A curing method for imparting an elegant woody aroma to tobacco

Abstract

The present application relates to a kind of imparting elegant woody aroma of tobacco curing method.The method comprises: tobacco harvesting;Tobacco is woven;Tobacco is prepared before curing;Four-stage curing process is used, the first segment is air-drying, then yellowing period, color fixing period and dry muscle period are controlled in turn, and the amount of wood and sawdust is controlled, i.e.to obtain a kind of imparting elegant woody aroma of tobacco curing method, the tobacco obtained by the method is the tobacco obtained by the aforementioned conditioning method.The present application imparts elegant woody aroma to tobacco during curing, and different woody aroma can be obtained according to the difference of the type of wood and sawdust used, which contributes significantly to the expansion of tobacco raw materials.

Description

Technical Field

[0001] This invention belongs to the field of tobacco curing technology, specifically relating to a curing method that imparts an elegant woody aroma to tobacco leaves. Background Technology

[0002] The foundation of tobacco leaf products lies in the diversity of tobacco leaf raw materials. Besides the type of tobacco leaf, the processing methods and techniques are crucial for creating this diversity. Currently, by employing various suitable processing techniques tailored to different tobacco varieties and ecological conditions cultivated in my country, a diverse range of high-quality tobacco leaves can be produced. Sun-cured and smoked tobacco are in relatively small demand in my country, resulting in limited production in a few regions. However, given the severe homogenization of tobacco leaves in my country's cigarette industry, there is an urgent need to expand research into tobacco leaf processing methods and techniques to promote innovation in the primary tobacco processing industry and drive high-quality development in my country's tobacco sector.

[0003] With the implementation of global tobacco control and ban policies, the structure of new tobacco products is rapidly adjusting towards diversification and smokeless production. These products include oral cigarettes, e-cigarettes, and heated tobacco products (heated cigarettes). Among them, heated cigarettes are considered a lower-harm option, possessing three main characteristics: no combustion required, virtually no tar, and the provision of nicotine. Therefore, targeted improvements in tobacco raw material type, variety, production, and processing, as well as research on the quality of raw tobacco leaves for heated cigarettes and the synergistic harm reduction mechanism, are currently a hot research topic.

[0004] Therefore, the present invention can provide a roasting method that imparts an elegant woody aroma to tobacco leaves. The resulting tobacco leaves with an elegant woody aroma can expand the supply of tobacco raw materials in my country and also have unique advantages as raw materials for heated cigarettes. Summary of the Invention

[0005] The first objective of this invention is to provide a roasting method that imparts an elegant woody aroma to tobacco leaves, and the second objective of this invention is the tobacco leaves obtained based on the first objective.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] The technical solution for achieving the first objective of this invention is:

[0008] A. Tobacco leaf harvesting: Harvest slightly overripe flue-cured tobacco leaves;

[0009] B. Standard for tobacco binding and loading: When binding and loading tobacco, the tobacco should be sparser than in conventional baking, maintaining a denser top and sparser bottom, gradually reducing the amount of tobacco by 2-3 rods to form a staggered and overlapping pattern, with the amount of tobacco loaded being 80% of that in conventional baking;

[0010] C. Preparations before curing: Prepare 3 to 4 stoves and place them on the floor of the curing barn. The height between the stoves and the lower layer of tobacco leaves should be about 2.5-3m.

[0011] D. Hanging: open the circulating fan of the curing barn, set to high speed, and hang the prepared tobacco leaves in the curing barn for 24-28 h until the tobacco leaves begin to turn yellow and wither;

[0012] E. Yellowing period: the yellowing period includes the pre-yellowing period, the mid-yellowing period, and the post-yellowing period. The circulating fan is kept at low speed throughout the yellowing period;

[0013] The pre-yellowing period is heated at a heating rate of 1℃ / h, the dry-bulb temperature is raised from room temperature to about 35℃, the wet-bulb temperature is adjusted from room temperature to about 33℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24-28 h until the tobacco leaves are three-fifths yellow. Wood and sawdust are used to fire the furnace during this stage;

