Baking method for promoting chlorophyll degradation of reviving tobacco leaves

Abstract

The invention discloses a baking method for promoting chlorophyll degradation of reviving tobacco leaves, and relates to the field of tobacco leaf baking. The method comprises a high-temperature and high-humidity yellowing promoting step, a low-temperature and low-humidity slow color fixing step and a stable-temperature, humidity-discharging and stem-drying step. In the middle stage of the yellowing stage, the activity of hydrolase is activated and maintained by maintaining a high-temperature and high-humidity environment with the dry-bulb temperature being 38 DEG C and the wet-bulb temperature being 36 DEG C, smooth starting of chlorophyll degradation is promoted, and in the end stage of the yellowing stage, a temperature stabilizing point with the dry-bulb temperature being 40 DEG C and the wet-bulb temperature being 36 DEG C is additionally arranged, and chlorophyll degradation of the branch veins is promoted; temperature stabilizing points with the dry-bulb temperature being 44 DEG C and the wet-bulb temperature being 36 DEG C are additionally arranged at the initial stage of the color fixing stage, and the difficulty that thick and strong main veins turn yellow is emphatically overcome. According to the method, a temperature and humidity control curve from the yellowing stage to the initial color fixing stage is systematically optimized, a key temperature stabilizing point is introduced, a gradient slow temperature rising strategy is adopted, and the technical problem that dehydration and yellowing of the reviving tobacco leaves are difficult to coexist is solved.

Description

Technical Field

[0001] This invention relates to the field of tobacco curing, and in particular to a curing method for promoting the degradation of chlorophyll in regreened tobacco leaves. Background Technology

[0002] Yunnan, as a major high-quality flue-cured tobacco producing area in my country, boasts a diverse and varied climate characterized by low latitude, high altitude, and large diurnal temperature range, providing an excellent ecological foundation for the formation of its sweet and fragrant high-quality tobacco leaves. However, during the tobacco harvesting and curing season, tobacco-producing areas often experience prolonged periods of rainy weather lasting more than half a month. Excessive rainfall weakens the photosynthesis of tobacco plants, leading to an imbalance in carbon and nitrogen metabolism. This causes nearly mature tobacco leaves to exhibit a "greening-back" phenomenon, where the leaves turn noticeably green and tender, losing their original mature characteristics. Greening-back tobacco leaves have the following prominent characteristics: extremely high moisture content, brittle and tender leaf tissue, extremely uneven maturity, and extremely poor curing resistance. During the curing process, the high moisture content makes it difficult for the tobacco leaves to lose water smoothly during the yellowing stage, and the poor dehydration severely inhibits chlorophyll degradation, making yellowing difficult. In addition, greening-back tobacco leaves are brittle and tender, sensitive to environmental changes. If dehumidification is too rapid, they are prone to greening during curing; if the temperature stabilization time is insufficient, they are prone to ash buildup. The overall curing loss rate is significantly higher than that of normal tobacco leaves.

[0003] Currently, there is a lack of a dedicated curing process that can effectively address the high moisture content and low curing tolerance of re-greened tobacco leaves, resulting in severe damage to the quality and economic benefits of the cured leaves. Therefore, there is an urgent need for an innovative curing method that can effectively promote chlorophyll degradation and coordinate the dehydration and yellowing processes of tobacco leaves. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides a baking method for promoting chlorophyll degradation in greening tobacco leaves. By optimizing the temperature, humidity, path and time, the method solves the technical bottleneck of the coexistence of difficulty in dehydration and yellowing of greening tobacco leaves, and the coexistence of easy greening and easy ash accumulation, thereby promoting efficient degradation of chlorophyll and improving the quality after baking.

