A curing method for reducing mechanical damage to tobacco leaf

Abstract

The application discloses a kind of methods for reducing mechanical damage of tobacco leaf, comprising S1, reducing fresh tobacco leaf mechanical damage;S2, appropriate density loading;S3, curing, slow down the temperature rising speed of dry ball temperature 36~45℃, slow down the water loss drying speed of tobacco leaf from ignition to dry ball temperature 40℃, appropriately extend the temperature rising and stabilizing curing time of dry ball temperature 37~40℃, 42~45℃, appropriately improve the yellowing degree of mechanical damage tobacco leaf blade, especially the ear of tobacco leaf base, scientific curing is carried out using two-reduction-one-long curing process.After using the method of the application, the following advantages are obtained: significantly reducing fresh tobacco leaf mechanical damage, significantly reducing the proportion of green tobacco in cured tobacco leaf with mechanical damage, improving the proportion of orange tobacco and grade structure.

Description

Technical Field

[0001] This invention relates to a method for harvesting and curing tobacco leaves to reduce mechanical damage, belonging to the field of tobacco curing technology. Background Technology

[0002] The uniformity of the quality of first-cured tobacco leaves is a crucial factor affecting the grade of raw tobacco. Recent production data shows that many producing areas have experienced significant mechanical damage and high green content in cured tobacco leaves due to improper harvesting and curing, and mechanical damage to fresh leaves. This is particularly pronounced at the leaf base, severely impacting the uniformity of the cured tobacco quality and reducing its usability. Poor maturity of fresh tobacco leaves, with a denser leaf structure and lower looseness, makes them prone to breakage during harvesting, resulting in a higher green content in the cured leaves. Furthermore, both arid and rainy climates increase leaf breakage and mechanical damage. Rough handling during harvesting, transportation, and packing can easily cause cell rupture in fresh tobacco leaves, leading to accelerated water loss at damaged areas. This abnormal water loss during curing accelerates drying at the damaged areas, prematurely halting material transformation, especially the degradation of plastid pigments, resulting in a higher green content at mechanically damaged areas. Additionally, the lack of shade structures on transport vehicles increases the risk of sunscald, further increasing the green content of the cured tobacco leaves due to mechanical damage. In response to the current production situation, adopting some key harvesting and curing techniques can effectively avoid mechanical damage to fresh tobacco leaves, solve the problems of increased green smoke content due to mechanical damage to fresh tobacco leaves and mechanical damage to cured tobacco leaves, and improve the uniformity and usability of cured tobacco leaves. Summary of the Invention

[0003] Therefore, the object of the present invention is to provide a harvesting and curing method for reducing mechanical damage to tobacco leaves, so as to at least solve the problems mentioned in the background art.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] Methods for preventing mechanical damage to harvested and cured tobacco leaves include:

[0006] S1, Reduce mechanical damage to fresh tobacco leaves: Reduce the degree of breakage and mechanical damage to fresh tobacco leaves by harvesting them at maturity, arranging the harvesting time in a reasonable manner, and using light transportation and light packing.

[0007] S2, Dense Packing: Increase the packing density of tobacco in dense curing barns, reduce the dehumidification rate of the curing barn and the rate of water loss of tobacco leaves, thereby ensuring that mechanically damaged tobacco leaves have sufficient time to lose water and turn yellow;

[0008] S3 employs a two-reduction-one-length baking process for scientific baking: slowing down the rate of increase in dry bulb temperature from 36℃ to 45℃, slowing down the rate of water loss and drying of tobacco leaves from ignition to dry bulb temperature of 40℃, and extending the baking time for maintaining a stable dry bulb temperature of 37℃ to 40℃ and 42℃ to 45℃, thereby increasing the degree of yellowing of the auricles at the base of mechanically damaged tobacco leaves.

[0009] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing is characterized by the following features: the mature fresh tobacco leaves harvested in S1 are characterized by obvious fading of the leaf auricles and loose, soft leaves; when harvesting tobacco leaves, the leaf stalk should be pinched during harvesting, and it is important to avoid grasping the base of the tobacco leaf with your hands during harvesting, and the leaves should be handled gently.

