A flavoring microcapsule for heated non-combustible cigarettes, its preparation method and application

Abstract

This invention discloses a flavoring microcapsule for heated tobacco products, its preparation method, and its application, belonging to the field of heated tobacco technology. The preparation method includes the following steps: dissolving zein in an aqueous ethanol solution to obtain a zein solution; dissolving chitosan in an aqueous acetic acid solution to obtain a chitosan solution; then adding heterocyclic flavorings, polyvinyl alcohol, and antioxidants to the chitosan solution and mixing to obtain a flavoring solution; mixing and stirring the zein solution and flavoring solution evenly; then emulsifying under cold conditions and freeze-drying to obtain the flavoring microcapsule for heated tobacco products. The preparation method of this invention can obtain heterocyclic flavoring microcapsules with good morphology, high heterocyclic flavoring encapsulation rate, and high flavor loading capacity. When used in heated tobacco products, these microcapsules exhibit a suitable sustained-release rate, long-lasting aroma, and good consistency in each puff; moreover, the preparation method is simple, safe, and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of heated tobacco technology, and more particularly to a flavoring microcapsule for heated tobacco cigarettes, its preparation method, and its application. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Heated tobacco products, also known as heated cigarettes, are a new type of tobacco product that uses a special heat source to heat a core made of tobacco shreds or other tobacco materials without burning it. They mainly consist of three parts: a tobacco section, a cooling section, and an acetate fiber section. The key characteristic of heated tobacco products is that they use an external heat source to heat the tobacco instead of igniting it. The heating temperature of the tobacco section is generally around 300℃, while traditional cigarettes are lit and inhaled, with the combustion cone temperature around 900℃. Therefore, heated tobacco products release less harmful components than traditional cigarettes.

[0004] Because heated tobacco products release their aroma through heating and baking rather than combustion, the relatively low temperature results in insufficient flavor satisfaction. Therefore, other flavoring substances are usually added to compensate for this deficiency. However, since commonly used flavorings have low boiling points and are highly volatile, when they are used in heated tobacco products, the cigarettes are heated simultaneously, resulting in easy loss of aroma, short aroma retention time, and poor consistency of aroma components in each puff.

[0005] Microcapsule controlled-release technology has significant advantages in solving the problems of volatile flavorings and poor consistency in each puff. It uses natural polymer materials or synthetic materials to encapsulate flavoring components, effectively protecting active ingredients that are easily decomposed by light, oxidized, and highly volatile, thereby achieving controlled-release or sustained-release effects. There are few studies on flavoring microcapsules for heated tobacco products in the existing technology. Hao Hui et al. (Journal of Yunnan University (Natural Science Edition), 2023, 45(5): 1081-1088) used papermaking sheet liquid as core material and chitosan as wall material to prepare microcapsules by complex coagulation method. The microcapsules prepared by this method have a low encapsulation rate (less than 40%), a high content of surface flavorings (unencapsulated flavorings), and serious adhesion of microcapsules. Therefore, the surface flavorings evaporate quickly, while the flavorings inside the microcapsules are released slowly. This leads to poor aroma stability and consistency in each puff, and a short aroma retention time.

[0006] Therefore, how to provide a flavor microcapsule for heated non-combustible cigarettes with a high flavor encapsulation rate, a suitable flavor release rate, high flavor stability, and good consistency in each puff is an urgent problem to be solved. Summary of the Invention

[0007] In view of this, the present invention provides a flavoring microcapsule for heated tobacco products, its preparation method and application. The flavoring microcapsule for heated tobacco products prepared by the present invention has good morphology, high flavor loading and flavor encapsulation rate, and has a suitable sustained release rate. Smoking tests show that its flavor stability and puff consistency are good.

[0008] In a first aspect, the present invention provides a method for preparing flavoring microcapsules for heat-not-burn cigarettes, comprising the following steps:

[0009] Zeat protein was dissolved in an aqueous ethanol solution to obtain a zeat protein solution;

[0010] Chitosan was dissolved in an aqueous acetic acid solution to obtain a chitosan solution. Then, heterocyclic fragrance, polyvinyl alcohol and antioxidant were added to the chitosan solution and mixed to obtain a flavored solution.

