Preparation method and application of tobacco stem Maillard spice with low humidity and free radical inhibition

Abstract

The invention relates to the technical field of tobacco flavor, in particular to a preparation method and application of tobacco stem Maillard flavor with low humidity and free radical inhibition. The method comprises the following specific steps: taking tobacco stems, mixing different types of amino acids and an anti-tarnishing agent in deionized water, uniformly spraying the mixture on the surfaces of the tobacco stems, carrying out Maillard reaction, and cooling to obtain the tobacco stems after the Maillard reaction. Soaking with pure water, boiling, condensing and refluxing; and after filtering, decompressing and concentrating the filtrate to obtain a tobacco stem extraction concentrated solution for later use. Through optimization of a low-humidity Maillard reaction process and cooperative regulation and control of the free radical inhibitor, reaction intermediate free radicals are effectively removed, oxidation chain transmission is blocked, the content of reactive oxygen species in a final product is reduced, and the color stability and aroma quality of the tobacco stem perfume are remarkably improved. A new technical path is provided for high-value utilization of the tobacco stems, and the method has important application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco flavors, and in particular to a method for preparing tobacco stem Maillard flavors with low humidity and synergistic free radical inhibition and application thereof. Background Art

[0002] As my country's economy shifts from high-speed growth to high-quality development, in order to effectively safeguard the interests of consumers, reducing tar and reducing harm in cigarettes has been placed in a more prominent position. How to reduce tar without reducing aroma has become an important issue in the tobacco industry. Developing new natural tobacco flavors is the key to solving this problem.

[0003] Tobacco stem byproducts produced during tobacco processing account for about 25% of the total raw materials, and their efficient utilization is an important issue for the sustainable development of the tobacco industry. In the traditional tobacco processing process, tobacco stems usually undergo a series of mechanical treatments, including reorganization or extraction steps, to prepare tobacco products such as reconstituted tobacco leaves and stem shreds. However, the products prepared by this method often have some problems, such as insufficient aroma and obvious characteristics of woody smell, which affect the overall quality of the product and the smoking experience of consumers. In recent years, the preparation technology of tobacco stem flavors based on the Maillard Reaction has gradually attracted attention. It can generate aroma substances such as pyrazine and furan through the thermal reaction of amino acids and reducing sugars, which can theoretically improve the sensory quality of tobacco stem products. However, studies have found that the Maillard reaction of tobacco stems under the conventional water extract system has significant limitations: on the one hand, tobacco stems are rich in cellulose, hemicellulose and lignin, and the water extract contains a large amount of polysaccharides, which are prone to excessive condensation to form melanoidins under high temperature and high humidity conditions, resulting in a darker color and lower transmittance of the reaction products, which directly affects their applicability in light-colored cigarette paper or sheets; on the other hand, small molecules such as furfural and acrylamide produced in the later stage of the Maillard reaction are irritating and may aggravate the generation of free radicals during cigarette combustion, leading to an increased sense of dryness in the smoke and a noticeable burning sensation in the throat, which reduces consumer acceptance.

[0004] Further studies have shown that the adverse sensory performance of tobacco stem Maillard products is closely related to the uncontrollability of the reaction path. Under high moisture conditions, the Maillard reaction tends to undergo deep condensation, which promotes the massive production of melanoidins while accelerating free radical chain reactions to form reactive oxygen species such as hydroxyl radicals (·OH) and superoxide anions (O2-). These free radicals not only reduce the stability of the flavors, but also synergize with smoke components during the combustion process to produce harmful aldehydes and ketones, affecting the comfort of smoking.

[0005] Therefore, how to directionally regulate the Maillard reaction pathway while inhibiting excessive melanoidin production and free radical accumulation has become a key issue in improving the quality of tobacco stem flavors. Summary of the Invention

[0006] Based on at least one of the above technical problems, the present invention proposes a new type of tobacco stem flavor, constructs an efficient extraction, purification and preparation method for tobacco stem flavor, which has a certain promoting effect on meeting social needs, reducing production costs and increasing the market value of tobacco stems, and also lays a foundation for the further development and application of tobacco stems.

[0007] In view of this, the present invention proposes a preparation method and application of a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, wherein the tobacco stems used in the present invention are from Hongta Liaoning Tobacco Co., Ltd.