[0010] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing includes the following requirements for the reasonable arrangement of harvesting time in S1: in arid areas, tobacco leaves should be harvested with dew, and the harvesting time should be between 11 pm and 8 am. In the absence of light or in dim light, light sources should be provided, and the fresh tobacco leaves should be transported back to the sorting and binding area before 10 am; in rainy conditions, tobacco leaves should be harvested on cloudy days or in the afternoon of sunny days to reduce the moisture on the surface of the tobacco leaves and prevent them from being exposed to the sun.

[0011] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing includes, in S1, lightweight transportation, which refers to the use of soft packaging materials or open-top tobacco transport devices to reduce excessive compression or improper handling of fresh tobacco leaves, avoid the phenomenon of scattered stacking of fresh tobacco leaves, and use of shade canopy devices on the tobacco transport vehicle to avoid sunburn.

[0012] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing means that the "lightweight tobacco-clamping" in S1 refers to handling the tobacco gently during the clamping process, primarily using the thumb, index finger, and middle finger, and avoiding gripping it with the hands.

[0013] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing involves a standard for increased tobacco density in S2, where the tobacco load in each standard dense curing barn is between 360 and 390 rods / clamp, which is 10% to 20% higher than the conventional tobacco load in non-standard dense curing barns.

[0014] The aforementioned method for reducing mechanical damage to tobacco leaves during harvesting and curing includes the following steps in S3 for scientific curing using a two-reduction-one-long curing process:

[0015] S3-1, Yellowing Stage: After ignition, raise the dry-bulb temperature to 34℃~36℃ at a rate of 1℃ / h, with a dry-bulb-wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 3~5 hours until the tobacco leaves in the high-temperature layer turn 10% yellow; then, raise the dry-bulb temperature to 37℃~38℃ at a rate of 1℃ / 2~3 hours, with a dry-bulb-wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 20~35 hours until the tobacco leaves in the high-temperature layer turn 60%-70% yellow; then, raise the dry-bulb temperature to... At 40℃, with a dry-bulb and wet-bulb temperature difference of 2℃~2.5℃, bake at a stable temperature for 6~10 hours. After that, keep the dry-bulb temperature constant and appropriately increase the dry-bulb and wet-bulb temperature difference to 3℃~4℃, bake at a stable temperature until the tobacco leaves in the high-temperature layer turn 80%~90% yellow. Then, raise the dry-bulb temperature to 42℃ at a rate of 1℃ / 3~5 hours, increase the dry-bulb and wet-bulb temperature difference to 5℃~7℃, and appropriately extend the stable temperature baking time by 3~5 hours, bake at a stable temperature until the tobacco leaves in the high-temperature layer turn yellow with green veins, and the mechanically damaged areas at the base of the leaves basically turn green.

[0016] S3-2, Color Fixing Period: Raise the dry-bulb temperature to 45℃ at a rate of 1℃ / 6~8h, increasing the dry-bulb-wet-bulb temperature difference to 8℃~9℃, and appropriately extend the stable-temperature baking time by 4~6h. Baking at a stable temperature until the base of all tobacco leaves, including mechanically damaged leaves, turns yellow and the leaf tips curl. Then, raise the dry-bulb temperature to 48℃ at a rate of 1℃ / 2h, increasing the dry-bulb-wet-bulb temperature difference to 10℃~11℃, and baking at a stable temperature until more than 1 / 2 of the tobacco leaves are dry. Then, raise the dry-bulb temperature to 53℃~54℃ at a rate of 1℃ / 2h, increasing the dry-bulb-wet-bulb temperature difference to 14℃~16℃, and baking at a stable temperature for 10~20h until all tobacco leaves are completely dry.

