Perfume microcapsule for heat-not-burn cigarette as well as preparation method and application of perfume microcapsule

Abstract

The invention discloses a spice microcapsule for heating non-combustion cigarettes as well as a preparation method and application of the spice microcapsule, and belongs to the technical field of heating non-combustion tobaccos. The preparation method comprises the following steps: dissolving zein in an ethanol water solution to obtain a zein solution; the preparation method comprises the following steps: dissolving chitosan in an acetic acid aqueous solution to obtain a chitosan solution, then adding heterocyclic perfume, polyvinyl alcohol and an antioxidant into the chitosan solution, and uniformly mixing to obtain a perfumed solution; uniformly mixing and stirring the zein solution and the flavoring solution; and then refrigerating, emulsifying and freeze-drying to obtain the spice microcapsule for the heat-not-burn cigarette. According to the preparation method disclosed by the invention, the heterocyclic perfume microcapsule which is good in form, high in heterocyclic perfume embedding rate and high in perfume carrying amount can be obtained, and the heterocyclic perfume microcapsule has a proper slow release rate, long perfume retention time and good puff-by-puff consistency when being used for heating non-combustible cigarettes; and the preparation method is simple, safe and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-not-burn tobacco, and in particular to a flavor microcapsule for heat-not-burn cigarettes, and a preparation method and application thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Heat-not-burn cigarettes, also known as heated cigarettes, are new tobacco products that use a special heat source to heat the tobacco core made of shredded tobacco or other tobacco materials. The tobacco core is only heated but not burned. It mainly includes three parts: tobacco segment, cooling segment and acetate segment. The main feature of heat-not-burn tobacco products is that they use an external heat source to heat tobacco instead of burning it. The heating temperature of the tobacco segment is generally around 300°C, while traditional cigarettes are burned and smoked, and the combustion cone temperature is around 900°C. Therefore, the release of harmful components in heat-not-burn cigarettes is lower than that of traditional cigarettes.

[0004] Since heat-not-burn cigarettes emit tobacco flavor through heating and baking rather than burning, the relatively low temperature results in insufficient aroma satisfaction, so other flavoring substances are usually added to make up for the lack of aroma. However, since commonly used spices have a low boiling point and are easily volatile, when they are used in heat-not-burn products, the cigarettes are heated simultaneously, so the aroma is easily lost, the aroma lasts for a short time, and the consistency of the aroma components is poor from puff to puff.

[0005] The controlled and sustained release technology of microcapsules has significant advantages in solving the problem of easy volatility of spices and poor consistency from mouth to mouth. It uses natural polymer materials or synthetic materials to wrap the spices, effectively protecting the active ingredients that are easily decomposed and oxidized by light and are highly volatile, thereby achieving the effect of controlled release or sustained release. There are few studies on spices microcapsules for heat-not-burn cigarettes in the prior art. Hao Hui et al. (Journal of Yunnan University (Natural Science Edition), 2023, 45(5): 1081-1088) used papermaking thin sheet liquid as core material and chitosan as wall material to prepare microcapsules by complex coacervation. The microcapsules prepared by their method have a low embedding rate (less than 40%), a high content of spices on the surface (unembedded spices), and a serious adhesion of the microcapsules. Therefore, the volatilization rate of the spices on the surface is fast, while the release rate of the spices inside the microcapsules is slow, which leads to poor fragrance stability and consistency from mouth to mouth, and a short fragrance retention time.

[0006] Therefore, how to provide a flavor microcapsule for heat-not-burn cigarettes with a high flavor embedding rate and a suitable flavor release rate, high flavor stability and good puff-by-puff consistency is an urgent problem to be solved. Summary of the invention

[0007] In view of this, the present invention provides a flavor microcapsule for heat-not-burn cigarettes, and a preparation method and application thereof. The flavor microcapsule for heat-not-burn cigarettes prepared by the present invention has good morphology, high flavor loading capacity and flavor encapsulation rate, and a suitable sustained release rate. The smoking test shows that the flavor stability and puff-by-puff consistency are good.