[0005] This invention provides a baking method for promoting chlorophyll degradation in regreening tobacco leaves, comprising: The tobacco leaves are loaded into the curing barn and then sealed and ignited. In the early stage of yellowing, the dry and wet bulb temperatures are raised from room temperature to 34°C and baked at the above dry and wet bulb temperatures for 2 hours. Then, the dry bulb temperature is raised to 36°C and the wet bulb temperature is adjusted to 34.5°C. Baking is carried out at the above dry and wet bulb temperatures for 14 to 16 hours until the tips of the tobacco leaves in the high-temperature layer begin to turn yellow. During the middle of the yellowing period, the dry bulb temperature is raised to 38°C, and the wet bulb temperature is raised to 36°C. The tobacco leaves are baked at the above dry and wet bulb temperatures for 18 to 20 hours until the tobacco leaves in the high-temperature layer turn 70 to 80% yellow. At the end of the yellowing period, raise the dry bulb temperature to 40°C and maintain the wet bulb temperature at 36°C. Bake at these dry and wet bulb temperatures for 10-16 hours until the tobacco leaves in the high-temperature layer are completely yellow and soft and droopy. Then raise the dry bulb temperature to 42°C and adjust the wet bulb temperature to 35.5°C. Bake at these dry and wet bulb temperatures for 12-16 hours until the tobacco leaves in the high-temperature layer have green veins, yellow leaves, hooked tips, and curled edges. In the early stage of color fixation, the dry bulb temperature is raised to 44℃ and the wet bulb temperature is raised to 36℃. The leaves are baked at the above dry and wet bulb temperatures for 14-18 hours until the leaf tissue of the high-temperature layer is 50% dry and the leaf veins of the low-temperature layer are green and yellow, and the main veins are soft and collapsed. The dry bulb temperature is raised to 48℃ and the wet bulb temperature is maintained at 36℃. The leaves are baked at the above dry and wet bulb temperatures for 16-20 hours until the main veins of the high-temperature layer turn green and all the branch veins turn white. In the middle of the color fixation period, the dry bulb temperature is raised to 52℃ and the wet bulb temperature is raised to 37℃. The leaves are baked at the above dry and wet bulb temperatures for 14 to 18 hours until the main vein of the tobacco leaves in the low-temperature layer turns green and all the branch veins turn white. At the end of the color fixation period, the dry bulb temperature is raised to 56°C and the wet bulb temperature is raised to 38°C. The tobacco leaves are baked at the above dry and wet bulb temperatures for 10 to 14 hours until all the tobacco leaf tissue in the oven is completely dry. During the drying period, raise the dry bulb temperature to 68°C and the wet bulb temperature to 40°C. Bake at these temperatures for 28-36 hours until all tobacco leaves in the curing barn are dry.

[0006] Furthermore, in the early stage of the yellowing period, the heating rate for raising the dry bulb temperature from room temperature to 34°C is 1°C / 4h to 1°C / 6h, and the heating rate for raising the dry bulb temperature to 36°C is 1°C / 2h.

[0007] Furthermore, during the middle of the yellowing period, the heating rate for raising the dry bulb temperature to 38°C is 1°C / 2h.

[0008] Furthermore, at the end of the yellowing period, the heating rate to raise the dry bulb temperature to 40°C is 1°C / 2h, and the heating rate to raise the dry bulb temperature to 42°C is 1°C / 3h.

[0009] Furthermore, in the initial stage of the color fixation period, the heating rate for raising the dry bulb temperature to 44°C is 1°C / 3h, and the heating rate for raising the dry bulb temperature to 48°C is 1°C / 3h.

[0010] Furthermore, during the middle of the color-fixing period, the heating rate for raising the dry bulb temperature to 52°C is 1°C / 2h.

[0011] Furthermore, at the end of the color-fixing period, the heating rate for raising the dry bulb temperature to 56°C is 1°C / 2h.

[0012] Furthermore, during the drying period, the heating rate for raising the dry bulb temperature to 68°C is 1°C / h.

[0013] Furthermore, the process involves loading tobacco leaves into the curing barn, using a method of 7-8 kg / pole or 10-12 kg / clump of tobacco, and a speed of 42-45 kg / m. 3 The tobacco is loaded at a certain density in the curing barn, which is a dense curing barn with descending airflow.

[0014] Furthermore, the tobacco leaves include any one of KRK26, Honghua Dajinyuan, and Yunyan 87.

[0015] The present invention provides a baking method for promoting chlorophyll degradation in regreening tobacco leaves, which has the following beneficial effects: The method of this invention is simple, easy to master and promote. By maintaining a suitable dry-bulb temperature at each stage and finely controlling the wet-bulb temperature, it achieves coordinated yellowing and dehydration of the tobacco leaves under high moisture background during the curing process. By setting a stable and suitable temperature during the yellowing period, adding key stable temperature points and reducing the heating rate, it systematically solves the fundamental problem of asynchronous yellowing of leaves and veins in the tobacco leaves. Ultimately, it achieves the curing goal of fully and uniformly yellowing the tobacco leaves and fixing the color, effectively overcoming the technical defects of easy greening and easy ash accumulation, improving the color uniformity of the cured tobacco leaves, significantly increasing the proportion of medium and high grade tobacco leaves, and reducing the green tobacco content. This invention promotes yellowing through high temperature and high humidity. During the middle of the yellowing period, a temperature combination of 38°C dry bulb temperature and 36°C wet bulb temperature is used to maximize the activation and maintenance of hydrolytic enzyme activity. This not only promotes rapid yellowing of leaves, but also initiates the necessary physiological and biochemical processes for yellowing of leaf veins, laying a solid foundation for subsequent overall synergistic yellowing. This invention provides mild and sufficient thermal conditions for leaf veins by adding a stable temperature point of 40°C for dry bulb and 36°C for wet bulb at the end of the yellowing period, which effectively promotes the degradation of chlorophyll in the branch veins and main veins. This invention utilizes a low-temperature, low-humidity, slow color fixation method. In the early stages of the color fixation period, by adding stable temperature points of 44°C for dry bulb and 36°C for wet bulb, and by using continuous heat effect and humidity protection, it effectively overcomes the difficulty of yellowing the robust main vein, thereby achieving the synergy and unity of the yellowing process of the leaf, branch veins, and main vein. This invention features a simple dry-bulb temperature setting and a clear wet-bulb temperature control process, making it easy to learn and master. By targeting the characteristics of re-greening tobacco leaves, it structurally optimizes the yellowing period and adds key temperature points during the curing process. The core objective is to resolve the inherent contradiction between the asynchronous yellowing of leaf veins and leaves. This effectively solves the technical bottleneck of the coexistence of difficulty in dehydration and yellowing, and the coexistence of easy greening and easy ash accumulation in this type of tobacco leaf, thereby more effectively improving the yellow tobacco rate and reducing curing losses. Attached Figure Description

