A baking method suitable for the upper leaves of flue-cured tobacco variety K326

Abstract

The invention discloses a baking method suitable for upper leaves of a flue-cured tobacco variety K326. The method comprises the following steps: S1, harvesting upper leaves of mature tobacco plants and loading them into a tobacco loading chamber of a flue-curing barn; and S2, baking the loaded upper leaves, wherein the baking comprises an early yellowing stage, a middle yellowing stage, a late yellowing stage, an early color fixation stage, a middle color fixation stage, a late color fixation stage, and a tendon drying stage. The dry-bulb temperature steadily increases in the seven stages of the early yellowing stage, the middle yellowing stage, the late yellowing stage, the early color fixation stage, the middle color fixation stage, the late color fixation stage, and the tendon drying stage. The wet-bulb temperature exhibits a "V"-shaped change in the five stages of the middle yellowing stage, the late yellowing stage, the early color fixation stage, the middle color fixation stage, and the late color fixation stage. In the middle yellowing stage and the late yellowing stage, the dry-bulb temperature remains unchanged, showing "double 39-40°C and double 41-42°C", respectively, while the wet-bulb temperature decreases by 0.5-1°C in the latter stage of each stage. The method bakes the upper leaves, significantly reducing the ash content and proportion of the upper leaves, increasing the hue of the tobacco leaves, and improving the proportion of tobacco leaf grades, thereby significantly improving the baking quality of the upper leaves and the income of tobacco farmers.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco leaf processing, and in particular to a baking method suitable for upper leaves of the flue-cured tobacco K326 variety. Background Art

[0002] As one of the main varieties commonly cultivated in my country's flue-cured tobacco production, K326 flue-cured tobacco has the advantages of orange color after curing, rich color, sufficient aroma, good aroma quality, high oil content, pure taste, moderate concentration and strength, and strong combustibility. It can better meet the needs of my country's cigarette industry to create high-quality and high-end brand cigarettes.

[0003] K326 flue-cured tobacco boasts stable characteristics, good resistance, and medium-to-high yields, making it a popular choice among tobacco farmers. In Shaoyang's tobacco-growing areas, K326 boasts a more pronounced sweet-scorched aroma and a stronger strong-flavor profile than the Yunyan 87 variety. However, this variety suffers from poor leaf opening, poor leaf base maturity, a thick, dense structure, and difficulty losing water. Its high PPO activity makes it difficult to cure, particularly in the upper leaves.

[0004] At present, the upper leaves of K326 variety in Shaoyang tobacco area are mainly baked with conventional "three-stage" baking method. During the baking process, the tobacco is often damaged, such as being baked green, baked black, covered with ash, and having large color difference between the front and back sides. As a result, its purchase price is much lower than Yunyan 87, and tobacco farmers have low acceptance and willingness to plant. At the same time, it also seriously affects the industrial availability of tobacco leaves, and flue-cured tobacco industrial enterprises are unwilling to allocate them.

[0005] In recent years, the planting scale has shown a downward trend. Therefore, it is of great significance to provide practical baking technology for the promotion of K326, encourage tobacco farmers to accept the K326 variety, adapt to industrial needs, fully demonstrate the quality characteristics of Shaoyang's strong-flavor tobacco leaves, improve the baking process and improve the baking quality of the upper tobacco leaves of the K326 variety. Summary of the Invention

[0006] Based on the above-mentioned prior art, the present invention provides a baking method suitable for the upper leaves of the flue-cured tobacco variety K326. According to the method, the upper leaves are baked, the ash degree and proportion of the upper leaves are significantly reduced, the color of the tobacco leaves is darker, the proportion of tobacco leaf grades is increased, the baking quality of the upper leaves is significantly improved, and the income of tobacco farmers is significantly increased.

[0007] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0008] A method for baking upper leaves of the flue-cured tobacco variety K326, comprising the following steps:

[0009] S1. Harvest the upper leaves of mature tobacco plants and load them into the tobacco loading room of the flue-curing barn;

[0010] S2. The loaded upper leaves are baked. The baking process includes the early yellowing stage, the middle yellowing stage, the late yellowing stage, the early color fixing stage, the middle color fixing stage, the late color fixing stage and the dry tendon stage. The baking method for each stage is as follows:

[0011] 1) Early stage of yellowing:

[0012] The dry-bulb temperature is 35.0-36.0°C, the wet-bulb temperature is 34.0-35.0°C, and the temperature difference between the dry-bulb and wet-bulb is controlled at 1.0-2.0°C. When the dry-bulb temperature stabilizes, the tobacco leaves are baked for 4-6 hours until the tips of the high-temperature layer tobacco leaves turn yellow and soften, and lose 8%-12% of water. The dry-bulb temperature is then raised to 37.0-38.0°C, and the wet-bulb temperature is raised to 36.0-37.0°C. The temperature difference between the dry-bulb and wet-bulb is controlled at 0-2.0°C. When the dry-bulb temperature stabilizes, the tobacco leaves are baked for 12-14 hours until they turn 60%-70% yellow and lose 15%-18% of water.