[0008] A tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, the preparation method comprising the following steps:

[0009] 1) Weigh a certain amount of tobacco stems, mix different kinds of amino acids and anti-discoloration agents in deionized water, and evenly spray them on the surface of the tobacco stems; 2) Perform Maillard reaction on the tobacco stems treated in step 1), and cool to room temperature after the reaction to obtain the treated tobacco stems; 3) Soak the tobacco stems treated in step 2) in an aqueous solution, perform extraction by condensation reflux, filter and then concentrate under reduced pressure to a fixed mass ratio to obtain a concentrated solution of tobacco stem extract for use; 4) Refrigerate the above concentrated solution of tobacco stem extract to obtain a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition.

[0010] For the above-mentioned tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, in step 1), the amino acid is one or more of histidine, glutamic acid, proline, aspartic acid, and theanine.

[0011] For the above-mentioned tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, in step 1), the anti-discoloration agent is one or more of vitamin C, tea polyphenols, glutathione, curcumin, and transaminase.

[0012] For the above-mentioned tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, in step 1), the concentration of the amino acid is 0.5 - 2.5%, and the concentration of the anti-discoloration agent is 0.5 - 2.5%.

[0013] For the above-mentioned tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, in step 2), the temperature of the Maillard reaction is 110 - 150 °C, and the reaction time is 1 - 5 h.

[0014] For the above-mentioned preparation method and application of a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, in step 2), the temperature of the Maillard reaction is 130 °C, and the reaction time is 2 h.

[0015] In the above method for preparing and applying a tobacco stem Maillard spice with low humidity synergistic free radical inhibition, in step 3), the soaking is for 0.5 h, and the condensation reflux is boiling at 100 - 140 °C for 1 h.

[0016] In the above method for preparing and applying a tobacco stem Maillard spice with low humidity synergistic free radical inhibition, in step 3), the soaking is for 0.5 h, and the condensation reflux is boiling at 110 °C for 1 h.

[0017] In the above method for preparing and applying a tobacco stem Maillard spice with low humidity synergistic free radical inhibition, in step 3), the material - liquid ratio of tobacco stem to pure water is 1:2 - 1:10, and extraction is carried out 2 times. The obtained concentrated solution is one - fourth of the mass of the original solution.

[0018] In the above method for preparing and applying a tobacco stem Maillard spice with low humidity synergistic free radical inhibition, in step 3), the material - liquid ratio of tobacco stem to pure water is 1:6, and extraction is carried out 2 times. The obtained concentrated solution is one - fourth of the mass of the original solution.

[0019] In the above tobacco stem Maillard spice with low humidity synergistic free radical inhibition, in step 4), the refrigeration temperature of the tobacco stem extract is - 50 - 10 °C, and the refrigeration time is 4 - 48 h.

[0020] Application of the above tobacco stem Maillard spice with low humidity synergistic free radical inhibition in the preparation of cigarettes.

[0021] In the above application, the above cigarette products are cigarettes, low - grade flue - cured tobacco leaves, and cigar tobacco leaves.

[0022] The obtained tobacco stem Maillard spice is treated with ethanol, configured to 2 mg / mL, and after filtration through a filter membrane, it is used for sensory evaluation.

[0023] Referring to GB / T 14454.2 - 2008 "Method for the Evaluation of the Aroma of Spices", 8 professional sensory assessors are organized to conduct olfactory evaluation of the spice by the flavor profile method. Scoring is carried out from 5 aspects: sweet aroma, caramel aroma, balsamic aroma, fruity aroma, and baking aroma. The maximum score for each aspect is 5 points, and the minimum score is 0 points. The result is the average value of the scores of 8 sensory assessors.

[0024] The sample is dissolved in CH2Cl2, and after filtration through a filter membrane, it is subjected to GC - MS analysis;

[0025] The tobacco stem extract was formulated into a 2 mg / mL solution with 70% anhydrous ethanol. 5 μL of the solution was evenly injected into the blank cigarette tobacco section by the central injection method to prepare the test cigarettes. The cigarettes injected with an equal amount of 70% ethanol were used as the control. After the cigarettes were equilibrated and adsorbed for 48 h under constant temperature and humidity (temperature 20 ± 2 °C, relative humidity 60 ± 5%), sensory evaluation was carried out by 8 professional smokers, and the results were averaged.