[0011] The zein solution and the flavoring solution are mixed and stirred evenly, wherein the mass ratio of zein, chitosan, heterocyclic flavoring, polyvinyl alcohol and antioxidant is (25-35):(8-15):(6-9):(1-3):(4-6); then the mixture is refrigerated and emulsified, and freeze-dried to obtain flavoring microcapsules for heated non-combustible cigarettes.

[0012] Secondly, the present invention provides flavoring microcapsules for heated non-combustible cigarettes prepared by the above-described preparation method.

[0013] Thirdly, the present invention provides the application of the above-mentioned flavoring microcapsules for heated tobacco products in heated tobacco products, wherein the application is to add the flavoring microcapsules for heated tobacco products to the tobacco segment of the heated tobacco product.

[0014] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0015] (1) This invention uses zein as the capsule wall material, chitosan to adsorb heterocyclic fragrances to form the core material, and polyvinyl alcohol to assist in the formation of the microcapsule particle structure. Under appropriate ratio, heterocyclic fragrance microcapsules with good morphology, uniform size, high heterocyclic fragrance embedding rate and high fragrance loading can be obtained. When used in heated non-combustible cigarettes, they have a suitable slow release rate, long fragrance retention time and good consistency in each puff.

[0016] (2) In the preparation of microcapsules, the present invention does not require the introduction of additional emulsifiers and crosslinking agents, nor does it require energy-intensive steps such as ultrasonic and high-speed homogenization emulsification. It only requires cold emulsification after stirring and mixing. The resulting emulsion is stable and does not separate into layers. The overall preparation method is simple to operate and safe and environmentally friendly. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] Figure 1 These are scanning electron microscope images of the Zein / CS / PVA@heterocyclic fragrance microcapsules of Example 1 of this invention;

[0019] Figure 2 These are scanning electron microscope images of the Zein / PVA@heterocyclic fragrance product obtained in Comparative Example 1 of this invention;

[0020] Figure 3 These are scanning electron microscope images of the Zein / CS@heterocyclic fragrance product obtained in Comparative Example 2 of this invention;

[0021] Figure 4 These are scanning electron microscope images of the CS / PVA@heterocyclic fragrance product obtained in Comparative Example 3 of this invention;

[0022] Figure 5 These are scanning electron microscope images of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in Comparative Example 4 of this invention;

[0023] Figure 6 These are scanning electron microscope images of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in Comparative Example 5 of this invention;

[0024] Figure 7 These are the thermogravimetric analysis curves of the products of Example 1, Comparative Example 1 and Comparative Example 3 of the present invention, as well as 2,3-diethyl-5-methylpyrazine (DEMP). Detailed Implementation

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] This invention provides a method for preparing flavoring microcapsules for heat-not-burn cigarettes, comprising the following steps:

[0027] Zeat protein was dissolved in an aqueous ethanol solution to obtain a zeat protein solution;

[0028] Chitosan was dissolved in an aqueous acetic acid solution to obtain a chitosan solution. Then, heterocyclic fragrance, polyvinyl alcohol and antioxidant were added to the chitosan solution and mixed to obtain a flavored solution.

[0029] The zein solution and the flavoring solution are mixed and stirred evenly, wherein the mass ratio of zein, chitosan, heterocyclic flavoring, polyvinyl alcohol and antioxidant is (25-35):(8-15):(6-9):(1-3):(4-6); then the mixture is refrigerated and emulsified, and freeze-dried to obtain flavoring microcapsules for heated non-combustible cigarettes.

[0030] Heterocyclic flavorings, when used in heated tobacco products, are prone to rapid degradation due to their low boiling point and high heating temperature (around 300°C), resulting in poor aroma retention and inconsistent flavor profiles. Therefore, this invention uses zein as the capsule wall material and chitosan to adsorb heterocyclic flavorings and form the core material. Both chitosan and polyvinyl alcohol possess excellent film-forming properties; their introduction into microcapsules gives them a good particulate structure, further enhancing their structural stability and flavor loading capacity. Furthermore, they exhibit good heat resistance, showing no significant decomposition or deterioration during heating. In addition, chitosan possesses both hydrophilic amino and hydrophobic acetyl groups, giving it amphiphilic properties. Since zein also has good emulsifying properties, mixing chitosan and zein solutions forms a stable emulsion without the need for other emulsifiers, making the process very simple. The microcapsule structure formed by zein, chitosan and polyvinyl alcohol can play a good role in the sustained release of heterocyclic fragrances inside. Under the appropriate ratio of the three, heterocyclic fragrance microcapsules with good morphology, high heterocyclic fragrance encapsulation rate and high fragrance loading can be obtained. When used in heated tobacco products, they have a suitable sustained release rate, so that the heterocyclic fragrances are slowly released when heated in heated tobacco products, which improves the stability of the aroma, the long-lasting aroma, and the good consistency of each puff.

