A kind of drying method of black storm tobacco leaves

Abstract

The invention discloses a method for baking dry black storm tobacco leaves. Fresh tobacco leaves are baked after being harvested, including a softening and withering period; before and after the leaf discoloration; before, middle and late stages of leaf drying; before and after the main vein drying. The softening and withering period promotes the rapid discharge of free water inside the tobacco leaves, and the conversion of bound water to free water, which promotes the rapid start of yellowing of the tobacco leaves and shortens the yellowing period. In the early and late stages of leaf discoloration, on the premise of ensuring that the tobacco leaves turn yellow smoothly, the further conversion of bound water inside the tobacco leaves to free water is promoted, so as to achieve the yellowing and drying coordination of tobacco leaves and reduce the risk of bad tobacco. The early and middle stages of leaf drying are respectively set at 45°C and 47°C, so as to ensure that the internal moisture of the tobacco leaves is stably and efficiently discharged to the outside, and avoid the situation that the tobacco leaves are badly baked due to the high temperature in the early stage of leaf drying. The invention can shorten the baking time and reduce the baking energy consumption; improve the single leaf weight and grade quality of the tobacco leaves after baking, improve the tobacco leaf evaluation quality, and increase the availability of cigarette raw materials.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco leaf baking, in particular to an intensive baking method for drought-affected black storm tobacco leaves. Background Art

[0002] With the continuous deterioration of the global climate in recent years, the ecological environment of tobacco leaves faces severe challenges. Extreme drought weather occurs frequently. Moreover, in order to continuously pursue flue-cured tobacco production, tobacco farmers apply nitrogen fertilizers far exceeding the specified amount. As a result, a large amount of drought-induced black tobacco is produced every year. During the baking process, black tobacco is often difficult to turn yellow and fix color. After baking, the tobacco leaves are obviously black, rotten and green. Therefore, the above situation has brought great economic losses to tobacco farmers.

[0003] Due to the high chlorophyll content of drought-resistant black tobacco, it is extremely difficult to turn yellow during the baking process; in addition, the bound water content of black tobacco is relatively high, making it difficult to dehumidify during the baking process. Based on the above two factors, the baking of drought-resistant black tobacco is extremely difficult.

[0004] At present, the three-stage six-step, precise ten-point and quality-enhancing aroma baking processes promoted by tobacco-producing areas are mainly for normal mature tobacco leaves, but they have not shown good baking effects for drought-affected black storm tobacco leaves. In addition, the existing baking processes in foreign countries such as the United States, Japan, Brazil, and Zimbabwe have also failed to solve the baking problem of drought-affected black storm tobacco leaves. Summary of the invention

[0005] In view of the shortcomings of the existing baking process, the present invention provides a simple and effective tobacco baking process to solve the problem of drought-resistant black storm tobacco leaves, promote the smooth yellowing and withering and water loss of drought-resistant black storm tobacco leaves, and improve the grade quality of the baked tobacco leaves.

[0006] In order to solve the above technical problems, the technical method adopted by the present invention is:

[0007] A method for baking dry black storm tobacco leaves, wherein the fresh tobacco leaves are baked after being harvested, and the baking includes a softening and withering period, an early stage of leaf color change, a late stage of leaf color change, an early stage of leaf drying, a middle stage of leaf drying, a late stage of leaf drying, an early stage of main vein drying, and a late stage of main vein drying, which are specifically as follows:

[0008] (1) Softening and wilting stage

[0009] After the tobacco is loaded and ignited, the dry bulb temperature is raised to 40-41°C and the wet bulb temperature is raised to 36°C within 4-5 hours. The speed of the circulating fan is set to 1440 r / min and maintained for 10-15 hours. The tobacco leaves in the high-temperature layer are completely soft and the leaf tips turn yellow by 15-20cm. The tobacco leaves in the low-temperature layer are basically soft and the leaf tips turn yellow by 9-11cm.

[0010] (2) Early stage of leaf color change

[0011] The dry bulb temperature was lowered to 38℃ at a rate of 1℃ / h, and the wet bulb temperature was maintained at 36℃ for 30-35h. The circulating fan was maintained at 1440 r / min for the first 12h, and then reduced to 960 r / min. The tobacco leaves in the high temperature layer were baked until they were completely yellow and the leaf tips were dry by 2-4cm. The leaves in the medium temperature layer were yellow by 70%-75%, with the leaf tips curled, and the leaves in the low temperature layer were yellow by 45%-50%, and the leaves were completely soft.

