55%, specifically 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or 55%.
[0048] The mechanical principle diagram of the steam explosion device used in this invention is as follows: Figure 2 As shown, the steam explosion equipment mainly includes a steam generator, a steam explosion tank, a discharge valve, a receiver, and a feed inlet. Its working principle is as follows:
[0049] (1) Feeding stage
[0050] Pre-treated materials (crushing, humidifying, etc.), such as shiitake mushroom stem powder, are fed into the steam explosion tank through the inlet. After feeding is completed, the inlet is sealed, making the steam explosion tank a relatively closed space to prepare for subsequent steam action.
[0051] (2) Steam action stage
[0052] The steam generator-boiler produces high-temperature, high-pressure steam: In this invention, the pressure control range is 0.6~1.4 MPa, which is transported to the steam explosion tank via pipeline. After entering the tank, the steam comes into full contact with the material, using high temperature to soften the lignin and partially degrade the hemicellulose. At the same time, the high-pressure environment allows the steam to penetrate into the interior of the material fibers, changing the bonding state between fibers and laying the groundwork for subsequent explosion and disintegration. During this stage, the temperature, pressure, and duration of the steam can be adjusted by controlling the parameters of the steam generator: corresponding to the pressure maintenance time of 30~150 s in this invention.
[0053] (3) Explosion stage
[0054] Once the material has undergone steam treatment within the explosion tank (reaching the set pressure maintenance time), the release valve opens rapidly, instantly depressurizing the high-pressure environment inside the explosion tank towards the outside (the receiver). Under the influence of steam expansion force and pressure difference, the material inside the tank undergoes drastic physical structural changes—the fibers, originally "weakened and bound" by steam treatment, experience dissociation / fiber structure breakage due to the mechanical force generated by the sudden pressure drop, achieving the effect of pre-treating the material and improving the subsequent cellulose extraction rate.
[0055] This invention involves steam explosion at a pressure of 0.6–1.4 MPa for 30–150 seconds; specifically, the pressure is 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, or 1.4 MPa; the pressure holding time is 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, 130 seconds, 140 seconds, or 150 seconds. This invention separates cellulose from lignin and hemicellulose through steam explosion treatment. Preferably, the product is dried after steam explosion, preferably in a forced-air drying oven at 40°C, and the resulting pretreated shiitake mushroom stem powder is then ready for use.
[0056] In this invention, the pretreated shiitake mushroom stems are mixed with water, the pH is adjusted to 6.0, heat-stable α-amylase is added, the mixture is stirred, the pH is adjusted to 8.0, alkaline protease is added, the mixture is stirred again, the pH is adjusted to 5.5, amyloglucosidase is added, the mixture is shaken, the enzyme is inactivated after enzymatic hydrolysis, the mixture is centrifuged, and the precipitate is freeze-dried to obtain insoluble dietary fiber.
[0057] In this invention, the mass ratio of pretreated shiitake mushrooms to water is 1:28~32, specifically 1:28, 1:29, 1:30, 1:31, or 1:32; the amount of heat-stable α-amylase added accounts for 4.5~5.5 wt% of the shiitake mushroom stem powder, specifically 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, 5.0 wt%, 5.1 wt%, 5.2 wt%, 5.3 wt%, 5.4 wt%, or 5.5 wt%. After adding the heat-stable α-amylase, it is preferably stirred at 88~92℃ for 27~32 min, specifically at 90℃ for 30 min. This invention preferably uses a water bath heating method.
[0058] After adding heat-stable α-amylase, the pH is adjusted to 8.0, and then 3.8–4.2 wt% alkaline protease of shiitake mushroom stem powder is added, specifically 3.8%, 3.9%, 4.0%, 4.1%, or 4.2%. The mixture is stirred at 58–63°C for 28–33 min, specifically at 60°C for 30 min. This invention is preferably carried out under water bath conditions.
[0059] After adding alkaline protease, stir again and adjust the pH to 5.5 before adding amylase. The amount of amylase added is 9.5-10.5 wt% of the shiitake mushroom stem powder, specifically 9.5 wt%, 9.6 wt%, 9.7 wt%, 9.8 wt%, 9.9 wt%, 10.0 wt%, 10.1 wt%, 10.2 wt%, 10.3 wt%, 10.4 wt%, or 10.5 wt%. In this invention, after adding amylase, it is preferably shaken in a water bath at 58-63°C for 28-33 minutes; specifically, shaken in a water bath at 60°C for 30 minutes.