[0031] In this invention, the concentration of the zein solution is 1-3 wt%, and the volume fraction of ethanol in the aqueous ethanol solution is 80-92%. Within this volume fraction range, zein has good solubility.

[0032] In this invention, the volume fraction of acetic acid in the aqueous acetic acid solution is 1-3%. Acetic acid molecules break the hydrogen bonds between chitosan molecules, making its structure looser and thus promoting the dissolution of chitosan. The chitosan preferably has a molecular weight of 100,000 to 400,000 Daltons and a degree of deacetylation of over 70%, making it readily soluble in the aqueous acetic acid solution. The concentration of chitosan in the chitosan solution is 0.3-1 wt%.

[0033] In this invention, the heterocyclic flavoring is selected from one or more of pyrazine flavoring, pyridine flavoring, pyrrole flavoring or furan flavoring. The use of multiple flavorings can enhance the aroma layers of cigarettes and make the cigarette flavor richer.

[0034] In this invention, the pyrazine fragrance is selected from 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-acetylpyrazine, 2,3-diethyl-5-methylpyrazine, 2,3-diethylpyrazine, 2-isobutyl-3-methoxypyrazine, 2-methoxy-3-methylpyrazine, 5-methoxy-5-methylpyrazine, 6-methoxy-3-methylpyrazine, 2-methylpyrazine, 2,3,5,6-tetramethylpyrazine, 2,3,5-trimethylpyrazine, 2-methoxy-3-isopropylpyrazine, 2-methoxy-5 - One or more of isopropylpyrazine, 2-methoxy-6-isopropylpyrazine, 2-methoxypyrazine, 2-methyl-3-methylthiopyrazine, 2-methyl-5-methylthiopyrazine, 2-methyl-6-methylthiopyrazine, 2-ethyl-5-methylpyrazine, 2-ethylpyrazine, 2-methyl-3-ethoxypyrazine, 2-methyl-5-ethoxypyrazine, or 2-methyl-6-ethoxypyrazine; the pyridine fragrance is selected from one or more of 3-acetylpyridine, 2-acetylpyridine, 3,5-dimethylpyridine, or 3-ethylpyridine; the pyrrole fragrance is selected from 2-acetylpyrrole; the furan fragrance is selected from one or more of furfuryl alcohol, furfural, or 5-methylfuranaldehyde.

[0035] In this invention, the antioxidant is selected from tea polyphenols or vitamin E. The introduction of antioxidants is to improve the antioxidant properties of the fragrance, extend its shelf life, prevent oxidation and deterioration during processing or storage, and enhance the functionality of the product.

[0036] In this invention, the mixing and stirring time for 20-60 minutes is used in the step of mixing and stirring the zein solution and the flavoring solution to ensure better mixing of zein with chitosan, heterocyclic flavoring, polyvinyl alcohol and antioxidants, which is beneficial for forming microcapsules with good structure and morphology.

[0037] In this invention, the temperature of the refrigerated emulsification is 2–5°C, more preferably 4°C; the refrigerated emulsification time is 5–15 hours. Refrigerated emulsification, i.e., emulsification by standing at a lower temperature, serves two purposes: firstly, to prevent the fragrance from evaporating, and secondly, to prepare for the subsequent freeze-drying process.

[0038] The present invention provides microcapsules for flavoring heated non-combustible cigarettes prepared by the above preparation method. The obtained microcapsules for flavoring heated non-combustible cigarettes have good particle morphology and effectively encapsulate and control the release of heterocyclic flavorings.

[0039] The present invention provides the application of the above-mentioned flavoring microcapsules for heated tobacco products in heated tobacco products. The application is to add the flavoring microcapsules for heated tobacco products to the tobacco segment of the heated tobacco product. The preferred amount of the flavoring microcapsules for heated tobacco products is 10-15 mg / cigarette.