[0014] The mid-yellowing period is then entered, which is still heated at a heating rate of 1℃ / h, the dry-bulb temperature is raised from room temperature to about 38℃, the wet-bulb temperature is adjusted from room temperature to about 35℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24-28 h until the tobacco leaves are yellow with green stems. The amount of sawdust is increased based on the pre-yellowing period, and the smoke concentration in the curing barn is increased. The post-yellowing period is then entered, which is still heated at a heating rate of 1℃ / h, the dry-bulb temperature is raised from room temperature to about 42℃, the wet-bulb temperature is adjusted from room temperature to about 36℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24-28 h until the tobacco leaves are fully yellow, and the leaves are soft and the veins are unbreakable. The amount of sawdust is further increased based on the mid-yellowing period, and the smoke concentration in the curing barn is further increased;

[0015] F. Color fixing period: the color fixing period includes the pre-color fixing period, the mid-color fixing period, and the post-color fixing period. The circulating fan is kept at high speed throughout the color fixing period;

[0016] The pre-color fixing period is heated at a heating rate of 0.5℃ / h after the end of the yellowing period, the dry-bulb temperature is raised to about 45℃, the wet-bulb temperature is adjusted to about 37℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24 h until the branches are fully yellow and the tips are curled;

[0017] The mid-color fixing period is then entered, which is still heated at a heating rate of 0.5℃ / h, the dry-bulb temperature is raised to about 48℃, the wet-bulb temperature is adjusted to about 37℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24 h until the tobacco leaves are small rolled tubes;

[0018] The post-color fixing period is then entered, which is still heated at a heating rate of 0.5℃ / h, the dry-bulb temperature is raised to about 54℃, the wet-bulb temperature is adjusted to about 38℃, and the dry-bulb and wet-bulb temperatures are stabilized for 24 h until the whole furnace is large rolled tubes;

[0019] G. Dry vein period: the dry vein period includes the pre-dry vein period and the post-dry vein period. The circulating fan is used at low speed in the pre-dry vein period and at high speed in the post-dry vein period;

[0020] The first segment is airing, then the drying parameters and the amount of wood and sawdust in the yellowing period, color fixing period and dry muscle period are controlled in turn, and the specific technical solutions are as follows:

[0021] Finally, the dry muscle late stage is entered, the fire is heated at a heating rate of 1.5 DEG C / h, the dry bulb temperature is increased to about 67 DEG C, the wet bulb temperature is adjusted to about 40 DEG C, the dry and wet bulb temperature is stabilized and baked for 30h, and the main vein of the whole furnace is dried, and the main vein is dried and stopped at low temperature, and the remaining wood and the biomass combustion machine can be used to complete the drying of the tobacco leaves.

[0022] The method for realizing the second object of the present application is: the tobacco leaves obtained by the baking method of the first object.

[0023] Compared with the prior art, the present application has at least the following beneficial effects:

[0024] The baking method for imparting elegant woody aroma to tobacco leaves provided by the present application is scientific and effective, the whole baking process is easy to operate and easy to understand, and the quality of the tobacco leaves obtained after baking is excellent, and the tobacco leaves have unique elegant woody aroma. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with examples, but the present application is not limited in any way by the examples, and any transformation or replacement based on the teaching of the present application belongs to the protection scope of the present application.

[0026] A baking method for imparting elegant woody aroma to tobacco leaves, comprising: tobacco leaf harvesting; tobacco leaf bundling and loading specification; preparation before loading and baking; adopting a four-stage baking process, the first stage is airing, then the drying parameters and the amount of wood and sawdust in the yellowing period, color fixing period and dry muscle period are controlled in turn, and the specific technical solutions are as follows:

[0027] A. Tobacco leaf harvesting: harvesting slightly overripe flue-cured tobacco fresh leaves, the slightly overripe flue-cured tobacco fresh leaves refer to harvesting the suitable tobacco leaves in the field for 3-5d more;

[0028] B. Tobacco leaf bundling and loading specification: the tobacco leaves are bundled and loaded more sparsely than conventional baking, the upper part is dense and the lower part is sparse, 2-3 bundles of tobacco leaves are gradually reduced, the tobacco leaves are formed in staggered and crossed manner, and the loading amount is 80% of the conventional baking, if the height of the bottom platform of the baking room is less than 2m, the bottom platform is not loaded with tobacco leaves;