[0060] After enzymatic hydrolysis, the enzyme was inactivated at 95±1 ℃ for 10 min, centrifuged, and the precipitate was freeze-dried to obtain insoluble dietary fiber; the centrifugation temperature was 3700~3900 rpm and the time was 9~11 min; specifically, centrifugation was carried out at 3800 rpm for 10 min.
[0061] This invention involves mixing insoluble dietary fiber, NaOH, and H2O2, stirring, adding deionized water to terminate the reaction, centrifuging, washing with water until neutral, and then freeze-drying to obtain lentinan cellulose. This invention prepares 9% NaOH aqueous solution and 0.7% H2O2 aqueous solution separately; in a specific embodiment, the volume ratio of 9% NaOH aqueous solution to 0.7% H2O2 aqueous solution is 1:1. This invention adds insoluble dietary fiber at a material-to-liquid ratio of 1:7.5, and stirs in a water bath at 68-73℃ for 55-65 minutes, specifically stirring in a water bath at 70℃ for 60 minutes. Deionized water is added to terminate the reaction, and centrifugation is preferably continued at 3700-3900 rpm for 12-17 minutes; after centrifugation, the mixture is washed with water until neutral, and then freeze-dried to obtain lentinan cellulose.
[0062] The present invention uses scanning electron microscopy to characterize the structure of shiitake mushroom stem cellulose prepared before and after steam explosion. The yield of shiitake mushroom stem cellulose after steam explosion is higher than that of untreated shiitake mushroom stem cellulose; in a specific embodiment, the yield is increased by 2.6%.
[0063] This invention disperses the cellulose from shiitake mushroom stems in an acetate buffer solution, adds cellulase for enzymatic hydrolysis, followed by ultrasonic treatment, centrifugation, and washing to obtain a nanocellulose suspension. The dispersion in the acetate buffer solution is carried out at a material-to-liquid ratio of 1:48-52; the pH of the acetate buffer solution is 4.5-4.8; in a specific embodiment, the material-to-liquid ratio is 1:50, and the pH of the acetate buffer solution is 4.7. After dispersion, 100 U / g to 250 U / g of cellulase is added, specifically 100 U / g, 110 U / g, 120 U / g, 130 U / g, 140 U / g, 150 U / g, 160 U / g, 170 U / g, 180 U / g, 190 U / g, 200 U / g, 210 U / g, 220 U / g, 230 U / g, 240 U / g, or 250 U / g. The enzymatic hydrolysis temperature is 48-52℃, and the hydrolysis time is 8-20 hours; specifically, enzymatic hydrolysis at 50℃ for 12 hours. The ultrasonic treatment power is 150W-300W, specifically 150W, 160W, 170W, 180W, 190W, 200W, 210W, 220W, 230W, 240W, 250W, 260W, 270W, 280W, 290W, or 300W; the ultrasonic treatment time is 15-30 minutes, specifically 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, or 30 minutes. A nanocellulose suspension is obtained after centrifugation and washing; the concentration is 1% w / v.
[0064] This invention characterized the structure of shiitake mushroom stem nanocellulose using transmission electron microscopy, and performed particle size, infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction analysis on shiitake mushroom stem cellulose and shiitake mushroom stem nanocellulose after steam explosion. The results showed that the shiitake mushroom stem nanocellulose was in the form of long filament bundles with a diameter of (10.96±1.14) nm and a length in the micrometer range. The particle size distribution of the shiitake mushroom stem nanocellulose was uniform. The shiitake mushroom stem nanocellulose still maintained the basic chemical structure of shiitake mushroom stem cellulose, and its crystallinity (82.31%) was higher than that of shiitake mushroom stem cellulose (70.64%), and it also had higher thermal stability.
[0065] After obtaining the nanocellulose suspension, the present invention mixes the nanocellulose suspension with the gelatinized acetylated starch suspension and freeze-dries it under vacuum to obtain a cigarette holder aerogel.
[0066] This invention preferably uses a 5% w / v acetylated starch suspension gelatinized at 90°C and then mixed with a nanocellulose suspension at a volume ratio of 1:1. The acetylated starch can be potato acetylated starch, corn acetylated starch, or wheat acetylated starch. This invention employs a vacuum freeze dryer for vacuum freeze drying, preferably at a vacuum speed of 10~90 Pa / min, specifically 10 Pa / min, 20 Pa / min, 30 Pa / min, 40 Pa / min, 50 Pa / min, 60 Pa / min, 70 Pa / min, 80 Pa / min, or 90 Pa / min.
