A method for tobacco re-humidification and its composite tobacco

Abstract

The present application belongs to the technical field of tobacco processing, and provides a tobacco moisture conditioning method and composite tobacco. The composite tobacco comprises a tobacco base and a plant-derived functional layer attached to the surface of the tobacco base. The tobacco base has a connected microporous structure with a gradient distribution of pore diameters. The microporous pore wall surface is connected to the outer surface of the tobacco base and forms a continuous and through surface interface. The plant-derived functional layer is formed by spraying a mixed dry powder containing extract components of Asarum and sodium citrate onto the surface of the tobacco base after dispersion in an aqueous phase. The mixed dry powder at least partially penetrates into the connected microporous structure and adheres to the pore wall surface. The sodium citrate is distributed on the surface interface, and the extract components of Asarum are co-distributed on the surface interface and the inner wall of the micropores. The connected microporous structure is formed after low-temperature freeze-thaw phase transition excitation pretreatment of the tobacco base. The treatment method and the composite tobacco obtained after treatment can solve the problem of poor performance of tobacco.

Description

Technical Field

[0001] This application relates to the field of tobacco processing technology, and in particular to a method for rehydrating tobacco and its composite tobacco. Background Technology

[0002] As a widely cultivated economic crop globally, tobacco leaves' initial and deep processing after harvesting directly determines the upper limit of the final product's quality. In the complete cigarette industry chain, fresh tobacco leaves first undergo scientific curing to fix color and aroma and remove most of the free water. They are then processed into shredded tobacco through cutting and screening, ultimately entering the rolling stage. During this process, the physicochemical properties of the shredded tobacco, especially the stability of its physical structure and chemical composition, are core factors determining the cigarette's combustibility, filling value, and sensory experience. Notably, the moisture content of the shredded tobacco, as a key process control indicator, not only profoundly affects the tissue structure of tobacco sheets and leaves, such as flexibility, elasticity, and filling capacity, but also directly regulates the activity and migration rate of various chemical components within the tobacco. Therefore, implementing precise rehydration treatment for over-dried tobacco to restore its moisture content to the process standard range is an indispensable key step in ensuring the integrity of the tobacco, reducing breakage rate, optimizing subsequent processing performance, and improving the final cigarette quality. Thus, it is necessary to develop efficient and uniform tobacco rehydration technology to adapt to the physical property requirements of different types of tobacco.

[0003] Although there are many existing technologies for rehydrating tobacco shreds, the resulting shreds lack sufficient color and antibacterial effect, and contain many impurities, resulting in high irritation. For example, patent application CN114732149A discloses a method for expanding tobacco shreds and its storage device. This method includes the following steps: Rehydration: After pre-treatment of the raw materials, a leaf-moistening treatment is performed. Impregnation: The moistened leaves are shredded and then screened a second time, followed by depressurization treatment of the tobacco shreds in a container. Storage: The pressure is reduced to near standard atmospheric pressure without damaging the microporous structure of the tobacco cells. Expansion: Water vapor or other heated inert media is injected into the container to rapidly increase the temperature inside the container, allowing the tobacco shreds to expand and set. Rehydration: The pressure inside the container is reduced again, and the tobacco shreds are vacuumed and moistened again to avoid excessive breakage due to brittleness. Screening: Atmospheric atmosphere is introduced to raise the pressure inside the container to standard atmospheric pressure, and a third screening is performed. After air separation, the tobacco shreds are boxed and stored. This invention ensures the temperature during rehydration of expanded tobacco, improves the flexibility of the expanded tobacco, and reduces breakage during rehydration. However, this method relies solely on multiple rehydration processes (leaf moistening, vacuum leaf moistening) to adjust the moisture content to 12%~25%, without introducing any humectants, chelating agents, or plant-derived functional components. As a result, the antibacterial effect is poor, and the color tends to darken.