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments. The present invention does not impose any special restrictions on the source of reagents used in the following embodiments; commercially available products well known to those skilled in the art can be used.

[0041] In the following examples, 85% ethanol aqueous solution and 2.5% acetic acid aqueous solution refer to volume fractions, and room temperature refers to 25±3℃.

[0042] Example 1

[0043] This embodiment provides a method for preparing flavoring microcapsules for heat-resistant, non-combustible cigarettes, comprising the following steps:

[0044] (1) Add 300 mg of zein to 20 mL of 85% ethanol aqueous solution and stir at room temperature for 30 min to obtain zein solution;

[0045] (2) Add 100 mg chitosan (CS) to 20 mL of 2.5% acetic acid aqueous solution, stir in a water bath at 50 °C for 30 min to obtain chitosan solution, then add 80 mg heterocyclic fragrance (2,3-diethyl-5-methylpyrazine, DEMP), 20 mg polyvinyl alcohol (PVA) and 50 mg tea polyphenols to the chitosan solution, mix well to obtain a flavored solution;

[0046] (3) Mix the zein solution and the flavoring solution for 30 min, then place them at 4℃ for 12 h for emulsification. The emulsion has good stability and no stratification occurs. Then freeze-dry to obtain powdered flavoring microcapsules for heated non-combustible cigarettes, denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0047] The scanning electron microscope (SEM) image of the Zein / CS / PVA@heterocyclic fragrance microcapsules prepared in this embodiment is shown below. Figure 1 As shown, the microcapsules have a good spherical shape, relatively uniform particle size, and particle diameter concentrated between 300 and 600 nm. The spherical particles do not stick together, and the surface of the microcapsules has micropores, which is beneficial for the controlled release of the internal fragrance.

[0048] Example 2

[0049] This embodiment provides a method for preparing flavoring microcapsules for heat-resistant non-combustible cigarettes, comprising the following steps:

[0050] (1) Add 300 mg of zein to 20 mL of 85% ethanol aqueous solution and stir at room temperature for 30 min to obtain zein solution;

[0051] (2) Add 100 mg chitosan (CS) to 20 mL of 2.5% acetic acid aqueous solution, stir in a water bath at 50 °C for 30 min to obtain chitosan solution, then add 80 mg heterocyclic fragrance (2-acetylpyridine), 20 mg polyvinyl alcohol and 50 mg tea polyphenol to chitosan solution, mix well to obtain fragrance solution;

[0052] (3) Mix the zein solution and the flavoring solution for 30 min, then place them at 4℃ for 12 h for emulsification. The emulsion has good stability and no stratification occurs. Then freeze-dry to obtain powdered flavoring microcapsules for heated non-combustible cigarettes, denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0053] Example 3

[0054] This embodiment provides a method for preparing flavoring microcapsules for heat-resistant non-combustible cigarettes, comprising the following steps:

[0055] (1) Add 300 mg of zein to 20 mL of 85% ethanol aqueous solution and stir at room temperature for 30 min to obtain zein solution;

[0056] (2) Add 100 mg chitosan (CS) to 20 mL of 2.5% acetic acid aqueous solution, stir in a water bath at 50 °C for 30 min to obtain chitosan solution, and then add 80 mg heterocyclic fragrance (20 mg 2,3-diethyl-5-methylpyrazine, 20 mg 2-acetylpyridine, 30 mg furfural, 10 mg 5-methylfuranaldehyde), 20 mg polyvinyl alcohol and 50 mg tea polyphenols to the chitosan solution, mix well to obtain a flavored solution;

[0057] (3) Mix the zein solution and the flavoring solution for 30 min, then place them at 4℃ for 12 h for emulsification. The emulsion has good stability and no stratification occurs. Then freeze-dry to obtain powdered flavoring microcapsules for heated non-combustible cigarettes, denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0058] Example 4

[0059] This embodiment provides a method for preparing flavoring microcapsules for heat-resistant non-combustible cigarettes, comprising the following steps:

[0060] (1) Add 320 mg of zein to 20 mL of 85% ethanol aqueous solution and stir at room temperature for 30 min to obtain zein solution;