[0067] This invention characterized the structure of the cigarette filter aerogel material using scanning electron microscopy, analyzed its mechanical properties through texture analysis, and tested it in mainstream cigarette smoke. The results show that the prepared cigarette filter material has a dense and uniform pore size, exhibiting a three-dimensional nanoporous network structure. It captures tar particles through van der Waals forces and adsorbs polar harmful substances through hydrogen bonds. It possesses good mechanical properties and a significant tar reduction and harm mitigation effect, making it suitable as a novel cigarette filter rod material.
[0068] This invention provides a biodegradable cigarette filter rod with tar reduction and harm reduction effects, comprising a cigarette mouthpiece aerogel prepared by the preparation method described above.
[0069] The biodegradable cigarette filter rod is a ternary composite filter rod, with the upper and lower parts being cellulose acetate filter rods, and an aerogel column or ball inserted in the middle for the cigarette mouthpiece. See the structural diagram below. Figure 3 .
[0070] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a method for preparing a cigarette aerogel and a biodegradable cigarette filter rod material with tar-reducing and harm-reducing effects. However, these descriptions should not be construed as limiting the scope of protection of the present invention.
[0071] according to Figure 4 The process shown is used to prepare the cigarette holder aerogel;
[0072] Example 1
[0073] The shiitake mushroom stems are crushed to 40-120 mesh, with a moisture content controlled at 15%-55%. A momentary ejection-type steam explosion device is used to maintain pressure at 0.6-1.4 MPa for 30-150 s, separating cellulose from lignin and hemicellulose. After steam explosion, the mushrooms are dried in a 40℃ forced-air drying oven for later use.
[0074] After steam explosion, shiitake mushroom stem powder was mixed with deionized water (solid-to-liquid ratio 1:30), the pH was adjusted to 6.0, and 5% heat-stable α-amylase was added. The mixture was stirred in a 90℃ water bath for 30 min. The pH was then adjusted to 8.0, and 4% alkaline protease was added. The mixture was stirred in a 60℃ water bath for 30 min. Finally, the pH was adjusted to 5.5, and 10% amylase was added. The mixture was shaken in a 60℃ water bath for 30 min. After enzymatic hydrolysis, the enzyme was inactivated at 95±1℃ for 10 min, centrifuged at 3800 r / min for 10 min, and the precipitate was freeze-dried to obtain insoluble dietary fiber.
[0075] Prepare 9% NaOH aqueous solution and 0.7% H2O2 aqueous solution respectively, mix them at a volume ratio of 1:1, add insoluble dietary fiber at a material-to-liquid ratio of 1:7.5, stir in a water bath at 70 ℃ for 1 h, add deionized water to terminate the reaction, centrifuge at 3800 r / min for 15 min, wash with water until neutral, and freeze dry to obtain shiitake stem cellulose.
[0076] The freeze-dried cellulose was dispersed in acetate buffer (pH 4.7) at a material-to-liquid ratio of 1:50. 100–250 U / g cellulase was added, and enzymatic hydrolysis was performed at 50 °C for 8–20 h. The mixture was then treated with ultrasound at 150–300 W for 15–30 min, followed by centrifugation and washing to obtain a nanocellulose suspension (1% w / v). The structure of the shiitake mushroom stem nanocellulose was characterized by transmission electron microscopy, and particle size, infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction analysis were performed on the steam-exploded shiitake mushroom stem cellulose and nanocellulose.
[0077] A 5% (w / v) potato acetylated starch suspension was prepared, gelatinized at 90 °C, and then mixed with a nanocellulose suspension at a ratio of 1:1 (v / v). The mixture was then freeze-dried using a vacuum freeze dryer at a vacuum rate of 10–90 Pa / min to obtain a cigarette filter aerogel.
[0078] Figure 5 shows the relationship between raw material mesh size and cellulose yield. The yield first increases and then decreases with increasing mesh size, reaching a peak at 60 mesh. This is because 40 mesh particles are relatively coarse, resulting in insufficient steam penetration and a low cellulose yield; 60 mesh particles are finer, allowing for more sufficient steam contact and promoting cellulose separation; and when the mesh size exceeds 60 mesh, the excessively fine particles cause the cellulose molecular chains to break due to mechanical force, leading to a reduction in cellulose.
