Tobacco leaf curing method of bulk curing barn with airflow rising and falling switchable

Abstract

The invention discloses a bulk curing barn tobacco leaf curing method capable of switching airflow rising and falling. The method comprises the steps that S1, fresh tobacco leaves are harvested at proper time; s2, reasonably classifying and weaving the fresh tobacco leaves; s3, reasonably loading the fresh tobacco leaves into a kang; and S4, baking: adopting a twice-descending and twice-ascending baking process in a yellowing period and a color fixing period, and adopting an airflow descending type or an ascending type in a stem drying period. The two-step descending means that ignition starts to 38 DEG C stable-temperature baking ends in the yellowing period, airflow descending type baking is adopted from 42 DEG C stable-temperature baking ends to 48 DEG C stable-temperature baking ends in the color fixing period, and the two-step ascending means that stable-temperature baking ends from 38 DEG C stable-temperature baking ends to 42 DEG C stable-temperature baking ends in the yellowing period, and airflow ascending type baking ends from 48 DEG C stable-temperature baking ends to 54 DEG C stable-temperature baking ends in the color fixing period. By adopting the picking and baking method, the technical problems of more green and mixed-color tobaccos, stiff tobaccos, mildewed tobacco and the like after baking and the like are solved, and the quality of the baked tobacco leaves is improved.

Description

Technical Field

[0001] The invention relates to a tobacco leaf baking method in a dense baking room with switchable ascending and descending airflows, belonging to the technical field of tobacco leaf baking. Background Art

[0002] In order to stabilize the quality of cigarettes, the cigarette industry has higher and higher requirements for the uniformity of tobacco raw materials. There are many factors that affect the uniformity and quality stability of tobacco raw materials, such as variety, climate, cultivation management measures and baking. Among them, baking is an important factor affecting the stability of tobacco quality. At present, it is common in production that the lower leaves are harvested overmature, and the middle and upper tobacco leaves are harvested undermature and physiologically mature. At present, domestic tobacco baking is still mainly based on three-stage intensive baking rooms, but the yellowing progress of tobacco leaves between different layers of the baking room during the baking process is inconsistent, resulting in significant differences in the quality of each layer of tobacco leaves after baking. Moreover, in recent years, there have been more green and variegated tobacco, stiff tobacco, and moldy tobacco after baking, which has restricted the development of tobacco baking to a certain extent.

[0003] The patent document (publication number CN113261694A) discloses a tobacco leaf intensive curing room with a reversible circulating fan, which reduces the tobacco leaf curing cost and realizes the alternating operation of the airflow rising mode and the airflow falling mode in the tobacco loading room, effectively solving the problem that the existing tobacco leaves turn yellow and dehydrate at different speeds, and the tobacco leaf curing quality of the upper and lower sheds is difficult to balance. The patent document (publication number CN109820225A) discloses a method for controlling the circulating fan of a intensive curing room to reduce the loss of tobacco leaf aroma substances.

[0004] However, although the above scheme can improve the uniformity of tobacco leaf baking temperature and reduce the loss of tobacco leaf aroma substances, there are still technical problems such as excessive green and variegated tobacco, stiff tobacco, and moldy butt tobacco after baking, and poor uniformity. In recent years, we have developed a flue-curing room with switchable rising and falling airflow (patent authorization announcement number CN215736835U), and carried out a series of studies based on the airflow movement mode of the flue-curing room, which solved the technical problems such as excessive green and variegated tobacco, stiff tobacco, and moldy butt tobacco after baking, improved the quality and uniformity of the flue-cured tobacco leaves, and formed a flue-curing method for tobacco leaves in a dense flue-curing room with switchable rising and falling airflow. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a tobacco leaf baking method in a switchable intensive curing room with rising and falling airflow, so as to at least solve the problems mentioned in the background technology.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The rising and falling airflow can switch the tobacco leaf curing methods of the dense curing room, including:

[0008] S1, timely harvesting of fresh tobacco leaves: reduce the maturity of fresh tobacco leaves at the bottom, and the degree of yellowing of leaves during harvesting is 0-10% lower than the normal degree; increase the maturity of fresh tobacco leaves at the middle and upper parts, and the degree of yellowing of leaves during harvesting is 0-10% higher than the normal degree;

[0009] S2, Reasonable classification and arrangement of fresh tobacco leaves: According to the appearance and maturity characteristics of the tobacco leaves, the fresh tobacco leaves are roughly divided into two categories: low maturity and high maturity tobacco leaves. Unripe, overripe and diseased tobacco leaves with no baking value are removed, and classified and arranged into poles. Each pole is arranged with 140 to 160 leaves, and each clip is arranged with 230 to 250 leaves.