[0061] (2) Add 110 mg of chitosan to 20 mL of 2.5% acetic acid aqueous solution, stir in a water bath at 50 °C for 30 min to obtain chitosan solution, then add 85 mg of heterocyclic fragrance (2,3-diethyl-5-methylpyrazine), 25 mg of polyvinyl alcohol and 50 mg of tea polyphenols to the chitosan solution, mix well to obtain a flavored solution;

[0062] (3) Mix the zein solution and the flavoring solution for 30 min, then place them at 4℃ for 12 h for emulsification. The emulsion has good stability and no stratification occurs. Then freeze-dry to obtain powdered flavoring microcapsules for heated non-combustible cigarettes, denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 1 is that chitosan is not added in this comparative example. The specific preparation method is as follows:

[0065] 300 mg of zein was added to 20 mL of 85% ethanol aqueous solution and stirred at room temperature for 30 min to obtain a zein solution. 80 mg of heterocyclic fragrance (2,3-diethyl-5-methylpyrazine), 20 mg of polyvinyl alcohol and 50 mg of tea polyphenols were added to the zein solution and stirred for 30 min to obtain a flavoring solution. The flavoring solution was then placed in a 4℃ refrigerator for emulsification for 12 h and freeze-dried to obtain the product Zein / PVA@heterocyclic fragrance.

[0066] The scanning electron microscope image of the Zein / PVA@heterocyclic fragrance product obtained in this comparative example is as follows: Figure 2 As shown, the particle size is relatively large, exceeding 1 μm, and the particle morphology is poor, with severe adhesion between particles, which is not conducive to the release of internal fragrance; indicating that the addition of chitosan can promote the formation of microcapsule spherical structures.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that polyvinyl alcohol is not added in this comparative example, while the remaining steps are the same as in Example 1, to obtain Zein / CS@heterocyclic fragrance microcapsules.

[0069] The scanning electron microscope image of the Zein / CS@heterocyclic fragrance product obtained in this comparative example is as follows: Figure 3As shown, it can be seen that the adhesion between particles is quite serious, and the spherical particles are concentrated on the sheet-like substrate, which is not conducive to the release of internal fragrance. From the comparison between Comparative Example 2 and Example 1, it can be seen that PVA can improve the dispersibility of microcapsule particles and make the microcapsules present a good particulate morphology.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that this comparative example does not contain zein. The specific steps are as follows:

[0072] 100 mg of chitosan was added to 20 mL of 2.5% acetic acid aqueous solution and stirred in a water bath at 50 °C for 30 min to obtain a chitosan solution. Then, 80 mg of heterocyclic fragrance (2,3-diethyl-5-methylpyrazine), 20 mg of polyvinyl alcohol and 50 mg of tea polyphenols were added to the chitosan solution and stirred for 30 min to obtain a flavored solution. The flavored solution was then placed in a refrigerator at 4 °C for 12 h for emulsification and freeze-dried to obtain the product CS / PVA@heterocyclic fragrance.

[0073] The scanning electron microscope image of the CS / PVA@heterocyclic fragrance product obtained in this comparative example is as follows: Figure 4 As shown, it can be seen that no spherical particles can be observed at the same magnification as in Example 1, indicating that no microcapsule structure was formed and the whole thing is a relatively smooth film.

[0074] Comparative Example 4

[0075] The difference between this comparative example and Example 1 is that in step (1) of this comparative example, the mass of zein is 200 mg and the mass of chitosan is 200 mg.

[0076] The scanning electron microscope (SEM) images of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in this comparative example are as follows: Figure 5 As shown, the spherical particles exhibit increased adhesion and have fewer pores on their surface.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Example 1 is that heterocyclic flavorings are added to the zein solution in this comparative example. The specific steps are as follows:

[0079] (1) Add 300 mg of zein to 20 mL of 85% ethanol aqueous solution, stir at room temperature for 30 min to obtain zein solution, then add 80 mg of heterocyclic fragrance (2,3-diethyl-5-methylpyrazine) to zein solution, stir for 0.5 h to obtain fragrance solution;

[0080] (2) Add 100 mg chitosan to 20 mL of 2.5% acetic acid aqueous solution, stir in a water bath at 50 °C for 30 min to obtain chitosan solution, then add 20 mg polyvinyl alcohol and 50 mg tea polyphenols to chitosan solution, mix well to obtain chitosan / polyvinyl alcohol solution.