[0012] (3) Late stage of leaf discoloration

[0013] Raise the dry bulb temperature to 41-42℃ and the wet bulb temperature to 37℃ at a rate of 1℃ / h, maintain for 15-18h, increase the speed of the circulating fan to 1440 r / min, and bake until the tobacco leaves in the whole room have yellow leaves and blue veins;

[0014] (4) Early stage of leaf drying

[0015] Raise the dry bulb temperature to 45°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, maintain the circulating fan speed at 1440 r / min, and bake until the high-temperature layer tobacco leaves are completely dry;

[0016] (5) Mid-stage leaf drying

[0017] Raise the dry bulb temperature to 47°C at a rate of 0.5°C / h, and then to 38°C, and maintain this temperature for 12-18 hours. Maintain the speed of the circulating fan at 1440 r / min, and bake until the tobacco leaves in the middle temperature layer are basically dry.

[0018] (6) Late stage of leaf drying

[0019] Raise the dry bulb temperature to 53°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, maintain the circulating fan speed at 1440 r / min, and bake until the tobacco leaves in the whole room are dry;

[0020] (7) Early stage of main vein drying

[0021] Raise the dry bulb temperature to 60℃ and the wet bulb temperature to 40℃ at a rate of 1℃ / h, maintain for 12-16h, reduce the speed of the circulating fan to 960 r / min, and bake until the main veins of the high-temperature layer tobacco leaves are completely dry;

[0022] (8) Late stage of main vein drying

[0023] Raise the dry bulb temperature to 70℃ and the wet bulb temperature to 41℃ at a rate of 1℃ / h, maintain for 25-30h, maintain the circulating fan speed at 960 r / min, and bake until the main veins of the tobacco leaves in the whole room are completely dry.

[0024] It is further preferred that the dry-bulb temperature and wet-bulb temperature involved in the softening and withering stage, the early stage of leaf color change, the late stage of leaf color change, the early stage of leaf drying, the middle stage of leaf drying, the late stage of leaf drying, the early stage of main vein drying and the late stage of main vein drying are all the dry-bulb temperature and wet-bulb temperature of the high-temperature layer tobacco leaves.

[0025] It is further preferred that the complete softening during the softening and withering period refers to the softening of the leaf blade and the branch veins as well as the main vein 10 cm away from the leaf tip.

[0026] It is further preferred that the substantially softening of the low-temperature layer during the softening and withering period refers to the complete softening of the leaves and branch veins.

[0027] It is further preferred that the leaves are baked in the later stage of leaf color change until the whole room of tobacco leaves are yellow and blue veins, at which time the tips of the high-temperature layer tobacco leaves are dried by 5-7cm, the tips of the medium-temperature layer tobacco leaves are dried by 2-4cm, and the tips of the low-temperature layer tobacco leaves are curled.

[0028] It is further preferred that the basic drying of the mesothermal tobacco leaves in the middle stage of leaf drying means that all leaves are dried except for the leaves in the left and right areas 1-2 cm away from the main vein.

[0029] The technical points of the present invention are:

[0030] (1) During the softening and wilting period, the dry bulb temperature is raised to 40-41°C and the wet bulb temperature is raised to 36°C within 4-5 hours after the fire. The speed of the circulating fan is set to 1440 r / min to promote the rapid discharge of free water inside the tobacco leaves and the conversion of bound water into free water. At the same time, it promotes the rapid yellowing of tobacco leaves and shortens the yellowing period.

[0031] (2) In the early and late stages of leaf color change, on the premise of ensuring that the tobacco leaves turn yellow smoothly, the conversion of bound water inside the tobacco leaves into free water is promoted to achieve coordinated yellowing and drying of the tobacco leaves, thereby reducing the risk of bad tobacco.

[0032] (3) The temperature of the leaf is set at 45℃ and 47℃ in the early stage and middle stage respectively. The two-stage method of one low and one high is adopted to ensure that the moisture inside the tobacco leaves is stably and efficiently discharged to the outside, so as to avoid the situation that the tobacco leaves are damaged due to the high temperature in the early stage of the leaf drying period. In addition, setting the temperature at 45℃ in the early stage of leaf drying can make up for the defect that some tobacco leaves may not turn yellow completely during the yellowing period, promote the further degradation and transformation of macromolecular substances such as starch, protein and lipids, and improve the quality of tobacco leaves.