[0016] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic flowchart of a baking method for promoting chlorophyll degradation in regreening tobacco leaves according to an embodiment of this application; Figure 2 This is a line graph showing the temperature and humidity changes of a baking method for promoting chlorophyll degradation in regreening tobacco leaves, provided in one embodiment of this application. Figure 3 This is a comparison chart of chlorophyll a degradation rate of leaves in a baking method for promoting chlorophyll degradation in tobacco leaves according to an embodiment of this application; Figure 4 This is a comparison chart of the chlorophyll b degradation rate of leaves in a baking method for promoting chlorophyll degradation in tobacco leaves according to an embodiment of this application; Figure 5 This is a comparison chart of the degradation rate of chlorophyll a in the veins of tobacco leaves using a baking method to promote chlorophyll degradation in regreened tobacco leaves, provided in one embodiment of this application. Figure 6 This is a comparison chart of the degradation rate of chlorophyll b in the veins of tobacco leaves using a baking method that promotes chlorophyll degradation in regreened tobacco leaves, provided in one embodiment of this application. Figure 7 This is a comparison diagram of the degradation rate of chlorophyll a in the main vein of a baking method for promoting chlorophyll degradation in greening tobacco leaves, provided in one embodiment of this application; Figure 8 This is a comparison diagram of the degradation rate of chlorophyll b in the main vein of a baking method for promoting chlorophyll degradation in greening tobacco leaves, provided in one embodiment of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0019] It should be understood that although the terms first, second, third, etc., may be used to describe the acquisition modules in the embodiments of the present invention, these acquisition modules should not be limited to these terms. These terms are only used to distinguish the acquisition modules from each other.

[0020] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0021] It should be noted that the directional terms such as "upper," "lower," "left," and "right" used in the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should be understood that when it is mentioned that an element is formed "upper" or "lower" of another element, it can not only be formed directly "upper" or "lower" of the other element, but also indirectly "upper" or "lower" of the other element through an intermediate element.