[0029] C. Preparation before baking: 3-4 fire furnaces are prepared and placed on the ground of the baking room, the height between the fire furnace and the lower tobacco leaves is about 2.5-3m, if the height of the bottom platform of the baking room is less than 2m, the bottom platform is not loaded with tobacco leaves;

[0030] D. Hanging: open the circulating fan of the curing barn, set to high speed, and hang the prepared tobacco leaves in the curing barn for 24-28 h until the tobacco leaves begin to yellow and wither;

[0031] E. Yellowing period: the yellowing period includes pre-yellowing period, mid-yellowing period and post-yellowing period, and the circulating fan is kept at low speed during the whole yellowing period;

[0032] The pre-yellowing period is heated at a heating rate of 1℃ / h, the dry bulb temperature is raised from room temperature to about 35℃, the wet bulb temperature is adjusted from room temperature to about 33℃, and the dry and wet bulb temperatures are stabilized for 24-28 h until the tobacco leaves are three-fifths yellow. Wood and sawdust are used for heating in the stove during this stage;

[0033] Then the mid-yellowing period is entered, which is still heated at a heating rate of 1℃ / h, the dry bulb temperature is raised from room temperature to about 38℃, the wet bulb temperature is adjusted from room temperature to about 35℃, and the dry and wet bulb temperatures are stabilized for 24-28 h until the tobacco leaves are yellow with green stems. The amount of sawdust is increased and the smoke concentration in the curing barn is increased during this stage based on the pre-yellowing period;

[0034] Then the post-yellowing period is entered, which is still heated at a heating rate of 1℃ / h, the dry bulb temperature is raised from room temperature to about 42℃, the wet bulb temperature is adjusted from room temperature to about 36℃, and the dry and wet bulb temperatures are stabilized for 24-28 h until the tobacco leaves are fully yellow, the leaves are soft, and the veins are unbreakable. The amount of sawdust is continuously increased and the smoke concentration in the curing barn is further increased during this stage based on the mid-yellowing period. The tool for adding sawdust is a shovel. The amount of sawdust added is 1.5 kg each time during the pre-yellowing period, 2 kg each time during the mid-yellowing period, and 2.5 kg each time during the post-yellowing period;

[0035] F. Color fixing period: the color fixing period includes pre-color fixing period, mid-color fixing period and post-color fixing period, and the circulating fan is kept at high speed during the whole color fixing period;

[0036] The pre-color fixing period is heated at a heating rate of 0.5℃ / h after the end of the yellowing period, the dry bulb temperature is raised to about 45℃, the wet bulb temperature is adjusted to about 37℃, and the dry and wet bulb temperatures are stabilized for 24 h until the branches are fully yellow and the tips are curled;

[0037] Then the mid-color fixing period is entered, which is still heated at a heating rate of 0.5℃ / h, the dry bulb temperature is raised to about 48℃, the wet bulb temperature is adjusted to about 37℃, and the dry and wet bulb temperatures are stabilized for 24 h until the tobacco leaves are small rolled tubes;

[0038] Then the post-color fixing period is entered, which is still heated at a heating rate of 0.5℃ / h, the dry bulb temperature is raised to about 54℃, the wet bulb temperature is adjusted to about 38℃, and the dry and wet bulb temperatures are stabilized for 24 h until the whole stove is large rolled tubes. The amount of sawdust added is 2 kg each time during the color fixing period;

[0039] G. Dry stem period: dry stem period includes dry stem pre-stage and dry stem post-stage, the pre-stage uses low speed and the post-stage uses high speed;

[0040] Dry stem pre-stage is to increase the temperature at a rate of 1℃ / h after the end of the color fixing stage, to increase the dry bulb temperature to about 60℃, and to adjust the wet bulb temperature to about 39℃, to stabilize the dry and wet bulb temperature for 24h to dry more than one third of the main vein of the tobacco leaf, to open the biomass burner of the curing barn, which is a general burner of the curing barn, and to stop adding sawdust;

[0041] Finally, enter the dry stem post-stage, increase the temperature at a rate of 1.5℃ / h, increase the dry bulb temperature to about 67℃, adjust the wet bulb temperature to about 40℃, stabilize the dry and wet bulb temperature for 30h to dry the main vein of the whole furnace, and when checking the tobacco, mainly use low temperature area, and dry the main vein to stop fire, which can not add wood at this stage, and use the remaining wood and the burner to complete the drying of the tobacco leaf.