[0004] For example, patent CN103126063B discloses a novel tobacco sensory moisturizing agent and its application method in tobacco. This moisturizing agent uses purified water and glucosamine sulfate as raw materials, and is evenly sprayed onto tobacco leaves during the leaf moistening and rehydration process or evenly sprayed onto tobacco shreds during the addition process. It is simple to operate and can significantly improve the sensory moisture content of tobacco products without significantly altering their physical hygroscopic properties. When smoking, the dryness and irritation of the tobacco product are significantly improved, the smoke is smooth and delicate, and the aroma of the tobacco product can be appropriately enriched. However, this solution lacks an active bactericidal and antioxidant chelating system, making it prone to mold growth and color deterioration; glucosamine sulfate itself has weak antibacterial ability, and at low dosages of 0.001% to 0.1%, it is even more difficult to inhibit the growth of mold and bacteria in a humid environment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for rehydrating tobacco shreds and its composite tobacco shreds. After treatment by this invention, the (composite) tobacco shreds have suitable humidity, good integrity, low breakage rate, high filling value, harmonious aroma, good color, low irritation, few off-flavors, are not prone to mold, have good antibacterial effect, and can achieve a high filling value, thus meeting the required specifications.

[0006] To achieve the above and related objectives, the present invention employs the following technical means:

[0007] The first aspect of the present invention provides a composite tobacco shred, comprising a tobacco shred matrix and a plant-derived functional layer attached to the surface of the tobacco shred matrix;

[0008] The tobacco matrix has an interconnected microporous structure inside, with the pore size of the interconnected microporous structure being gradient-distributed, and the surface of the micropore wall is connected to the outer surface of the tobacco matrix, together forming a continuous and interconnected surface interface.

[0009] The plant-derived functional layer is formed by spraying a mixed dry powder containing Asarum extract and sodium citrate onto the surface of tobacco substrate after being dispersed in an aqueous phase. The mixed dry powder penetrates at least partially into the interconnected microporous structure and adheres to the surface of the pore walls.

[0010] Sodium citrate is distributed on the surface and interface, while Asarum extract is distributed on both the surface and interface and the inner wall of the micropores. The interconnected microporous structure is formed after the tobacco matrix is ​​subjected to low-temperature freeze-thaw phase change excitation pretreatment.

[0011] Furthermore, the mixed dried powder also includes wood butterfly extract components.

[0012] Furthermore, the cryogenic freeze-thaw phase change excitation pretreatment includes:

[0013] The tobacco substrate is cooled to -40℃ to -20℃ at a cooling rate of 5℃ / min to 10℃ / min and held for 10min to 30min. Then, it is rapidly heated to 30℃ to 50℃ at a heating rate of 5℃ / min to 10℃ / min.

[0014] As can be seen from the above technical means, the structural improvement of the composite tobacco shreds in this invention originates from the synergistic effect of physical phase change excitation and chemical interface modification. Specifically, this invention first uses low-temperature freeze-thaw phase change excitation pretreatment to cause the moisture inside the tobacco shreds to form ice crystals during rapid cooling, resulting in volume expansion and internal pressure on the cell walls, causing microcracks. Subsequently, rapid heating triggers the instantaneous phase change vaporization of the ice crystals, generating micro-explosions and thermal stress, thereby forming a connected microporous network with a gradient pore size distribution within the tobacco shred matrix, and making the micropore walls interconnected with the outer surface. During the chemical interface modification process, the Asarum (Oroxylum indicum) extract, with its rich content of flavonoids, polysaccharides, and volatile essential oils, partially penetrates into the micropores during spraying and adhesion with the aqueous medium. It is anchored to the pore walls using hydrogen bonds and van der Waals forces, playing a role in harmonizing the aroma and masking impurities. Meanwhile, sodium citrate, generated from the neutralization of citric acid, preferentially accumulates at the continuous, interconnected surface of the tobacco shreds due to its excellent water solubility and chelating properties. On one hand, it forms stable chelate ring structures with metal ions such as iron and copper ions through carboxylate ions, blocking the oxidation reaction catalyzed by metal ions and achieving color protection and mold prevention. On the other hand, the hydrophilic film layer formed by sodium citrate and plant polysaccharides enhances the wettability of the surface and reduces the irritation of the smoke. This invention, through a coupled structure of physical micropore construction, directional anchoring of chemical components, and integrated surface and interface functions, ultimately achieves a simultaneous improvement in the filling value, flexibility, and sensory quality of the tobacco shreds.

[0015] A second aspect of the present invention provides a method for rehydrating tobacco shreds, comprising the following steps:

[0016] (1) The tobacco substrate is subjected to low-temperature freeze-thaw phase change vibration pretreatment, which includes:

[0017] The tobacco substrate is cooled to -40℃ to -20℃ at a cooling rate of 5℃ / min to 10℃ / min and held for 10min to 30min, and then rapidly heated to 30℃ to 50℃ at a heating rate of 5℃ / min to 10℃ / min.

