Dual-responsiveness perfume microcapsule for cigarettes as well as preparation method and application of dual-responsiveness perfume microcapsule

Abstract

The invention discloses a preparation and application method of a dual-responsiveness perfume microcapsule for cigarettes, which adopts a simple, low-cost and high-efficiency electron transfer catalytic regeneration atom transfer radical polymerization (ARGET ATPR) method, takes natural plant essential oil as a core material, takes modified chitosan derivatives and polymethylacrylic acid N, N-dimethylaminoethyl ester (PDMAEMA) as wall materials, and adopts a one-step method to prepare the dual-responsiveness perfume microcapsule for the cigarettes. The prepared plant essential oil loaded perfume microcapsule is uniform in shape and size, compact in structure, high in mechanical strength, large in perfume loading amount, high in encapsulation efficiency, high in stability in a normal-temperature environment and long in perfume retention time, and can quickly respond and release weak acid gas generated by cigarette combustion and in a high-temperature environment; the spice microcapsule is added into cigarette tobacco shreds in a spraying or direct mixing mode, the sensory quality of cigarettes can be remarkably improved during combustion, offensive odor is reduced, irritation is reduced, aftertaste is improved, the cigarettes are endowed with unique plant source characteristic aroma, and smoking experience is richer and more diversified.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tobacco flavoring technology, in particular to a preparation method and application of a double-responsive flavor microcapsule with core-shell structure for cigarettes. BACKGROUND

[0002] In cigarette production, flavoring is a key process to improve the aroma of cigarettes, improve the smoking quality and enhance the characteristic flavor. Many natural plant essential oils with unique aroma, such as peppermint essential oil and clove essential oil, are widely used due to their flavoring effect of enhancing aroma, improving quality, reducing bitterness and removing impurities. However, these essential oil components are volatile and easily oxidized small hydrophobic molecules, which are severely lost during tobacco storage and cigarette combustion, resulting in short aroma retention time, large sensory quality fluctuation and poor long-term stability of products.

[0003] Microcapsule technology is one of the effective means to solve the above problems. It can encapsulate flavor in nanometer or micrometer-sized capsules, isolate it from the external environment, thereby improving the stability and durability of the flavor and achieving controllable release under specific conditions. At present, the wall materials of flavor microcapsules applied to cigarettes are mainly natural polymers such as gelatin, gum arabic, β-cyclodextrin and sodium alginate, or some semi-synthetic prepolymers. These wall materials have problems such as insufficient mechanical strength, generation of odors during combustion, unsatisfactory controlled release performance or poor compatibility with plant essential oils.

[0004] Chitosan is a natural cationic polysaccharide with good biocompatibility and film-forming property. The amino groups in the molecule can also react with harmful gases such as crotonaldehyde and hydrogen cyanide in smoke, but its stability and compactness as a wall material need to be improved. Poly (N, N-dimethylaminoethyl methacrylate) (PDMAEMA) is an intelligent polymer with temperature and pH dual responsiveness. Its chain segment will undergo conformational transition under specific conditions, which is expected to act as an intelligent switch in the combustion environment of cigarettes to control the release of essential oils. How to combine the film-forming property of chitosan with the intelligent responsiveness of PDMAEMA to construct a new type of composite wall material with stable structure and precise controlled release is a direction worthy of research in this field. Atom transfer radical polymerization (ATPR) is a kind of living / controllable radical polymerization technology, which can accurately control the length and structure of polymer chains. ARGET ATPR method using atom transfer catalytic regeneration (ARGET) combined with ATPR in situ polymerization at the interface of emulsion can construct a polymer wall material with compact structure and controllable thickness. SUMMARY

[0005] The purpose of the present application is to provide a pH and heat dual-responsive flavor microcapsule with chitosan derivative and PDMAEMA as wall material, prepared by ARGET ATPR method, and its application in cigarette flavoring, to solve the problem of insufficient flavoring in the background technology.