[0042] In steps E, F and G, the dry and wet bulb temperature of the curing barn and the temperature stabilization time are adjusted according to the state of the tobacco leaf, the addition of wood is gradually realized on the basis of ensuring that the temperature does not drop, the wood and sawdust used are wood with special aroma after burning, and the frequency of adding sawdust in steps E and F is once every 4h.

[0043] After the above steps, a tobacco leaf obtained by a curing method for imparting elegant woody aroma to tobacco leaf is obtained.

[0044] Example 1

[0045] A. Tobacco harvesting: K326 tobacco leaves slightly overripe were harvested in Wanqiao Town, Dali Prefecture for this experiment.

[0046] B. Loading tobacco: The harvested fresh tobacco leaves were loaded into the curing barn according to the loading amount of conventional curing.

[0047] C. Curing: The tobacco leaves were cured using the local main curing process.

[0048] Example 2

[0049] A method for imparting elegant woody aroma to tobacco leaf, comprising the following steps:

[0050] A. Tobacco harvesting: K326 tobacco leaves slightly overripe were harvested in Wanqiao Town, Dali Prefecture for this experiment.

[0051] B. Tobacco leaf coding and loading specification: The harvested fresh tobacco leaves were coded slightly thinner than conventional curing, and loaded into the curing barn at 80% of the loading amount of conventional curing.

[0052] C. Preparation before loading and curing: hanging: the coded tobacco leaves were hung in the curing barn for 26h to make the tobacco leaves in the curing barn begin to yellow and wither.

[0053] D. Yellowing Stage: The yellowing stage includes the early, middle, and late stages. Throughout the yellowing stage, the circulating fan maintains a low speed. In the early stage, the temperature is increased by 1℃ / h, raising the dry-bulb temperature from room temperature to about 35℃ and the wet-bulb temperature from room temperature to about 33℃. The dry and wet-bulb temperatures are stabilized for 26 hours until the tobacco leaves are about 30% yellow. During this stage, firewood and sawdust are used to fuel the fire in the stove. Then, in the middle stage of yellowing, the temperature is increased by 1℃ / h, raising the dry-bulb temperature from room temperature to about 38℃ and the wet-bulb temperature from room temperature to about 33℃. At around 35℃, stabilize the dry and wet bulb temperatures for 26 hours until the tobacco leaves turn from green stems to yellow leaves. During this stage, increase the amount of sawdust used compared to the early yellowing stage to increase the smoke concentration in the curing barn. Then, in the later yellowing stage, continue heating at a rate of 1℃ / h, raising the dry bulb temperature from room temperature to around 42℃ and the wet bulb temperature from room temperature to around 36℃. Stabilize the dry and wet bulb temperatures for 26 hours until the tobacco leaves are completely yellow, soften, and the veins cannot be broken. During this stage, continue increasing the amount of sawdust used compared to the middle yellowing stage to further increase the smoke concentration in the curing barn. Add 1.5kg of sawdust each time during the early yellowing stage, 2kg each time during the middle yellowing stage, and 2.5kg each time during the later yellowing stage.

[0054] E. Color Fixing Period: The color fixing period includes the early, middle, and late stages. Throughout the entire color fixing period, the circulating fan maintains a high speed. In the early stage, after the yellowing period, the temperature is increased at a rate of 0.5℃ / h to raise the dry bulb temperature to about 45℃ and the wet bulb temperature to about 37℃. The dry and wet bulb temperatures are stabilized for 24 hours until the veins are fully yellow and the tips and edges are curled. Then, in the middle stage, the temperature is increased at a rate of 0.5℃ / h to raise the dry bulb temperature to about 48℃ and the wet bulb temperature to about 37℃. The dry and wet bulb temperatures are stabilized for 24 hours until the tobacco leaves are rolled into small rolls. Then, in the late stage, the temperature is increased at a rate of 0.5℃ / h to raise the dry bulb temperature to about 54℃ and the wet bulb temperature to about 38℃. The dry and wet bulb temperatures are stabilized for 24 hours until the leaves are rolled into large rolls. 2kg of sawdust is added each time during the color fixing period.