[0018] (2) The tobacco substrate treated in step (1) is placed in a vacuum environment and steam is introduced for rehumidification.

[0019] (3) Spray the treatment liquid onto the tobacco substrate after step (2). The treatment liquid is prepared by dispersing a mixed dry powder containing Asarum extract and sodium citrate in an aqueous phase.

[0020] Further, in step (2), the rehydration treatment satisfies at least one of the following conditions (a) to (c):

[0021] (a) The steam temperature is 60℃~110℃;

[0022] (b) Steam pressure is 0.02 MPa to 0.15 MPa;

[0023] (c) The rehumidification treatment time is 1 min to 8 min.

[0024] Furthermore, before proceeding to step (2), the tobacco substrate treated in step (1) is subjected to sterilization treatment, which is sterilization under ultraviolet light irradiation.

[0025] Alternatively, high-pressure sterilization can be performed at 50℃~80℃ and 50MPa~80MPa.

[0026] As can be seen from the above technical means, since the present invention has undergone low-temperature freeze-thaw phase change excitation pretreatment, if it directly enters the high-temperature and high-humidity vacuum rehumidification process, it is very easy to induce mold growth. Therefore, the present invention performs pre-sterilization treatment between vacuum rehumidification to effectively kill bacteria and mold spores on the surface of tobacco and in the micropores.

[0027] Furthermore, in step (3), the preparation method of the Asarum extract includes:

[0028] After being pulverized, Asarum was roasted under nitrogen protection, followed by ultrasonic extraction with a mixed ethanol-acetone solution, extraction with citric acid aqueous solution, and pH neutralization treatment. The extracts were combined, concentrated and dried to obtain dried powder.

[0029] In the ethanol-acetone mixed solution, the volume ratio of ethanol to acetone is 2:1; and the mass concentration of citric acid in the citric acid aqueous solution is 1.5% to 3.2%.

[0030] Furthermore, during the step of pulverizing Asarum, 25% to 40% of the weight of Asarum powder is added to Oroxylum indicum powder, and the powder is then roasted, extracted, and post-processed together.

[0031] Furthermore, the baking treatment satisfies at least one of the following conditions (d) to (e):

[0032] (d) Baking temperature is 50℃~80℃;

[0033] (e) Baking time is 10 min to 50 min.

[0034] According to the above technical means, the present invention first performs medium and low temperature roasting under nitrogen protection to deactivate the activity of oxidase under the condition of oxygen isolation, prevent the loss of volatile aroma components in Asarum (and co-treated Oroxylum indicum) through pyrolysis, and at the same time promote the hydrolysis of glycoside precursor substances through mild thermal reaction, release more free aroma components, and provide a coordinated aroma substrate for tobacco.

[0035] This invention utilizes the synergistic solubility of mixed solvents on polar / weakly polar components through ethanol-acetone ultrasonic extraction, efficiently extracting volatile oils from Asarum heterotropoides and flavonoids and polysaccharides from Oroxylum indicum. Citric acid aqueous solution extraction promotes the hydrolysis of pectin and cellulose in plant cell walls through an acidic environment, releasing bound phenolic acids and polysaccharides. Simultaneously, citric acid neutralizes with subsequently added sodium hydroxide to generate sodium citrate in situ, which can chelate iron and copper ions and other pro-oxidative metal ions in tobacco, thereby blocking the oxidation chain reaction. This significantly improves the color stability and anti-mold ability of tobacco, regulates the pH of tobacco, neutralizes alkaline irritants in the smoke, reduces off-flavors, results in a smoother taste, prevents tobacco deterioration, extends shelf life, and improves the moisture retention of tobacco.

[0036] Furthermore, the blending, concentration, and drying process of this invention integrates the above-mentioned extractive components with different polarities and functions into the dried powder. The addition of wood butterfly powder further introduces flavonoid glycosides, which produce a synergistic effect of reducing irritation, increasing sweetness, and moisturizing with the asarum component. After being sprayed onto the surface of the rehydrated tobacco, the treatment liquid can form a plant-derived functional layer on its surface, further enhancing its moisturizing and antibacterial properties, ultimately achieving a comprehensive performance improvement in tobacco with harmonious aroma, low irritation, resistance to mold, and high filling value.

[0037] Furthermore, the mass content of the mixed dried powder in the treatment liquid in step (3) is 6%~15%.

