Preparation method of tea polyphenol-based antibacterial material and application of tea polyphenol-based antibacterial material in tobacco extract

Abstract

The application discloses a preparation method of a tea polyphenol-based antibacterial material and application of the antibacterial material in tobacco extract liquid. The antibacterial material comprises a core material and a pH response coating layer coated on the surface of the core material. The core material comprises the following components in parts by mass: tea polyphenol 10-40%, ethyl cellulose 30-50%, microcrystalline cellulose 20-40% and propylene glycol 5-10%. The pH response coating layer comprises hydroxypropyl methyl cellulose phthalate, triethyl citrate and talc powder in a mass ratio of 100:(12-18):(15-25). The mass ratio of the core material to the pH response coating layer is 100:(10-15). The application realizes self-catalytic closed-loop slow release of tea polyphenol by means of nano-pore diffusion and pH response dissolution controlled release mechanism, relies on pH change of the system, can efficiently inhibit microbial proliferation in the tobacco extract liquid, supports tablet recycling and reuse, and provides a safe, green, long-acting and stable antibacterial solution for the tobacco extract liquid.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a method for preparing a tea polyphenol-based antibacterial material and its application in tobacco extract. Background Technology

[0002] Tobacco extract, as the core matrix in reconstituted tobacco production, is rich in invert sugars, amino acids, and heat-sensitive aroma compounds (such as terpenes, aldehydes, and ketones) in its aqueous phase. During storage and processing, it is susceptible to microbial contamination, leading to fermentation, gas production, mold growth, and spoilage, seriously threatening product stability. However, traditional preservatives (such as potassium sorbate) pose a risk of chemical residue, and traditional heat sterilization processes (such as high-temperature instantaneous sterilization) easily result in the loss of volatile flavor components and intensified Maillard reactions, causing the extract to darken in color and deteriorate in aroma. Therefore, developing non-thermal sterilization technologies suitable for heat-sensitive systems has become an urgent industry need.

[0003] As a mixture of natural polyphenols, tea polyphenols possess a triple mechanism of synergistic antibacterial action through the active groups of catechol / pyrogallol in their molecular structure: (1) disrupting the integrity of microbial cell membranes, leading to leakage of contents; (2) competitively inhibiting key enzymes in fatty acid synthesis; and (3) chelating metal cofactors such as Fe²⁺ / Cu²⁺, blocking the oxidative respiratory chain. This characteristic gives it the potential to replace chemical preservatives. However, tea polyphenols have excellent water solubility at room temperature (solubility ≥50g / L in water at 25℃) and are sensitive to thermal oxidation. Direct addition can lead to rapid dissolution of the active ingredients and make them difficult to withstand high-temperature processes, limiting their application in liquid systems.

[0004] Existing tea polyphenol encapsulation products mostly use sodium alginate and chitosan hydrophilic gel carriers, which are used for tobacco extracts that easily absorb water and swell excessively, resulting in a burst release of active ingredients and making them unrecyclable. There are currently no tablet products using a cellulose composite backbone combined with hydroxypropyl methylcellulose phthalate (HPMCP) pH-responsive coating for the preservation of tobacco extracts. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for preparing tea polyphenol-based antibacterial materials and their application in tobacco extracts. This technology overcomes the technical bottlenecks of low mechanical strength and severe thermal degradation of traditional encapsulation materials through the synergistic effect of rigid skeleton mechanical reinforcement and gradient coating. Combined with the intelligent controlled release characteristics of pH-responsive layer, it achieves efficient retention, targeted release and carrier recycling of antibacterial active ingredients, providing an innovative solution for the design of functional ingredient encapsulation systems.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0007] A tea polyphenol-based antibacterial material includes a core material and a pH-responsive coating layer covering the surface of the core material; the core material comprises the following components in parts by weight: 10%~40% tea polyphenols, 30%~50% ethyl cellulose, 20%~40% microcrystalline cellulose, and 5%~10% propylene glycol; the pH-responsive coating layer comprises hydroxypropyl methylcellulose phthalate, triethyl citrate, and talc in a mass ratio of 100:(12~18):(15~25); the mass ratio of the core material to the pH-responsive coating layer is 100:(10-15).

[0008] Among the aforementioned components, tea polyphenols are a collective term for polyphenolic substances in tea, possessing various biological activities such as antioxidant, antibacterial, and antiviral properties. They are readily soluble in water, existing in aqueous solutions in molecular or ionic form, thus providing the basis for the active ingredients in the subsequent granulation process.