[0055] F. Drying Period: The drying period includes the early and late stages. During this stage, the circulating fan uses a low speed in the early stage and a high speed in the later stage. In the early stage, after the color-fixing period, the fire is heated at a rate of 1℃ / h to raise the dry bulb temperature to about 60℃ and the wet bulb temperature to about 39℃. The dry and wet bulb temperatures are stabilized and the tobacco leaves are baked for 24 hours until more than one-third of the main vein is dry. At this stage, the biomass burner in the curing barn is turned on and the addition of sawdust is stopped. Finally, in the late stage of drying, the fire is heated at a rate of 1.5℃ / h to raise the dry bulb temperature to about 67℃ and the wet bulb temperature to about 40℃. The dry and wet bulb temperatures are stabilized and the tobacco leaves are baked for 30 hours until the main vein of the entire furnace is completely dry. When observing the tobacco, the low-temperature zone is the main focus. The fire is stopped when the main vein is dry. At this stage, no more firewood needs to be added. The remaining firewood and the burner are used to complete the drying of the tobacco leaves. In this embodiment, the firewood and sawdust used are Yunnan pine, which has a special aroma after burning.

[0056] Example 3

[0057] A roasting method that imparts an elegant woody aroma to tobacco leaves includes the following steps:

[0058] A. Tobacco leaf harvesting: Harvested slightly overripe fresh tobacco leaves of K326 planted in Wanqiao Town, Dali Prefecture, for this experiment.

[0059] B. Standard for tobacco binding and loading: The harvested fresh tobacco leaves are bound into bamboo poles with a slightly sparser binding than usual, and then loaded into the curing barn with 80% of the usual amount of tobacco.

[0060] C. Preparations before curing after loading tobacco: Hanging and drying: Hanging and drying involves hanging the woven tobacco leaves in the curing barn for 26 hours, allowing the tobacco leaves near the inside of the barn to begin to turn yellow and wither.

[0061] D. Yellowing Stage: The yellowing stage includes the early, middle, and late stages. Throughout the yellowing stage, the circulating fan maintains a low speed. In the early stage, the temperature is increased by 1℃ / h, raising the dry-bulb temperature from room temperature to about 35℃ and the wet-bulb temperature from room temperature to about 33℃. The dry and wet-bulb temperatures are stabilized for 26 hours until the tobacco leaves are about 30% yellow. During this stage, firewood and sawdust are used to fuel the fire in the stove. Then, in the middle stage of yellowing, the temperature is increased by 1℃ / h, raising the dry-bulb temperature from room temperature to about 38℃ and the wet-bulb temperature from room temperature to about 33℃. At around 35℃, maintain stable dry and wet bulb temperatures for 24-28 hours until the tobacco leaves turn from green stems to yellow leaves. During this stage, increase the amount of sawdust used compared to the early yellowing stage to increase the smoke concentration in the curing barn. Then, in the later yellowing stage, continue heating at a rate of 1℃ / h, raising the dry bulb temperature from room temperature to around 42℃ and the wet bulb temperature from room temperature to around 36℃. Stabilize the dry and wet bulb temperatures for 26 hours until the tobacco leaves are completely yellow, soften, and the veins cannot be broken. During this stage, continue increasing the amount of sawdust used compared to the middle yellowing stage to further increase the smoke concentration in the curing barn. Add 3kg of sawdust each time during the early yellowing stage, 4kg each time during the middle yellowing stage, and 5kg each time during the later yellowing stage.

[0062] E. Color Fixing Period: The color fixing period includes the early, middle, and late stages. Throughout the entire color fixing period, the circulating fan maintains a high speed. In the early stage, after the yellowing period, the temperature is increased at a rate of 0.5℃ / h to raise the dry-bulb temperature to approximately 45℃ and the wet-bulb temperature to approximately 37℃. The dry and wet-bulb temperatures are stabilized for 24 hours until the veins are fully yellow and the tips and edges are curled. Next, in the middle stage, the temperature is increased at a rate of 0.5℃ / h to raise the dry-bulb temperature to approximately 48℃ and the wet-bulb temperature to approximately 37℃. The dry and wet-bulb temperatures are stabilized for 24 hours until the tobacco leaves are rolled into small coils. Then, in the late stage, the temperature is increased at a rate of 0.5℃ / h to raise the dry-bulb temperature to approximately 54℃ and the wet-bulb temperature to approximately 38℃. The dry and wet-bulb temperatures are stabilized for 24 hours until the entire batch of tobacco leaves is rolled into large coils. 4 kg of sawdust is added each time during the color fixing period.