[0038] The beneficial technical effects of this invention are as follows:

[0039] The (composite) tobacco shreds treated by the tobacco shred rehydration treatment method of the present invention have the advantages of suitable humidity, good tobacco shred integrity, low breakage rate, high filling value, harmonious aroma, good color, low irritation, few impurities, not easy to mold, and good antibacterial effect. In addition, it can achieve a high filling value and meet the index requirements.

[0040] This invention utilizes low-temperature freeze-thaw phase change excitation pretreatment to construct a connected microporous network with a gradient pore size distribution inside the tobacco fibers by utilizing ice crystal expansion and thermal stress. This structure significantly improves the elasticity and fluffiness of the tobacco, resulting in a substantial increase in the filling value. At the same time, the buffering effect of the micropores can effectively absorb mechanical impacts during subsequent processing, reducing the breakage rate and loss of whole tobacco fibers.

[0041] The sodium citrate in the treatment solution sprayed in this invention not only acts as a humectant but also as a chelating agent, forming stable complexes with metal ions such as iron and copper ions on the surface and micropore walls of tobacco. This blocks the oxidation reaction catalyzed by metal ions, preventing mold growth and pigment degradation in the tobacco (color protection). On the other hand, by adjusting the pH of the tobacco, it neutralizes the alkaline and irritating components in the smoke, making the taste smoother.

[0042] The extracts of Asarum and Oroxylum indicum of this invention are rich in volatile essential oils and flavonoids. After being roasted in nitrogen and extracted with a specific solvent, the active ingredients are preserved. These components adhere to the inner wall of the micropores and can harmonize the natural aroma of tobacco and mask off-flavors when burned, thereby significantly reducing irritation and giving the smoke a unique herbal aroma.

[0043] The present invention combines vacuum steam rehydration with low-temperature freeze-thaw phase change excitation pretreatment to ensure that the moisture in the tobacco shreds penetrates evenly from the inside out, avoiding the phenomenon of external wetness and internal dryness that is easy to occur in conventional rehydration, making the moisture content of the tobacco shreds more balanced, which is beneficial to the stability of subsequent cutting and rolling processes.

[0044] Furthermore, through the synergistic effect of physical sterilization, chemical chelation, and natural antibacterial components, this invention can significantly reduce the microbial load on the surface of tobacco shreds, inhibit the growth of mold and other fungi, and has excellent antibacterial effect.

[0045] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0046] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that certain features of the invention (described in the context of separate embodiments for clarity) may also be provided in a single embodiment. Conversely, multiple features of the invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or, where appropriate, in any other described embodiment of the invention. Certain features described in the context of various embodiments will not be considered essential features of those embodiments unless the embodiment is inoperable without those elements. The invention is further illustrated below by specific examples; however, it should be noted that the specific process conditions and results described in the embodiments of the invention are merely illustrative and should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be covered within the scope of protection of the invention.

[0047] This application provides a composite tobacco shred, including a tobacco shred matrix and a plant-derived functional layer attached to the surface of the tobacco shred matrix;

[0048] The tobacco matrix has an interconnected microporous structure inside, with the pore size of the interconnected microporous structure being gradient-distributed, and the surface of the micropore wall is connected to the outer surface of the tobacco matrix, together forming a continuous and interconnected surface interface.

[0049] The plant-derived functional layer is formed by spraying a mixed dry powder containing Asarum extract and sodium citrate onto the surface of tobacco substrate after being dispersed in an aqueous phase. The mixed dry powder penetrates at least partially into the interconnected microporous structure and adheres to the surface of the pore walls.

[0050] Sodium citrate is distributed on the surface and interface, while Asarum extract is distributed on both the surface and interface and the inner wall of the micropores. The interconnected microporous structure is formed after the tobacco matrix is ​​subjected to low-temperature freeze-thaw phase change excitation pretreatment.

[0051] Furthermore, the mixed dried powder also includes wood butterfly extract components.

[0052] Furthermore, the cryogenic freeze-thaw phase change excitation pretreatment includes:

[0053] The tobacco substrate is cooled to -40℃ to -20℃ at a cooling rate of 5℃ / min to 10℃ / min and held for 10min to 30min. Then, it is rapidly heated to 30℃ to 50℃ at a heating rate of 5℃ / min to 10℃ / min.