[0033] (4) In the later stage of leaf drying, keep the leaves for 24 hours to promote the formation of a large amount of aroma substances and further improve the quality of tobacco leaves.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) Shorten the baking time and reduce the energy consumption of tobacco baking;

[0036] (2) Improve the weight and grade of single-leaf tobacco leaves after flue-curing, and increase the economic benefits of farmers;

[0037] (3) Improve the smoking quality of tobacco leaves and increase the availability of cigarette raw materials. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to specific examples.

[0039] A method for baking dry black storm tobacco leaves, wherein fresh tobacco leaves are baked after being harvested, and the baking room used is a standard airflow ascending intensive baking room, the baking room is loaded with three layers of tobacco, the tobacco loading capacity is 4500kg / room, and the temperature and humidity control method is high temperature layer control. Baking includes the softening and withering period, the early stage of leaf color change, the late stage of leaf color change, the early stage of leaf drying, the middle stage of leaf drying, the late stage of leaf drying, the early stage of main vein drying and the late stage of main vein drying. The dry-bulb temperature and wet-bulb temperature involved in the softening and withering period, the early stage of leaf color change, the late stage of leaf color change, the early stage of leaf drying, the middle stage of leaf drying, the late stage of leaf drying, the early stage of main vein drying and the late stage of main vein drying are all the dry-bulb temperature and wet-bulb temperature of tobacco leaves in the high temperature layer. The details are as follows:

[0040] (1) Softening and wilting stage

[0041] After the tobacco is loaded and ignited, the dry bulb temperature is raised to 40-41°C and the wet bulb temperature is raised to 36°C within 4-5 hours. The speed of the circulating fan is set to 1440 r / min and maintained for 10-15 hours. The tobacco leaves in the high-temperature layer are completely soft and the leaf tips turn yellow by 15-20cm. The tobacco leaves in the low-temperature layer are basically soft and the leaf tips turn yellow by 9-11cm.

[0042] The high-temperature layer tobacco leaves are completely soft, which means that the leaves and the side veins are soft, and the main vein is obviously soft 10 cm away from the tip of the leaf; the low-temperature layer is basically soft, which means that the leaves and the side veins are completely soft;

[0043] (2) Early stage of leaf color change

[0044] The dry bulb temperature was lowered to 38℃ at a rate of 1℃ / h, and the wet bulb temperature was maintained at 36℃ for 30-35h. The circulating fan was maintained at 1440 r / min for the first 12h, and then reduced to 960 r / min. The tobacco leaves in the high temperature layer were baked until they were completely yellow and the leaf tips were dry by 2-4cm. The leaves in the medium temperature layer were yellow by 70%-75%, with the leaf tips curled, and the leaves in the low temperature layer were yellow by 45%-50%, and the leaves were completely soft.

[0045] (3) Late stage of leaf discoloration

[0046] Raise the dry bulb temperature to 41-42℃ and the wet bulb temperature to 37℃ at a rate of 1℃ / h, maintain for 15-18h, increase the speed of the circulating fan to 1440 r / min, and bake until the tobacco leaves in the whole room are yellow and have blue veins; at this time, the tips of the tobacco leaves in the high-temperature layer are dry to 5-7cm, the tips of the tobacco leaves in the medium-temperature layer are dry to 2-4cm, and the tips of the tobacco leaves in the low-temperature layer are curled;

[0047] (4) Early stage of leaf drying

[0048] Raise the dry bulb temperature to 45°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, maintain the circulating fan speed at 1440 r / min, and bake until the high-temperature layer tobacco leaves are completely dry;

[0049] (5) Mid-stage leaf drying

[0050] The dry bulb temperature is raised to 47°C at a rate of 0.5°C / h, and the dry bulb temperature is raised to 38°C, and maintained for 12-18 hours, and the speed of the circulating fan is maintained at 1440 r / min, and the mesophilic layer tobacco leaves are baked until the leaves are basically dry; the mesophilic layer tobacco leaves are basically dry, which means that the leaves are dried except for the leaves on the left and right sides 1-2 cm away from the main vein;

[0051] (6) Late stage of leaf drying

[0052] Raise the dry bulb temperature to 53°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, preferably 24 hours, maintain the circulating fan speed at 1440 r / min, and bake until the tobacco leaves in the whole room are dry;

[0053] (7) Early stage of main vein drying

[0054] Raise the dry bulb temperature to 60℃ and the wet bulb temperature to 40℃ at a rate of 1℃ / h, maintain for 12-16h, reduce the speed of the circulating fan to 960 r / min, and bake until the main veins of the high-temperature layer tobacco leaves are completely dry;

[0055] (8) Late stage of main vein drying

[0056] Raise the dry bulb temperature to 70℃ and the wet bulb temperature to 41℃ at a rate of 1℃ / h, maintain for 25-30h, maintain the circulating fan speed at 960 r / min, and bake until the main veins of the tobacco leaves in the whole room are completely dry.

