A method for improving the quality of upper leaves of tobacco cured under arid climatic conditions

Abstract

This invention discloses a method for improving the curing quality of upper tobacco leaves under arid conditions. This method targets upper leaves in arid climates, characterized by a compact structure, low leaf water content, and water bound to cellular tissue. During the yellowing stage, a dry-bulb temperature of 42-43℃ and a wet-bulb temperature of 38-39℃ are used to keep the stomata on both sides of the leaf open, ensuring the smooth removal of moisture from the tobacco leaf and allowing O2 from the curing barn to continuously enter the leaf through the stomata, aiding in the degradation of macromolecular organic matter and thus guaranteeing the quality of the tobacco leaf. This invention improves the curing quality of upper leaves under arid climates and reduces the occurrence of ash and discoloration during the curing process.

Description

Technical Field

[0001] This invention relates to a method for improving the curing quality of upper tobacco leaves under arid climatic conditions, belonging to the field of flue-cured tobacco technology. Background Technology

[0002] During tobacco curing, it is essential to ensure that moisture within the tobacco leaves can be smoothly expelled through the stomata, and that oxygen from the curing barn continuously enters the leaves through these stomata. This process helps degrade large organic molecules, resulting in the industrially desirable qualities and thus guaranteeing the quality of the tobacco leaves. The upper leaves, due to their more compact structure and lower water content, have water that is bound to the cell tissue. Because this bound water is difficult to expel during the curing process, the upper leaves are particularly susceptible to moisture loss.

[0003] Existing technologies, when used for curing upper tobacco leaves in arid climates, employ high-temperature, low-humidity methods to create a vapor pressure difference between the inside and outside of the leaves, thus expelling moisture. However, due to the low humidity in the air or curing barn (i.e., high temperature and low humidity), the stomata of the upper leaves naturally close. Even if the moisture inside the leaves manages to escape the constraints of the leaf tissue, the closed stomata prevent the moisture from escaping, causing the upper tobacco leaves to continue turning brown or black during curing, or forming steamed tobacco flakes, severely impacting the quality of the tobacco leaves.

[0004] Meanwhile, the curing of upper tobacco leaves under arid climate conditions occurs in autumn, when the leaves have low moisture content, making it difficult to meet the required humidity for curing. This is especially true for upper tobacco leaves grown in hot, low-humidity environments under arid conditions, where insufficient moisture is a common occurrence during curing. To address the humidity problem during curing, most tobacco farmers resort to adding water to the curing barn before curing or spraying water mist onto the tobacco leaves. However, this approach is flawed in several ways: first, adding water to increase humidity is complex and increases workload; second, the increased moisture primarily increases air humidity, but during curing, the amount of humid air circulating within the barn is minimal and has little effect; and third, the increased moisture is limited to the surface of the tobacco leaves, while yellowing occurs inside the leaves, thus failing to solve the fundamental problem.

[0005] Therefore, there is a need for a method to improve the quality of upper leaf baking under drought conditions in order to reduce the problem of ash and discoloration on the upper leaves during baking. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a method for improving the curing quality of upper tobacco leaves under drought conditions, which can overcome the shortcomings of the prior art.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] This invention discloses a method for improving the curing quality of upper tobacco leaves under arid climatic conditions. The method targets upper leaves under arid climatic conditions, which have a compact structure, low leaf water content, and water and cell tissue bound together. During the yellowing stage, a dry-bulb temperature of 42-43℃ and a wet-bulb temperature of 40℃-41℃ are used to keep the stomata on both sides of the leaf open, ensuring that the water in the tobacco leaf can be smoothly discharged through the stomata. This also ensures that O2 in the curing barn continuously enters the leaf through the stomata, helping to continuously degrade macromolecular organic matter, thereby ensuring the quality of the tobacco leaf.

[0009] The above-mentioned curing steps for the yellowing stage of upper tobacco leaves under arid climatic conditions are as follows:

[0010] Step 1: Use high temperature to turn the tobacco yellow. After ignition, the tobacco tips will not turn green. Increase the temperature to 40℃ at 1℃ / 1h, with a wet bulb temperature of 39℃. Maintain the temperature for 5-6 hours to ensure the tobacco leaves are heated evenly and adapt to the ambient temperature in the curing barn. Then increase the temperature to 42℃~43℃, with a wet bulb temperature of 40℃~41℃. Maintain the temperature for 40-50 hours until all the tobacco leaves in the curing barn are completely yellow. Then switch to the color-fixing stage.