[0013] 2) Middle stage of yellowing:

[0014] The dry-bulb temperature is 39.0-40.0°C, the wet-bulb temperature is 37.0-38.0°C, and the temperature difference between the dry-bulb and wet-bulb is controlled at 1.0-3.0°C. When the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 18-20 hours until they are 70% to 80% yellow, the leaves become soft, and the water loss is 20%-22%. Then, the dry-bulb temperature is kept constant at 39.0-40.0°C, the wet-bulb temperature is lowered to 36.0-37.0°C, and the temperature difference between the dry-bulb and wet-bulb is controlled at 1.0-3.0°C. The tobacco leaves in the high-temperature layer are baked for 12-14 hours until they are 80% yellow and the leaves in the low-temperature layer become soft.

[0015] 3) Late yellowing stage:

[0016] The dry-bulb temperature is 41.0-42.0°C, the wet-bulb temperature is 36.5-37.0°C, and the temperature difference between the dry-bulb and wet-bulb is controlled at 4.0-6.0°C. When the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 8-10 hours, until they are 80-90% yellow, the main veins are softened, and the water loss is 30%-35%. Then, the dry-bulb temperature is kept constant at 41.0-42.0°C, the wet-bulb temperature is lowered to 36.0-36.5°C, and the temperature difference between the dry-bulb and wet-bulb is controlled at 4.0-6.0°C. The tobacco leaves in the high-temperature layer are baked for 20-24 hours, until the leaves in the high-temperature layer are more than 90% yellow, the yellow leaves have blue veins, and they are obviously withered, with hooked and curled edges, and a water loss of about 40%-50%. In addition, the leaves in the low-temperature layer are slightly withered.

[0017] 4) Early stage of color fixing:

[0018] The dry bulb temperature is 43.0-44.0℃, the wet bulb temperature is 36.0-36.5℃, and the temperature difference between the dry bulb and wet bulb is controlled at 6.5-8.0℃. When the dry bulb temperature is stable, bake for 8-10 hours until the high temperature layer tobacco leaves turn yellow, the main veins turn green, the tips of the tobacco leaves in the whole room are curled, and the water loss is more than 50%;

[0019] 5) Mid-color fixation stage:

[0020] The dry bulb temperature is 47.0-48.0℃, the wet bulb temperature is 37.0-37.5℃, and the temperature difference between the dry bulb and wet bulb is controlled at 9.5-11.0℃. When the dry bulb temperature is stable, bake for 16-18 hours until the tobacco leaves in the high temperature layer lose more than 60% of their water content, and more than half of the area becomes dry and hard. The tobacco leaves in the whole room turn yellow, with yellow leaves and yellow veins.

[0021] 6) Color fixation stage:

[0022] The dry bulb temperature is 53.0-54.0℃, the wet bulb temperature is 38.0-39.0℃, and the temperature difference between the dry bulb and the wet bulb is controlled at 14.0-24.0℃. When the dry bulb temperature is stable, the tobacco leaves are baked for 16-20 hours until the leaves in the high-temperature layer are almost completely dry, forming small rolls or at least part of large rolls, but the base of the main vein is not dried, and the water loss is 70%-80%. The dry area of ​​the tobacco leaves in the low-temperature layer is more than half, and the main veins of the tobacco leaves in the whole furnace lose water and shrink.

[0023] 7) Drying period:

[0024] The dry-bulb temperature is 60.0-61.0℃, and the wet-bulb temperature is 39.0-40.0℃. When the dry-bulb temperature stabilizes, bake for 6-8 hours until the main veins of the tobacco leaves in the high-temperature layer shrink and turn purple; then raise the dry-bulb temperature to 67.0-68.0℃, and the wet-bulb temperature to 41.0-42.0℃. When the dry-bulb temperature stabilizes, continue baking for 20-24 hours until the main veins of the tobacco leaves in the entire furnace are dry, and then end the baking.