[0022] See Figure 1 This invention provides a baking method for promoting chlorophyll degradation in regreening tobacco leaves, comprising: The steps are: high temperature and high humidity to promote yellowing, low temperature and low humidity to slow color setting, and stable temperature and moisture removal to dry the skin. The steps for promoting yellowing through high temperature and high humidity include: Step S101: Load the tobacco leaves into the curing barn. The tobacco leaves include any one of KRK26, Honghua Dajinyuan, and Yunyan 87. The curing barn is a dense curing barn with descending airflow. The tobacco leaves are bundled at a rate of 7-8 kg / pole or 10-12 kg / clamp. If using poles, the tobacco leaf stems are tied to the poles at a rate of 7-8 kg / pole. If using clamps, the tobacco leaf stems are clamped in the clamps at a rate of 10-12 kg / clamp. Then, the tobacco leaves are loaded at a rate of 42-45 kg / m. 3 The tobacco is loaded at the specified density, the curing room is sealed, and the fire is ignited. Step S102: In the early stage of yellowing, the dry and wet bulb temperatures are raised from room temperature to 34°C at a heating rate of 1°C / 4h to 1°C / 6h, and baked at the above dry and wet bulb temperatures for 2h; then the dry bulb temperature is raised to 36°C at a heating rate of 1°C / 2h, and the wet bulb temperature is adjusted to 34.5°C, and baked at the above dry and wet bulb temperatures for 14 to 16h, until the tips of the tobacco leaves in the high-temperature layer begin to turn yellow; In step S103, during the middle of the yellowing period, the dry-bulb temperature is raised to 38°C at a rate of 1°C / 2h, while the wet-bulb temperature is raised to 36°C. The leaves are then baked at these dry and wet-bulb temperatures for 18-20h until the leaves in the high-temperature layer turn 70-80% yellow. Since the re-greening tobacco leaves have high moisture content and brittle tissue, under conventional processes, premature dehumidification or insufficient temperature can cause the leaves to lose water too quickly, hindering chlorophyll degradation and ultimately leading to premature yellowing. To address this issue, this step maintains a specific high-temperature and high-humidity environment of 38°C dry-bulb temperature and 36°C wet-bulb temperature to maximize the activation and maintenance of hydrolytic enzyme activity, providing the necessary physiological and biochemical conditions for chlorophyll degradation. This not only promotes the rapid yellowing of the leaves but also initiates the initial physiological and biochemical process for the yellowing of the leaf veins, laying a solid foundation for subsequent synergistic yellowing. Step S104: At the end of the yellowing period, the dry-bulb temperature is increased to 40℃ at a rate of 1℃ / 2h, while the wet-bulb temperature is maintained at 36℃. The leaves are then baked at these temperatures for 10-16h until the leaves in the high-temperature layer are completely yellow and soft and droopy. Next, the dry-bulb temperature is increased to 42℃ at a rate of 1℃ / 3h, while the wet-bulb temperature is adjusted to 35.5℃. The leaves are then baked at these temperatures for 12-16h until the leaves in the high-temperature layer have green veins, yellow scales, and curled tips. Addressing the issue of asynchronous yellowing of the veins, this step innovatively adds a stable temperature point of 40℃ for the dry bulb and 36℃ for the wet bulb, providing a gentle gradient temperature transition platform. This provides an environment to consolidate the yellowing effect of leaves that have already begun to yellow, and provides gentle yet sufficient thermal conditions for the veins, promoting chlorophyll degradation in the veins and reducing the formation of fine green veins.

[0023] The low-temperature, low-humidity, slow color-fixing process includes: Step S105: In the early stage of color fixation, the dry-bulb temperature is raised to 44℃ and the wet-bulb temperature to 36℃ at a heating rate of 1℃ / 3h. The leaves are baked at these temperatures for 14-18h until the leaf tissue in the high-temperature layer is 50% dry, and the leaf veins in the low-temperature layer turn yellow and the midrib softens and collapses. Then, the dry-bulb temperature is raised to 48℃ at a heating rate of 1℃ / 3h, while the wet-bulb temperature is maintained at 36℃. The leaves are baked at these temperatures for 16-20h until the midrib of the high-temperature layer fades and all the lateral veins turn white. This step innovatively adds a preferred stable temperature point of 44℃ for the dry-bulb and 36℃ for the wet-bulb. Utilizing continuous heat and humidity protection, it effectively overcomes the difficulty of yellowing the robust midrib, providing sufficient time and heat for the chlorophyll to fully degrade, thus achieving the fading of the midrib and softening of the midrib. Ultimately, this ensures the coordinated and unified yellowing process of the leaf, lateral veins, and midrib. Step S106: In the middle of the color fixation period, the dry bulb temperature is raised to 52°C and the wet bulb temperature is raised to 37°C at a heating rate of 1°C / 2h. The leaves are baked at the above dry and wet bulb temperatures for 14 to 18 hours until the main vein of the tobacco leaves in the low-temperature layer turns bluish and all the branch veins turn white. Step S107: At the end of the color fixation period, the dry bulb temperature is raised to 56°C and the wet bulb temperature is raised to 38°C at a heating rate of 1°C / 2h. The leaves are then baked at the above dry and wet bulb temperatures for 10-14h until all tobacco leaf tissue is completely dry. Step S108, the temperature stabilization and moisture removal drying process includes: during the drying period, the dry bulb temperature is raised to 68°C and the wet bulb temperature is raised to 40°C at a heating rate of 1°C / h, and the tobacco leaves are baked at the above dry and wet bulb temperatures for 28~36 hours until the tobacco leaves in the entire curing barn are dry.

[0024] Example 1 In Jiuxi Town, Yuxi City, after a period of continuous rainy weather, the middle leaves of the Honghua Dajinyuan variety of tobacco, which have turned green and tender, lost their mature and mottled appearance, have thick main veins, are crisp and tender, and have a very high water content, are harvested and then packed into dense curing barns according to conventional methods and cured using the curing method described in this invention.