[0011] Step 2, Color Fixing Stage: In the initial stage of color fixing, stabilize the dry-bulb temperature at 42-43℃ and the wet-bulb temperature at 38-39℃, and slowly remove moisture. Observe the yellowing of the tobacco leaves; the tips and edges of the second layer of tobacco leaves should curl, and the entire batch of leaves should become soft and droopy, with the main veins remaining intact. Increase the temperature at a rate of 1℃ / 5-6 hours until the dry-bulb temperature reaches 45℃, while maintaining the wet-bulb temperature at 38-39℃. Then stabilize the temperature for 4-5 hours until all the leaf veins turn yellow. The temperature is increased at a rate of h until the dry bulb temperature reaches 48℃, while the wet bulb temperature is maintained at 38-39℃. This temperature is maintained for 8-10 hours until the main vein of the tobacco leaf turns white and shiny. Then, the temperature is increased at a rate of 1℃ / 5-6h until the dry bulb temperature reaches 54℃, while the wet bulb temperature is maintained at 38-39℃. This temperature is maintained for 8-12 hours to synchronize water loss and drying. The leaves dry and wrinkle simultaneously until they are completely dry and the color of both the front and back of the leaf is similar. This marks the transition from the late color-fixing stage to the dry vein stage.

[0012] Step 3, Drying stage: Increase the temperature at a rate of 1℃ / 2h until the dry bulb temperature reaches 60℃ and the wet bulb temperature rises from 39℃ to 40℃. Then stabilize the temperature for 8-10 hours. At this time, half of the main vein of the tobacco leaf is dry. Increase the temperature at a rate of 1℃ / 1h until the dry bulb temperature reaches 65℃ and the wet bulb temperature rises from 40℃ to 41℃. Stabilize the dry bulb temperature and extend the time to complete the drying stage.

[0013] The yellowing stage mentioned above is mainly at a temperature of 42-43℃ for the upper tobacco leaves. After yellowing, moisture is removed to prevent rapid water loss and ensure proper drying of the leaf tips in the rising airflow curing barn or the leaf ear in the descending airflow curing barn. Then, the curing process is carried out according to steps 1 to 3 above.

[0014] The aforementioned expression for the respiration of tobacco leaves during the yellowing stage is: Organic matter + Oxygen => Carbon dioxide + Water + Heat; the main component of organic matter is starch, and the starch conversion process is also a starch hydrolysis process. Sufficient water is required for the hydrolysis process, and the starch hydrolysis reaction can be represented by the following chemical formula:

[0015]

[0016] Therefore, during the drying process, the drying rate is kept stable at 42-43℃, which promotes a vigorous respiration rate of tobacco leaf cells, continuously producing moisture (H2O). The increased moisture inside the leaves is beneficial for both the yellowing of the tobacco leaves and the decomposition of organic matter.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention improves the yellowing temperature: the main yellowing temperature of the original yellowing stage is adjusted from 38℃ to 42℃-43℃ for high-temperature yellowing and baking, which makes the tobacco leaves yellow faster and more uniformly, shortens the yellowing time of tobacco leaves by about 25 hours, saves baking fuel, and reduces baking costs by about 150 yuan.

[0019] 2. Slow heating and extended color-fixing period: The heating rate of 1℃ / 2-3h in the 42-54℃ stage is slowed down to 1℃ / 5-6h. The upper leaf structure is compact, and moisture is not easily removed, which easily produces smooth and stiff tobacco leaves. By flexibly controlling the temperature stabilization time and heating and dehumidifying at a uniform rate, the water loss and drying process of tobacco leaves are synchronized and coordinated. After curing, the tobacco leaf tissue structure is loose and the color is bright, which improves the grade structure of the upper leaves.

[0020] 3. Reduce airflow to stabilize tobacco aroma and oil content: Use low speed for the circulating fan during the yellowing stage, high speed for the circulating fan between 42-48℃, and low speed for the circulating fan after 48℃ to extend the 54℃ stabilization time and promote the formation of aroma compounds in the tobacco. Stabilize the temperature at 60℃ for 8-10 hours to fix the aroma compounds in the tobacco and prevent excessive airflow from causing the aroma and oil to evaporate. Control the airflow speed: before 42℃, the circulating fan speed should be 960r / min or run intermittently; between 42-48℃, the circulating fan speed should be 1440r / min; and from 48℃ to the dry rib stage, the circulating fan speed should be 960r / min.