[0017] S3-3, Drying stage: Increase the dry bulb temperature to 60℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 20℃~21℃, and maintain the temperature for 3~5 hours; then, increase the dry bulb temperature to 65℃~67℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 25℃~28℃, and maintain the temperature for 20~25 hours until all tobacco leaves in the kiln are completely dry.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention, through mature harvesting of fresh tobacco leaves, reasonable scheduling of harvesting time, and convenient transportation and packing, ensures that fresh tobacco leaves retain a certain degree of softness and elasticity, reducing mechanical damage and breakage, thereby lowering the proportion of mechanically damaged green tobacco leaves after curing and improving the appearance quality of the cured tobacco leaves. Secondly, by appropriately increasing the packing density in the dense curing barn, the ventilation and dehumidification resistance of the packing chamber is increased to a certain extent, reasonably reducing the dehumidification rate of the curing barn and the rate of water loss from the tobacco leaves, thus ensuring that mechanically damaged leaves have sufficient time to yellow. Furthermore, regarding the curing process, by slowing down the heating rate of the dry bulb temperature (36℃~45℃), slowing down the rate of water loss and drying of the tobacco leaves from ignition to a dry bulb temperature of 40℃, appropriately extending the heating and stabilization time at dry bulb temperatures of 37℃~40℃ and 42℃~45℃, and appropriately increasing the yellowing degree of mechanically damaged tobacco leaves, especially the auricles at the base of the leaves, the yellowing time of mechanically damaged leaves was extended to a certain extent, and the water loss and drying process of mechanically damaged leaves was slowed down. This ensured that mechanically damaged tobacco leaves had sufficient environmental conditions to yellow and fix their color, thereby improving the appearance quality and grade structure of the cured tobacco leaves.

[0020] The following advantages are clearly evident when using the tobacco harvesting and curing method of the present invention compared with conventional harvesting and curing methods:

[0021] 1. Significantly reduces mechanical damage to fresh tobacco leaves;

[0022] 2. Significantly improves the appearance and color of flue-cured tobacco leaves, significantly reduces mechanically damaged tobacco leaves and the proportion of green tobacco, and increases the proportion of orange-yellow tobacco;

[0023] 3. Significantly improves the grade structure of flue-cured tobacco leaves.

[0024] 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.

[0025] Instruction manual illustrations

[0026] Figure 1 This is a photograph of tobacco leaves after curing using the method of this invention;

[0027] Figure 2 This is the second photograph of tobacco leaves after curing using the method of this invention;

[0028] Figure 3 This is the third photograph of tobacco leaves after curing using the method of this invention;

[0029] Figure 4 This is a photo of tobacco leaves after being cured using a conventional curing process.

[0030] Figure 5 This is the second photo of tobacco leaves after being cured using the conventional curing process;

[0031] Figure 6 This is the third photo of tobacco leaves after being cured using the conventional curing process. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the tables in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1. A method for harvesting and curing tobacco leaves to reduce mechanical damage, comprising:

[0034] S1. Reduce mechanical damage to fresh tobacco leaves: Reduce the degree of breakage and mechanical damage to fresh tobacco leaves by harvesting mature leaves, rationally arranging harvesting time, and using lightweight transportation and lightweight packing. The characteristics of mature fresh tobacco leaves are obvious fading of the leaf auricle and loose and soft leaves. When harvesting tobacco leaves, pinch the leaf stalk and avoid grasping the base of the tobacco leaf with your hands. Handle the leaves gently. The requirements for rationally arranging the harvesting time are as follows: in arid areas, tobacco leaves should be harvested while still wet with dew, and the harvesting time should be between 11 pm and 8 am. In the absence of light or in low light conditions, light sources should be provided, and the fresh tobacco leaves should be transported back to the packing area before 10 am. In rainy conditions, tobacco leaves should be harvested on cloudy days or in the afternoon of sunny days to reduce the moisture on the surface of the tobacco leaves and prevent sun exposure. Lightweight transportation refers to using soft packaging materials or open tobacco transport devices to reduce excessive compression or improper handling of fresh tobacco leaves, avoid the phenomenon of scattered stacking of fresh tobacco leaves, and use shade devices on tobacco transport vehicles to prevent sunburn. Lightweight cigarette clipping refers to handling cigarettes gently during the process, primarily using the thumb, index finger, and middle finger, and avoiding gripping them with the hands.

[0035] S2, Dense Packing: Increase the packing density of tobacco in dense curing barns, reduce the dehumidification rate of the curing barn and the rate of water loss of tobacco leaves, thereby ensuring that mechanically damaged tobacco leaves have sufficient time to lose water and turn yellow; the standard for dense packing is that the packing amount of tobacco in each standard dense curing barn is 360 rods / clamp, which is 10% more than the conventional packing amount of tobacco in a standard dense curing barn.