[0006] To achieve the above object, the present application provides the following technical solutions: The present application provides a preparation method of a double-responsive flavor microcapsule for cigarettes, comprising the following steps: Step 1, dissolve chitosan in 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, slowly add triethylamine (TEA) solution and 2-bromoisobutyryl bromide (BIBB) solution dissolved in N, N-dimethylformamide (DMF) in sequence, warm to room temperature, and continue to stir the reaction; Step 2, sequentially wash with 1 M NaOH solution, 1 M HCl solution, and distilled water to remove HBr and ammonium salt, and dry the product in a vacuum drying box to obtain a modified chitosan-based macroinitiator; Step 3, uniformly mix natural plant essential oil and dispersant to form an oil phase; Step 4, dissolve the modified chitosan-based macroinitiator in 1% acetic acid aqueous solution, and uniformly mix with an emulsifier to form an aqueous phase; Step 5, use a high-speed homogenizer to shear the oil phase and the aqueous phase to form a stable O / W emulsion, and introduce high-purity nitrogen to remove all dissolved oxygen; Step 6, under nitrogen protection, add an aqueous solution of CuBr2 catalyst and pentamethyldiethylene triamine (PMDETA) ligand, slowly inject dimethylaminoethyl methacrylate (DMAEMA) monomer, continuously stir, quickly add L-sodium ascorbate reducing agent after the system is uniformly mixed, continuously stir the reaction, expose the system to air to terminate the reaction, and obtain a plant essential oil-loaded double-responsive flavor microcapsule; Step 7, centrifuge the double-responsive flavor microcapsule and wash it with distilled water multiple times to remove catalyst, ligand, reducing agent byproduct, and unreacted monomer impurities, and add it to cigarette tobacco after freeze-drying, with a spraying or direct mixing addition method.

[0007] Further, in step 1, the molar ratio of the amino glucose unit of chitosan, TEA, and BIBB is 1:0.1~0.2:0.2~0.3, the mass ratio of chitosan to 1% acetic acid aqueous solution is 1:10~20, the mass fraction of TEA in the TEA solution is 1.0%~5.0%, the mass fraction of BIBB in the BIBB solution is 5.0%~10.0%, and the stirring reaction time is 15~36 h.

[0008] Further, in step 3, the mass ratio of the natural plant essential oil and the dispersant is 1:0.01-0.05, the natural plant essential oil is one or more of green peel essential oil, orange peel essential oil, orange red essential oil, day day flower essential oil, bergamot essential oil, baizhi essential oil, sea buckthorn essential oil and green fruit essential oil, and the dispersant is one or more of Tween 40, Tween 60, Tween 80, Span 40, Span 60 and Span 80.

[0009] Further, in step 4, the mass ratio of the modified chitosan-based macromolecular initiator and the emulsifier is 1:0.01-0.05, the mass fraction of the modified chitosan-based macromolecular initiator in the water phase is 5.0%-10.0%, and the emulsifier is one or more of sodium dodecyl benzene sulfonate (SDBS), sodium lignin sulfonate and sodium lignin carboxylate.

[0010] Further, in step 5, the mass ratio of the oil phase and the water phase is 3:4-6, the rotation speed of the high-speed homogenizer is 10,000-30,000 rpm, and the time is 30-300 s.

[0011] Further, in step 6, the mass ratio of the DMAEMA, the modified chitosan-based macromolecular initiator, CuBr2 and PMDETA is 1:0.25-1.00:0.01-0.05:0.01-0.05, the mass fraction of PMDETA in the PMDETA solution is 5.0%-10.0%, the mass ratio of CuBr2 to sodium L-ascorbate is 1:1-10, the reaction temperature is 20-30℃, and the reaction time is 15-36 h.

[0012] The application further provides a double-responsive flavor microcapsule for cigarettes prepared by the preparation method.

[0013] The application further provides application of the double-responsive flavor microcapsule for cigarettes in cigarettes.

[0014] Further, the double-responsive flavor microcapsule is added to the tobacco section of the cigarette in a spraying or direct mixing manner.

[0015] Further, the addition mass ratio of the double-responsive flavor microcapsule in the tobacco section of the cigarette is 0.01%-0.05%.

[0016] Compared with the prior art, the application has the following beneficial effects: (1) The ARGET ATRP technology is applied to the preparation of cigarette flavor microcapsules for the first time. The BIBB is used to modify chitosan, so that the chitosan has the dual functions of initiator and natural film-forming material. On this basis, the PDMAEMA is in-situ grafted and polymerized by ARGET ATRP reaction, so as to form a composite wall material with the modified chitosan derivative as a connecting skeleton and the pH and thermal responsive PDMAEMA as a smart switch. The double-responsive flavor microcapsule structure formed by wrapping the plant essential oil core material with the wall material is compact, has high mechanical strength, has good fragrance loading capacity and encapsulation effect on hydrophobic essential oil, is high in stability and long in fragrance retention time.