[0009] Of the above components, ethyl cellulose is insoluble in water and exists in the form of solid particles. During granulation, it can serve as a skeletal material for the particles, increasing their mechanical strength and stability. Simultaneously, ethyl cellulose exhibits excellent film-forming properties, forming a hydrophobic film on the particle surface. This helps control the release rate of tea polyphenols, improves particle stability, and prevents rapid dissolution of tea polyphenols in the aqueous environment.

[0010] Of the above components, microcrystalline cellulose is insoluble in water but can form a colloidal or dispersion system in water. It can fill the interior of particles, increasing their porosity and specific surface area, which is beneficial for the loading and subsequent release of tea polyphenols. Moreover, microcrystalline cellulose has a certain degree of adhesiveness, which can bind tea polyphenols, ethyl cellulose, and other components together during the granulation process to form particles with a certain strength.

[0011] Of the components mentioned above, propylene glycol is a commonly used plasticizer. It can lower the glass transition temperature of polymers such as ethyl cellulose, increasing their flexibility and processability, and helping to form uniform and stable particles during granulation. Meanwhile, although ethyl cellulose is insoluble in water, propylene glycol can partially dissolve it, improving its dispersibility in the system and promoting interactions between the components. The addition of propylene glycol can improve the wettability and adhesion of the system, which is beneficial for the subsequent tableting process.

[0012] The pH-responsive coating material, hydroxypropyl methylcellulose phthalate (HPMCP), is a weakly acidic polymer. In neutral and weakly acidic environments (pH > 5.0, the native pH range of tobacco extract), the molecules are in a dense, coiled state, resulting in a tight, hydrophobic coating film that prevents the rapid dissolution of tea polyphenols from the core material. When microorganisms proliferate and produce acid, causing the local pH of the system to drop below 5.0, the carboxyl groups on the HPMCP molecules dissociate, the polymer chains expand and swell, the film gradually dissolves and ruptures, the pores open, and tea polyphenols are released. After the tea polyphenols exert their antibacterial effect and inhibit the reproduction of acid-producing bacteria, the pH of the system rises back to the neutral range, and the remaining undissolved coating returns to a dense, hydrophobic state, thus achieving a pH self-feedback cyclic controlled release.

[0013] Preferably, in the above technical solution, the core material comprises the following components by weight: 30% tea polyphenols, 30% ethyl cellulose, 30% microcrystalline cellulose, and 10% propylene glycol; the tea polyphenol-based antibacterial material is a tablet, and the tablet has a diameter of 3mm-5mm.

[0014] Preferably, in the above technical solution, the pH-responsive coating layer is prepared using a fluidized bed coating process, and the mixed solvent used in the coating solution is selected from at least one of the following: ethanol and water in a volume ratio of 8:2, ethanol and dichloromethane in a volume ratio of 1:1, methanol and acetone in a volume ratio of 1:1, or methanol and dichloromethane in a volume ratio of 1:1.

[0015] A method for preparing a tea polyphenol-based antibacterial material, wherein the tea polyphenol-based antibacterial material is a tablet, includes the following steps:

[0016] (1) Preparation of core material:

[0017] (11) Dissolve tea polyphenols in water to prepare a tea polyphenol aqueous solution with a mass concentration of 0.1~0.4 g / mL;

[0018] (12) Add ethyl cellulose and microcrystalline cellulose to the tea polyphenol aqueous solution and stir evenly to obtain a mixed system; wherein the mass concentration of ethyl cellulose is 0.3~0.5 g / mL and the mass concentration of microcrystalline cellulose is 0.2~0.4 g / mL;

[0019] (13) Add propylene glycol to the mixture and continue stirring until the mass concentration of propylene glycol in the system is 0.05~0.1 g / mL;

[0020] (14) Extrude the resulting mixture into strips and compress them into tablets;

[0021] (2) Preparation of pH-responsive coating solution: Hydroxypropyl methylcellulose phthalate was dissolved in a mixed solvent, triethyl citrate and talc were added, and the mixture was stirred for 20-40 min and then filtered to obtain the coating solution;

[0022] (3) Coating: The fluidized bed coating process is used to coat the surface of the tablets obtained in step (1) with the coating liquid to form a coating layer. The air inlet temperature is controlled at 60℃~70℃ to obtain tea polyphenol-based antibacterial tablets.

[0023] Preferably, in the above technical solution, the tablet is compressed and the tablet diameter is controlled to be 3mm~5mm in step (14).

[0024] Preferably, in the above technical solution, in step (2) of preparing the coating solution, the mixed solvent is selected from at least one of the following: ethanol and water in a volume ratio of 8:2, ethanol and dichloromethane in a volume ratio of 1:1, methanol and acetone in a volume ratio of 1:1, or methanol and dichloromethane in a volume ratio of 1:1.