[0026] The tobacco stem extract spice mainly contains flavor components such as alcohols, aldehydes and ketones, as well as the key flavor precursor component DDMP.

[0027] Through the optimization of the low-humidity Maillard reaction process and the synergistic regulation of free radical inhibitors (anti-discoloration agents), the present invention effectively scavenges free radicals of reaction intermediates, blocks the oxidation chain transfer, reduces the content of reactive oxygen species in the end products, and significantly improves the color stability and aroma quality of the tobacco stem spice. The present invention provides a new technical route for the high-value utilization of tobacco stems and has important application prospects.

[0028] The present invention provides a preparation and application method of a tobacco stem Maillard spice, which has the following beneficial effects:

[0029] 1. By carrying out aqueous solution condensation reflux treatment on tobacco stems at 110 °C, various active ingredients therein can be effectively dissolved and extracted. This method is particularly aimed at the aroma substances in tobacco stems, such as methyl palmitate and neophytadiene, etc., and selectively releases these key aroma components through the high-temperature water swelling effect. In addition, the design of condensation reflux helps to reduce the loss of volatile components and ensure the stability of thermosensitive substances. This process uses water as a green solvent, and by adjusting the pH value or adding a small amount of ethanol and other azeotropic auxiliary means, the extraction efficiency of non-polar components can be further improved. This technology is simple to operate, low in cost, and suitable for large-scale production. The extract can be directly applied to tobacco flavoring or the spice industry, significantly improving the utilization rate of tobacco stem resources.

[0030] 2. The spice of the tobacco stem extract mainly contains flavor components such as alcohols, aldehydes and ketones, as well as the key flavor precursor component DDMP.

[0031] 3. The spice, preparation and impurity removal process of the tobacco stem extract provided by the present invention are simple, convenient for industrial production applications, easy to operate when used, and do not require special treatment.

[0032] 4. The tobacco stem Maillard spice prepared by the present invention can be applied in cigarettes, low-grade flue-cured tobacco leaves and cigar tobacco leaves. The applicable raw materials have a wide range, and it is suitable for large-scale production.

[0033] The tobacco stem Maillard spice can be applied in the quality improvement of tobacco products and also lays a foundation for the next-step industrial development. Description of the Drawings

[0034] Figure 1 Shows the olfactory evaluation scores of amino acids, amino acid concentrations, anti-discoloration agents, and anti-discoloration agent concentrations that are most suitable for tobacco stem treatment in Examples 2-5 of the present invention.

[0035] Figure 2 Shows the olfactory evaluation aroma profile diagram of the spices obtained at different Maillard reaction temperatures in Example 6 of the present invention.

[0036] Figure 3 Shows the olfactory evaluation aroma profile diagram of the spices obtained at different Maillard reaction times in Example 7 of the present invention.

[0037] Figure 4 Shows the olfactory evaluation scores of the tobacco stem leaching liquid ratio after Maillard reaction at different levels in Example 8 of the present invention.

[0038] Figure 5 Shows the olfactory evaluation scores of the boiling reflux temperature of the tobacco stems after Maillard reaction at different levels in Example 8 of the present invention.

[0039] Figure 6 Shows the color difference comparison effect diagram of the tobacco stem extract obtained by adding different concentrations of vitamin C in Example 10 of the present invention. Detailed implementation manners

[0040] In order to more clearly understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0041] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0042] Example 1 Maillard spices for tobacco stems with low humidity and free radical inhibition

[0043] Lay the tobacco stems flat and let them air-dry naturally in a cool place for 7 days. Then place them in an oven at 50 °C and dry for 30 min. Weigh a certain amount of tobacco stems. Mix 0.5% proline and 2.0% vitamin C in deionized water and evenly spray it on the surface of the tobacco stems. Place the treated tobacco stems in a closed reactor and carry out the Maillard reaction at 130 °C for 2 h. After the reaction, cool to room temperature to obtain the tobacco stems after the Maillard reaction. According to the solid-liquid ratio of 1:6, soak the reacted tobacco stems in pure water for 0.5 h, then carry out boiling and condensation reflux extraction at 110 °C, keep it in a slightly boiling state for 1 h, and extract twice to obtain the tobacco stem extract. After filtration, concentrate the filtrate under reduced pressure to obtain the concentrated tobacco stem extract. The concentration ratio is that 100 g of the filtrate is concentrated into 25 g of the concentrated liquid for standby, denoted as sample B.