[0017] (2) The modified chitosan derivative and the PDMAEMA are used as main wall materials, and the natural plant essential oil is used as a core material to prepare the double-responsive flavor microcapsule for cigarettes. The flavor microcapsule is relatively stable at room temperature, and can trigger the phase transition and protonation of the PDMAEMA under the high-temperature and weak-acid gas environment generated by tobacco combustion, so as to realize the rapid and large release of the loaded flavor at the required time point. In addition, the chitosan can also react with hydrogen cyanide, crotonaldehyde and other harmful gases in the smoke, so as to add unique plant source aroma to the cigarettes and reduce the negative effects of toxic and harmful substances on the human body. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Figure (A: green peel essential oil microcapsule; B: orange peel essential oil microcapsule; C: bergamot essential oil microcapsule) for the plant essential oil-loaded microcapsules prepared in example 1 to example 3 of the present application. Figure 2 Figure (A: oil / water ratio is 3:4; B: oil / water ratio is 3:5.55) for the orange peel essential oil microcapsules with different oil / water ratios prepared in example 1 and example 4 of the present application. Figure 3 Figure for the bergamot essential oil microcapsule before freeze-drying prepared in example 3 of the present application.

[0019] Figure 4 Figure (A: chitosan-based macroinitiator; B: microcapsule shell after step 6 reaction) for the FT-IR spectrum of the chitosan-based macroinitiator and the microcapsule shell after reaction prepared in example 1 of the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0021] The preparation and application method of the double-responsive flavor microcapsule for cigarettes comprises the following steps: Step 1, dissolve chitosan in 50-200 mL of 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, slowly add TEA solution and BIBB solution dissolved in DMF in turn, the molar ratio of chitosan, TEA and BIBB is 1:0.1-0.2:0.2-0.3, the mass ratio of chitosan to 1% acetic acid aqueous solution is 1:10-20, the mass fraction of TEA in TEA solution is 1.0%-5.0%, the mass fraction of BIBB in BIBB solution is 5.0%-10.0%, and the temperature is raised to room temperature, and the stirring reaction is continued for 15-36 h; Step 2, sequentially wash with 500-1000 mL of 1 M NaOH solution, 500-1000 mL of 1 M HCl solution and 500-1000 mL of distilled water to remove HBr and ammonium salt, and the product is placed in a vacuum drying oven at 30-50℃ for 6-12 h to obtain the modified chitosan-based macromolecular initiator; Step 3, uniformly mix one kind of natural plant essential oil selected from green peel essential oil, orange peel essential oil, orange red essential oil, day day flower essential oil, bergamot essential oil, white peony essential oil, sea buckthorn essential oil and green fruit essential oil, and one or more dispersants selected from Tween40, Tween60, Tween80, Span40, Span60 and Span80 according to a mass ratio of 1:0.01-0.05, and slowly stir for 3-7 min to form an oil phase; Step 4, dissolve the modified chitosan-based macromolecular initiator in 1% acetic acid aqueous solution, uniformly mix one or more emulsifiers selected from SDBS, sodium lignosulfonate and sodium lignin carboxylate according to a mass ratio of 1:0.01-0.05, slowly stir for 3-7 min to form an aqueous phase, and the mass fraction of the modified chitosan-based macromolecular initiator in the aqueous phase is 5.0%-10.0%; Step 5, use a high-speed homogenizer to shear the oil phase and the aqueous phase with a mass ratio of 3:4-6 to form a stable O / W emulsion, the rotation speed of the high-speed homogenizer is 10000-30000 rpm, and the time is 30-300 s, and then high-purity nitrogen is introduced for 20-40 min to remove all dissolved oxygen; Step 6, under the protection of nitrogen, an aqueous solution of CuBr2 catalyst and PMDETA ligand is added, and the DMAEMA monomer is slowly injected, the mass ratio of DMAEMA to modified chitosan-based macromolecular initiator, CuBr2, PMDETA is 1:0.25~1.00:0.01~0.05:0.01~0.05, the mass fraction of PMDETA in the PMDETA solution is 5.0%~10.0%, continuous stirring, after the system is mixed uniformly, the L-ascorbic acid sodium reducing agent is quickly added, the mass ratio of CuBr2 to L-ascorbic acid sodium is 1:1~10, continuous stirring reaction for 15~36 h, the reaction temperature is maintained at 20~30℃, after the reaction is completed, the system is exposed to air to terminate the reaction; Step 7, the microcapsules prepared by the reaction are centrifuged at a speed of 2000~4000 rpm and washed with 1000~2000 mL of distilled water for multiple times to remove catalysts, ligands, reducing agent byproducts and unreacted monomers and other impurities, and then frozen and dried at a temperature of-40~-20℃ for 18~36 h to obtain the plant essential oil loaded double-responsive flavor microcapsules; The double-responsive flavor microcapsules after freeze-drying are added to the cut tobacco, and the mass ratio of addition is 0.01%~0.05%, and the addition method is spraying or direct mixing.