[0025] Furthermore, the upper leaves are the stem portion of the upper 4-6 leaves of the mature tobacco plant with a full growth period of 125-130 days.

[0026] Furthermore, during the drying process in the early, middle, late and late stages of yellowing, the temperature rise rate of the dry bulb is 1°C / 2h; during the drying process in the early and middle stages of color fixing, the temperature rise rate of the dry bulb is 1°C / 3h; during the drying process in the dry tendon stage, the temperature rise rate of the dry bulb is 1°C / 1h.

[0027] Furthermore, the baking room is an intensive baking room.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. The present invention fully grasps the maturity of the field. The maturity of the upper leaves of the tobacco plant is extended by about 7 days on the basis of Yunyan. The upper leaves are harvested in layers and with stems at one time.

[0030] 2. The dry-bulb temperature of the present invention increases steadily in the seven periods of early yellowing, middle yellowing, late yellowing, early color fixation, middle color fixation, late color fixation and dry tendon stage. The wet-bulb temperature shows a "V"-shaped change in the five periods of middle yellowing, late yellowing, early color fixation, middle color fixation and late color fixation. In the two critical periods of middle yellowing and late yellowing, the dry-bulb temperature remains unchanged, showing "double 39-40°C and double 41-42°C" respectively, while the wet-bulb temperature decreases by 0.5-1°C in the late stage of each period. In short, the present invention clearly shows that the critical temperature of the browning reaction of the upper leaves is 42°C, and adopts new baking technologies such as "slow heating, slow color fixation, and stable moisture removal" to bake the upper leaves.

[0031] 3. The method of the present invention bakes the upper leaves, and the proportion of ash and green tobacco in the obtained upper flue-cured tobacco leaves is significantly reduced, the color is more orange, the tissue structure is looser, the oil content is higher, the color is darker, and the smoking quality is better, which significantly improves the baking quality of the upper leaves. At the same time, the proportion of high-quality tobacco is significantly increased, the average price is significantly increased, and the income of tobacco farmers is significantly increased. DETAILED DESCRIPTION

[0032] The present invention is described in detail below.

[0033] Example 1

[0034] S1. Harvest 5 mature upper tobacco leaves with a full growth period of 128 days and place them in the tobacco loading room of the intensive flue-curing barn;

[0035] S2. The loaded upper leaves are baked. The baking process includes the early yellowing stage, the middle yellowing stage, the late yellowing stage, the early color fixing stage, the middle color fixing stage, the late color fixing stage and the dry tendon stage. The baking method for each stage is as follows:

[0036] 1) Early stage of yellowing:

[0037] The dry-bulb temperature is 36.0°C, the wet-bulb temperature is 35.0°C, the dry-bulb heating rate is controlled at 1°C / 2h, and after the dry-bulb temperature stabilizes, the tobacco leaves are baked for 4h until the tips of the high-temperature layer tobacco leaves turn yellow and soften, and lose about 10% of their water. The dry-bulb temperature is raised to 38.0°C, the wet-bulb temperature is raised to 37.0°C, and the dry-bulb heating rate is controlled at 1°C / 2h. After heating for 4h, the dry-bulb temperature stabilizes at 38.0°C. After the dry-bulb temperature stabilizes, the tobacco leaves are baked for 12h until they turn 60% yellow and lose about 15% of their water.

[0038] 2) Middle stage of yellowing:

[0039] The dry-bulb temperature is 40.0°C and the wet-bulb temperature is 38.0°C. The dry-bulb heating rate is controlled at 1°C / 2h. After heating for 4h, the dry-bulb temperature reaches a stable level of 40.0°C. After the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 18h until they are 70% yellow, soften, and have lost about 20% of their water. Then, the dry-bulb temperature is kept constant at 40.0°C, the wet-bulb temperature is lowered to 37.0°C, and baking is continued for 12h until the tobacco leaves in the high-temperature layer are 80% yellow and the tobacco leaves in the low-temperature layer are softened.

[0040] 3) Late yellowing stage:

[0041] The dry-bulb temperature is 42.0°C, the wet-bulb temperature is 36.5°C, and the dry-bulb heating rate is controlled at 1°C / 2h. After heating for 4h, the dry-bulb temperature reaches a stable level of 42.0°C. After the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 8h, until they are 90% yellow, the main veins are softened, and the water loss is about 30%. Then, the dry-bulb temperature is kept constant at 42.0°C, the wet-bulb temperature is lowered to 36.0°C, and baking is continued for 24h, until the tobacco leaves in the high-temperature layer are more than 90% yellow, the yellow leaves have blue veins, and they are obviously withered, with hooked tips and curled edges, and a water loss of about 45%, and the tobacco leaves in the low-temperature layer are slightly withered.