[0081] (3) Mix the chitosan / polyvinyl alcohol solution and the flavoring solution and stir for 30 min, then place them in a 4°C refrigerator for 12 h for emulsification, and freeze dry to obtain powdered flavoring microcapsules for heated non-combustible cigarettes, denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0082] The scanning electron microscope (SEM) images of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in this comparative example are as follows: Figure 6 As shown, there is no obvious spherical structure, and the adhesion phenomenon is serious, with very few pores on the surface.

[0083] Test case

[0084] 1. Encapsulation rate test:

[0085] The encapsulation rate test reference is "Microencapsulation of Papermaking Sheet Liquid and Its Application in Heated Tobacco Cigarettes" (Journal of Yunnan University (Natural Science Edition), 2023, 45(5): 1081-1088). The specific steps are as follows:

[0086] (1) Determination of total oil in microcapsules: Accurately weigh 1.0 g (accurate to 0.001 g) of microcapsule sample and 50 mL of dichloromethane into a beaker and sonicate for 30 min, then let stand for 30 min, and finally filter into a conical flask of known mass. Evaporate the dichloromethane in a low temperature water bath and calculate the mass fraction (w1) of total oil in microcapsules by the weight loss method.

[0087] (2) Determination of surface oil of microcapsules: Accurately weigh 1.0 g (accurate to 0.001 g) of microcapsule sample and put it into a centrifuge tube. Add 15 mL of dichloromethane solution, shake well for 30 s, centrifuge for 2 min (6000 r / min), repeat 3 times, then combine the supernatants, filter into a conical flask of known mass, concentrate in a low temperature water bath, evaporate the dichloromethane, and obtain the surface oil mass fraction (w2) of the product by the weight loss method.

[0088] The encapsulation efficiency (M) of the microcapsules is calculated according to the following formula (1):

[0089] M = [(w1 - w2) / w1] (1)

[0090] The encapsulation rate test results of the products in Examples 1-4 and Comparative Examples 1-5 are shown in Table 1.

[0091] Table 1. Test results of product encapsulation rate in Examples 1-4 and Comparative Examples 1-5.

[0092] serial number Encapsulation rate (%) serial number Encapsulation rate (%) Example 1 65.1 Comparative Example 1 45.1 Example 2 65.5 Comparative Example 2 55.3 Example 3 64.7 Comparative Example 3 29.5 Example 4 62.8 Comparative Example 4 53.7 Comparative Example 5 44.2

[0093] As shown in Table 1, the encapsulation efficiency of the microcapsules in the examples all reached over 60%, which is beneficial for prolonging the release time of the fragrance and giving it a suitable sustained-release effect. A comparison of the encapsulation efficiency data between Comparative Examples 1-3 and Example 1 shows that zein, chitosan, and polyvinyl alcohol all affect the encapsulation efficiency. The microcapsules prepared by adding all three together have the highest encapsulation efficiency, which is beneficial for improving the stability of the fragrance. Comparative Example 3 has the lowest encapsulation efficiency, which is likely because it cannot form a microcapsule structure; therefore, most of the heterocyclic fragrance exists on the surface, resulting in a low encapsulation efficiency. The relatively small proportion of zein in Comparative Example 4 also affects the encapsulation efficiency. The low encapsulation efficiency of Comparative Example 5 indicates that the addition step of the heterocyclic fragrance also has a significant impact on the encapsulation efficiency.

[0094] 2. Storage stability

[0095] Storage stability tests were conducted on the products of Examples 1-4 and Comparative Examples 1-5. 0.3g of the product (accurate to 0.001g) was accurately weighed and stored in a dust-free and ventilated environment for 120 days. The mass after storage was then weighed and the rate of change in mass was measured. The results are summarized in Table 2.

[0096] Table 2. Results of 120-day storage stability tests on products from Examples 1-4 and Comparative Examples 1-5.

[0097] serial number Quality change rate (%) serial number Quality change rate (%) Example 1 1.7 Comparative Example 1 4.7 Example 2 1.6 Comparative Example 2 2.6 Example 3 1.9 Comparative Example 3 8.3 Example 4 1.8 Comparative Example 4 3.0 Comparative Example 5 4.1

[0098] As can be seen from Table 2, the microcapsules in the embodiments have good storage stability.