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

[0009] dissolving zein in an ethanol aqueous solution to obtain a zein solution;

[0010] Dissolving chitosan in an acetic acid aqueous solution to obtain a chitosan solution, then adding heterocyclic fragrance, polyvinyl alcohol and an antioxidant to the chitosan solution, and mixing well to obtain a fragrance solution;

[0011] The zein solution and the flavoring solution are mixed and stirred uniformly, wherein the mass ratio of zein, chitosan, heterocyclic flavor, polyvinyl alcohol and antioxidant is (25-35):(8-15):(6-9):(1-3):(4-6); then refrigerated emulsification and freeze-drying are carried out to obtain flavoring microcapsules for heat-not-burn cigarettes.

[0012] In a second aspect, the present invention provides flavor microcapsules for heat-not-burn cigarettes prepared by the above-mentioned preparation method.

[0013] In a third aspect, the present invention provides an application of the above-mentioned heat-not-burn cigarette flavor microcapsules in heat-not-burn cigarettes, wherein the application is to add the heat-not-burn cigarette flavor microcapsules into the tobacco segment of the heat-not-burn cigarette.

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

[0015] (1) The present invention uses zein as the capsule wall material, uses chitosan to adsorb heterocyclic flavors to form the core material, and polyvinyl alcohol assists in the formation of the particle structure of the microcapsule. Under appropriate ratios, heterocyclic flavor microcapsules with good morphology, uniform size, high heterocyclic flavor embedding rate and high flavor loading can be obtained. When used in heat-not-burn cigarettes, they have a suitable sustained release rate, a long flavor retention time, and good puff-by-puff consistency.

[0016] (2) In the preparation process of the microcapsules, the present invention does not require the introduction of additional emulsifiers and cross-linking agents, nor does it require high-energy-consuming steps such as ultrasound and high-speed homogenization emulsification. It only needs to be emulsified by refrigeration after stirring and mixing. The obtained emulsion is stable and does not undergo stratification. The overall preparation method is simple to operate and is safe and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a scanning electron microscope image of Zein / CS / PVA@heterocyclic fragrance microcapsules of Example 1 of the present invention;

[0019] Figure 2 This is a scanning electron microscope image of the Zein / PVA@heterocyclic fragrance product obtained in Comparative Example 1 of the present invention;

[0020] Figure 3 This is a scanning electron microscope image of the Zein / CS@heterocyclic fragrance product obtained in Comparative Example 2 of the present invention;

[0021] Figure 4 This is a scanning electron microscope image of the CS / PVA@heterocyclic fragrance product obtained in Comparative Example 3 of the present invention;

[0022] Figure 5 This is a scanning electron microscope image of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in Comparative Example 4 of the present invention;

[0023] Figure 6 This is a scanning electron microscope image of the Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in Comparative Example 5 of the present invention;

[0024] Figure 7 It is the thermogravimetric analysis curve of the products of Example 1, Comparative Example 1 and Comparative Example 3 of the present invention and 2,3-diethyl-5-methylpyrazine (DEMP). DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

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

[0027] dissolving zein in an ethanol aqueous solution to obtain a zein solution;

[0028] Dissolving chitosan in an acetic acid aqueous solution to obtain a chitosan solution, then adding heterocyclic fragrance, polyvinyl alcohol and an antioxidant to the chitosan solution, and mixing well to obtain a fragrance solution;

[0029] The zein solution and the flavoring solution are mixed and stirred uniformly, wherein the mass ratio of zein, chitosan, heterocyclic flavor, polyvinyl alcohol and antioxidant is (25-35):(8-15):(6-9):(1-3):(4-6); then refrigerated emulsification and freeze-drying are carried out to obtain flavoring microcapsules for heat-not-burn cigarettes.