[0042] 4) Early stage of color fixing:

[0043] The dry bulb temperature is 44.0℃, the wet bulb temperature is 36.0℃, and the dry bulb heating rate is controlled at 1℃ / 3h. After heating for 6h, the dry bulb temperature reaches a stable temperature of 42.0℃. After the dry bulb temperature stabilizes, the tobacco leaves are baked for 8h until all the high-temperature layer leaves turn yellow, the main veins turn green, the tips of the tobacco leaves in the whole room are curled, and the water loss is more than 50%;

[0044] 5) Mid-color fixation stage:

[0045] The dry bulb temperature is 47.0℃, the wet bulb temperature is 37.0℃, and the dry bulb heating rate is controlled at 1℃ / 3h. After heating for 9h, the dry bulb temperature reaches a stable level of 47.0℃. After the dry bulb temperature stabilizes, the tobacco leaves are baked for 16h until the high temperature layer loses more than 60% of its water content, and more than half of its area becomes dry and hard. The tobacco leaves in the entire room turn yellow, with yellow leaves and yellow veins.

[0046] 6) Color fixation stage:

[0047] The dry bulb temperature is 54.0℃, the wet bulb temperature is 38.0℃, and the dry bulb heating rate is controlled at 1℃ / 2h. After heating for 14h, the dry bulb temperature reaches a stable level of 54.0℃. After the dry bulb temperature stabilizes, the tobacco leaves are cured for 16h until the leaves in the high-temperature layer are almost completely dry, forming small rolls or at least some large rolls, but the base of the main vein is not dried, with a water loss of 80%. The dry area of ​​the tobacco leaves in the low-temperature layer reaches more than half, and the main veins of the tobacco leaves in the whole furnace lose water and shrink.

[0048] 7) Drying period:

[0049] The dry-bulb temperature is 60.0℃, the wet-bulb temperature is 40.0℃, and the dry-bulb heating rate is controlled at 1℃ / 1h. After heating for 6h, the dry-bulb temperature stabilizes at 60.0℃. After the dry-bulb temperature stabilizes, it is baked for 6h until the main veins of the tobacco leaves in the high-temperature layer shrink and turn purple; then the dry-bulb temperature is heated to 68.0℃, the wet-bulb temperature is heated to 42.0℃, and the dry-bulb heating rate is controlled at 1℃ / 1h. After heating for 8h, the dry-bulb temperature stabilizes at 68.0℃. After the dry-bulb temperature stabilizes, it is baked for 20h until the main veins of the tobacco leaves in the whole furnace are dry, and the baking is ended.

[0050] Comparative Example 1

[0051] S1. Harvest 5 mature upper tobacco leaves with a full growth period of 128 days and place them in the tobacco loading room of the intensive flue-curing barn;

[0052] S2. The loaded upper leaves are baked. The baking process includes the yellowing stage, the withering stage, the color fixing stage and the dry stage. The baking method for each stage is as follows:

[0053] 1) Yellowing stage:

[0054] The dry-bulb temperature is 36.0℃, the wet-bulb temperature is 35.0℃, and the dry-bulb heating rate is controlled to be 1℃ / h. When the dry-bulb temperature is stable, bake for 4 hours until the tips of the high-temperature layer tobacco leaves turn yellow and soften, and lose about 10% of water; then raise the dry-bulb temperature to 38.0℃, the wet-bulb temperature to 36.0℃, and control the dry-bulb heating rate to be 1℃ / h. When the dry-bulb temperature is stable, continue baking for 18 hours until the high-temperature layer tobacco leaves reach 70% yellow, and lose about 15% of water; then raise the dry-bulb temperature to 40.0℃, the wet-bulb temperature to 36.5℃, and control the dry-bulb heating rate to be 0.5℃ / h. When the dry-bulb temperature is stable, bake for 24 hours until the high-temperature layer tobacco leaves reach 80% yellow, the leaves become soft, and lose about 20% of water.

[0055] 2) Withering period:

[0056] The dry bulb temperature is 42.0℃, the wet bulb temperature is 36.5℃, and the dry bulb heating rate is controlled at 0.5℃ / h. When the dry bulb temperature is stable, the tobacco leaves in the high-temperature layer are baked for 24 hours until they are more than 90% yellow, with blue veins on the yellow leaves and obvious withering. The leaves have hooked and curled edges and lose about 45% of water. The tobacco leaves in the low-temperature layer are slightly withered.