[0044] Example 2

[0045] According to the method described in Example 1, histidine, glutamic acid, aspartic acid, and theanine were used to replace proline respectively to prepare tobacco stem Maillard spices, and they were made into 2 mg / mL solutions with absolute ethanol, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The scoring results of each item are shown in Table 1. The total score is as Figure 1 shown in (A) below.

[0046] Table 1 Olfactory evaluation results of spices obtained with different amino acids

[0047]

[0048] Example 3

[0049] According to the method described in Example 1, 1.0% proline, 1.5% proline, 2.0% proline, and 2.5% proline were used to replace 0.5% proline respectively to prepare tobacco stem Maillard spices, and they were made into 2 mg / mL solutions with absolute ethanol, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The scoring results of each item are shown in Table 2, and the total score is as Figure 1 shown in (C) below.

[0050] Table 2 Olfactory evaluation results of spices obtained with different proline concentrations

[0051]

[0052]

[0053] Example 4

[0054] According to the method described in Example 1, tea polyphenols, glutathione, curcumin, and transaminase were used to replace vitamin C respectively to prepare tobacco stem Maillard flavor, which was formulated into a 2 mg / mL solution with absolute ethanol, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The results of each score are shown in Table 3, and the total score is as Figure 1 shown in (B) therein.

[0055] Table 3 Olfactory evaluation results of flavors obtained with different anti-discoloration agents

[0056]

[0057] Example 5

[0058] According to the method described in Example 1, 0.5% vitamin C, 1.0% vitamin C, 1.5% vitamin C, and 2.5% vitamin C were used to replace 2.0% vitamin C respectively to prepare tobacco stem Maillard flavor, which was formulated into a 2 mg / mL solution with absolute ethanol, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The results of each score are shown in Table 4, and the total score is as Figure 1 shown in (D) therein.

[0059] Table 4 Olfactory evaluation results of flavors obtained with different concentrations of vitamin C

[0060]

[0061] Example 6

[0062] According to the method described in Example 1, 110 °C, 120 °C, 140 °C, and 150 °C were used to replace 130 °C for Maillard reaction to prepare the concentrated solution, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The results of each score Figure 2 are shown.

[0063] Example 7

[0064] According to the method described in Example 1, reaction times of 1 h, 3 h, 4 h, and 5 h were used to replace 2 h for Maillard reaction to prepare the concentrated solution, and scored according to GB / T 14454.2-2008 "Method for Evaluating the Aroma of Spices". The results of each score Figure 3 are shown.

[0065] Example 8

[0066] The tobacco stems after the Maillard reaction were soaked in aqueous solutions with a material-liquid ratio of 1:2, 1:4, 1:6, 1:8, and 1:10 for 0.5 h respectively. Then, they were boiled under reflux with condensation at 100 °C to 140 °C, maintained in a slightly boiling state for 1 h, and the filtrate was obtained by filtering the residue. Subsequently, the filtrate was concentrated under reduced pressure at 50 °C, and the concentration ratio was that 100 g of the filtrate was concentrated into 25 g of the concentrated solution.

[0067] The concentrated solution was treated with 70% ethanol, configured to 2 mg / mL, filtered through a membrane filter, and then the above solution was evenly injected into the 0# blank cigarettes of the Technology R & D Center of Hongta Liaoning Tobacco Co., Ltd. by the central injection method, 5 μL was injected into each cigarette, and the aroma evaluation was carried out. The results are as Figure 4 、 Figure 5 shown. The results show that when the tobacco stem powder was soaked in aqueous solutions with a material-liquid ratio of 1:2, 1:4, 1:6, 1:8, and 1:10 and the boiling temperature was lower than 110 °C, the improvement effect of the woody off-flavor was not obvious and the aftertaste was slightly uncomfortable. When the material-liquid ratio exceeded 1:6 and the temperature was higher than 110 °C, the extraction treatment was excessive. The woody off-flavor was improved to some extent, but the aroma quantity decreased, and there was slightly stale and protein off-flavor. Therefore, the preferred process parameters are a material-liquid ratio of 1:6 and a temperature of 110 °C.