[0025] Preferably, in the above technical solution, in step (2) of preparing the coating solution, the mass ratio of hydroxypropyl methylcellulose phthalate, triethyl citrate and talc is 100:(12-18):(15-25).

[0026] Preferably, in the above technical solution, in step (2) of preparing the coating solution, the mass ratio of the core material to the pH-responsive coating layer is 100:(10-15).

[0027] Application of a tea polyphenol-based antibacterial material in the microbial control of tobacco extract.

[0028] Preferably, in the above technical solution, the amount of antibacterial material added is 1.0% to 1.2% of the mass of the tobacco extract, wherein the net content of tea polyphenols is 0.2% to 0.4% of the mass of the tobacco extract.

[0029] In addition to tobacco extract, the antibacterial material of this invention can also be applied to the natural antibacterial and preservation of heat-sensitive liquid materials such as plant extracts and fruit and vegetable extracts.

[0030] The above-described technical solution of the present invention has the following beneficial effects:

[0031] (1) Closed-loop antibacterial technology: Driven by molecular diffusion channels (nanoscale pores) and concentration gradient, the water solubility limitation of tea polyphenols is overcome, and the "antibacterial-filtration-regeneration" closed-loop application is realized. In the tobacco extract system, the sudden dissolution rate of tea polyphenols is <5%, and the overall antibacterial rate of the system is >99%.

[0032] (2) Intelligent controlled release and green economy: Relying on the self-feedback mechanism of acid-base dissociation of weak acid polymer HPMCP, the pH-sensitive coating layer (HPMCP) accelerates release in the microbial acid-producing area (pH<5) and accurately inhibits bacteria; the tablets can be recycled and reused ≥3 times, reducing raw material costs by 30%, reducing dependence on chemical preservatives, and conforming to the tobacco “harm reduction” trend.

[0033] (3) Industrial compatibility: The composite skeleton of ethyl cellulose and microcrystalline cellulose and the secondary coating technology enhance stability (tea polyphenol retention rate >90%) and achieve sustained release function. The tablets have uniform diameter (3~5mm) and are compatible with industrial filtration equipment, supporting large-scale production. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0035] Figure 1 is a schematic cross-sectional view of the tea polyphenol-based antibacterial tablet of the present invention. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available. Unless otherwise specified, the equipment used in the experiments is well known to those skilled in the art.

[0038] Example 1

[0039] Preparation method of tea polyphenol materials:

[0040] (1) Weigh a certain amount of tea polyphenols and add them to water. Stir to dissolve them completely to obtain an aqueous solution of tea polyphenols, wherein the mass concentration of tea polyphenols is 0.3 g / mL.

[0041] (2) Weigh a certain amount of ethyl cellulose and microcrystalline cellulose, and slowly add them to the tea polyphenol aqueous solution while stirring continuously to ensure that the cellulose is evenly dispersed in the solution. The mass concentrations of ethyl cellulose and microcrystalline cellulose are 0.3 g / mL and 0.3 g / mL, respectively.

[0042] (3) Then add a small amount of propylene glycol to the mixture and continue to stir until homogeneous. The mass concentration of propylene glycol in the system is 0.1 g / mL.

[0043] (4) Finally, the mixture is extruded into strips by an extruder and then pressed into tablets in a tablet press, while controlling the tablet diameter to be 3 mm.

[0044] The tablets contain 30% tea polyphenols, 30% ethyl cellulose, 30% microcrystalline cellulose, and 10% propylene glycol. The tablet structure is as follows: Figure 1As shown, it includes tea polyphenols 1, a cellulose backbone 2, and a coating layer 3. The tea polyphenols are loaded inside the cellulose backbone 2, which provides support and fixation. The coating layer 3 completely covers the outside of the cellulose backbone 2.

[0045] Hydroxypropyl methylcellulose phthalate was added to ethanol and water (v:v=8:2) and stirred until dissolved. Triethyl citrate and talc were added according to the mass ratio of hydroxypropyl methylcellulose phthalate: triethyl citrate: talc = 100:15:20. After stirring for 30 minutes, the mixture was filtered to obtain the coating solution.

[0046] Fluidized bed coating was used, with the inlet air temperature controlled at 60-70℃, resulting in a 10% weight gain for the coating, to obtain coated functional tablet A. The tobacco extract was prepared by adding 4 times the mass of deionized water to tobacco powder, extracting at 55-60℃ for 2 hours, followed by filtration, residue removal, and concentration. Tablet A was added at 1.1% of the mass of the tobacco extract (30wt%~40wt% solids) to make the net content of tea polyphenols 0.3% of the extract mass. This extract is solution A.