[0036] S3 employs a two-reduction-one-length baking process for scientific baking: slowing down the rate of increase in dry bulb temperature from 36℃ to 45℃, slowing down the rate of water loss and drying of tobacco leaves from ignition to dry bulb temperature of 40℃, and extending the baking time for maintaining a stable dry bulb temperature of 37℃ to 40℃ and 42℃ to 45℃, thereby increasing the degree of yellowing of the auricles at the base of mechanically damaged tobacco leaves.

[0037] The scientific baking process using the "two reductions and one extension" baking technique is as follows:

[0038] S3-1, Yellowing Stage: After ignition, raise the dry-bulb temperature to 34℃ at a rate of 1℃ / h, with a dry-bulb-wet-bulb temperature difference of 0.5℃, and maintain this temperature for 5 hours until the tobacco leaves in the high-temperature layer turn 10% yellow; then, raise the dry-bulb temperature to 37℃ at a rate of 1℃ / 2-3 hours, with a dry-bulb-wet-bulb temperature difference of 0.5℃, and maintain this temperature for 35 hours until the tobacco leaves in the high-temperature layer turn 60-70% yellow; then, raise the dry-bulb temperature to 40℃ at a rate of 1℃ / 3-4 hours. The dry-bulb and wet-bulb temperature difference is 2.5℃, and the temperature is maintained for 10 hours. After that, the dry-bulb temperature is kept constant, and the dry-bulb and wet-bulb temperature difference is appropriately increased to 3℃. The temperature is maintained for 10 hours until the tobacco leaves in the high-temperature layer turn 80-90% yellow. Then, the dry-bulb temperature is increased to 42℃ at a rate of 1℃ / 3-5 hours, the dry-bulb and wet-bulb temperature difference is increased to 5℃, and the temperature is maintained for 10 hours until the tobacco leaves in the high-temperature layer turn yellow with green veins, and the mechanically damaged parts at the base of the leaves are basically degreened.

[0039] S3-2, Color Fixing Period: Increase the dry-bulb temperature to 45℃ at a rate of 1℃ / 6~8h, increase the dry-bulb-wet-bulb temperature difference to 8℃, and appropriately extend the stable temperature baking time by 6h. Baking at a stable temperature until the base of all tobacco leaves, including mechanically damaged leaves, turns yellow and the leaf tips curl and curl. Then, increase the dry-bulb temperature to 48℃ at a rate of 1℃ / 2h, increase the dry-bulb-wet-bulb temperature difference to 10℃, and bake at a stable temperature until more than 1 / 2 of the tobacco leaves in the entire kiln are dry. Then, increase the dry-bulb temperature to 53℃ at a rate of 1℃ / 2h, increase the dry-bulb-wet-bulb temperature difference to 14℃, and bake at a stable temperature for 20h until all the tobacco leaves in the entire kiln are completely dry.

[0040] S3-3, Drying stage: Increase the dry bulb temperature to 60℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 20℃, and bake at a stable temperature for 5 hours; then, increase the dry bulb temperature to 67℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 28℃, and bake at a stable temperature for 25 hours until all tobacco leaves in the kiln are completely dry.

[0041] Example 2. A harvesting and curing method to reduce mechanical damage to tobacco leaves:

[0042] S1. Reduce mechanical damage to fresh tobacco leaves: Reduce the degree of breakage and mechanical damage to fresh tobacco leaves by harvesting mature leaves, rationally arranging harvesting time, and using lightweight transportation and lightweight packing. The characteristics of mature fresh tobacco leaves are obvious fading of the leaf auricle and loose and soft leaves. When harvesting tobacco leaves, pinch the leaf stalk and avoid grasping the base of the tobacco leaf with your hands. Handle the leaves gently. The requirements for rationally arranging the harvesting time are as follows: in arid areas, tobacco leaves should be harvested while still wet with dew, and the harvesting time should be between 11 pm and 8 am. In the absence of light or in low light conditions, light sources should be provided, and the fresh tobacco leaves should be transported back to the packing area before 10 am. In rainy conditions, tobacco leaves should be harvested on cloudy days or in the afternoon of sunny days to reduce the moisture on the surface of the tobacco leaves and prevent sun exposure. Lightweight transportation refers to using soft packaging materials or open tobacco transport devices to reduce excessive compression or improper handling of fresh tobacco leaves, avoid the phenomenon of scattered stacking of fresh tobacco leaves, and use shade devices on tobacco transport vehicles to prevent sunburn. Lightweight cigarette clipping refers to handling cigarettes gently during the process, primarily using the thumb, index finger, and middle finger, and avoiding gripping them with the hands.

[0043] S2, Dense Packing: Increase the packing density of tobacco in dense curing barns, reduce the dehumidification rate of the curing barn and the rate of water loss of tobacco leaves, thereby ensuring that mechanically damaged tobacco leaves have sufficient time to lose water and turn yellow; the standard for dense packing is that the packing amount of tobacco in each standard dense curing barn is 330-375 rods / clamp, which is 15% more than the conventional packing amount of tobacco in a standard dense curing barn.

[0044] S3 employs a two-reduction-one-length baking process for scientific baking: slowing down the rate of increase in dry bulb temperature from 36℃ to 45℃, slowing down the rate of water loss and drying of tobacco leaves from ignition to dry bulb temperature of 40℃, and extending the baking time for maintaining a stable dry bulb temperature of 37℃ to 40℃ and 42℃ to 45℃, thereby increasing the degree of yellowing of the auricles at the base of mechanically damaged tobacco leaves.

[0045] The scientific baking process using the "two reductions and one extension" baking technique is as follows:

[0046] S3-1, Yellowing Stage: After ignition, raise the dry-bulb temperature to 35℃ at a rate of 1℃ / h, with a dry-bulb-wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 4 hours until the tobacco leaves in the high-temperature layer turn 10% yellow; then, raise the dry-bulb temperature to 37℃ at a rate of 1℃ / 2~3 hours, with a dry-bulb-wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 28 hours until the tobacco leaves in the high-temperature layer turn 60%-70% yellow; then, raise the dry-bulb temperature to 40℃ at a rate of 1℃ / 3~4 hours. The dry-bulb and wet-bulb temperature difference is 2℃~2.5℃, and the temperature is kept stable for 8 hours. After that, the dry-bulb temperature is kept constant, and the dry-bulb and wet-bulb temperature difference is appropriately increased to 3℃~4℃. The temperature is kept stable until the tobacco leaves in the high-temperature layer turn 80% to 90% yellow. Then, the dry-bulb temperature is increased to 42℃ at a rate of 1℃ / 3~5h, the dry-bulb and wet-bulb temperature difference is increased to 6℃, and the temperature is kept stable for 4 hours. The temperature is kept stable until the tobacco leaves in the high-temperature layer turn yellow with green veins, and the mechanically damaged parts at the base of the leaves are basically degreened.

[0047] S3-2, Color Fixing Period: Raise the dry-bulb temperature to 45℃ at a rate of 1℃ / 6~8h, increase the dry-bulb-wet-bulb temperature difference to 8℃, and appropriately extend the stable temperature baking time by 5h. Baking at a stable temperature until the base of all tobacco leaves, including mechanically damaged leaves, turns yellow and the leaf tips curl. Then, raise the dry-bulb temperature to 48℃ at a rate of 1℃ / 2h, increase the dry-bulb-wet-bulb temperature difference to 10℃~11℃, and bake at a stable temperature until more than 1 / 2 of the tobacco leaves in the entire kiln are dry. Then, raise the dry-bulb temperature to 54℃ at a rate of 1℃ / 2h, increase the dry-bulb-wet-bulb temperature difference to 15℃, and bake at a stable temperature for 15h until all the tobacco leaves in the entire kiln are completely dry.

[0048] S3-3, Drying stage: Increase the dry bulb temperature to 60℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 20℃~21℃, and bake at a stable temperature for 3~5 hours; then, increase the dry bulb temperature to 66℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 26℃, and bake at a stable temperature for 22 hours until all tobacco leaves in the kiln are completely dry.