[0030] When heterocyclic spices are applied to heat-not-burn cigarettes, due to the low boiling point and high heating temperature (about 300°C), they are easily rapidly invalidated due to high volatility and instability, and the fragrance cannot be maintained for a long time, and the consistency is poor. Therefore, the present invention uses zein as the capsule wall material, and chitosan adsorbs heterocyclic spices to form a core material, and chitosan and polyvinyl alcohol both have good film-forming properties. When they are introduced into microcapsules, the microcapsules can have a good particle structure, thereby further improving the structural stability and fragrance carrying capacity of the microcapsules, and the heat resistance is good, and there is no obvious decomposition or deterioration when heated. In addition, chitosan has a hydrophilic group amino group and a hydrophobic group acetyl group, so that it has a biphilic effect, and because zein also has good emulsification, when the chitosan solution is mixed with the zein solution, a stable emulsion can be formed, without the introduction of other emulsifiers, and the operation method is very simple. The microcapsule structure formed by zein, chitosan and polyvinyl alcohol can have a good sustained-release effect on the heterocyclic flavors inside. Under the appropriate ratio of the three, heterocyclic flavor microcapsules with good morphology, high heterocyclic flavor encapsulation rate and high flavor loading can be obtained. When used in heat-not-burn cigarettes, the microcapsules have a suitable sustained-release rate, so that the heterocyclic flavors are slowly released when heated in the heat-not-burn cigarettes, thereby improving the stability of the aroma, prolonging the aroma retention time, and having good puff-by-puff consistency.

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

[0032] In the present invention, the volume fraction of acetic acid in the acetic acid aqueous solution is 1-3%, and the acetic acid molecules loosen the structure of chitosan by destroying the hydrogen bonds between chitosan molecules, thereby promoting the dissolution of chitosan. The molecular weight of the chitosan is preferably 100,000 to 400,000 Daltons, and the degree of deacetylation is above 70%, so that it is easily soluble in the acetic acid aqueous solution. In the chitosan solution, the concentration of chitosan is 0.3-1wt%.

[0033] In the present invention, the heterocyclic fragrance is selected from one or more of pyrazine fragrance, pyridine fragrance, pyrrole fragrance or furan fragrance. The use of multiple fragrances can enhance the flavor level of cigarettes and enrich the flavor of cigarettes.

[0034] In the present 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 -isopropyl pyrazine, 2-methoxy-6-isopropyl pyrazine, 2-methoxy pyrazine, 2-methyl-3-methylthio pyrazine, 2-methyl-5-methylthio pyrazine, 2-methyl-6-methylthio pyrazine, 2-ethyl-5-methyl pyrazine, 2-ethyl pyrazine, 2-methyl-3-ethoxy pyrazine, 2-methyl-5-ethoxy pyrazine or 2-methyl-6-ethoxy pyrazine; the pyridine fragrance is selected from one or more of 3-acetyl pyridine, 2-acetyl pyridine, 3,5-dimethyl pyridine, 3-ethyl pyridine; the pyrrole fragrance is selected from 2-acetyl pyrrole; the furan fragrance is selected from one or more of furfuryl alcohol, furfural or 5-methyl furanaldehyde.

[0035] In the present invention, the antioxidant is selected from tea polyphenols or vitamin E. The introduction of antioxidants is to improve the antioxidant properties of spices, extend the shelf life of spices, prevent spices from oxidative deterioration during processing or storage, and enhance the functionality of products.

[0036] In the present invention, in the step of uniformly mixing the zein solution and the flavoring solution, the mixing time is 20 to 60 minutes, so that the zein, chitosan, heterocyclic spices, polyvinyl alcohol and antioxidants are better mixed, which is conducive to forming microcapsules with good structure and morphology.

[0037] In the present invention, the temperature of the refrigerated emulsification is 2-5°C, more preferably 4°C, and the time of the refrigerated emulsification is 5-15 hours. Refrigerated emulsification is standing emulsification at a relatively low temperature, which is to prevent the volatilization of the flavor on the one hand, and to prepare for the next step of freeze drying on the other hand.

[0038] The present invention provides heat-not-burn cigarette flavor microcapsules prepared by the above-mentioned preparation method. The obtained heat-not-burn cigarette flavor microcapsules have good particle morphology and play an effective role in encapsulating and controlling the sustained release of heterocyclic flavors.

[0039] The present invention provides an application of the above-mentioned heat-not-burn cigarette flavor microcapsules in heat-not-burn cigarettes, wherein the application is to add the heat-not-burn cigarette flavor microcapsules into the tobacco segment of the heat-not-burn cigarette, and the added amount of the heat-not-burn cigarette flavor microcapsules is preferably 10 to 15 mg / cigarette.

[0040] The technical solution of the present invention is further described below in conjunction with specific examples. The present invention has no particular limitation on the source of the reagents used in the following examples, and commercially available products 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°C.