[0068] Comparative Example 1

[0069] The tobacco stems were laid flat and naturally air-dried in a cool place for 7 days, then dried in an oven at 50 °C for 30 min, and deionized water was evenly sprayed on the surface of the tobacco stems; the treated tobacco stems were placed in a closed reaction kettle and subjected to the Maillard reaction at 130 °C for 2 h. After the reaction, it was cooled to room temperature to obtain the tobacco stems after the Maillard reaction. According to the material-liquid ratio of 1:6, the reacted tobacco stems were soaked in pure water for 0.5 h, and then boiled under reflux with condensation at 110 °C for extraction, maintaining a slightly boiling state for 1 h, and extracted twice to obtain the tobacco stem extract. After filtration, the filtrate was concentrated under reduced pressure to obtain the concentrated tobacco stem extract, and the concentration ratio was that 100 g of the filtrate was concentrated into 25 g of the concentrated solution for standby, denoted as Sample A.

[0070] Analysis of the flavor components of the tobacco stem extract spice in Example 9

[0071] 10 mL of the tobacco stem extract was added with an equal volume of dichloromethane, and after extraction and liquid separation, the extraction was repeated once. The organic phases were combined and concentrated to 1.0 mL, and 100 μL of the ethyl phenylacetate internal standard solution (1 mg / mL) was added for GC-MS analysis.

[0072] GC conditions: Agilent 7890B-5977 (30 m × 250 μm i.d. × 0.25 μm d.f.) chromatographic column; injection port temperature 250 °C; carrier gas He; column flow rate 1 mL / min; temperature programming, initial temperature 50 °C, held for 4 min, heated to 250 °C at 2 °C / min, held for 6 min; injection volume 1 μL; split ratio 5:1.

[0073] MS conditions: ionization mode electron impact ionization source (EI); transfer line temperature 280 °C; ion source temperature 230 °C; quadrupole temperature 150 °C; ionization energy 70 eV; solvent delay 4 min; scan mode MRM.

[0074] The results are shown in Table 5. The results indicate that the Maillard reaction characteristic components such as DDMP and HMF are present in relatively high contents in the spices extracted from tobacco stems after Maillard reaction. Among them, phytol has a fresh aroma, 2-acetylpyrrole has a roasted aroma, methyl palmitate has the aroma of iris with oil and wax, and linoleic acid has a coconut aroma, etc., which can enrich the fruity and fresh aromas of cigarettes, soften the smoke, and reduce the irritation of cigarettes. Phytol is the component with the highest content among the neutral volatiles in tobacco, can directly enter the smoke, has the functions of reducing irritation and mellowing the smoke, and is the source of the fresh aroma of the smoke.

[0075] Table 5 GC-MS flavor component analysis of tobacco stem spices

[0076]

[0077]

[0078] Note: Sample A is the Maillard reaction sample of the tobacco stem extract without adding amino acids and exogenous inhibitors, obtained from Comparative Example 1; Sample B is the Maillard reaction product after adding exogenous amino acids and exogenous inhibitors, obtained from Example 1.

[0079] Color difference analysis of the spices from the tobacco stem extract in Example 10

[0080] Through the color difference analysis of the tobacco stem extract, the research results clearly show that when 2% vitamin C is added during the Maillard reaction, a significant change can be observed: as the concentration of vitamin C increases, the color of the extract becomes lighter, as Figure 4As shown. In addition, when the addition amount of vitamin C is 2%, vitamin C not only visually improves the color of the tobacco extract, but also has a positive impact on the sensory evaluation quality. The smoking evaluation results show that the addition of vitamin C not only optimizes the aroma level, but also significantly reduces the irritation, making the smoking process more gentle and the overall sensory evaluation score significantly improved. This dual effect of vitamin C not only enhances the market competitiveness of tobacco products, but also meets the dual needs of current consumers for health and quality, providing new ideas for the innovative development of the tobacco industry.