[0054] This application also provides a method for treating tobacco shreds to regain moisture, including the following steps:

[0055] (1) The tobacco substrate is subjected to low temperature freeze-thaw phase change vibration pretreatment. The low temperature freeze-thaw phase change vibration pretreatment includes: cooling the tobacco substrate to -40℃ to -20℃ at a cooling rate of 5℃ / min to 10℃ / min and holding it for 10min to 30min, and then rapidly heating it to 30℃ to 50℃ at a heating rate of 5℃ / min to 10℃ / min.

[0056] (2) The tobacco substrate treated in step (1) is placed in a vacuum environment and steam is introduced for rehumidification.

[0057] Specifically, the steps are detailed below:

[0058] The tobacco substrate treated in step (1) is sterilized by ultraviolet light irradiation; or, high-pressure sterilization is carried out at 50℃~80℃ and 50MPa~80MPa, such as high-pressure sterilization at 50℃~80℃ and 60MPa~70MPa for 3min~10min.

[0059] The sterilized tobacco substrate is added to the processing chamber, and the air in the processing chamber is evacuated to a vacuum. Steam is generated using a steam generator, and then steam is introduced into the processing chamber to rehydrate the tobacco substrate. The steam temperature is 60℃~110℃, the steam pressure is 0.02MPa~0.15MPa, and the rehydration time is 1min~8min.

[0060] (3) Spray the treatment liquid onto the tobacco substrate after step (2). The treatment liquid is prepared by dispersing a mixed dry powder containing Asarum extract and sodium citrate in an aqueous phase.

[0061] Specifically, the steps are detailed below:

[0062] Preparation of treatment solution:

[0063] Asarum is pulverized to obtain Asarum powder, and the Asarum powder is placed at 50℃~80℃ and roasted in nitrogen for 10min~50min.

[0064] Asarum powder was placed in an ethanol-acetone mixed solution at 60℃~85℃ and soaked for 1h~5h under ultrasonic treatment. Then it was filtered to obtain a primary filtrate and a primary filter powder. The volume ratio of ethanol to acetone was 2:1.

[0065] The primary filter powder is soaked in a citric acid aqueous solution at 65℃~95℃ for 1h~4h, neutralized with sodium hydroxide solution until neutral, and then filtered to obtain a secondary filtrate and a secondary filter powder. The citric acid content in the citric acid aqueous solution is 1.5%~3.2%.

[0066] The primary filtrate and the secondary filtrate are mixed, concentrated, and dried to obtain a mixed and dried powder.

[0067] The mixed dry powder is dissolved and dispersed in water at 60℃~90℃ to obtain a treatment solution.

[0068] Optionally, the mass content of the mixed dried powder in the processing liquid of this application is 6% to 15%.

[0069] Optionally, in the step of pulverizing Asarum, this application also adds Oroxylum indicum powder at a mass of 25% to 40% of the Asarum powder mass, and together they are roasted, extracted and post-processed.

[0070] Furthermore, the composite tobacco shreds described in this application can be obtained by the aforementioned tobacco shreds rehydration treatment method.

[0071] The present invention will be described in detail below through specific examples and embodiments. It should also be understood that the following embodiments are only for specific illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0072] Comparative Example 1

[0073] (1) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0074] (2) Steam is generated by a steam generator and then introduced into the processing chamber to rehydrate the tobacco. The steam temperature is 60℃, the steam pressure is 0.15MPa, and the rehydration time is 8min.

[0075] Comparative Example 2

[0076] (1) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0077] (2) Steam is generated by a steam generator and then steam is introduced into the processing chamber to rehydrate the tobacco. The steam temperature is 110℃, the steam pressure is 0.02MPa, and the rehydration time is 1min.

[0078] Comparative Example 3

[0079] (1) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0080] (2) Steam is generated by a steam generator and then introduced into the processing chamber to rehydrate the tobacco. The steam temperature is 80℃, the steam pressure is 0.1MPa, and the rehydration time is 4min.

[0081] Comparative Example 4

[0082] (1) Add tobacco into the processing chamber, cool the temperature in the processing chamber to -20°C at a rate of 5°C / min, keep it for 30 min, and then quickly heat it to 30°C at a rate of 5°C / min.

[0083] (2) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0084] (3) Use a steam generator to generate steam, and then introduce steam into the processing chamber to rehydrate the tobacco. The steam temperature is 80℃, the steam pressure is 0.1MPa, and the rehydration time is 4min.

[0085] Comparative Example 5

[0086] (1) Add tobacco into the processing chamber, cool the temperature in the processing chamber to -40℃ at a rate of 10℃ / min, keep it for 10min, and then quickly heat it to 50℃ at a rate of 10℃ / min.