[0047] Example 2

[0048] The difference from Example 1 is that the proportion of tea polyphenols in the tablet is 20%, the proportion of ethyl cellulose is 35%, the proportion of microcrystalline cellulose is 35%, and the proportion of propylene glycol is 10%, resulting in tablet B. The amount of tablet B added is 1.1% of the tobacco extract, so that the net content of tea polyphenols is about 0.2% of the mass of the extract, which is solution B.

[0049] Example 3

[0050] Unlike Example 1, the tablet contains 40% tea polyphenols, 25% ethyl cellulose, 25% microcrystalline cellulose, and 10% propylene glycol, resulting in tablet C. The amount of tablet C added is 1.1% of the tobacco extract, so that the net content of tea polyphenols is about 0.4% of the extract mass, which is solution C.

[0051] Comparative Example 1

[0052] Unlike Example 1, no antibacterial material was added as solution D.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that 0.1% potassium sorbate was added as solution E.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that 0.3% tea polyphenols were added as solution F.

[0057] Comparative Example 4

[0058] The difference from Example 1 is that sodium alginate-chitosan-tea polyphenol microcapsules are added, wherein the net content of tea polyphenols is about 0.3% of the mass of the extract, as solution G.

[0059] Effect evaluation

[0060] 1. Determination of the retention rate of tea polyphenols in antibacterial materials

[0061] The retention rates of the effective antibacterial components of each antibacterial material after being placed in the air at room temperature for one month are shown in Table 1.

[0062] Table 1. Retention rate of tea polyphenols in antibacterial materials

[0063]

[0064] Table 1 shows that potassium sorbate and tea polyphenols are prone to hygroscopic agglomeration and oxidative deterioration when directly exposed to air. Encapsulating tea polyphenols in sodium alginate-chitosan microcapsules provides some protection, but the hydrophilic gel network easily swells in high humidity environments, leading to increased oxygen permeability and accelerating polyphenol oxidation, thus limiting long-term retention. However, by combining tea polyphenols with ethyl cellulose and microcrystalline cellulose to form a tablet core material and then coating it with a pH-responsive coating layer, a dual-barrier effect significantly improves the stability of tea polyphenols.

[0065] 2. Determination of total bacterial count in extract

[0066] The total number of colonies in solutions A to G was determined using a fully automated colony counter in accordance with GB 4789.2-2022. The results are shown in Table 2.

[0067] Table 2. Antibacterial effects of different antibacterial materials

[0068]

[0069] As shown in Table 2, all antibacterial solutions exhibit significant activity, but each single component has inherent defects: potassium sorbate (solution E) easily leads to flavor deterioration; although tea polyphenols (solution F) are naturally safe (low allergenicity, long history of consumption), their utilization rate is limited by environmental factors (<60%) and high addition amounts mask the natural aroma of tobacco; sodium alginate-chitosan-tea polyphenol microcapsules (solution G) enhance antibacterial efficacy through synergistic effects, but face the risk of uncontrolled swelling in tobacco extract (excessive swelling leads to burst release and abnormal flavor).

[0070] In light of this, the tea polyphenol-based antibacterial tablets (solutions A-C) achieve precise release through a dual controlled-release mechanism: 1) pH-responsive coatings dissolve gradient-wise in the extract (pH≈5.0); 2) an ethyl cellulose / microcrystalline cellulose matrix constructs nanoporous channels, driving the slow release of tea polyphenols according to their concentration gradient. When fermentation causes a decrease in pH, a self-feedback mechanism is triggered to accelerate release (when the pH value decreases, the pH-responsive coating dissolves more rapidly, thereby increasing the release rate of tea polyphenols, enhancing the antibacterial effect, effectively inhibiting microbial fermentation, and ultimately causing the system pH value to rise again), forming a targeted cycle. These tablets resulted in a >65% reduction in total bacterial count after 30 days of extract storage compared to the control group, demonstrating both long-lasting antibacterial effect and stability.

[0071] 3. Sensory evaluation

[0072] Extracts A through G from each group were added to blank cigarette tobacco at a ratio of 0.5%. After equilibration in a constant temperature and humidity environment for 48 hours, sensory evaluation was conducted by 7 professional cigarette sensory evaluators using a blind evaluation method. The sensory evaluation results are shown in Table 3.

[0073] Table 3. Effects of different antibacterial materials on the sensory quality of tobacco extract.