[0022] By the above method, the preparation and application method of the double-responsive flavor microcapsules for cigarettes, which adopts the simple, low-cost and efficient ARGET ATPR method, the plant essential oil loaded flavor microcapsules obtained have uniform size and shape, large fragrance loading capacity, high encapsulation efficiency, strong stability at room temperature, long fragrance retention time, and can be released in response to weak acidic gas and high temperature environment generated by cigarette combustion. In the form of spraying or mixing, it is added to the tobacco, which can significantly improve the sensory quality of the cigarette, reduce the odor, reduce the irritation, improve the aftertaste, and endow the cigarette with unique plant source characteristic aroma, so that the smoking experience is more diverse.

[0023] The application will be further described in detail below in conjunction with specific examples, but the protection scope of the application is not limited thereto.

[0024] Example 1

[0025] Step 1, 5.4347 g of chitosan (70% deacetylation degree) containing 0.0236 mol of amino groups is dissolved in 100 mL of 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, 0.0035 mol of TEA and 0.0059 mol of BIBB are slowly added in sequence, TEA and BIBB are dissolved in DMF to prepare a solution with a mass fraction of 3.5% and 8.0%, respectively, after the temperature is raised to room temperature, the stirring reaction is continued for 17 h; Step 2, sequentially wash the impurities with 650 mL of 1 M NaOH solution, 650 mL of 1 M HCl solution, 800 mL of distilled water, and dry the product in a vacuum drying oven at 30°C for 7 h to obtain the modified chitosan-based macromolecular initiator; Step 3, uniformly mix 2.0 g of orange peel essential oil, 0.02 g of Tween 80, and 0.02 g of Span 60 dispersant, and form an oil phase after slow stirring for 4 min; Step 4, dissolve 1.0 g of the modified chitosan-based macromolecular initiator in 1% acetic acid aqueous solution to prepare a 5.0% mass fraction solution, add 0.01 g of SDBS emulsifier and mix uniformly, and form an aqueous phase after slow stirring for 5 min; Step 5, use a high-speed homogenizer to shear 1.2245 g of the oil phase and 1.6326 g of the aqueous phase at a speed of 12000 rpm for 40 s to form a stable O / W emulsion, and then pass high-purity nitrogen for 35 min; Step 6, under nitrogen protection, add 0.0041 g of CuBr2 and 0.0082 g of PMDETA, dissolve PMDETA in water to prepare a 5.0% mass fraction solution, slowly inject 0.2041 g of DMAEMA monomer, continuously stir, and after the system is uniformly mixed, quickly add 0.0062 g of sodium L-ascorbate, continuously stir for 24 h, and maintain the reaction temperature at 25°C; after the reaction is completed, expose the system to air to terminate the reaction; Step 7, centrifuge the microcapsules prepared by the reaction at a speed of 2500 rpm, wash with 1500 mL of distilled water for multiple times, freeze-dry at a temperature of -35°C for 24 h, and obtain the double-responsive microcapsules loaded with orange peel essential oil.

[0026] Step 8, weigh 0.0300 g of the dried orange peel essential oil microcapsules and directly mix and add them to 149.9341 g of cigarette tobacco, store in a constant temperature and humidity box to balance the water vapor for 72 h, manually roll the tobacco to make 15 samples, ask 5 experts to smoke the samples, each person repeats 3 times, and compare with the parallel samples. The results are as follows: the encapsulation rate of the orange peel essential oil microcapsules is 74.7±0.9%, the drug loading is 30.1±0.8%, the aroma of the orange peel essential oil is coordinated with the tobacco aroma, can improve the quality and comfort of the cigarette, reduce the irritation, and significantly improve the aftertaste.