[0087] (2) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0088] (3) Use a steam generator to generate steam, and then introduce steam into the processing chamber to rehydrate the tobacco. The steam temperature is 80℃, the steam pressure is 0.1MPa, and the rehydration time is 4min.

[0089] Example 1

[0090] (1) Add tobacco into the processing chamber, cool the temperature in the processing chamber to -20°C at a rate of 5°C / min, keep it for 30 min, and then quickly heat it to 30°C at a rate of 5°C / min.

[0091] (2) Add the tobacco into the processing chamber and extract the air from the processing chamber to a vacuum;

[0092] (3) Use a steam generator to generate steam, and then introduce steam into the processing chamber to rehydrate the tobacco. The steam temperature is 80℃, the steam pressure is 0.1MPa, and the rehydration time is 4min.

[0093] (4) A spray that applies a treatment solution to tobacco shreds, wherein the preparation method of the treatment solution includes:

[0094] Asarum is pulverized to obtain Asarum powder;

[0095] The asarum powder was roasted at 50°C in nitrogen for 50 minutes.

[0096] Then, the asarum powder was soaked in an ethanol-acetone mixed solution at 85°C for 1 hour under ultrasonic treatment, and then filtered to obtain a primary filtrate and a primary filter powder. The volume ratio of ethanol to acetone was 2:1.

[0097] The primary filter powder was soaked in a citric acid aqueous solution at 65℃ for 4 hours, then neutralized to neutral with a 1.2 mol / L sodium hydroxide solution, and then filtered to obtain a secondary filtrate and secondary filter powder; the citric acid content in the citric acid aqueous solution was 1.5%.

[0098] The primary filtrate and the secondary filtrate are mixed, concentrated, and dried to obtain a dried powder, which is used as a treatment agent.

[0099] The dried powder was dissolved and dispersed in water at 90°C to obtain a treatment solution;

[0100] The mass content of the dried powder in the treatment solution is 6%.

[0101] Example 2

[0102] The difference between this embodiment and Embodiment 1 is that:

[0103] (4) A spray that applies a treatment solution to tobacco shreds, wherein the preparation method of the treatment solution includes:

[0104] Asarum is pulverized to obtain Asarum powder;

[0105] The asarum powder was roasted at 80°C in nitrogen for 10 minutes.

[0106] Then, the asarum powder was soaked in an ethanol-acetone mixed solution at 60℃ for 5 hours under ultrasonic treatment, and then filtered to obtain a primary filtrate and a primary filter powder. The volume ratio of ethanol to acetone was 2:1.

[0107] The primary filter powder was soaked in a citric acid aqueous solution at 95℃ for 1 hour, then neutralized with a 1.2 mol / L sodium hydroxide solution until neutral, and then filtered to obtain a secondary filtrate and secondary filter powder; the citric acid content in the citric acid aqueous solution was 3.2%;

[0108] The primary filtrate and the secondary filtrate are mixed, concentrated, and dried to obtain a dried powder, which is used as a treatment agent.

[0109] The dried powder was dissolved and dispersed in water at 60°C to obtain a treatment solution;

[0110] The mass content of the dried powder in the treatment solution is 15%.

[0111] Example 3

[0112] The difference between this embodiment and Embodiment 1 is that:

[0113] (4) A spray that applies a treatment solution to tobacco shreds, wherein the preparation method of the treatment solution includes:

[0114] Asarum is pulverized to obtain Asarum powder;

[0115] The asarum powder was roasted at 60°C in nitrogen for 30 minutes.

[0116] Then, the asarum powder was soaked in an ethanol-acetone mixed solution at 75°C for 3 hours under ultrasonic treatment, and then filtered to obtain a primary filtrate and a primary filter powder. The volume ratio of ethanol to acetone was 2:1.

[0117] The primary filter powder was soaked in a citric acid aqueous solution at 75℃ for 2.5 hours, then neutralized to neutral with a 1.2 mol / L sodium hydroxide solution, and finally filtered to obtain a secondary filtrate and secondary filter powder; the citric acid content in the citric acid aqueous solution was 2.2%;

[0118] The primary filtrate and the secondary filtrate are mixed, concentrated, and dried to obtain a dried powder, which is used as a treatment agent.

[0119] The dried powder was dissolved and dispersed in water at 70°C to obtain a treatment solution;

[0120] The mass content of the dried powder in the treatment solution is 10%.