[0074]

[0075] As shown in Table 3, potassium sorbate, direct addition of tea polyphenols, and ordinary tea polyphenol microcapsules all increase the off-flavors, irritation, and bitterness of tobacco extract to varying degrees, thus damaging the sensory quality of cigarettes. However, the tea polyphenol-based antibacterial tablets prepared in this invention can achieve long-lasting antibacterial effects while enhancing the freshness and smoothness of smoke, reducing off-flavors, and improving the aftertaste. It is the only antibacterial solution that can simultaneously guarantee the antibacterial effect and the sensory quality of cigarettes, and is more suitable for the actual production and application needs of tobacco extract.

[0076] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various different choices and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A tea polyphenol-based antibacterial material, characterized in that, The product comprises a core material and a pH-responsive coating layer covering the surface of the core material; the core material comprises the following components in parts by weight: 10%~40% tea polyphenols, 30%~50% ethyl cellulose, 20%~40% microcrystalline cellulose, and 5%~10% propylene glycol; the pH-responsive coating layer comprises hydroxypropyl methylcellulose phthalate, triethyl citrate, and talc in a mass ratio of 100:(12~18):(15~25); the mass ratio of the core material to the pH-responsive coating layer is 100:(10-15).

2. The tea polyphenol-based antibacterial material according to claim 1, characterized in that, The core material comprises the following components by weight: 30% tea polyphenols, 30% ethyl cellulose, 30% microcrystalline cellulose, and 10% propylene glycol; the tea polyphenol-based antibacterial material is a tablet with a diameter of 3mm-5mm.

3. The tea polyphenol-based antibacterial material according to claim 1, characterized in that, The pH-responsive coating layer is prepared using a fluidized bed coating process. The mixed solvent used in the coating solution is selected from at least one of the following: ethanol and water in a volume ratio of 8:2, ethanol and dichloromethane in a volume ratio of 1:1, methanol and acetone in a volume ratio of 1:1, or methanol and dichloromethane in a volume ratio of 1:

1.

4. A method for preparing a tea polyphenol-based antibacterial material, characterized in that, The tea polyphenol-based antibacterial material is in the form of tablets. Includes the following steps: (1) Preparation of core material: (11) Dissolve tea polyphenols in water to prepare a tea polyphenol aqueous solution with a mass concentration of 0.1~0.4 g / mL; (12) Add ethyl cellulose and microcrystalline cellulose to the tea polyphenol aqueous solution and stir evenly to obtain a mixed system; wherein the mass concentration of ethyl cellulose is 0.3~0.5 g / mL and the mass concentration of microcrystalline cellulose is 0.2~0.4 g / mL; (13) Add propylene glycol to the mixture and continue stirring until the mass concentration of propylene glycol in the system is 0.05~0.1 g / mL; (14) Extrude the resulting mixture into strips and compress them into tablets; (2) Preparation of pH-responsive coating solution: Hydroxypropyl methylcellulose phthalate was dissolved in a mixed solvent, triethyl citrate and talc were added, and the mixture was stirred for 20-40 min and then filtered to obtain the coating solution; (3) Coating: The fluidized bed coating process is used to coat the surface of the tablets obtained in step (1) with the coating liquid to form a coating layer. The air inlet temperature is controlled at 60℃~70℃ to obtain tea polyphenol-based antibacterial tablets.

5. The method for preparing the tea polyphenol-based antibacterial material according to claim 4, characterized in that, In step (14), the tablets are compressed and the tablet diameter is controlled to be 3mm~5mm.

6. The method for preparing the tea polyphenol-based antibacterial material according to claim 4, characterized in that, In step (2) of preparing the coating solution, the mixed solvent is selected from at least one of the following: ethanol and water in a volume ratio of 8:2, ethanol and dichloromethane in a volume ratio of 1:1, methanol and acetone in a volume ratio of 1:1, or methanol and dichloromethane in a volume ratio of 1:

1.

7. The method for preparing the tea polyphenol-based antibacterial material according to claim 4, characterized in that, In step (2) of preparing the coating solution, the mass ratio of hydroxypropyl methylcellulose phthalate, triethyl citrate and talc is 100: (12-18): (15-25).

8. The method for preparing the tea polyphenol-based antibacterial material according to claim 4, characterized in that, In step (2), the mass ratio of the core material to the pH-responsive coating layer is 100:(10~15).

9. The application of a tea polyphenol-based antibacterial material in the microbial control of tobacco extract, characterized in that, The tea polyphenol-based antibacterial material is prepared by the method according to any one of claims 4-8.

10. The application of the tea polyphenol-based antibacterial material according to claim 9 in the microbial control of tobacco extract, characterized in that, The amount of antibacterial material added is 1.0% to 1.2% of the mass of the tobacco extract, wherein the net content of tea polyphenols is 0.2% to 0.4% of the mass of the tobacco extract.

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