[0027] Example 2

[0028] Step 1, 2.7001 g of chitosan (degree of deacetylation 80%) containing 0.0134 mol of amino groups was dissolved in 150 mL of 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, 0.0023 mol of TEA and 0.0038 mol of BIBB were slowly added in turn, TEA and BIBB were dissolved in DMF to prepare 2.0% and 7.5% mass fraction solutions, respectively, after warming to room temperature, continue to stir for 30 h; Step 2, remove HBr and ammonium salt by washing with 800 mL of 1 M NaOH solution, 750 mL of 1 M HCl solution, 900 mL of distilled water in turn, the product was placed in a vacuum drying oven at 35℃ and dried for 7 h, and a modified chitosan-based macromolecular initiator was obtained; Step 3, 1.5 g of green peel essential oil and 0.0375 g of Tween80 dispersant were uniformly mixed, and an oil phase was formed after slow stirring for 6 min; Step 4, 1.5 g of modified chitosan-based macromolecular initiator was dissolved in 1% acetic acid aqueous solution to prepare a 7.0% mass fraction solution, 0.018 g of SDBS emulsifier was added and uniformly mixed, and a water phase was formed after slow stirring for 5 min; Step 5, use a high-speed homogenizer to shear 1.4761 g of oil phase and 2.5881 g of water phase at a speed of 18000 rpm for 75 s to form a stable O / W emulsion, and then pass high-purity nitrogen for 25 min to remove all dissolved oxygen; Step 6, under nitrogen protection, 0.0143 g of CuBr2 and 0.0199 g of PMDETA were added, PMDETA was dissolved in water to prepare a 8.5% mass fraction solution, 0.4330 g of DMAEMA monomer was slowly injected, and the system was mixed uniformly after continuous stirring, then 0.1144 g of sodium L-ascorbate was quickly added, and the reaction was continuously stirred for 30 h, the reaction temperature was maintained at 27℃, and the reaction was terminated after the system was exposed to air; Step 7, the microcapsules prepared by the reaction were centrifuged at a speed of 2000 rpm and washed with 1800 mL of distilled water for several times, and then freeze-dried at a temperature of-24℃ for 28 h to obtain double-responsive microcapsules loaded with green peel essential oil.

[0029] Step 8: Weigh 0.0606 g of dried green tangerine peel essential oil microcapsules and directly mix them into 178.3673 g of cigarette tobacco. After storing in a constant temperature and humidity chamber for 72 hours to balance the moisture, manually produce 15 samples and have a panel of 5 experts taste them. Each expert performs the test 3 times, and the results are compared with parallel samples. The results show that the encapsulation rate of the green tangerine peel essential oil microcapsules is 81.5±0.6%, the drug loading is 34.1±0.7%, the aroma of green tangerine peel essential oil blends well with the tobacco aroma, the taste is rich and layered, refreshing and mellow, which can improve the texture and comfort of cigarettes and reduce irritation and off-flavors.

[0030] Example 3

[0031] Step 1: Dissolve 1.4792 g of chitosan (85% degree of deacetylation) containing 0.0078 mol of amino groups in 100 mL of 1% acetic acid aqueous solution. Under the protection of ice water bath and nitrogen, slowly add 0.0014 mol of TEA and 0.0020 mol of BIBB dropwise. TEA and BIBB are dissolved in DMF respectively to prepare solutions with a mass fraction of 1.5% and 9.0%. After heating to room temperature, continue stirring the reaction for 31 h. Step 2: Wash with 800 mL of 1 M NaOH solution, 700 mL of 1 M HCl solution and 950 mL of distilled water to remove impurities. Place the product in a vacuum drying oven at 34℃ and dry for 8 h to obtain the modified chitosan-based macromolecular initiator. Step 3: Mix 1.25 g of bergamot essential oil and 0.0425 g of Span60 dispersant evenly, and stir slowly for 7 minutes to form the oil phase; Step 4: Dissolve 1.33 g of the modified chitosan-based macromolecular initiator in a 1% acetic acid aqueous solution to prepare a 10.0% mass fraction solution. Add 0.0136 g of sodium lignosulfonate and 0.0198 g of sodium lignocarboxylate emulsifier and mix evenly. Stir slowly for 6 min to form an aqueous phase. Step 5: Using a high-speed homogenizer, 0.8757 g of oil phase and 1.6884 g of aqueous phase are sheared at 24000 rpm for 35 s to form a stable O / W emulsion, and then high-purity nitrogen is introduced for 30 min. Step 6: Under nitrogen protection, add 0.0256 g of CuBr2 and 0.0216 g of PMDETA. Dissolve PMDETA in water to prepare a 5.5% (w / w) solution. Slowly inject 0.5825 g of DMAEMA monomer and stir continuously. After the system is mixed evenly, quickly add 0.1792 g of L-ascorbic acid sodium. Stir continuously for 32 h and maintain the reaction temperature at 28℃. After the reaction is completed, expose the system to air to terminate the reaction. Step 7, centrifuge the prepared microcapsules at a speed of 4000 rpm and wash with 1200 mL of distilled water for several times, and then freeze-dry at a temperature of -28℃ for 32 h to obtain the double-responsive microcapsules loaded with bergamot essential oil.