[0063] F. Drying Period: The drying period includes the early and late stages. During this stage, the circulating fan uses a low speed in the early stage and a high speed in the later stage. In the early stage, after the color-fixing period, the fire is heated at a rate of 1℃ / h to raise the dry bulb temperature to about 60℃ and the wet bulb temperature to about 39℃. The dry and wet bulb temperatures are stabilized and the tobacco leaves are baked for 24 hours until more than one-third of the main vein is dry. At this stage, the biomass burner in the curing barn is turned on and the addition of sawdust is stopped. Finally, in the late stage of drying, the fire is heated at a rate of 1.5℃ / h to raise the dry bulb temperature to about 67℃ and the wet bulb temperature to about 40℃. The dry and wet bulb temperatures are stabilized and the tobacco leaves are baked for 30 hours until the main vein of the entire furnace is completely dry. When observing the tobacco, the low-temperature zone is the main focus. The fire is stopped when the main vein is dry. At this stage, no more firewood needs to be added. The remaining firewood and the burner are used to complete the drying of the tobacco leaves. In this embodiment, the firewood and sawdust used are Yunnan pine, which has a special aroma after burning.

[0064] Experimental Example

[0065] The tobacco leaves obtained from Examples 1, 2, and 3 were subjected to sensory quality evaluation, and the results are as follows.

[0066] As shown in Table 1, compared with Example 1, Examples 2 and 3 impart an elegant woody aroma to the tobacco leaves while ensuring that the sensory evaluation scores are similar.

[0067] Compared with Example 1, the tobacco leaves obtained in Example 2 have a better aroma, with an added elegant woody aroma. The woody aroma is well-coordinated with other aromas, the tobacco aroma is smooth, and the overall sensory quality is significantly improved.

[0068] Compared with Example 1, the tobacco leaves obtained in Example 3 have slightly increased woody and spicy aromas, and the aroma is richer, but the aroma harmony is slightly worse, the spiciness is increased, and the overall sensory quality is reduced.

[0069] Table 1 Sensory Quality Evaluation of K326 Wood-Smoked Tobacco Leaves from Wanqiao Town, Dali Prefecture

[0070]

[0071]