[0057] The conventional baking process is as follows:

[0058] (1) Yellowing stage

[0059] The first step is to increase the temperature of the baking room to 35℃ with a low fire and maintain the wet bulb temperature at 33~34℃ until the leaf tips turn yellow. The fan runs at a low speed.

[0060] The second step is to raise the dry bulb temperature to 38°C at a rate of 1°C every 2 hours, extend the temperature stabilization time, control the wet bulb temperature at 35-36°C, and make 80% of the tobacco leaves in the thermometer shed in the curing room reach 70-80% yellow, and the leaves become soft. The fan runs at a low speed.

[0061] The third step is to raise the temperature to 41-42°C at a rate of 1°C every 2 hours, and maintain the wet bulb temperature at 36-37°C, so that the tobacco leaves are yellow with slightly green veins, withered and collapsed frames, and the main veins are soft. The fan runs at high speed.

[0062] (2) Color fixing stage

[0063] In the first step, the dry-bulb temperature is raised to 45-48°C at a rate of 1°C every 2-3 hours (generally 45°C for lower leaves, 45-47°C for middle leaves, and 47-48°C for upper leaves) and maintained stable, while the wet-bulb temperature is maintained at 37-38°C. The time is extended so that the tobacco veins turn yellow and the water is lost to the point of small curling.

[0064] The second step is to increase the temperature to 54-55°C at a rate of 1°C every 1-2 hours, maintain a steady temperature for 8-12 hours, maintain the wet-bulb temperature at 38-39°C, and extend the time to dry the leaves.

[0065] (3) Drying period

[0066] In the first step, the dry-bulb temperature is raised from 54°C to 58~59°C at a rate of 1°C / h, and the wet-bulb temperature is maintained at 39~40°C for 8~12 hours to make the tobacco leaves and veins turn purple.

[0067] In the second step, the dry bulb temperature is raised from 58~59℃ to 65~68℃ at a rate of 1℃ / h, and the wet bulb temperature is maintained at 40~42℃ for more than 12 hours to dry the tobacco. In this stage, the wet bulb temperature should not exceed 42℃, and the moisture inlet and outlet can be gradually closed to reduce the ventilation volume.

[0068] Compared with the prior art, the baking process of the present invention and the conventional baking process have the following effects:

[0069] (1) Economic characteristics of flue-cured tobacco leaves

[0070] Table 1 Economic characteristics of flue-cured tobacco leaves

[0071]

[0072] As shown in Table 1, compared with the conventional baking process, the baking process of the present invention can effectively improve the economic benefits of flue-cured tobacco, wherein the baking process of the present invention can increase the proportion of high-quality tobacco by 38.96%, the proportion of medium-quality tobacco by 13.56%, the average price by 28.15%, the output value per hectare by 28.15%, the energy consumption by 18.33%, and the baking time by 18.04%.

[0073] (2) Evaluation of smoking quality of flue-cured tobacco leaves

[0074] Table 2 Smoking quality scores of tobacco leaves after different curing processes

[0075]

[0076] As shown in Table 2, compared with the conventional baking process, the baking process of the present invention can effectively improve the sensory quality and industrial availability of flue-cured tobacco, wherein the baking process of the present invention can improve the aroma quality by 6.93%, the aroma amount by 5.40%, the miscellaneous gas by 2.70%, the permeability by 1.54%, the concentration by 8.58%, the strength by 4.17%, the fineness by 7.00%, the clumping by 8.45%, the cleanliness by 1.35%, and the sweet aftertaste by 4.35%; the irritation is the same as that of the conventional baking process, the dryness score is 1.52% lower than that of the conventional baking process, and the total score is 5.30 percentage points higher than that of the conventional baking process.

[0077] The present invention and its implementation methods are described above, but the description is not restrictive, and the examples listed are only one of the implementation methods of the present invention, but the actual implementation is not limited to this. Therefore, if the staff in this field, without departing from the purpose of the invention, designs a structure and an implementation method similar to the technical solution without creativity, they should all fall within the protection scope of the present invention.