[0081] Example 11 Cigarette Flavoring Application

[0082] The Maillard reaction samples of tobacco stem extract without the addition of amino acids and exogenous inhibitors (Sample A obtained in Comparative Example 1) and the Maillard reaction products after treatment with exogenous amino acids and exogenous inhibitors (Sample B obtained in Example 1) were respectively applied to cigarette flavoring, with unflavored cigarettes as the control (blank group). Samples A and B were treated with 70% ethanol and configured to 2 mg / mL. After filtration through a filter membrane, the above solutions were evenly injected into the 0# blank cigarettes of the Technology R & D Center of Hongta Liaoning Tobacco Co., Ltd. using the central injection method, with 5 μL injected into each cigarette, and sensory evaluation was carried out. The results are shown in Table 6. The sensory evaluation results show that after Maillard treatment and the addition of exogenous amino acids and exogenous inhibitors, the sweetness of the cigarette is significantly improved, the aroma richness is enhanced, there is a mellow feeling, the irritation is significantly reduced, the off-odor is alleviated, and the usability is increased.

[0083] Table 6 Sensory Evaluation Scores of Flavors

[0084]

[0085] In summary, the present invention proposes a Maillard spice for tobacco stems with low humidity and free radical inhibition, constructs a preparation process of condensing and refluxing tobacco stem spices and an efficient extraction and impurity removal process, which has a certain promoting effect on meeting social needs, reducing production costs, and increasing the market value of tobacco stems, and also lays a foundation for the further development and application of tobacco stems.

[0086] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition, characterized in that: The preparation method comprises the following steps: 1) Weigh a certain amount of tobacco stems, mix different types of amino acids and anti-discoloration agents in deionized water, and spray evenly on the surface of the tobacco stems; 2) subjecting the treated tobacco stems in step 1) to a Maillard reaction, and cooling to room temperature after the reaction to obtain treated tobacco stems; 3) soaking the tobacco stems treated in step 2) in a pure aqueous solution, condensing and refluxing for extraction, filtering and concentrating under reduced pressure to obtain a tobacco stem extract concentrate with a fixed mass ratio for standby use; 4) Refrigerating the tobacco stem extract concentrate to obtain tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition.

2. The low-humidity synergistic free radical inhibition tobacco stem Maillard flavor according to claim 1, characterized in that: In step 1), the amino acid is one or more of histidine, glutamic acid, proline, aspartic acid, and theanine.

3. The low-humidity synergistic free radical inhibition tobacco stem Maillard flavor according to claim 1, characterized in that: In step 1), the anti-discoloration agent is one or more of vitamin C, tea polyphenols, glutathione, curcumin, and transaminase.

4. The low-humidity synergistic free radical inhibition tobacco stem Maillard flavor according to claim 1, characterized in that: In step 1), the concentration of the amino acid is 0.5-2.5%, and the concentration of the anti-discoloration agent is 0.5-2.5%.

5. The low-humidity synergistic free radical inhibition tobacco stem Maillard flavor according to claim 1, characterized in that: The Maillard reaction temperature in step 2) is 110-150° C., and the reaction time is 1-5 h.

6. The method for preparing a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition and its application according to claim 5, characterized in that: The Maillard reaction temperature in step 2) is 130° C. and the reaction time is 2 h.

7. The method for preparing a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition and its application according to claim 1, characterized in that: In step 3), the soaking is for 0.5 h, and the condensation reflux is boiling at 100-140° C. and maintained for 1 h.

8. The method for preparing a tobacco stem Maillard flavor with low humidity and synergistic free radical inhibition and its application according to claim 1, characterized in that: In step 3), the solid-liquid ratio of tobacco stems to pure water is 1:6, and extraction is performed twice. The obtained concentrated solution is one quarter of the mass of the original solution.

9. The tobacco stem Maillard flavoring with low humidity and synergistic free radical inhibition according to claim 1, characterized in that: The tobacco stem extract described in step 4) is refrigerated at a temperature of -50 to 10° C. and for a refrigeration time of 4 to 48 hours.

10. Use of the low-humidity synergistic free radical-inhibiting tobacco stem Maillard flavoring according to any one of claims 1 to 9 in the preparation of cigarette products.

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