[0099] 3. Thermogravimetric analysis:

[0100] Thermogravimetric analysis was performed on the products of Example 1, Comparative Example 1 and Comparative Example 3, as well as 2,3-diethyl-5-methylpyrazine (DEMP). Figure 7 As shown, the product of Comparative Example 1 exhibits good thermal stability, mainly due to the high thermal stability of zein; DEMP experiences rapid mass loss, beginning to lose weight at 70°C and completely losing weight at 150°C; Comparative Example 3, lacking zein, experiences faster mass loss, while the microcapsules of Example 1 experience slower mass loss, with less than 25% loss at 300°C, demonstrating good thermal stability and sustained-release effect. Moreover, the mass loss rate remains essentially consistent across the temperature range from room temperature to 300°C, indicating a constant evaporation rate of DEMP, which is beneficial for improving the aroma stability and puff consistency when applied to heated tobacco products.

[0101] 4. Evaluation and simulation of heated tobacco smoking:

[0102] Accurately weigh 5 mg, 10 mg, and 15 mg of Zein / CS / PVA@heterocyclic flavoring microcapsules from Example 1 and add them to tobacco powder to prepare heated tobacco sheets. The resulting heated tobacco sheets with added Zein / CS / PVA@heterocyclic flavoring microcapsules were then placed in a constant temperature and humidity chamber at 22±1℃ and 60±3% for 48 hours to equilibrate. A sensory evaluation panel of seven professionals conducted sensory evaluations of the heated tobacco sheets with different amounts of microcapsules and those without microcapsules, according to the GB / T5604.4—2005 sensory evaluation standard for cigarettes. The results are shown in Table 3.

[0103] Table 3 shows the sensory evaluation results of heated tobacco products with different microcapsule addition amounts in Example 1.

[0104] Serial Number Added amount Sensory evaluation results 1 0mg The aroma is unbalanced, contains many impurities, and is highly irritating. 2 5mg The aroma is somewhat harmonious, but contains many impurities and is quite pungent. 3 10mg The aroma is harmonious, with few off-odors and moderate irritation. 4 15mg The aroma is relatively harmonious with few off-odors and is not irritating.

[0105] As can be seen from Table 3, the heated non-combustible cigarettes with added microcapsules have good sensory evaluation effects, which can reduce irritation, soften the smoke, improve the aroma, increase the aroma quantity, and reduce the differences in sensory aroma between puffs.

[0106] The heated tobacco products supported by the products of Examples 1-4 and Comparative Examples 1-5 were evaluated by smoking with a microcapsule addition of 10 mg. The results are shown in Table 4.

[0107] Table 4 Evaluation of heated non-combustible cigarette smoking in Examples 1-4 and Comparative Examples 1-5

[0108]

[0109]

[0110] Note: a) DEMP refers to the direct addition of 2 mg of 2,3-diethyl-5-methylpyrazine (DEMP) to tobacco powder to prepare heated non-combustible cigarettes; b) Microcapsule-free means that no microcapsules are added to the tobacco powder.

[0111] The samples prepared above were subjected to puff-by-puff smoke simulation in a smoking machine. The specific smoking parameters were: smoking volume 55 mL, smoking duration 2 s, and smoking interval 30 s. The flavor content in the mainstream smoke was tested and determined by gas chromatography-mass spectrometry. The results are shown in Table 5. The values ​​in the table are in micrograms (μg).

[0112] Table 5. Flavor content of smoke from each puff of heated non-combustible cigarettes in Examples 1-4 and Comparative Examples 1-5

[0113] serial number First bite Second bite The third bite Fourth bite Fifth Sixth mouth The seventh mouth Example 1 65 72 75 73 72 70 68 Example 2 64 68 70 71 70 68 65 Example 3 66 71 74 73 72 72 70 Example 4 65 69 72 73 71 70 69 Comparative Example 1 65 68 59 57 55 54 54 Comparative Example 2 65 66 60 58 57 57 55 Comparative Example 3 75 80 75 64 55 46 35 Comparative Example 4 64 55 54 54 53 53 51 Comparative Example 5 68 57 50 46 43 40 38 DEMP* 78 85 68 51 36 23 15

[0114] Note: *DEMP refers to the preparation of heated non-combustible cigarettes by directly adding 2mg of 2,3-diethyl-5-methylpyrazine (DEMP) to tobacco powder.