[0121] Example 4

[0122] The difference between this embodiment and Embodiment 3 is as follows:

[0123] The asarum powder also contains: oroxylum indicum powder, which accounts for 25% of the asarum powder's weight.

[0124] Example 5

[0125] The difference between this embodiment and Embodiment 3 is as follows:

[0126] The asarum powder also contains: wood butterfly powder, which accounts for 40% of the asarum powder.

[0127] Performance testing

[0128] Tobacco performance: The performance of the tobacco shreds after rehydration treatment in each comparative example and each embodiment was tested, and the test results are shown in Table 1.

[0129] Antibacterial performance: The antibacterial effect of the treatment solutions prepared in each example was tested, and the test results are shown in Table 2.

[0130] The experimental data and analysis are as follows:

[0131] Table 1. Test results of tobacco shreds after rehydration treatment

[0132]

[0133] As shown in Table 1, Comparative Examples 1 to 3 of this application only underwent vacuum steam rehydration, while Comparative Examples 4 to 5 introduced low-temperature freeze-thaw phase change vibration pretreatment. Examples 1 to 5, however, represent the complete rehydration scheme of this application. Compared to the comparative examples, the tobacco shreds prepared in this application showed a continuous decrease in breakage rate, a steady increase in filling value, and good sensory quality. This is because the low-temperature freeze-thaw phase change vibration pretreatment of this application constructs a connected gradient microporous structure inside the tobacco shreds, significantly enhancing steam permeation efficiency and fiber swelling stability. Subsequent vacuum-steam pressure difference rehydration further opens up the pore walls and outer surface, forming a continuous and interconnected interface, allowing moisture and active substances to be evenly infiltrated. Finally, a composite treatment liquid containing Asarum / Oroxylum indicum and sodium citrate is sprayed, which not only enhances aroma and reduces thorniness through plant-derived components but also chelates metal ions and inhibits oxidative mold growth with the help of sodium citrate, while its hydrophilic groups strengthen capillary water retention capacity. In contrast, Comparative Examples 1 to 3 relied solely on traditional rehydration, resulting in incomplete pore penetration, loose structure, high breakage rate, and low filling value. Comparative Examples 4 and 5, while involving freeze-thaw cycles, lacked a treatment solution, thus lacking interfacial functionalization and antibacterial / antioxidant protection, and therefore their performance was still inferior to the examples. In particular, Example 4 (with 25% *Oroxylum indicum* powder added) exhibited the lowest breakage rate (0.91%) and the highest filling value (4.98), demonstrating the excellent synergistic effect of plant compounding, structural modification, and chelated moisture retention.

[0134] Table 2. Results of the antibacterial effect test of the treatment solution.

[0135]

[0136] As shown in Table 2, the treatment solutions prepared in Examples 1 to 5 of this application all exhibited antibacterial rates of 91.6% to 99.7% against *Escherichia coli*, *Aspergillus fumigatus*, *Penicillium chrysogenum*, and *Aspergillus niger*, demonstrating excellent overall antibacterial effects that showed an increasing trend with formulation / process optimization. Among these, Example 4 showed the best antibacterial performance, followed by Example 5, with Example 2 outperforming Example 1, and Example 3 showing moderate performance. This is because, in the formulation of Example 1 of this application, the *Asarum heterotropoides* extract contains volatile oils, asarone, and other natural antibacterial components, which, combined with the metal ion chelating effect of sodium citrate, jointly construct a basic antibacterial system, achieving an initial antibacterial rate of 90%+. In Example 2, the increased roasting temperature of *Asarum heterotropoides*, the increased concentration of citric acid, and the increased concentration of the treatment solution further enhanced the dissolution (roasting promotes the release of volatile oils) and chelating ability of the antibacterial components (high citric acid enhances metal ion capture), resulting in a further increase in the antibacterial rate. In Examples 4 and 5, *Oroxylum indicum* powder (containing flavonoids and glycosides, antibacterial substances) was added. This synergistically inhibited microbial cell membrane synthesis / enzyme activity with *Asarum heterotropoides* components. Combined with the chelation effect of sodium citrate and the inherent antibacterial properties of *Asarum heterotropoides*, the antibacterial rate exceeded 99%. In Example 3, the concentrations of baking, citric acid, and treatment solution were between those of Examples 1 and 2, and the antibacterial effect was also moderate. This demonstrates the synergistic dependence of process parameters and compounding ratios.