Claims

1. A method for baking dry black tobacco leaves, wherein fresh tobacco leaves are baked after being harvested, characterized in that: Baking includes the softening and withering stage, the early stage of leaf color change, the late stage of leaf color change, the early stage of leaf drying, the middle stage of leaf drying, the late stage of leaf drying, the early stage of main vein drying and the late stage of main vein drying, as follows: (1) Softening and wilting stage After the tobacco is loaded and ignited, the dry bulb temperature is raised to 40-41°C and the wet bulb temperature is raised to 36°C within 4-5 hours. The speed of the circulating fan is set to 1440 r / min and maintained for 10-15 hours. The tobacco leaves in the high-temperature layer are completely soft and the leaf tips turn yellow by 15-20 cm. The tobacco leaves in the low-temperature layer are basically soft and the leaf tips turn yellow by 9-11 cm. (2) Early stage of leaf color change The dry bulb temperature was lowered to 38℃ at a rate of 1℃ / h, and the wet bulb temperature was maintained at 36℃ for 30-35h. The circulating fan was maintained at 1440 r / min for the first 12h, and then reduced to 960 r / min. The tobacco leaves in the high temperature layer were baked until they were completely yellow and the leaf tips were dry by 2-4cm. The leaves in the medium temperature layer were yellow by 70%-75%, with the leaf tips curled, and the leaves in the low temperature layer were yellow by 45%-50%, and the leaves were completely soft. (3) Late stage of leaf discoloration Raise the dry bulb temperature to 41-42℃ and the wet bulb temperature to 37℃ at a rate of 1℃ / h, maintain for 15-18h, increase the speed of the circulating fan to 1440 r / min, and bake until the tobacco leaves in the whole room have yellow leaves and blue veins; (4) Early stage of leaf drying Raise the dry bulb temperature to 45°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, maintain the circulating fan speed at 1440 r / min, and bake until the high-temperature layer tobacco leaves are completely dry; (5) Mid-stage leaf drying Raise the dry bulb temperature to 47°C at a rate of 0.5°C / h, and then to 38°C, and maintain this temperature for 12-18 hours. Maintain the speed of the circulating fan at 1440 r / min, and bake until the tobacco leaves in the middle temperature layer are basically dry. (6) Late stage of leaf drying Raise the dry bulb temperature to 53°C at a rate of 0.5°C / h, maintain the wet bulb temperature at 37°C for 20-25 hours, maintain the circulating fan speed at 1440 r / min, and bake until the tobacco leaves in the whole room are dry; (7) Early stage of main vein drying Raise the dry bulb temperature to 60℃ and the wet bulb temperature to 40℃ at a rate of 1℃ / h, maintain for 12-16h, reduce the speed of the circulating fan to 960 r / min, and bake until the main veins of the high-temperature layer tobacco leaves are completely dry; (8) Late stage of main vein drying Raise the dry bulb temperature to 70℃ and the wet bulb temperature to 41℃ at a rate of 1℃ / h, maintain for 25-30h, maintain the circulating fan speed at 960 r / min, and bake until the main veins of the tobacco leaves in the whole room are completely dry.

2. The method for baking dry black storm tobacco leaves according to claim 1, characterized in that: The dry-bulb temperature and wet-bulb temperature involved in the softening and withering stage, the early stage of leaf color change, the late stage of leaf color change, the early stage of leaf drying, the middle stage of leaf drying, the late stage of leaf drying, the early stage of main vein drying and the late stage of main vein drying are all the dry-bulb temperature and wet-bulb temperature of the high-temperature layer tobacco leaves.

3. The method for baking drought-resistant black storm tobacco leaves according to claim 1, characterized in that: The complete softening of the high temperature layer tobacco leaves during the softening and withering period refers to the softening of the leaf blade and the branch veins as well as the main vein 10 cm away from the leaf tip being obviously softened.

4. The method for baking dry black storm tobacco leaves according to claim 1, characterized in that: The basic softening of the low-temperature layer tobacco leaves during the softening and withering period refers to the complete softening of the leaf blades and branch veins.

5. The method for baking dry black storm tobacco leaves according to claim 1, characterized in that: The leaves are baked in the late stage of leaf discoloration until the whole room of tobacco leaves are yellow and blue veins, at which time the tips of the high-temperature layer tobacco leaves are dried by 5-7cm, the tips of the medium-temperature layer tobacco leaves are dried by 2-4cm, and the tips of the low-temperature layer tobacco leaves are curled.

6. The method for baking dry black storm tobacco leaves according to claim 1, characterized in that: The basic drying of the mesothermal tobacco leaves in the middle stage of leaf drying means that all leaves are dried except for the leaves in the areas on the left and right sides 1-2 cm away from the main vein.

Images