[0079] like Figure 6 Cellulose yield initially increases and then decreases with increasing moisture content, reaching a peak at 35%. Low moisture content results in less steam and insufficient mass and heat transfer, making it difficult to break down lignin and other encapsulated structures, leading to low yield. At 35%, moisture facilitates steam penetration, pressure generation, and synergistically breaks down cell walls with high temperature, while also participating in hydrolysis to aid separation. Excessive moisture content lowers the temperature, weakens the destructive power of steam, leading to incomplete dissociation, and may cause excessive hydrolysis of cellulose, raw material agglomeration, and hinders steam action.
[0080] like Figure 7 Cellulose yield initially increases and then decreases with increasing steam explosion pressure, reaching a peak at 1.0 MPa. Below 1.0 MPa, the higher the pressure, the stronger the breakage and fiber dissociation. At 1.0 MPa, the cell wall is fully disrupted, cellulose is most exposed, and the yield is highest. Above 1.0 MPa, excessive pressure damages the cellulose structure, causing molecular chain breakage, reducing effective cellulose, and decreasing the yield.
[0081] like Figure 8 The cellulose yield of shiitake mushroom stems first increased and then decreased with increasing pressure time, reaching a peak at 90 s. If the pressure time was less than 90 s, steam penetration was insufficient, cell wall destruction was incomplete, cellulose was tightly wrapped, and the yield was low; at 90 s, steam diffused sufficiently, and cell wall destruction was complete; after 90 s, continuous high temperature and high pressure would lead to excessive degradation of cellulose and a decrease in yield.
[0082] like Figure 9 As shown, the yield of cellulose nanofibers from shiitake mushroom stems first increased and then decreased with increasing cellulase addition, reaching a peak at 200 U / g. At low enzyme levels, cellulose was not fully hydrolyzed, resulting in low yield. Increased enzyme levels led to more binding sites, more complete hydrolysis of amorphous regions and glycosidic bonds, and thus increased yield. Above 200 U / g, excessive hydrolysis of cellulose disrupted the degree of polymerization and crystalline structure, making it difficult to form nanofibers, thus decreasing the yield.
[0083] like Figure 10 As shown, the yield of nanocellulose from shiitake mushroom stems first increased and then decreased with prolonged enzymatic hydrolysis time, reaching its optimal value at 12 hours. Insufficient hydrolysis time resulted in an increased yield over time due to enhanced hydrolysis, more thorough destruction of amorphous regions, and increased crystallization area. After 12 hours, the yield decreased, possibly due to excessive hydrolysis of cellulose into glucose and the disruption of the crystalline structure and chemical bonds.
[0084] like Figure 11As shown, the yield of cellulose nanoparticles from shiitake mushroom stems first increases and then decreases with increasing ultrasonic power, reaching a peak at 250 W. At 150 W, the power is too low to completely separate the fibers, resulting in an extremely low yield. Between 200 and 250 W, increasing the power enhances the cavitation effect, weakens hydrogen bonding forces, refines fiber size, improves surface accessibility, promotes enzymatic hydrolysis, and increases the yield. Above 250 W, the high-intensity shear force destroys the cellulose molecular chains, leading to excessive hydrolysis into glucose, and the yield decreases.
[0085] like Figure 12 As shown, the yield of shiitake mushroom stem nanocellulose increased with increasing ultrasonic time, but decreased when the ultrasonic time exceeded 25 min. The yield significantly increased when the ultrasonic time increased from 15 min to 25 min. Ultrasonic treatment promoted the interaction between individual fibers and the microbubbles generated by the ultrasound, thereby decomposing micro-sized cellulose into nano-sized cellulose. However, the yield of shiitake mushroom stem nanocellulose decreased when the ultrasonic time increased from 25 min to 30 min. This may be because excessively long ultrasonic times disrupted the structure of the shiitake mushroom stem nanocellulose.
[0086] like Figure 13 As shown, scanning electron microscopy observation of aerogels prepared at different vacuuming speeds (10~90 Pa / min) revealed that: at 10~50 Pa / min, ice crystals slowly sublimated, forming interconnected macropores; at 70 Pa / min, ice crystals gradually sublimated and matched the shrinkage of the framework, resulting in dense and uniform pores, with nanocellulose supporting the pore walls through hydrogen bond cross-linking; at 90 Pa / min, the excessively fast pumping speed caused the ice crystals to vaporize instantaneously, and the pore walls collapsed due to the sudden increase in internal pressure.
[0087] 1.2 Key Experimental Data
[0088] Table 1. Orthogonal experimental design for optimizing cellulose extraction from shiitake mushroom stems using steam explosion treatment.