[0049] Example 3. A harvesting and curing method to reduce mechanical damage to tobacco leaves:

[0050] S1. Reduce mechanical damage to fresh tobacco leaves: Reduce the degree of breakage and mechanical damage to fresh tobacco leaves by harvesting mature leaves, rationally arranging harvesting time, and using lightweight transportation and lightweight packing. The characteristics of mature fresh tobacco leaves are obvious fading of the leaf auricle and loose and soft leaves. When harvesting tobacco leaves, pinch the leaf stalk and avoid grasping the base of the tobacco leaf with your hands. Handle the leaves gently. The requirements for rationally arranging the harvesting time are as follows: in arid areas, tobacco leaves should be harvested while still wet with dew, and the harvesting time should be between 11 pm and 8 am. In the absence of light or in low light conditions, light sources should be provided, and the fresh tobacco leaves should be transported back to the packing area before 10 am. In rainy conditions, tobacco leaves should be harvested on cloudy days or in the afternoon of sunny days to reduce the moisture on the surface of the tobacco leaves and prevent sun exposure. Lightweight transportation refers to using soft packaging materials or open tobacco transport devices to reduce excessive compression or improper handling of fresh tobacco leaves, avoid the phenomenon of scattered stacking of fresh tobacco leaves, and use shade devices on tobacco transport vehicles to prevent sunburn. Lightweight cigarette clipping refers to handling cigarettes gently during the process, primarily using the thumb, index finger, and middle finger, and avoiding gripping them with the hands.

[0051] S2, Dense Packing: Increase the packing density of tobacco in dense curing barns, reduce the dehumidification rate of the curing barn and the rate of water loss of tobacco leaves, thereby ensuring that mechanically damaged tobacco leaves have sufficient time to lose water and turn yellow; the standard for dense packing is that the packing amount of tobacco in each standard dense curing barn is between 390 sticks / clamp, and for non-standard dense curing barns, it is increased by 20%;

[0052] S3 employs a two-reduction-one-length baking process for scientific baking: slowing down the rate of increase in dry bulb temperature from 36℃ to 45℃, slowing down the rate of water loss and drying of tobacco leaves from ignition to dry bulb temperature of 40℃, and extending the baking time for maintaining a stable dry bulb temperature of 37℃ to 40℃ and 42℃ to 45℃, thereby increasing the degree of yellowing of the auricles at the base of mechanically damaged tobacco leaves.

[0053] The scientific baking process using the "two reductions and one extension" baking technique is as follows:

[0054] S3-1, Yellowing Stage: After ignition, raise the dry-bulb temperature to 36℃ at a rate of 1℃ / h, with a dry-bulb-wet-bulb temperature difference of 1℃, and maintain the temperature for 3 hours until the tobacco leaves in the high-temperature layer turn 10% yellow; then, raise the dry-bulb temperature to 38℃ at a rate of 1℃ / 2-3 hours, with a dry-bulb-wet-bulb temperature difference of 1℃, and maintain the temperature for 20 hours until the tobacco leaves in the high-temperature layer turn 60-70% yellow; then, raise the dry-bulb temperature to 40℃ at a rate of 1℃ / 3-4 hours, with a dry-bulb-wet-bulb temperature difference of 2.5℃, and maintain the temperature for 6 hours; then, keep the dry-bulb temperature constant, appropriately increase the dry-bulb-wet-bulb temperature difference to 4℃, and maintain the temperature for 80-90% yellow; then, raise the dry-bulb temperature to 42℃ at a rate of 1℃ / 3-5 hours, increase the dry-bulb-wet-bulb temperature difference to 7℃, and appropriately extend the temperature for 3 hours, maintaining the temperature for 3 hours until the tobacco leaves in the high-temperature layer turn yellow with green veins, and the mechanically damaged areas at the base of the leaves have basically faded from green;