[0025] The already bundled tobacco leaves are sized at 42kg / m 3 The smoke density is adjusted, and the smoke is loaded into a dense, airflow-descending drying chamber for baking using the baking method provided by this invention. The specific steps are as follows: High temperature and high humidity promote yellowing steps: The tobacco leaves are loaded into the curing barn and ignited in a sealed manner. At the beginning of the yellowing period, the dry and wet bulb temperatures are raised from room temperature to 34°C at a rate of 1°C / 4h. The leaves are then cured at the above dry and wet bulb temperatures for 2h. Then, the dry bulb temperature is raised to 36°C and the wet bulb temperature is raised to 34.5°C at a rate of 1°C / 2h. The leaves are then cured at the above dry and wet bulb temperatures for 14h until the tips of the tobacco leaves in the high-temperature layer begin to turn yellow. During the middle of the yellowing period, the dry bulb temperature was raised to 38°C at a heating rate of 1°C / 2h, while the wet bulb temperature was raised to 36°C. The tobacco leaves were baked at the above dry and wet bulb temperatures for 18h until the high-temperature layer tobacco leaves turned 70-80% yellow. At the end of the yellowing period, the dry bulb temperature is increased to 40°C at a rate of 1°C / 2h, while the wet bulb temperature is maintained at 36°C. The leaves are then baked at these dry and wet bulb temperatures for 16h until the tobacco leaves in the high-temperature layer are completely yellow and soft and droopy. The dry bulb temperature is then increased to 42°C at a rate of 1°C / 3h, while the wet bulb temperature is adjusted to 35.5°C. The leaves are then baked at these dry and wet bulb temperatures for 14h until the tobacco leaves in the high-temperature layer have green veins, yellow leaves, hooked tips, and curled edges.

[0026] Low temperature, low humidity, slow color setting steps: At the initial stage of color fixation, the dry-bulb temperature is increased to 44℃ and the wet-bulb temperature is increased to 36℃ at a heating rate of 1℃ / 3h. The leaves are then baked at these dry and wet-bulb temperatures for 14h until the leaf tissue in the high-temperature layer is 50% dry and the leaf veins in the low-temperature layer are greenish-yellow and the midribs are soft and collapsed. The dry-bulb temperature is then increased to 48℃ at a heating rate of 1℃ / 3h while the wet-bulb temperature is maintained at 36℃. The leaves are then baked at these dry and wet-bulb temperatures for 18h until the midribs of the high-temperature layer turn pale green and all the branch veins turn white. During the middle of the color fixation period, the dry bulb temperature was raised to 52°C and the wet bulb temperature was raised to 37°C at a heating rate of 1°C / 2h. The leaves were then baked at the above dry and wet bulb temperatures for 14h until the main veins of the tobacco leaves in the low-temperature layer turned bluish and all the branch veins turned white. At the end of the color-fixing period, the dry-bulb temperature is raised to 56°C and the wet-bulb temperature is raised to 38°C at a rate of 1°C / 2h. The tobacco leaves are then baked at the above dry and wet-bulb temperatures for 14h until all the tobacco leaf tissue in the oven is completely dry.

[0027] Temperature and humidity control drying process: During the drying period, raise the dry bulb temperature to 68°C and the wet bulb temperature to 40°C at a rate of 1°C / h. Bake at the above dry and wet bulb temperatures for 30 hours until all tobacco leaves in the curing barn are dry.

[0028] Experimental group 1 was cured according to the curing method of Example 1, while the control group was cured according to the conventional curing method. The chlorophyll degradation rates of leaves, midribs, and lateral veins during the curing process were compared between experimental group 1 and the control group. The experimental results are shown in [link to experimental results]. Figure 3-8 .

[0029] Figure 3 and Figure 4 This indicates that the baking method for promoting chlorophyll degradation in tobacco leaves according to the embodiments of the present invention can effectively reduce the chlorophyll content in the leaves after baking and reduce the greenness rate of the leaves. At a dry head temperature of 38℃ during the yellowing stage, a novel high-humidity environment is used to solve the problem of premature yellowing or even chlorosis caused by premature water loss in tobacco leaves during the yellowing period. This provides conditions for the continuous action of chlorophyllase. Yellowing occurs when water evaporates too quickly from the leaf surface, causing premature and rapid wilting of the leaves, but the internal chlorophyll has not yet had time to fully decompose, resulting in the yellowing process being forcibly interrupted or unable to start normally. At a dry head temperature of 40℃-42℃, the previously accumulated physiological potential is released, triggering rapid chlorophyll degradation. The process ends at 42℃. After the initial stage, the chlorophyll a and chlorophyll b contents of the leaves in experimental group 1 decreased by 680.13 μg / g and 43.97 μg / g, respectively, compared with the control group. After the dry bulb 48℃ stage ended, the degradation advantage continued to expand, and the chlorophyll a and chlorophyll b contents of the veins in experimental group 1 decreased by 173.78 μg / g and 8.63 μg / g, respectively, compared with the control group. After the baking was completed, the chlorophyll a and chlorophyll b contents of the leaves in experimental group 1 decreased by 44.11 μg / g and 0.38 μg / g, respectively, compared with the control group.