[0089]
[0090] Table 1 shows that, based on the single-factor experiment, steam explosion pressure (A), pressure maintenance time (B), raw material mesh size (C), and moisture content (D) were selected as influencing factors. The cellulose yield of shiitake mushroom stems was used as the indicator, and L9(3) was employed. 4 Orthogonal experimental design was used to optimize the steam explosion pretreatment extraction process. Each group of experiments was repeated 3 times. The factor levels are shown in Table 1.
[0091] Table 2 Results of Orthogonal Experiments
[0092]
[0093] As shown in Table 2, the optimal combination is A1B2C2D3, which corresponds to a steam explosion pressure of 0.8 MPa, a pressure holding time of 90 s, a raw material mesh size of 60 mesh, and a moisture content of 45%. After three verification experiments, the cellulose extraction rate of shiitake mushroom stems under this combination was 13.27%, which is 2.60% higher than the 10.67% without steam explosion treatment.
[0094] Table 3 Detection of mainstream cigarette smoke
[0095]
[0096] The results of the detection of mainstream cigarette smoke from the aerogel filter rod samples are shown in Table 3. Compared with the cellulose acetate filter rod, the new cigarette filter rod with 1% nanocellulose added reduced the CO content by 4.86%, the nicotine content by 16.26%, and the tar content by 17.11% in the cigarette smoke.
[0097] 1.3 Calculation Formula
[0098] 1.3.1 Calculation method for cellulose yield in shiitake mushroom stems:
[0099] X (%) = m1 / m2 × 100%;
[0100] Where: X is the yield of shiitake mushroom stem cellulose (%); m1 is the weight of shiitake mushroom stem cellulose (g); m2 is the weight of shiitake mushroom stem powder after steam explosion (g).
[0101] 1.3.2 The calculation method for nanofiber yield is as follows:
[0102]
[0103] Where Y is the yield of shiitake mushroom stem nanocellulose (%), m1 is the mass of shiitake mushroom stem nanocellulose and weighing bottle (g), m2 is the mass of weighing bottle (g), m3 is the mass of shiitake mushroom stem cellulose (g), V1 is the total volume of shiitake mushroom stem nanocellulose suspension (mL), and V2 is the volume of shiitake mushroom stem nanocellulose suspension measured (mL).
[0104] As shown in the above embodiments, this invention pre-treats shiitake mushroom stems with steam explosion. Through single-factor and orthogonal experiments, the optimal process parameters—60 mesh size, 45% moisture content, 0.8 MPa pressure, and 90 s pressure holding time—were obtained, increasing the cellulose yield by 2.60% compared to untreated stems. This provides sufficient raw materials for subsequent nanocellulose preparation and solves the problem of low utilization of shiitake mushroom stem waste. Nanocellulose prepared using an ultrasonic-assisted enzymatic method (200 U / g enzyme addition, 12 h enzymatic hydrolysis time, 200 W ultrasonic power, 25 min ultrasonic time) has a diameter of approximately 10.96 nm and a crystallinity of 82.31%, higher than the original cellulose's 70.64%. This high crystallinity endows it with excellent mechanical properties and adsorption potential.
[0105] The aerogel formed by mixing nanocellulose with 5% acetylated starch in a 1:1 ratio and freeze-drying at a vacuum speed of 70 Pa / min exhibits a dense and uniform three-dimensional porous structure. Through the synergistic effect of van der Waals forces and hydrogen bonds, it significantly removes total particulate matter and tar from mainstream cigarette smoke. Specifically, the aerogel with a 1% nanocellulose concentration reduced the tar content from 13.15 mg / cigarette to 10.90 mg / cigarette, demonstrating superior tar reduction and harm mitigation performance compared to traditional cellulose acetate filters. Furthermore, the raw materials are naturally biodegradable shiitake mushroom stems and starch, and the entire process utilizes green enzymatic hydrolysis and physical treatment, avoiding chemical pollution. This not only solves the environmental problem of the non-biodegradability of traditional filter materials but also achieves high-value utilization of agricultural waste, aligning with the principles of green and sustainable development.