[0057] 3) Color fixing period:

[0058] The dry-bulb temperature is 46.0℃, the wet-bulb temperature is 37℃, and the dry-bulb heating rate is controlled at 0.5℃ / h. When the dry-bulb temperature is stable, bake for 16 hours, the yellow leaves and white tendons, the leaves are one-third dry, and the high-temperature layer reaches the small roll; then the dry-bulb temperature is raised to 48.0℃, the wet-bulb temperature is 37.5℃, and the dry-bulb heating rate is controlled at 0.5℃ / h. When the dry-bulb temperature is stable, bake for 12 hours, bake until the high-temperature layer tobacco leaves are large rolls, and the leaves are more than half dry; then the dry-bulb temperature is raised to 54.0℃, the wet-bulb temperature is 38.0℃, and when the dry-bulb temperature is stable, bake for 16 hours, bake until the high-temperature layer tobacco leaves are completely dry, with a water loss of more than 70%.

[0059] 4) Drying period:

[0060] The dry-bulb temperature is 60.0℃ and the wet-bulb temperature is 39.0℃. When the dry-bulb temperature stabilizes, bake for 6 hours until the main veins of the tobacco leaves in the high-temperature layer shrink and turn purple; then raise the dry-bulb temperature to 68.0℃ and the wet-bulb temperature to 42.0℃. When the dry-bulb temperature stabilizes, continue baking for 24 hours until the main veins of the tobacco leaves in the entire furnace are dry, and then end baking.

[0061] Comparative Example 2

[0062] The upper leaves were roasted using a conventional three-stage roasting method.

[0063] The upper leaves were roasted using the methods of Example 1 and Comparative Example 1, and the roasting cost, economic characteristics, appearance quality, chemical composition and smoking quality were evaluated as follows:

[0064] 1. The comparison of baking costs is shown in Table 1:

[0065]

[0066] 2. The comparison of economic properties of flue-cured tobacco leaves is shown in Table 2:

[0067] method Total dry weight / kg Ratio of high-quality tobacco / % Medium smoke ratio / % Proportion of low-grade smoke / % Average price / (yuan / kg) Output value / yuan Comparative Example 1 35.27 59.54 34.9 5.56 26.49 934.3023 Comparative Example 2 35.10 55.42 37.79 6.79 26.22 920.322 Example 1 35.44 70.67 27.61 1.72 27.28 966.803

[0068] 3. The comparison of appearance quality after baking is shown in Table 3:

[0069] method color Maturity Organizational Structure Oil identity Chroma Comparative Example 1 Orange Mature Still loose Yes + Slightly thick powerful Comparative Example 2 Orange Mature Still loose - have Slightly thick powerful Example 1 Orange+ Mature Still loose Yes + Slightly thick Strong+

[0070] 4. The comparison of chemical components in tobacco leaves after baking is shown in Table 4:

[0071]

[0072] 5. Comparison of smoking quality of flue-cured tobacco is shown in Table 5:

[0073]

[0074]

[0075] The present invention adjusts the dry-bulb and wet-bulb temperatures. The wet-bulb temperature exhibits a V-shaped change during the five stages of mid-yellowing, late yellowing, early color fixation, mid-color fixation, and late color fixation. During the two critical periods of mid-yellowing and late yellowing, the dry-bulb temperature remains constant, reaching "double 40°C" and "double 42°C," respectively, while the wet-bulb temperature decreases by 0.5-1°C in the latter stages of each period. This adjustment increases the proportion of high-quality tobacco by approximately 10% and reduces the proportion of ash and green mixed tobacco by approximately 10%, improving the smoking quality of flue-cured tobacco, with significant increases in aroma quality, aroma volume, and aftertaste, and a significant reduction in mixed odors.