[0032] Step 8, 0.0933 g of dried bergamot essential oil microcapsules were directly mixed and added to 198.5773 g of cigarette tobacco, and then stored in a constant temperature and humidity box for 72 h to balance the water vapor. After that, 15 samples were manually rolled and smoked, and 5 experts were asked to taste and repeat 3 times. The results were as follows: the encapsulation efficiency of bergamot essential oil microcapsules was 53.3±0.2%, the drug loading was 25.4±0.6%, the bergamot essential oil aroma was rich, and the cigarette sweetness and softness were increased.

[0033] Example 4

[0034] Step 1, 5.6599 g of chitosan (90% deacetylation) containing 0.0316 mol of amino groups was dissolved in 175 mL of 1% acetic acid aqueous solution. Under the protection of ice water bath and nitrogen, 0.0044 mol of TEA and 0.0092 mol of BIBB were slowly added dropwise, and TEA and BIBB were dissolved in DMF to prepare 4.5% and 5.0% mass fraction solutions, respectively. After warming to room temperature, the stirring was continued for 20 h; Step 2, sequentially washed with 900 mL of 1 M NaOH solution, 950 mL of 1 M HCl solution, and 1000 mL of distilled water to remove impurities. The product was placed in a vacuum drying oven at 40℃ for 6.5 h to obtain the modified chitosan-based macromolecular initiator; Step 3, 2.5 g of orange peel essential oil, 0.029 g of Span40, and 0.041 g of Tween60 dispersant were uniformly mixed to form an oil phase after slow stirring for 6 min; Step 4, 2.0 g of modified chitosan-based macromolecular initiator was dissolved in 1% acetic acid aqueous solution to prepare a 9.0% mass fraction solution. 0.026 g of SDBS emulsifier was uniformly mixed and stirred slowly for 4 min to form an aqueous phase; Step 5, use a high-speed homogenizer to shear 2.4073 g of oil phase and 4.4535 g of aqueous phase at a speed of 11000 rpm for 90 s to form a stable O / W emulsion, and then pass high-purity nitrogen for 30 min; Step 6, under nitrogen protection, 0.0168 g of CuBr2 and 0.0257 g of PMDETA were added, PMDETA was dissolved in water to form a solution with a mass fraction of 9.0%, 0.9887 g of DMAEMA monomer was slowly injected, stirring was continued, after the system was uniformly mixed, 0.0840 g of sodium L-ascorbate was quickly added, stirring was continued for 35 h, the reaction temperature was maintained at 22°C, after the reaction was completed, the system was exposed to air to terminate the reaction; Step 7, the prepared microcapsules were centrifuged at a speed of 2400 rpm and washed with 2000 mL of distilled water for multiple times, after freeze-drying at a temperature of -25°C for 19 h, the double-responsive microcapsules loaded with orange peel essential oil were obtained.

[0035] Step 8, 0.0600 g of dried orange peel essential oil microcapsules were directly mixed and added into 166.6752 g of cigarette tobacco, after storing in a constant temperature and humidity box for 72 h to balance the water vapor, 15 samples were manually rolled and smoked, 5 experts were invited to taste, each person repeated 3 times, and the parallel samples were compared. The results are as follows: the encapsulation efficiency of the orange peel essential oil microcapsules is 88.7±0.4%, the drug loading is 36.6±0.3%, the aroma of the orange peel essential oil is significant, the aroma quality is better, and the irritation can be reduced to improve the comfort.