[0115] As shown in Table 5, the microcapsules in the examples exhibit good puff consistency, stable aroma release, and high aroma loading. Comparative Examples 1-2 and 4 show relatively good puff consistency and stable aroma release, but lower aroma loading. The heated tobacco product in Comparative Example 3 shows poor puff consistency and rapid aroma loss. The DEMP without microcapsules has a large initial release, but also a large loss per puff, resulting in very poor puff consistency. The flavor content in Comparative Example 5 initially decreases rapidly and then stabilizes, but the overall aroma loading is low, which may be related to its relatively few pores on the surface, thus resulting in a lower flavor release.

[0116] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing flavoring microcapsules for heat-not-burn cigarettes, characterized in that, Includes the following steps: Zeat protein was dissolved in an aqueous ethanol solution to obtain a zeat protein solution; Chitosan was dissolved in an aqueous acetic acid solution to obtain a chitosan solution. Then, heterocyclic fragrance, polyvinyl alcohol and antioxidant were added to the chitosan solution and mixed to obtain a flavored solution. The zein solution and the flavoring solution are mixed and stirred evenly, wherein the mass ratio of zein, chitosan, heterocyclic flavoring, polyvinyl alcohol and antioxidant is (25~35): (8~15): (6~9): (1~3): (4~6); then the mixture is refrigerated and emulsified, and freeze-dried to obtain flavoring microcapsules for heated non-combustible cigarettes.

2. The preparation method according to claim 1, characterized in that, The concentration of the zein solution is 1-3 wt%, and the volume fraction of ethanol in the aqueous ethanol solution is 80-92%.

3. The preparation method according to claim 1, characterized in that, In the acetic acid aqueous solution, the volume fraction of acetic acid is 1-3%; in the chitosan solution, the concentration of chitosan is 0.3-1 wt%.

4. The preparation method according to claim 1, characterized in that, The heterocyclic fragrance is selected from one or more of pyrazine fragrances, pyridine fragrances, pyrrole fragrances, and furan fragrances.

5. The preparation method according to claim 4, characterized in that, The pyrazine fragrance is selected from 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-acetylpyrazine, 2,3-diethyl-5-methylpyrazine, 2,3-diethylpyrazine, 2-isobutyl-3-methoxypyrazine, 2-methoxy-3-methylpyrazine, 5-methoxy-5-methylpyrazine, 6-methoxy-3-methylpyrazine, 2-methylpyrazine, 2,3,5,6-tetramethylpyrazine, 2,3,5-trimethylpyrazine, 2-methoxy-3-isopropylpyrazine, 2-methoxy-5-isopropylpyrazine, 2-methoxy-6-isopropylpyrazine, 2-methoxypyrazine, 2-methyl-3-methylthiopyrazine. The fragrance is selected from one or more of the following: pyrazine, 2-methyl-5-methylthiopyrazine, 2-methyl-6-methylthiopyrazine, 2-ethyl-5-methylpyrazine, 2-ethylpyrazine, 2-methyl-3-ethoxypyrazine, 2-methyl-5-ethoxypyrazine, and 2-methyl-6-ethoxypyrazine; the pyridine fragrance is selected from one or more of 3-acetylpyridine, 2-acetylpyridine, 3,5-dimethylpyridine, and 3-ethylpyridine; the pyrrole fragrance is selected from 2-acetylpyrrole; and the furan fragrance is selected from one or more of furfuryl alcohol, furfural, and 5-methylfuranaldehyde.

6. The preparation method according to claim 4, characterized in that, The antioxidant is selected from tea polyphenols or vitamin E.

7. The preparation method according to claim 1, characterized in that, In the step of mixing and stirring the corn gliadin solution and the flavoring solution evenly, the mixing and stirring time is 20~60 minutes.

8. The preparation method according to claim 1, characterized in that, The temperature for refrigerated emulsification is 2~5℃, and the refrigerated emulsification time is 5~15h.

9. Flavor microcapsules for heated non-combustible cigarettes prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the flavoring microcapsules for heated tobacco products as described in claim 9 in heated tobacco products, characterized in that, The application involves adding the flavoring microcapsules for heated tobacco products to the tobacco segments of the heated tobacco products.

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