Claims

1. A method for baking the upper leaves of the flue-cured tobacco variety K326, comprising the following steps: S1. Harvest 5 mature upper tobacco leaves with a full growth period of 128 days and place them in the tobacco loading room of the intensive flue-curing barn; S2. The loaded upper leaves are baked. The baking process includes the early yellowing stage, the middle yellowing stage, the late yellowing stage, the early color fixing stage, the middle color fixing stage, the late color fixing stage and the dry tendon stage. The baking method for each stage is as follows: 1) Early stage of yellowing: The dry-bulb temperature is 36.0°C, the wet-bulb temperature is 35.0°C, the dry-bulb heating rate is controlled at 1°C / 2h, and after the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 4h until the tips turn yellow and soften, and lose 10% of their water. The dry-bulb temperature is raised to 38.0°C, the wet-bulb temperature is raised to 37.0°C, and the dry-bulb heating rate is controlled at 1°C / 2h. After 4h of heating, the dry-bulb temperature stabilizes at 38.0°C. After the dry-bulb temperature stabilizes, baking is continued for 12h, until the tobacco leaves in the high-temperature layer turn 60% yellow, and lose 15% of their water. 2) Middle stage of yellowing: The dry-bulb temperature is 40.0°C and the wet-bulb temperature is 38.0°C. The dry-bulb heating rate is controlled at 1°C / 2h. After heating for 4h, the dry-bulb temperature reaches a stable level of 40.0°C. After the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are baked for 18h until they are 70% yellow, soften, and have lost 20% of their water. Then, the dry-bulb temperature is kept constant at 40.0°C, the wet-bulb temperature is lowered to 37.0°C, and baking is continued for 12h until the tobacco leaves in the high-temperature layer are 80% yellow and the tobacco leaves in the low-temperature layer are softened. 3) Late yellowing stage: The dry-bulb temperature is 42.0°C and the wet-bulb temperature is 36.5°C. The dry-bulb heating rate is controlled at 1°C / 2h. After heating for 4h, the dry-bulb temperature reaches a stable level of 42.0°C. After the dry-bulb temperature stabilizes, the tobacco leaves in the high-temperature layer are cured for 8h until they are 90% yellow, the main veins are softened, and the water loss is 30%. Then, the dry-bulb temperature is kept constant at 42.0°C, the wet-bulb temperature is lowered to 36.0°C, and the tobacco leaves are cured for another 24h until the leaves in the high-temperature layer are more than 90% yellow, the yellow leaves have blue veins, and they are obviously withered. The leaves have hooked tips and curled edges, and the water loss is 45%. In addition, the leaves in the low-temperature layer are slightly withered. 4) Early stage of color fixing: The dry bulb temperature is 44.0℃, the wet bulb temperature is 36.0℃, and the dry bulb heating rate is controlled at 1℃ / 3h. After heating for 6h, the dry bulb temperature reaches a stable temperature of 44.0℃. After the dry bulb temperature stabilizes, the tobacco leaves are baked for 8h until all the high-temperature layer leaves turn yellow, the main veins turn green, the tips of the tobacco leaves in the whole room are curled, and the water loss is more than 50%; 5) Mid-color fixation stage: The dry bulb temperature is 47.0℃, the wet bulb temperature is 37.0℃, and the dry bulb heating rate is controlled at 1℃ / 3h. After heating for 9h, the dry bulb temperature reaches a stable level of 47.0℃. After the dry bulb temperature stabilizes, the tobacco leaves are baked for 16h until the high temperature layer loses more than 60% of its water content, more than half of its area becomes dry and hard, and all the tobacco leaves in the room turn yellow, with yellow leaves and yellow veins. 6) Color fixation stage: The dry bulb temperature is 54.0℃, the wet bulb temperature is 38.0℃, and the dry bulb heating rate is controlled at 1℃ / 2h. After heating for 14h, the dry bulb temperature reaches 54.0℃ stably. After the dry bulb temperature stabilizes, the tobacco leaves are cured for 16h until the leaves in the high-temperature layer are completely dry, forming small rolls or at least part of large rolls, but the base of the main vein is not dry, with a water loss of 80%. The dry area of ​​the tobacco leaves in the low-temperature layer reaches more than half, and the main veins of the tobacco leaves in the whole furnace lose water and shrink. 7) Drying period: The dry-bulb temperature is 60.0℃, the wet-bulb temperature is 40.0℃, and the dry-bulb heating rate is controlled at 1℃ / 1h. After heating for 6h, the dry-bulb temperature stabilizes at 60.0℃. After the dry-bulb temperature stabilizes, it is baked for 6h until the main veins of the tobacco leaves in the high-temperature layer shrink and turn purple; then the dry-bulb temperature is heated to 68.0℃, the wet-bulb temperature is heated to 42.0℃, and the dry-bulb heating rate is controlled at 1℃ / 1h. After heating for 8h, the dry-bulb temperature stabilizes at 68.0℃. After the dry-bulb temperature stabilizes, it is baked for 20h until the main veins of the tobacco leaves in the whole furnace are dry, and the baking is ended.

Images