[0036] Example 5

[0037] Step 1, 8.0779 g of chitosan (degree of deacetylation 95%) containing 0.0451 mol of amino groups was dissolved in 100 mL of 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, 0.0068 mol of TEA and 0.0135 mol of BIBB were slowly added dropwise, TEA and BIBB were dissolved in DMF to form solutions with a mass fraction of 1.8% and 8.0% respectively, after warming to room temperature, stirring was continued for 32 h; Step 2, sequentially washed with 1000 mL of 1 M NaOH solution, 1000 mL of 1 M HCl solution and 950 mL of distilled water to remove impurities, the product was placed in a vacuum drying box at 45°C for 7 h to obtain a modified chitosan-based macromolecular initiator; Step 3, 2.5 g of angelica essential oil and 0.075 g of Span80 dispersant were uniformly mixed to form an oil phase; Step 4, 3.0 g of the modified chitosan-based macromolecular initiator was dissolved in 1% acetic acid aqueous solution to form a solution with a mass fraction of 6.0%, 0.060 g of lignin carboxylate sodium emulsifier was uniformly mixed, and the water phase was formed after slow stirring for 4 min; Step 5, using a high-speed homogenizer, 2.3785 g of the oil phase and 3.4885 g of the water phase are sheared at a speed of 28000 rpm for 30 s to form a stable O / W emulsion, and then high-purity nitrogen is passed in for 40 min; Step 6, under the protection of nitrogen, 0.0082 g of CuBr2 and 0.0106 g of PMDETA dissolved in water (10%, W / W) are added, 0.4830 g of DMAEMA monomer is slowly injected, stirring is continued, after the system is uniformly mixed, 0.03280 g of sodium L-ascorbate is quickly added, stirring is continued for 36 h, the reaction temperature is maintained at 30℃, and after the reaction is completed, the system is exposed to air to terminate the reaction; Step 7, the microcapsules prepared by the reaction are centrifuged at a speed of 3700 rpm and washed with 1750 mL of distilled water for multiple times, and after freeze-drying at a temperature of -21℃ for 35 h, the double-responsive microcapsules loaded with angelica essential oil are obtained.

[0038] Step 8, 0.0491 g of the dried angelica essential oil microcapsules are directly mixed and added into 122.6528 g of cigarette tobacco, and after storing in a constant-temperature and constant-humidity box for 72 h to balance the water vapor, 15 samples are manually rolled and smoked, 5 experts are invited to taste, each person repeats 3 times, and the parallel samples are compared. The results are as follows: the encapsulation rate of the angelica essential oil microcapsules is 64.6±0.5%, the drug loading is 33.7±0.3%, the angelica essential oil has a prominent medicinal herb aroma and a unique fragrance, and can meet the taste standard of specific people.

[0039] The photos of the plant essential oil-loaded microcapsules prepared in Examples 1-3 are as shown in Figure 1 The three kinds of plant essential oil microcapsules all have a round morphology, good mechanical strength and good monodispersity, indicating that the method selected in the application has good encapsulation effect on various plant essential oils and strong applicability.

[0040] The photos of the orange peel essential oil microcapsules prepared in Example 1 and Example 4 with different oil phase / water phase ratios are as shown in Figure 2 It is shown that the method selected in the application has a large range of applicable oil / water ratios, and plant essential oil microcapsules with ideal encapsulation and drug loading effects can be obtained within a suitable range.

[0041] The photos of the freeze-dried bergamot essential oil microcapsules prepared in Example 3 are as shown in Figure 3 The microcapsules in water have good dispersity, uniform size and complete shape, indicating that the reaction is fully complete and no local adhesion between the capsule shells occurs.

[0042] The FT-IR spectra of the chitosan-based macroinitiator prepared in Example 1 and the shell of the reacted empty microcapsule are shown in Fig. 1. Figure 4 The peak at 1740 cm -1 The signal intensity at 1740 cm -1 in the FT-IR spectrum of the shell of the reacted empty microcapsule is obviously higher than that of the modified chitosan-based macroinitiator, indicating that there are more C=O groups due to the introduction of PDMAEMA. The above observation proves that the reaction occurs and the modified chitosan-based macroinitiator reacts with PDMAEMA to form the shell.