[0055] S3-2, Color Fixing Period: Increase the dry-bulb temperature to 45℃ at a rate of 1℃ / 6~8h, increasing the dry-bulb-wet-bulb temperature difference to 9℃, and appropriately extend the stable temperature baking time by 4h. Baking at a stable temperature until the base of all tobacco leaves, including mechanically damaged leaves, turns yellow and the leaf tips curl and curl. Then, increase the dry-bulb temperature to 48℃ at a rate of 1℃ / 2h, increasing the dry-bulb-wet-bulb temperature difference to 11℃, and baking at a stable temperature until more than 1 / 2 of the tobacco leaves in the entire kiln are dry. Then, increase the dry-bulb temperature to 54℃ at a rate of 1℃ / 2h, increasing the dry-bulb-wet-bulb temperature difference to 16℃, and baking at a stable temperature for 10h until all the tobacco leaves in the entire kiln are completely dry.

[0056] S3-3, Drying stage: Increase the dry bulb temperature to 60℃ at a rate of 1℃ / h, increasing the dry bulb-wet bulb temperature difference to 21℃, and bake at a stable temperature for 3 hours; then, increase the dry bulb temperature to 67℃ at a rate of 1℃ / h, increasing the dry bulb-wet bulb temperature difference to 28℃, and bake at a stable temperature for 20 hours until all tobacco leaves in the kiln are completely dry.

[0057] The tobacco harvesting and curing method described in the examples was compared with conventional harvesting and curing methods, such as... Figures 1-3 and Figures 4-6 As shown, it can be seen that: 1. It significantly improves the appearance and color of the cured tobacco leaves, significantly reduces the proportion of mechanically damaged tobacco leaves and green tobacco, and increases the proportion of orange-yellow tobacco; 2. It significantly improves the grade structure of the cured tobacco leaves. The proportion of mechanically damaged fresh tobacco leaves in the middle section after tying was also statistically analyzed, and the appearance quality and grade structure of the middle section of the cured tobacco leaves were compared and contrasted. The results are shown in Tables 1 and 2.

[0058] Table 1 Effects of different treatments on mechanical damage to fresh tobacco leaves

[0059]

[0060] Table 2. Effects of different treatments on the appearance quality of cured tobacco leaves

[0061]

[0062] Table 3. Effects of different treatments on grade structure and mechanical damage of cured tobacco leaves, and the proportion of green tobacco content.

[0063]

[0064] Note: Different lowercase letters indicate significant differences between different treatments.