[0021] 4. High temperature promotes water removal: Under high temperature conditions, the stomata on both sides of the tobacco leaves open rapidly, and the kun-like substances in the tobacco leaf mesophyll are expelled with the vaporization of water, preventing the browning reaction of the tobacco leaves and reducing the number of discolored tobacco leaves.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0024] Figure 1 This image shows the upper leaves turning yellow under high temperature and high humidity during baking under arid conditions. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the preferred embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0026] like Figure 1 As shown, this invention discloses a method for improving the curing quality of upper tobacco leaves under drought conditions. The method is characterized by targeting upper tobacco leaves with a compact structure, low leaf water content, and a state where water and cell tissue are bound together under drought conditions. During the yellowing stage, a dry-bulb temperature of 42-43℃ and a wet-bulb temperature of 40-41℃ are used to keep the stomata on both sides of the leaf open, ensuring that water in the tobacco leaf is smoothly expelled through the stomata. This also ensures that O2 from the curing barn continuously enters the leaf through the stomata, helping to continuously degrade macromolecular organic matter, thereby ensuring the quality of the tobacco leaf.

[0027] For the upper tobacco leaves under drought conditions, the curing steps during the yellowing stage are as follows:

[0028] Step 1: Use high temperature to yellow the tobacco leaves and shorten the time for low temperature yellowing. After ignition, the tobacco tips should not turn green quickly. Increase the temperature to 40℃ at 1℃ / 1h, with a wet bulb temperature of 39℃. Maintain the temperature for 5-6 hours to ensure the tobacco leaves are heated evenly and adapt to the ambient temperature in the curing barn. Then increase the temperature to 42℃~43℃, with a wet bulb temperature of 40℃~41℃. Maintain the temperature for 40-50 hours until all the tobacco leaves in the curing barn are completely yellow. Then switch to the color-fixing stage.

[0029] Step 2, color setting stage. In the initial color-fixing stage, maintain a stable dry-bulb temperature of 42-43℃ and a wet-bulb temperature of 38-39℃, and slowly remove moisture. Observe the yellowing of the tobacco leaves; the tips and edges of the second layer of tobacco leaves should curl, and the entire batch of leaves should become soft and droopy, with the main vein remaining intact. Increase the temperature at a rate of 1℃ / 5-6 hours until the dry-bulb temperature reaches 45℃, while maintaining the wet-bulb temperature at 38-39℃. Stabilize the temperature for 4-5 hours until the leaf veins turn completely yellow. Increase the temperature at a rate of 1℃ / 5-6 hours until the dry-bulb temperature reaches 48℃, while maintaining the wet-bulb temperature at 38-39℃. Stabilize the temperature for 8-10 hours until the main veins of the tobacco leaves turn white and shiny. Then, increase the temperature at a rate of 1℃ / 5-6 hours until the dry-bulb temperature reaches 54℃, while maintaining the wet-bulb temperature at 38-39℃. Stabilize the temperature for 8-12 hours to synchronize water loss and drying. The leaves will wrinkle as they dry until they are completely dry, with the front and back of the leaves having similar colors. From the later stage of color-fixing, the leaf drying stage begins.

[0030] Step 3, Drying Stage: Increase the temperature at a rate of 1℃ / 2h until the dry-bulb temperature reaches 60℃ and the wet-bulb temperature rises from 39℃ to 40℃. Stabilize the temperature for 8-10 hours. At this point, the main vein of the tobacco leaf is half dry. Then, increase the temperature at a rate of 1℃ / 1h until the dry-bulb temperature reaches 65℃ and the wet-bulb temperature rises from 40℃ to 41℃. Stabilize the dry-bulb temperature and extend the drying time to complete the drying process. For details, see the baking chart below. Figure 1 As shown.

[0031] The normal curing of tobacco leaves is due to the photosynthetic products in the tobacco leaves being broken down by enzymes during the curing process, through the respiration of the tobacco leaves, to form aromatic substances. The original chlorophyll is converted into carotene, lutein, etc., thereby meeting industrial needs.

[0032] The expression for respiration in tobacco leaves during the yellowing stage is: Organic matter + Oxygen => Carbon dioxide + Water + Heat; the main component of organic matter is starch, and the starch conversion process is also a starch hydrolysis process. Sufficient water is required for hydrolysis. The starch hydrolysis reaction can be represented by the following chemical formula:

[0033]

[0034] Therefore, during the curing process, the tobacco leaves maintain a vigorous respiration rate, which continuously produces moisture (H2O). The increased moisture inside the leaves is beneficial for both yellowing and the decomposition of organic matter. Thus, the heating time can be determined in a timely manner according to the moisture requirements of the tobacco leaves during curing. However, the prolonged respiration process will reduce the weight of the tobacco leaves after curing. For every 108g increase in moisture, the weight of the tobacco leaves after curing will decrease by approximately 180g. That is, the longer the yellowing time during tobacco curing, the thinner the tobacco leaves become and the lighter they are. However, "bright yellow, soft, and fragrant" tobacco leaves are more in line with the requirements of industrial raw materials.