[0043] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0044] It should be noted that the above merely illustrates the technical idea of the present application and cannot limit the protection scope of the present application. For those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements all fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a double-responsive flavor microcapsule for a cigarette, characterized by, The method comprises the following steps: Step 1, dissolve chitosan in 1% acetic acid aqueous solution, under ice water bath and nitrogen protection, slowly add triethylamine solution and 2-bromoisobutyryl bromide solution dissolved in N, N-dimethylformamide in turn, and then warm to room temperature, continue to stir the reaction; Step 2, after the reaction, sequentially wash with 1 M NaOH solution, 1 M HCl solution and distilled water to remove HBr and ammonium salt, and then dry the product in a vacuum drying box to obtain a modified chitosan-based macromolecular initiator; Step 3, uniformly mix natural plant essential oil and dispersant to form an oil phase; Step 4, dissolve the modified chitosan-based macromolecular initiator in 1% acetic acid aqueous solution, and then uniformly mix with an emulsifier to form an aqueous phase; Step 5, use a high-speed homogenizer to shear the oil phase and the aqueous phase to form a stable O / W emulsion, and then introduce high-purity nitrogen to remove all dissolved oxygen; Step 6, under nitrogen protection, add an aqueous solution of catalyst CuBr2 and ligand pentamethyl diethylene triamine, slowly inject dimethylaminoethyl methacrylate monomer, continuously stir, quickly add L-sodium ascorbate reducing agent after the system is uniformly mixed, continuously stir the reaction, and then expose the system to air to terminate the reaction, to obtain plant essential oil loaded double-responsive perfume microcapsules; Step 7, centrifuge the double-responsive perfume microcapsules, wash with distilled water for multiple times, and then freeze-dry to obtain double-responsive perfume microcapsules.

2. The method of claim 1, wherein the method is characterized by, In step 1, the molar ratio of the glucosamine unit of chitosan, triethylamine and 2-bromoisobutyryl bromide is 1:0.1-0.2:0.2-0.3, the mass ratio of chitosan to 1% acetic acid aqueous solution is 1:10-20, the mass fraction of triethylamine in the triethylamine solution is 1.0%-5.0%, the mass fraction of 2-bromoisobutyryl bromide in the 2-bromoisobutyryl bromide solution is 5.0%-10.0%, and the stirring reaction time is 15-36 h.

3. The method of claim 1, wherein the method is characterized by, In step 3, the mass ratio of natural plant essential oil to dispersant is 1:0.01-0.05, the natural plant essential oil is one or more of green peel essential oil, orange peel essential oil, orange red essential oil, day day flower essential oil, bergamot essential oil, white peony essential oil, sea buckthorn essential oil and green fruit essential oil, and the dispersant is one or more of Tween 40, Tween 60, Tween 80, Span 40, Span 60 and Span 80.

4. The method of claim 1, wherein the method is characterized by, In step 4, the mass ratio of the modified chitosan-based macromolecular initiator to the emulsifier is 1:0.01-0.05, the mass fraction of the modified chitosan-based macromolecular initiator in the aqueous phase is 5.0%-10.0%, and the emulsifier is one or more of sodium dodecylbenzenesulfonate, sodium lignosulfonate and sodium lignosulfonate.

5. The method of claim 1, wherein the method is characterized by, In step 5, the mass ratio of the oil phase to the aqueous phase is 3:4-6, the rotation speed of the high-speed homogenizer is 10000-30000 rpm, and the time is 30-300 s.

6. The method of claim 1, wherein the method is characterized by, In step 6, the mass ratio of dimethylaminoethyl methacrylate, modified chitosan-based macromolecular initiator, CuBr2, and pentamethyldiethylenetriamine is 1:0.25-1.00:0.01-0.05:0.01-0.05, the mass fraction of pentamethyldiethylenetriamine in the pentamethyldiethylenetriamine solution is 5.0%-10.0%, the mass ratio of CuBr2 and sodium L-ascorbate is 1:1-10, the reaction temperature is 20-30°C, and the reaction time is 15-36 h.

7. A double-responsive flavor microcapsule for cigarettes prepared by the preparation method of any one of claims 1-6.

8. The double-responsive flavor microcapsule for cigarettes of claim 7 for use in cigarettes.

9. Use of the dual responsive flavor microcapsule according to claim 8 in a cigarette, characterized in that, The double-responsive flavor microcapsule is added to the tobacco section of the cigarette by spraying or direct mixing.

10. Use of the dual responsive flavor microcapsule according to claim 9 in a cigarette, characterized in that, The mass ratio of the double-responsive flavor microcapsule in the tobacco section of the cigarette is 0.01%-0.05%.

Images