[0065] As shown in Tables 1 to 3, the analytical data obtained by the method of the present invention indicate that the harvesting and curing method of the present invention can significantly reduce mechanical damage to fresh tobacco leaves, improve the appearance quality of cured tobacco leaves, and significantly increase the proportion of orange-yellow tobacco and grade structure after curing.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for harvesting and curing tobacco leaves to reduce mechanical damage, characterized in that, include: S1, Reduce mechanical damage to fresh tobacco leaves: Reduce the degree of breakage and mechanical damage to fresh tobacco leaves by harvesting them at maturity, arranging the harvesting time in a reasonable manner, and using light transportation and light packing. S2, Dense Packing: Increase the packing density of tobacco in dense curing barns, reduce the dehumidification rate of the curing barn and the rate of water loss of tobacco leaves, thereby ensuring that mechanically damaged tobacco leaves have sufficient time to lose water and turn yellow; S3 employs a scientific baking process with two reductions and one extension: slowing down the rate of increase in dry bulb temperature from 36℃ to 45℃, slowing down the rate of water loss and drying of tobacco leaves from ignition to dry bulb temperature of 40℃, and extending the heating and stabilization time at dry bulb temperatures of 37℃ to 40℃ and 42℃ to 45℃. This increases the degree of yellowing of mechanically damaged tobacco leaves, leaf bases, and leaf auricles, thereby reducing the proportion of green tobacco in mechanically damaged tobacco leaves after baking and increasing the proportion of orange-yellow tobacco and its grade structure. The requirement for reasonably arranging the harvesting time in S1 is that tobacco leaves in arid areas should be harvested with dew on them, and the harvesting time should be from 11 pm to 8 am. In the absence of light or in dim light, light sources should be provided, and the fresh tobacco leaves should be transported back to the sorting area before 10 am. In rainy conditions, tobacco leaves should be harvested on cloudy days or in the afternoon of sunny days to reduce the moisture on the surface of the tobacco leaves and prevent them from being exposed to the sun. S1 refers to the use of soft packaging materials or open tobacco transport devices to reduce excessive compression or improper operation of fresh tobacco leaves, avoid the phenomenon of scattered stacking of fresh tobacco leaves, and use of shade canopy devices on tobacco transport vehicles to avoid sunburn. The standard for increased tobacco loading in S2 is that the tobacco loading amount of each standard dense curing barn with 3 layers is between 360 and 390 rods / clamps, which is 10% to 20% higher than the conventional tobacco loading amount of a standard dense curing barn. The scientific baking process using the two-reduction-one-length baking technique in S3 is as follows: S3-1, Yellowing Stage: After ignition, raise the dry-bulb temperature to 34℃~36℃ at a rate of 1℃ / h, with a dry-bulb / wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 3~5 hours until the tobacco leaves in the high-temperature layer turn 10% yellow; then, raise the dry-bulb temperature to 37℃~38℃ at a rate of 1℃ / 2~3 hours, with a dry-bulb / wet-bulb temperature difference of 0.5℃~1℃, and maintain this temperature for 20~35 hours until the tobacco leaves in the high-temperature layer turn 60%~70% yellow; then, raise the dry-bulb temperature to 40℃ at a rate of 1℃ / 3~4 hours, with a dry-bulb / wet-bulb temperature difference of 2℃~2.5℃, and maintain this temperature for 6~10 hours; then, keeping the dry-bulb temperature constant, appropriately increase the dry-bulb / wet-bulb temperature difference to 3℃~4℃, and maintain this temperature for 80%~90% yellow; then, raise the dry-bulb temperature at a rate of 1℃ / 3~5 hours... The dry-bulb temperature is raised to 42℃ at a speed of h, the dry-bulb and wet-bulb temperature difference is increased to 5℃~7℃, the stable temperature baking time is appropriately extended to 3~5 h, and the high-temperature layer tobacco leaves are baked until the leaves turn yellow and green veins are visible, and the mechanically damaged parts at the base of the leaves are basically faded. S3-2, Color Fixing Period: Increase the dry-bulb temperature to 45℃ at a rate of 1℃ / 6~8 h, increase the dry-bulb-wet-bulb temperature difference to 8℃~9℃, and appropriately extend the stable-temperature baking time by 4~6 h. Baking at a stable temperature until the base of the entire batch of tobacco leaves and mechanically damaged leaves turn yellow and the leaf tips curl. Then, increase the dry-bulb temperature to 48℃ at a rate of 1℃ / 2 h, increase the dry-bulb-wet-bulb temperature difference to 10℃~11℃, and baking at a stable temperature until more than 1 / 2 of the entire batch of tobacco leaves are dry. Then, increase the dry-bulb temperature to 53℃~54℃ at a rate of 1℃ / 2 h, increase the dry-bulb-wet-bulb temperature difference to 14℃~16℃, and baking at a stable temperature for 10~20 h until the entire batch of tobacco leaves is completely dry. S3-3, Drying stage: Increase the dry bulb temperature to 60℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 20℃~21℃, and maintain the temperature for 3~5 hours; then, increase the dry bulb temperature to 65℃~67℃ at a rate of 1℃ / h, increase the dry bulb-wet bulb temperature difference to 25℃~28℃, and maintain the temperature for 20~25 hours until all tobacco leaves in the kiln are completely dry.

2. The harvesting and curing method for reducing mechanical damage to tobacco leaves according to claim 1, characterized in that, The characteristic features of mature fresh tobacco leaves harvested in S1 are that the auricles are obviously fading in green and the leaves are loose and soft. When harvesting tobacco leaves, the petiole should be pinched and the leaves should be harvested. It is important to avoid grasping the base of the tobacco leaf with your hands and to handle the leaves gently.

3. The method for reducing mechanical damage to tobacco leaves during harvesting and curing according to claim 1, characterized in that, The "lightweight cigarette clipping" mentioned in S1 refers to the process of handling cigarettes gently, primarily using the thumb, index finger, and middle finger, and avoiding gripping them with the hands.

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