[0030] Figure 5 and Figure 6 This indicates that the baking method for promoting chlorophyll degradation in tobacco leaves according to an embodiment of the present invention can effectively reduce the chlorophyll content in the leaves after baking and reduce the green vein rate. During the yellowing stage, at 38℃ for the dry bulb, the degradation potential of the veins was protected by a high-humidity environment. In the subsequent 40℃ dry bulb stage, rapid degradation of chlorophyll in the veins was triggered, with both chlorophyll a and b contents significantly and continuously reduced. After the 42℃ dry bulb stage, the chlorophyll a and b contents of the veins were significantly and continuously reduced, with the contents of chlorophyll a and chlorophyll b in experimental group 1 decreasing by 128.43 μg / g and 46.28 μg / g, respectively, compared to the control group. After the 48℃ dry bulb stage, the degradation advantage increased dramatically, with the contents of chlorophyll a and chlorophyll b in experimental group 1 decreasing by 117.80 μg / g and 23.52 μg / g, respectively, compared to the control group. After baking, the contents of chlorophyll a and chlorophyll b in experimental group 1 decreased by 85.45 μg / g and 27.89 μg / g, respectively, compared to the control group.

[0031] Figure 7 and Figure 8 This indicates that the baking method of the present invention for promoting chlorophyll degradation in tobacco leaves can effectively reduce the chlorophyll content in the leaves after baking and reduce the green vein rate. During the yellowing stage at 38℃, the trend was similar to that of the leaves and veins, with the optimized process group showing slightly higher chlorophyll content, further demonstrating the effective maintenance of the physiological activity of the midrib by the high humidity environment. In the 40℃-42℃ dry-bulb stage, the chlorophyll degradation mechanism of the midrib was effectively activated and accelerated after the gentle heating at the 40℃ transition plateau. After the 42℃ dry-bulb stage, the chlorophyll a and chlorophyll b contents of the veins in experimental group 1 decreased by 42.00 μg / g and 8.18 μg / g, respectively, compared to the control group. After the 48℃ dry-bulb stage, the degradation difference significantly increased, with the chlorophyll a and chlorophyll b contents of the veins in experimental group 1 decreasing by 64.52 μg / g and 20.20 μg / g, respectively, compared to the control group. After baking, the chlorophyll a and chlorophyll b contents of the midrib in experimental group 1 decreased by 3.25 μg / g and 3.12 μg / g, respectively, compared to the control group.

[0032] The embodiments of the present invention do not maintain high-speed degradation throughout the entire process, but follow scientific physiological laws. During the yellowing period, the activity of the dry bulb is protected at 38°C. During the middle stage of yellowing, the degradation of the dry bulb is initiated at 40°C-42°C. During the middle stage of color fixation, the degradation rate is significantly reversed and near-complete degradation is achieved at 48°C.

[0033] The strategy of combining high temperature and high humidity with gradient slow heating, i.e. adding stable temperature points of 40℃ and 44℃ in this embodiment of the invention, systematically coordinates the chlorophyll degradation process of different parts of tobacco leaves, including the mesophyll, lateral veins and main veins, and achieves synchronous and uniform yellowing of the whole leaf. In particular, the chlorophyll a of the lateral veins and main veins is almost completely degraded, which prevents the phenomenon of blue veins from a physiological and biochemical level.

[0034] The optimized baking method provided by this invention, through its unique temperature and humidity control curve, successfully solves the technical bottleneck of yellow leaf tissue but still green veins caused by asynchronous chlorophyll degradation in re-greening tobacco leaves, thus significantly improving the overall appearance quality of the tobacco leaves after baking.

[0035] Example 2 In Jiuxi Town, Yuxi City, after a period of continuous rainy weather, the middle leaves of the Honghua Dajinyuan variety of tobacco, which have turned green and tender, lost their mature and mottled appearance, have thick main veins, are crisp and tender, and have a very high water content, are harvested and then packed into dense curing barns according to conventional methods and cured using the curing method described in this invention.