[0042] Example 1

[0043] This embodiment provides a method for preparing flavor microcapsules for heat-not-burn 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 a zein solution;

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

[0046] (3) The zein solution and the flavoring solution were mixed and stirred for 30 minutes, and then refrigerated at 4°C for emulsification for 12 hours. The emulsion had good stability and no stratification occurred. The emulsion was then freeze-dried to obtain powdered heat-not-burn cigarette flavoring microcapsules, which were denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0047] The scanning electron microscope image of the Zein / CS / PVA@heterocyclic fragrance microcapsules prepared in this example is shown in FIG. Figure 1 As shown, it can be seen that the microcapsules have good spherical morphology, relatively uniform particle size, and the particle size is concentrated between 300 and 600 nm. There is no adhesion between the spherical particles, and the surface of the microcapsules has micropores, which is conducive to the controlled release of the internal fragrance.

[0048] Example 2

[0049] This embodiment provides a method for preparing flavor microcapsules for heat-not-burn 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 a zein solution;

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

[0052] (3) The zein solution and the flavoring solution were mixed and stirred for 30 minutes, and then refrigerated at 4°C for emulsification for 12 hours. The emulsion had good stability and no stratification occurred. The emulsion was then freeze-dried to obtain powdered heat-not-burn cigarette flavoring microcapsules, which were denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0053] Example 3

[0054] This embodiment provides a method for preparing flavor microcapsules for heat-not-burn 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 a zein solution;

[0056] (2) 100 mg of chitosan (CS) 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 (20 mg of 2,3-diethyl-5-methylpyrazine, 20 mg of 2-acetylpyridine, 30 mg of furfural, 10 mg of 5-methylfuranaldehyde), 20 mg of polyvinyl alcohol and 50 mg of tea polyphenols were added to the chitosan solution, and the mixture was mixed to obtain a fragrance solution.

[0057] (3) The zein solution and the flavoring solution were mixed and stirred for 30 minutes, and then refrigerated at 4°C for emulsification for 12 hours. The emulsion had good stability and no stratification occurred. The emulsion was then freeze-dried to obtain powdered heat-not-burn cigarette flavoring microcapsules, which were denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0058] Example 4

[0059] This embodiment provides a method for preparing flavor microcapsules for heat-not-burn cigarettes, comprising the following steps:

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

[0061] (2) adding 110 mg of chitosan to 20 mL of 2.5% acetic acid aqueous solution, stirring in a water bath at 50° C. for 30 min to obtain a chitosan solution, and then adding 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, and mixing well to obtain a fragrance solution;

[0062] (3) The zein solution and the flavoring solution were mixed and stirred for 30 minutes, and then refrigerated at 4°C for emulsification for 12 hours. The emulsion had good stability and no stratification occurred. The emulsion was then freeze-dried to obtain powdered heat-not-burn cigarette flavoring microcapsules, which were 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 the mixture was 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 the mixture was stirred for 30 min to obtain a fragrance solution, and the fragrance solution was refrigerated at 4°C 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 shown in FIG. Figure 2 As shown, it can be seen that the particle size is relatively large, reaching more than 1 μm, and the particle morphology is poor, and the adhesion between particles is serious, which is not conducive to the release of internal flavors; this shows that the addition of chitosan can promote the formation of a spherical structure of microcapsules.

[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, and the remaining steps are the same as those 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 serious, and the spherical particles are concentrated on the flaky substrate, which is not conducive to the release of internal fragrances. 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 granular 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 the mixture was stirred for 30 min to obtain a fragrance solution. The fragrance solution was then refrigerated at 4°C for emulsification for 12 h, 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 under the same magnification as in Example 1, indicating that no microcapsule structure is formed and the whole is in a relatively smooth film shape.

[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 image of Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in this comparative example is shown in Figure 5 As shown, it can be seen that the adhesion of spherical particles is aggravated and there are fewer pores on the surface.

[0077] Comparative Example 5

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

[0079] (1) 300 mg of zein was added to 20 mL of 85% ethanol aqueous solution, and the mixture was stirred at room temperature for 30 min to obtain a zein solution. Then 80 mg of heterocyclic fragrance (2,3-diethyl-5-methylpyrazine) was added to the zein solution, and the mixture was stirred for 0.5 h to obtain a fragrance solution.