[0072] Although the invention has been described herein with reference to illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of the disclosure and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A method for roasting tobacco leaves to impart an elegant woody aroma, characterized in that: Includes the following steps: Tobacco leaf harvesting; tobacco binding and packing specifications; preparation before curing after packing; a four-stage curing process is adopted, the first stage is hanging, and then the curing parameters and the amount of firewood and sawdust are controlled in sequence during the yellowing period, color fixing period and dry rib period. The specific technical solution is as follows: A. Tobacco leaf harvesting: Harvest slightly overripe flue-cured tobacco leaves; B. Tobacco Bundling and Loading Standards: When bundling and loading tobacco, the tobacco should be sparser than in conventional drying, maintaining a denser top and sparser bottom, gradually reducing the quantity by 2-3 sticks to create a staggered and overlapping pattern, with the tobacco loading amount being 80% of that in conventional drying. C. Preparations before curing after loading tobacco: Prepare 3-4 stoves and place them on the floor of the curing barn, with the height between the stoves and the lower layer of tobacco leaves being 2.5-3m; D. Hanging: Turn on the circulating fan in the curing barn and set it to high speed. Hang the woven tobacco leaves in the curing barn for 24-28 hours until the tobacco leaves begin to turn yellow and wither. E. Yellowing stage: The yellowing stage includes the early yellowing stage, the middle yellowing stage, and the late yellowing stage. Throughout the yellowing stage, the circulating fan is kept at a low speed. In the early yellowing stage, the temperature is increased by adding fire at a rate of 1℃ / h to raise the dry bulb temperature from room temperature to 35℃ and the wet bulb temperature from room temperature to 33℃. The dry and wet bulb temperatures are stabilized for 24-28 hours until the tobacco leaves are three-tenths yellow. Firewood and sawdust are used to burn the leaves in the stove. Then, as the yellowing process progresses, the temperature is increased at a rate of 1℃ / h, raising the dry bulb temperature from room temperature to 38℃ and the wet bulb temperature from room temperature to 35℃. The dry and wet bulb temperatures are stabilized for 24-28 hours until the tobacco leaves turn from green to yellow. Based on the early yellowing stage, the amount of sawdust is increased to increase the smoke concentration in the curing barn. Then, in the later stage of yellowing, the temperature is increased at a rate of 1℃ / h, raising the dry bulb temperature from room temperature to 42℃ and the wet bulb temperature from room temperature to 36℃. The dry and wet bulb temperatures are stabilized for 24-28 hours until the tobacco leaves are completely yellow, the leaves become soft, and the veins cannot be broken. On the basis of the middle stage of yellowing, the amount of sawdust is increased to further increase the smoke concentration in the curing barn. F. Color Fixing Period: The color fixing period includes the pre-color fixing stage, the middle color fixing stage, and the post-color fixing stage. Throughout the entire color fixing period, the circulating fan maintains a high speed. During the initial color-fixing stage, after the yellowing period, increase the temperature at a rate of 0.5℃ / h to raise the dry bulb temperature to 45℃ and the wet bulb temperature to 37℃. Stabilize the dry and wet bulb temperatures for 24 hours until the veins are completely yellow and the tips curl. Next, in the middle stage of color fixation, the temperature is increased at a rate of 0.5℃ / h to raise the dry bulb temperature to 48℃ and the wet bulb temperature to 37℃. The dry and wet bulb temperatures are stabilized for 24 hours until the tobacco leaves are rolled into small rolls. Then, in the later stage of color fixing, the temperature is increased at a rate of 0.5℃ / h to raise the dry bulb temperature to 54℃ and the wet bulb temperature to 38℃. The dry and wet bulb temperatures are stabilized for 24 hours until the entire furnace is filled with large rolls. G. Drying stage: The drying stage includes the early drying stage and the late drying stage. The circulating fan uses low speed in the early stage and high speed in the late stage. After the initial drying and color-fixing period, increase the temperature by 1℃ / h to raise the dry bulb temperature to 60℃ and the wet bulb temperature to 39℃. Stabilize the dry and wet bulb temperatures and bake for 24 hours until the main vein of the tobacco leaf is more than one-third dry. Then turn on the biomass burner in the curing barn and stop adding sawdust. Finally, in the later stage of drying, the fire is added at a heating rate of 1.5℃ / h to raise the dry bulb temperature to 67℃ and the wet bulb temperature to 40℃. The dry and wet bulb temperatures are stabilized and baked for 30 hours until the main vein of the entire furnace is completely dry. When observing the smoke, focus on the low temperature zone. Once the main vein is dry, the fire is stopped and no more firewood is added. The remaining firewood and the burner are used to complete the drying of the tobacco leaves. In step A, slightly overripe flue-cured tobacco leaves refer to tobacco leaves that have been allowed to mature in the field for an additional 3-5 days before harvesting. In step E, the tool used to add sawdust is a shovel. Add 1.5 kg of sawdust each time in the early stage of yellowing, 2 kg each time in the middle stage of yellowing, and 2.5 kg each time in the late stage of yellowing. In step F, 2 kg of sawdust is added each time during the color-fixing period; In steps E and F, sawdust is added once every 4 hours. The firewood and sawdust used in steps E, F, and G are from Yunnan pine.

2. The roasting method for imparting an elegant woody aroma to tobacco leaves according to claim 1, characterized in that: The biomass burner used in step G is a common burner used in drying rooms.

3. The roasting method for imparting an elegant woody aroma to tobacco leaves according to claim 1, characterized in that: In steps E, F, and G, the dry and wet bulb temperatures and temperature stabilization time of the curing barn should be adjusted according to the state of the tobacco leaves. The amount of firewood added should be gradually increased while ensuring that the temperature does not drop.

4. Tobacco leaves obtained by a roasting method according to any one of claims 1-3, which imparts an elegant woody aroma to tobacco leaves.

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