[0036] The already woven tobacco leaves are sized at 44 kg / m 3 The smoke density is adjusted, and the smoke is loaded into a densely packed, downward-flowing drying chamber for drying using the drying method provided by this invention. See the temperature and humidity variation line graph for this embodiment. Figure 2 The specific steps are as follows: High temperature and high humidity promote yellowing steps: The tobacco leaves are loaded into the curing barn and ignited in a sealed manner. At the beginning of the yellowing period, the dry and wet bulb temperatures are raised from room temperature to 34°C at a rate of 1°C / 6h. The leaves are then cured at the above dry and wet bulb temperatures for 2h. Then, the dry bulb temperature is raised to 36°C and the wet bulb temperature is raised to 34.5°C at a rate of 1°C / 2h. The leaves are then cured at the above dry and wet bulb temperatures for 16h, until the tips of the tobacco leaves in the high-temperature layer begin to turn yellow. During the middle of the yellowing period, the dry bulb temperature was raised to 38°C at a heating rate of 1°C / 2h, while the wet bulb temperature was raised to 36°C. The tobacco leaves were baked at the above dry and wet bulb temperatures for 20h until the tobacco leaves in the high-temperature layer turned 70-80% yellow. At the end of the yellowing period, the dry bulb temperature is increased to 40°C at a rate of 1°C / 2h, while the wet bulb temperature is maintained at 36°C. The leaves are then baked at these dry and wet bulb temperatures for 16h until the tobacco leaves in the high-temperature layer are completely yellow and soft and droopy. The dry bulb temperature is then increased to 42°C at a rate of 1°C / 3h, while the wet bulb temperature is adjusted to 35.5°C. The leaves are then baked at these dry and wet bulb temperatures for 16h until the tobacco leaves in the high-temperature layer have green veins, yellow leaves, hooked tips, and curled edges.

[0037] Low temperature, low humidity, slow color setting steps: At the beginning of the color-fixing period, the dry-bulb temperature was raised to 44℃ and the wet-bulb temperature to 36℃ at a rate of 1℃ / 3h. The leaves were baked at these dry and wet-bulb temperatures for 18h until the leaf tissue of the high-temperature layer was 50% dry and the leaf veins of the low-temperature layer were greenish-yellow and the midribs were soft and collapsed. The dry-bulb temperature was raised to 48℃ at a rate of 1℃ / 3h, while the wet-bulb temperature was maintained at 36℃. The leaves were baked at these dry and wet-bulb temperatures for 20h until the midribs of the high-temperature layer turned off the green color and all the branch veins turned white. During the middle of the color fixation period, the dry bulb temperature was raised to 52°C and the wet bulb temperature was raised to 37°C at a heating rate of 1°C / 2h. The leaves were then baked at the above dry and wet bulb temperatures for 18h until the main veins of the tobacco leaves in the low-temperature layer turned bluish and all the branch veins turned white. At the end of the color-fixing period, the dry-bulb temperature is raised to 56°C and the wet-bulb temperature is raised to 38°C at a rate of 1°C / 2h. The tobacco leaves are then baked at the above dry and wet-bulb temperatures for 14h until all the tobacco leaf tissue in the oven is completely dry.

[0038] Stable temperature and humidity drying process: During the drying process, raise the dry bulb temperature to 68°C and the wet bulb temperature to 40°C at a rate of 1°C / h. Bake at the above dry and wet bulb temperatures for 36 hours until all tobacco leaves in the curing barn are dry.

[0039] Experimental group 2 was roasted according to the roasting method of Example 2, while the control group was roasted according to the conventional roasting method. The quality of the roasted tobacco leaves of experimental group 2 and the control group was compared. The experimental results are shown in Table 1.

[0040] Table 1 Comparison of the quality of flue-cured tobacco leaves Table 1 shows that the tobacco leaves of Example 2 of the present invention, namely Experimental Group 2, have a high proportion of medium and high grade tobacco after curing, which is 8.3 percentage points higher than the traditional conventional curing method; a low green tobacco content, which is 6.5 percentage points lower than the traditional conventional curing method; and a high selling price, with an average price 1.1 yuan / kg higher than the traditional conventional curing method.

[0041] This invention provides a baking method to promote chlorophyll degradation in greening tobacco leaves. Addressing the core issues of high moisture content and difficulty in chlorophyll degradation in greening tobacco leaves, the method systematically optimizes the temperature and humidity control curve from the yellowing stage to the initial color fixation stage. This method innovatively introduces key stable temperature points such as 40℃ and 44℃ for dry bulbs and adopts a gradient slow heating strategy, successfully overcoming the technical bottleneck of the coexistence of difficulty in dehydration and yellowing in greening tobacco leaves. This method firstly activates and protects enzyme activity through a high-temperature and high-humidity environment in the early stages, ensuring the smooth initiation of the chlorophyll degradation process and fundamentally preventing premature yellowing or curing due to water loss. Secondly, through precise temperature and humidity control, it synergistically promotes the yellowing and dehydration processes of tobacco leaves and veins, including branch veins and main veins, solving the problem of asynchronous yellowing. This significantly reduces the green content and green vein rate of cured tobacco leaves and effectively avoids problems such as ash accumulation. This method can effectively improve the appearance quality and color uniformity of cured tobacco leaves, thereby effectively increasing the proportion of medium and high-grade tobacco and the average selling price. Moreover, the process parameters are clear, the operation is strong, and it is easy to promote and apply in tobacco-growing areas, providing reliable technical support for dealing with the problem of re-greening tobacco caused by abnormal climate.