[0106] This invention provides a method for preparing a cigarette holder aerogel, comprising the following steps: pulverizing shiitake mushroom stems to 40-120 mesh, controlling the moisture content to 15-55%, and subjecting them to steam explosion under a pressure of 0.6-1.4 MPa for 30-150 seconds to obtain pretreated shiitake mushroom stems; mixing the pretreated shiitake mushroom stems with water, adjusting the pH to 6.0, adding heat-stable α-amylase, stirring, then adjusting the pH to 8.0, adding alkaline protease, stirring again, adjusting the pH to 5.5, adding amylase, shaking, and inactivating the enzyme after enzymatic hydrolysis. Centrifuge, freeze-dry the precipitate to obtain insoluble dietary fiber; mix the insoluble dietary fiber, NaOH and H2O2, stir, add deionized water to terminate the reaction, centrifuge, wash with water until neutral, and freeze-dry to obtain shiitake stem cellulose; disperse the shiitake stem cellulose in acetate buffer, add cellulase for enzymatic hydrolysis, then sonicate, centrifuge, wash to obtain nanocellulose suspension; mix the nanocellulose suspension with gelatinized acetylated starch suspension, freeze-dry under vacuum to obtain cigarette filter aerogel. This method uses naturally biodegradable shiitake mushroom stems and starch as raw materials. Their molecular structure is easily decomposed by microorganisms and can be naturally degraded after disposal, thus solving the environmental pollution problem of cellulose acetate filter rods. Aerogels are prepared by combining shiitake mushroom stem nanocellulose with potato acetylated starch. The high specific surface area and three-dimensional porous structure of nanocellulose, combined with van der Waals forces and hydrogen bonding, can efficiently capture tar particles and polar harmful substances, solving the problems of single filtration mechanism and low efficiency in existing technologies. By using shiitake mushroom stems, a by-product of shiitake mushroom processing, as raw materials, the resource utilization of waste is realized, reducing costs.
[0107] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a cigarette mouthpiece aerogel, comprising the following steps: crushing Lentinus edodes stems to 40-120 mesh, controlling the moisture content to 15-55%, and performing steam explosion at 0.6-1.4 MPa for 30-150 s to obtain pretreated Lentinus edodes stems; mixing the pretreated Lentinus edodes stems with water, adjusting the pH to 6.0, adding heat-stable alpha-amylase, stirring, adjusting the pH to 8.0, adding alkaline protease, stirring again, adjusting the pH to 5.5, adding starch glucosidase, oscillating, inactivating the enzyme after enzymolysis, centrifuging, freeze-drying the precipitate, and obtaining insoluble dietary fiber; mixing the insoluble dietary fiber, NaOH, and H2O2, stirring, adding deionized water to terminate the reaction, centrifuging, freeze-drying after washing to neutral, and obtaining Lentinus edodes stem cellulose; dispersing the Lentinus edodes stem cellulose in an acetic acid buffer, adding cellulase for enzymolysis, ultrasonic treatment, centrifuging, and washing to obtain a nanocellulose suspension; mixing the nanocellulose suspension and a gelatinized and acetylated starch suspension, vacuum freeze-drying, and obtaining a cigarette mouthpiece aerogel.
2. The production method according to claim 1, characterized by, The mass ratio of the pretreated Lentinus edodes stems to water is 1:28-32. The amount of heat-stable alpha-amylase added is 4.5-5.5 wt% of the Lentinus edodes stem powder.
3. The preparation method according to claim 1, characterized in that, The amount of alkaline protease added is 3.8-4.2 wt% of the Lentinus edodes stem powder. The amount of starch glucosidase added is 9.5-10.5 wt% of the Lentinus edodes stem powder.
4. The method of claim 1, wherein, The amount of cellulase added is 100 U / g-250 U / g.
5. The preparation method according to claim 1, characterized in that, The temperature for enzymolysis after adding cellulase is 48-52℃, and the time is 8-20 h.
6. The method of claim 1, wherein, The ultrasonic treatment power is 150 W-300 W, and the time is 15-30 min.
7. The preparation method according to claim 1, characterized in that, The Lentinus edodes stem nanocellulose is in the form of long filament bundles, with a diameter of 10.96±1.14 nm and a length of microns.
8. The method of claim 1, wherein, The mass fraction of the gelatinized and acetylated starch suspension is 4.8-5.2% (w / v). The mass fraction of the nanocellulose suspension is 0.95-1.05% (w / v). The volume ratio of the cellulose suspension to the gelatinized and acetylated starch suspension is 1:
1.
9. The method of claim 1, wherein, Vacuum freeze-drying is performed at 10-90 Pa / min. 10.A degradable cigarette filter rod with a tar-reducing and harm-reducing effect, comprising a cigarette mouthpiece aerogel prepared by the method of any one of claims 1-9.