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

[0081] (3) The chitosan / polyvinyl alcohol solution and the flavoring solution were mixed and stirred for 30 minutes, then refrigerated at 4°C for emulsification for 12 hours, and freeze-dried to obtain powdered heat-not-burn cigarette flavoring microcapsules, which were denoted as Zein / CS / PVA@heterocyclic flavoring microcapsules.

[0082] The scanning electron microscope image of Zein / CS / PVA@heterocyclic fragrance microcapsules obtained in this comparative example is shown in Figure 6 As shown, it can be seen that there is no obvious spherical structure, the adhesion phenomenon is serious, and the number of pores on the surface is very small.

[0083] Test example

[0084] 1. Embedding rate test:

[0085] The embedding rate test refers to the literature "Microencapsulation of Papermaking Thin Sheet Liquid and Its Application in Heat-Not-Burn 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 in a beaker and ultrasonically vibrate for 30 min. Then let it stand for 30 min. Finally, filter it into a conical flask of known mass. Volatilize the dichloromethane in a low-temperature water bath and calculate the mass fraction of total oil in microcapsules (w) by weight loss method. 1 );

[0087] (2) Determination of microcapsule surface oil: Accurately weigh 1.0 g (accurate to 0.001 g) of microcapsule sample and place it in a centrifuge tube. Add 15 mL of dichloromethane solution, shake thoroughly for 30 seconds, centrifuge for 2 minutes (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 use the weight loss method to calculate the mass fraction of product surface oil (w 2 ).

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

[0089] M = [(w 1 -w 2 ) / w 1 ] (1)

[0090] The test results of the product embedding rates of Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 1.

[0091] Table 1: Test results of product embedding rate of Examples 1 to 4 and Comparative Examples 1 to 5

[0092] serial number Embedding rate (%) serial number Embedding 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 can be seen from Table 1, the embedding rate of the microcapsules of the embodiments has reached more than 60%, which is conducive to prolonging the release time of the fragrance and making it have a suitable sustained-release effect. From the comparison of the embedding rate data of Comparative Examples 1 to 3 and Example 1, it can be seen that zein, chitosan and polyvinyl alcohol will affect the embedding rate. The microcapsules prepared by adding the three together have the highest embedding rate, which is conducive to improving the stability of the fragrance. Comparative Example 3 has the lowest embedding rate, which is probably because it cannot form a microcapsule structure, so most of the heterocyclic fragrances exist on the surface and have a low embedding rate. Comparative Example 4 will also affect the embedding rate due to the small proportion of zein. The embedding rate of Comparative Example 5 is low, indicating that the addition step of heterocyclic fragrances will also have a significant impact on the embedding rate.

[0094] 2. Storage stability

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

[0096] Table 2 120-day storage stability test results of the products of Examples 1 to 4 and Comparative Examples 1 to 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] It can be seen from Table 2 that the microcapsules of the examples 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 and 2,3-diethyl-5-methylpyrazine (DEMP). Figure 7As shown. It can be seen that the product of comparative example 1 exhibits good thermal stability, which is mainly due to the high thermal stability of zein; DEMP loses mass rapidly, starts to lose weight at 70°C, and loses weight completely at 150°C; comparative example 3 does not contain zein, and its mass loss is fast, while the mass loss of the microcapsules of Example 1 is slow, with a mass loss of less than 25% at 300°C, having good thermal stability and sustained release effect, and its mass loss rate is basically the same in the temperature range from room temperature to 300°C, indicating that the volatilization rate of DEMP is constant, which is conducive to improving the flavor stability and puff-by-puff consistency when it is applied to heat-not-burn cigarettes.

[0101] 4. Evaluation and simulation of smoking of heat-not-burn cigarettes:

[0102] Accurately weigh 5 mg, 10 mg and 15 mg of Zein / CS / PVA@heterocyclic flavor microcapsules of Example 1 and add them to the cigarette dust to prepare heat-not-burn cigarette sheets. The heat-not-burn cigarettes with Zein / CS / PVA@heterocyclic flavor microcapsules added were placed in a constant temperature and humidity chamber at a temperature of 22±1°C and a relative humidity of 60±3% for 48 hours. A smoking evaluation team consisting of 7 professionals was organized to conduct sensory evaluation of heated cigarettes with different amounts of microcapsules added and heated cigarettes without microcapsules added according to the GB / T5604.4-2005 cigarette sensory evaluation standard. The results are shown in Table 3.