[0137] In summary, the tobacco shreds processed by the method of this application have a low breakage rate, good integrity, high filling value, good color, good aroma, sufficient aroma quantity, harmonious aroma, low irritation, no off-flavors, can achieve a high filling value, and have good overall quality, which can meet the requirements.

[0138] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A composite tobacco shred, characterized in that, It includes a tobacco substrate and a plant-derived functional layer attached to the surface of the tobacco substrate; The tobacco substrate has an internal interconnected microporous structure with a gradient distribution of pore size. The surface of the micropore wall is connected to the outer surface of the tobacco substrate and together they form a continuous and interconnected interface. The plant-derived functional layer is formed by spraying a mixed dry powder containing Asarum extract and sodium citrate onto the surface of the tobacco substrate after being dispersed in an aqueous phase. The mixed dry powder at least partially penetrates into the interconnected microporous structure and adheres to the surface of the pore walls. The sodium citrate is distributed on the surface and interface, and the Asarum extract is distributed on the surface and interface and the inner wall of the micropores; the interconnected microporous structure is formed after the tobacco matrix is ​​subjected to low-temperature freeze-thaw phase change vibration pretreatment.

2. The composite tobacco shreds according to claim 1, characterized in that, The mixed dried powder also includes wood butterfly extract.

3. The composite tobacco shreds according to claim 1, characterized in that, The low-temperature freeze-thaw phase change excitation pretreatment includes: The tobacco substrate is cooled to -40°C to -20°C at a cooling rate of 5°C / min to 10°C / min and held for 10 min to 30 min, and then rapidly heated to 30°C to 50°C at a heating rate of 5°C / min to 10°C / min.

4. A method for re-moistening tobacco shreds, characterized in that, Includes the following steps: (1) The tobacco substrate is subjected to low-temperature freeze-thaw phase change vibration pretreatment, wherein the low-temperature freeze-thaw phase change vibration pretreatment includes: The tobacco substrate is cooled to -40°C to -20°C at a cooling rate of 5°C / min to 10°C / min and held for 10 min to 30 min, and then rapidly heated to 30°C to 50°C at a heating rate of 5°C / min to 10°C / min. (2) The tobacco substrate treated in step (1) is placed in a vacuum environment and steam is introduced for rehumidification. (3) Spray the treatment liquid onto the tobacco substrate after the treatment in step (2), the treatment liquid being prepared by aqueous dispersion of a mixed dry powder containing asarum extract and sodium citrate.

5. The method for re-moistening tobacco shreds according to claim 4, characterized in that, In step (2), the re-moistening treatment satisfies at least one of the following conditions (a) to (c): (a) The steam temperature is 60℃~110℃; (b) Steam pressure is 0.02 MPa to 0.15 MPa; (c) The rehumidification treatment time is 1 min to 8 min.

6. The method for re-moistening tobacco shreds according to claim 4, characterized in that, Before performing step (2), the tobacco substrate treated in step (1) is subjected to sterilization treatment, which is sterilization under ultraviolet light irradiation. Alternatively, high-pressure sterilization can be performed at 50℃~80℃ and 50MPa~80MPa.

7. The method for re-moistening tobacco shreds according to claim 4, characterized in that, In step (3), the preparation method of the Asarum extract includes: After being pulverized, Asarum was roasted under nitrogen protection, followed by ultrasonic extraction with a mixed ethanol-acetone solution, extraction with citric acid aqueous solution, and pH neutralization treatment. The extracts were combined, concentrated and dried to obtain dried powder. The volume ratio of ethanol to acetone in the ethanol-acetone mixed solution is 2:1; the mass concentration of citric acid in the citric acid aqueous solution is 1.5% to 3.2%.

8. The method for re-moistening tobacco shreds according to claim 7, characterized in that, In the step of pulverizing the Asarum, 25% to 40% of the Asarum powder by weight of Oroxylum indicum powder is added, and the powder is then roasted, extracted, and post-processed together.

9. The method for re-moistening tobacco shreds according to claim 7, characterized in that, The baking process satisfies at least one of the following conditions (d) to (e): (d) Baking temperature is 50℃~80℃; (e) Baking time is 10 min to 50 min.

10. The method for re-moistening tobacco shreds according to claim 4, characterized in that, The mass content of the mixed dry powder in the treatment liquid in step (3) is 6%~15%.

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