[0035] After testing,

[0036] 1. This method compares the effects of tobacco leaves before and after yellowing during curing, which can shorten the yellowing time of tobacco leaves by about 25 hours, save curing fuel, and reduce curing costs by about 150 yuan.

[0037] 2. The method shows the effect of the ash-colored tobacco leaves before and after the process, and the proportion of ash-colored tobacco leaves is reduced by 5% from the original 18%.

[0038] 3. The method showed a comparison of the effects of smoothing stiff tobacco leaves before and after baking, reducing the proportion of smooth stiff tobacco leaves from 15% to 2%.

[0039] 4. The method shows that the upper tobacco leaves have a loose tissue structure and good elasticity, which improves the usability of the upper leaves and ensures the supply of industrial raw materials.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for improving the curing quality of upper tobacco leaves under arid climatic conditions, characterized in that, This method targets the upper leaves under arid climatic conditions, characterized by a compact structure, low leaf water content, and water within the leaves being bound to cellular tissues. During the yellowing stage, a dry-bulb temperature of 42-43℃ and a wet-bulb temperature of 40-41℃ are used to keep the stomata on both sides of the leaves open, ensuring that the moisture in the tobacco leaves can be smoothly expelled through the stomata. This also ensures that O2 from the curing barn continuously enters the leaves through the stomata, helping to continuously degrade macromolecular organic matter and thus ensuring the quality of the tobacco leaves. For upper tobacco leaves grown in arid climates, the curing steps during the yellowing stage are as follows: Step 1: Use high temperature to turn yellow. After ignition, the tobacco tips will not turn green. Increase the temperature to 40℃ at 1℃ / 1h, with a wet bulb temperature of 39℃. Stabilize the temperature for 5-6 hours to ensure the tobacco leaves are heated evenly and adapt to the ambient temperature in the curing barn. Then increase the temperature to 42℃~43℃, with a wet bulb temperature of 40℃~41℃. Stabilize the temperature for 40-50 hours until all the tobacco leaves in the curing barn are completely yellow. Then switch to the color-fixing stage. Step 2, Color Fixing Stage: In the initial stage of color fixing, stabilize the dry-bulb temperature at 42-43℃ and the wet-bulb temperature at 38-39℃, and slowly remove moisture. Observe the yellowing of the tobacco leaves; the tips and edges of the second layer of tobacco leaves should curl, and the entire batch of leaves should become soft and droopy, with the main veins remaining intact. Increase the temperature at a rate of 1℃ / 5-6 hours until the dry-bulb temperature reaches 45℃, while maintaining the wet-bulb temperature at 38-39℃. Then stabilize the temperature for 4-5 hours until all the leaf veins turn yellow. The temperature is increased at a rate of h until the dry bulb temperature reaches 48℃, while the wet bulb temperature is maintained at 38-39℃. This temperature is maintained for 8-10 hours until the main vein of the tobacco leaf turns white and shiny. Then, the temperature is increased at a rate of 1℃ / 5-6h until the dry bulb temperature reaches 54℃, while the wet bulb temperature is maintained at 38-39℃. This temperature is maintained for 8-12 hours to synchronize water loss and drying. The leaves dry and wrinkle simultaneously until they are completely dry and the color of both the front and back of the leaf is similar. This marks the transition from the late color-fixing stage to the dry vein stage. Step 3, Drying stage: Increase the temperature at a rate of 1℃ / 2h until the dry bulb temperature reaches 60℃ and the wet bulb temperature rises from 39℃ to 40℃. Then stabilize the temperature for 8-10 hours. At this time, half of the main vein of the tobacco leaf is dry. Increase the temperature at a rate of 1℃ / 1h until the dry bulb temperature reaches 65℃ and the wet bulb temperature rises from 40℃ to 41℃. Stabilize the dry bulb temperature and extend the time to complete the drying stage.

2. The method for improving the curing quality of upper tobacco leaves under arid climatic conditions according to claim 1, characterized in that: During the yellowing stage, the upper tobacco leaves mainly turn yellow at 42-43℃. After yellowing, dehumidify to prevent rapid water loss, which could cause the tips of the green leaves to be dried in an upward-flowing curing barn or the ear of the green leaves to be dried in an downward-flowing curing barn. Then, continue curing according to steps 1 to 3 above.

Images