[0103] Table 3 Sensory evaluation results of heat-not-burn cigarettes with different microcapsule addition amounts in Example 1

[0104] Serial number Addition amount Sensory evaluation results 1 0mg The aroma is not harmonious, there are many impurities, and it is very irritating 2 5mg The aroma is slightly harmonious, with more miscellaneous smells and stronger irritation 3 10mg The aroma is harmonious, with little impurity and moderate irritation 4 15mg The aroma is slightly harmonious, with less impurities and no irritation

[0105] As can be seen from Table 3, the sensory evaluation effect of the heat-not-burn cigarettes with added microcapsules is good, which can reduce irritation, soften smoke, improve aroma quality, increase aroma volume, and reduce the difference in sensory aroma from puff to puff.

[0106] A microcapsule addition amount of 10 mg was selected to conduct smoking evaluation on the heat-not-burn cigarettes supported by the products of Examples 1 to 4 and Comparative Examples 1 to 5. The results are shown in Table 4.

[0107] Table 4 Evaluation of smoking of heat-not-burn cigarettes of Examples 1 to 4 and Comparative Examples 1 to 5

[0108]

[0109]

[0110] Note: a. DEMP means directly adding 2 mg 2,3-diethyl-5-methylpyrazine (DEMP) into tobacco powder to prepare heat-not-burn cigarettes; b. No microcapsules means no microcapsules are added into tobacco powder.

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

[0112] Table 5 Puff-by-puff smoke flavor content of heat-not-burn cigarettes of Examples 1 to 4 and Comparative Examples 1 to 5

[0113] serial number First bite Second bite The third mouth The fourth mouth The fifth mouth The 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 directly adding 2 mg of 2,3-diethyl-5-methylpyrazine (DEMP) into tobacco powder to prepare heat-not-burn cigarettes.

[0115] As can be seen from Table 5, the microcapsules of the examples have good puff-by-puff consistency, stable flavor release, and high flavor loading; the puff-by-puff consistency of Comparative Examples 1-2 and Comparative Example 4 is good, the flavor release is relatively stable, but the flavor loading is low. The heat-not-burn cigarette of Comparative Example 3 has poor puff-by-puff consistency and rapid flavor loss; the initial release of DEMP without microcapsules is large, but the puff-by-puff loss is also large, and the puff-by-puff consistency is very poor. The flavor content of Comparative Example 5 starts to decrease rapidly, then tends to stabilize, but the overall flavor loading is low, which may be related to the fact that there are fewer pores on its surface, so its flavor release is relatively low.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing flavor microcapsules for heat-not-burn cigarettes, characterized in that: The steps include: dissolving zein in an ethanol aqueous solution to obtain a zein solution; Dissolving chitosan in an acetic acid aqueous solution to obtain a chitosan solution, then adding heterocyclic fragrance, polyvinyl alcohol and an antioxidant to the chitosan solution, and mixing well to obtain a fragrance solution; The zein solution and the flavoring solution are mixed and stirred uniformly, wherein the mass ratio of zein, chitosan, heterocyclic flavor, polyvinyl alcohol and antioxidant is (25-35):(8-15):(6-9):(1-3):(4-6); then refrigerated emulsification and freeze-drying are carried out to obtain flavoring microcapsules for heat-not-burn 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 ethanol aqueous 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 0.3-1wt%.

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

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, The invention relates to one or more of 2-methyl-3-methylthiopyrazine, 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 and 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-methylfurfural.

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 zein solution and the flavoring solution evenly, the mixing and stirring time is 20 to 60 minutes.

8. The preparation method according to claim 1, characterized in that: The temperature of the refrigerated emulsification is 2 to 5° C., and the time of the refrigerated emulsification is 5 to 15 hours.

9. Flavor microcapsules for heat-not-burn cigarettes prepared by the preparation method according to claims 1 to 8.

10. Use of the heat-not-burn cigarette flavor microcapsules according to claim 9 in heat-not-burn cigarettes, characterized in that: The application is to add the flavor microcapsules for heat-not-burn cigarettes into the tobacco segments of the heat-not-burn cigarettes.

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