[0042] The above description is merely a preferred embodiment of the present invention. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to the specific combination of the above-described technical features, but should also cover other technical solutions formed by any combination of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A baking method for promoting chlorophyll degradation in regreening tobacco leaves, characterized in that, include: The tobacco leaves are loaded into the curing barn and then sealed and ignited. In the early stage of yellowing, the dry and wet bulb temperatures are raised from room temperature to 34°C and baked at the above dry and wet bulb temperatures for 2 hours. Then, the dry bulb temperature is raised to 36°C and the wet bulb temperature is adjusted to 34.5°C. Baking is carried out at the above dry and wet bulb temperatures for 14 to 16 hours until the tips of the tobacco leaves in the high-temperature layer begin to turn yellow. During the middle of the yellowing period, the dry bulb temperature is raised to 38°C, and the wet bulb temperature is raised to 36°C. The tobacco leaves are baked at the above dry and wet bulb temperatures for 18 to 20 hours until the tobacco leaves in the high-temperature layer turn 70 to 80% yellow. At the end of the yellowing period, raise the dry bulb temperature to 40°C and maintain the wet bulb temperature at 36°C. Bake at these dry and wet bulb temperatures for 10-16 hours until the tobacco leaves in the high-temperature layer are completely yellow and soft and droopy. Then raise the dry bulb temperature to 42°C and adjust the wet bulb temperature to 35.5°C. Bake at these dry and wet bulb temperatures for 12-16 hours until the tobacco leaves in the high-temperature layer have green veins, yellow leaves, hooked tips, and curled edges. In the early stage of color fixation, the dry bulb temperature is raised to 44℃ and the wet bulb temperature is raised to 36℃. The leaves are baked at the above dry and wet bulb temperatures for 14-18 hours until the leaf tissue of the high-temperature layer is 50% dry and the leaf veins of the low-temperature layer are green and yellow, and the main veins are soft and collapsed. The dry bulb temperature is raised to 48℃ and the wet bulb temperature is maintained at 36℃. The leaves are baked at the above dry and wet bulb temperatures for 16-20 hours until the main veins of the high-temperature layer turn green and all the branch veins turn white. In the middle of the color fixation period, the dry bulb temperature is raised to 52℃ and the wet bulb temperature is raised to 37℃. The leaves are baked at the above dry and wet bulb temperatures for 14 to 18 hours until the main vein of the tobacco leaves in the low-temperature layer turns green and all the branch veins turn white. At the end of the color fixation period, the dry bulb temperature is raised to 56°C and the wet bulb temperature is raised to 38°C. The tobacco leaves are baked at the above dry and wet bulb temperatures for 10 to 14 hours until all the tobacco leaf tissue in the oven is completely dry. During the drying period, raise the dry bulb temperature to 68°C and the wet bulb temperature to 40°C. Bake at these temperatures for 28-36 hours until all tobacco leaves in the curing barn are dry.

2. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, In the early stage of the yellowing period, the heating rate for raising the dry bulb temperature from room temperature to 34°C is 1°C / 4h to 1°C / 6h, and the heating rate for raising the dry bulb temperature to 36°C is 1°C / 2h.

3. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, During the middle of the yellowing period, the rate of increase in temperature to 38°C for the dry bulb was 1°C / 2h.

4. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, At the end of the yellowing period, the heating rate to raise the dry bulb temperature to 40°C is 1°C / 2h, and the heating rate to raise the dry bulb temperature to 42°C is 1°C / 3h.

5. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, In the initial stage of the color fixation period, the heating rate to raise the dry bulb temperature to 44°C is 1°C / 3h, and the heating rate to raise the dry bulb temperature to 48°C is 1°C / 3h.

6. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, During the middle of the color fixation period, the heating rate to raise the dry bulb temperature to 52°C is 1°C / 2h.

7. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, At the end of the color fixation period, the rate of increase in temperature to 56°C for the dry bulb is 1°C / 2h.

8. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, During the drying period, the heating rate to raise the dry bulb temperature to 68°C is 1°C / h.

9. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 1, characterized in that, The process involves loading tobacco leaves into the curing barn, and then weaving them at a rate of 7-8 kg / pole or 10-12 kg / clamp, with a speed of 42-45 kg / m. 3 The tobacco is loaded at a certain density in the curing barn, which is a dense curing barn with descending airflow.

10. The baking method for promoting chlorophyll degradation in tobacco leaves according to claim 9, characterized in that, The tobacco leaves include any one of KRK26, Honghua Dajinyuan, and Yunyan 87.

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