[0010] S3, fresh tobacco leaves are properly loaded on the kang: classified and layered, with tobacco of the same quality loaded in the same layer, and low-maturity tobacco leaves loaded in the middle layer.

[0011] High-maturity tobacco leaves are packed in the lower and top layers;

[0012] S4, Baking: Two-descending baking processes and two-ascending baking processes are adopted in the yellowing period and the color fixing period, and either airflow descending or ascending baking processes can be adopted in the dry tendon period; the two-descending baking process refers to airflow descending baking from the start of ignition to the end of 38°C steady-temperature baking in the yellowing period, and from the end of 42°C steady-temperature baking to the end of 48°C steady-temperature baking in the color fixing period, and the two-ascending baking process refers to airflow ascending baking from the end of 38°C steady-temperature baking to the end of 42°C steady-temperature baking in the yellowing period, and from the end of 48°C steady-temperature baking to the end of 54°C steady-temperature baking in the color fixing period.

[0013] The tobacco leaf baking method of the aforementioned airflow rising and falling switchable intensive baking room is that the low maturity in S3 refers to the tobacco leaf harvesting maturity lower than the conventional harvesting maturity or physiologically mature tobacco leaves, and the high maturity refers to the tobacco leaf harvesting maturity higher than the conventional harvesting maturity or fully mature tobacco leaves.

[0014] The above-mentioned method for baking tobacco leaves in the dense curing room with switchable ascending and descending airflow is that the two descending baking processes and the two ascending baking processes are used in the yellowing period and the color fixing period, and the baking can be carried out by the descending airflow or the ascending airflow in the dry tendon period. The operation steps are as follows:

[0015] S4-1, yellowing period: after ignition, the curing room adopts airflow descent, and the dry bulb temperature is raised to 32-33℃ at a rate of 1℃ / h, and the wet bulb temperature is 32℃, and the temperature is kept constant for 2-4h; then, the dry bulb temperature is raised to 35℃-36℃ at a rate of 1℃ / h, and the wet bulb temperature is 34℃-35℃, and the temperature is kept constant for 5-6h, until the top layer of tobacco leaves turns 10%-20% yellow; then, the dry bulb temperature is raised to 38℃ at a rate of 1℃ / h, and the wet bulb temperature is 35℃-37℃, and the temperature is kept constant for 20-35h , until the top tobacco leaves turn 70% to 80% yellow and become soft, and the bottom tobacco leaves turn 50% to 60% yellow; then, the curing room adopts airflow rising, and the dry bulb temperature is raised to 40℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 36℃~37℃, and the temperature is kept constant for 8~12h, until the bottom tobacco leaves turn 80% to 90% yellow; then, the dry bulb temperature is raised to 42℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 35~37℃, and the temperature is kept constant for 10~15h, until the whole tobacco leaves turn yellow and have blue veins, and the base is slightly green and the frame collapses;

[0016] S4-2, color fixing period: the curing room adopts airflow descending type, and the dry bulb temperature is raised to 45℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 35℃~37℃, and the temperature is kept constant for 6~10h until the small tendons of the whole kang tobacco leaves turn white, and the main tendons of the leaf tips turn white; then, the dry bulb temperature is raised to 48℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 36~38℃, and the temperature is kept constant until more than 96% of the main tendons of the whole kang tobacco leaves turn white and more than 1 / 2 of the leaves are dry; then, the curing room adopts Airflow rising method, raise the dry bulb temperature to 50-51℃ at a heating rate of 1℃ / 3-4h, and the wet bulb temperature to 38℃-39℃, and bake at a steady temperature for 3-5h, until the main tendons of the whole kang tobacco leaves are basically completely white and the main veins are more than 2 / 3 dry; then, keep the airflow rising method, raise the dry bulb temperature to 54℃ at a heating rate of 1℃ / 2-3h, and the wet bulb temperature to 38℃-39℃, and bake at a steady temperature for 10-15h, until the leaves of the whole kang tobacco leaves are completely dry and the main veins are more than 1 / 3 dry;

[0017] S4-3, dry rib period: the flue-curing room can adopt airflow descending type or ascending type, and the dry bulb temperature is raised to 65℃~67℃ and the wet bulb temperature is 40℃~41℃ at a heating rate of 1℃ / h, and the whole tobacco leaves are dried at a stable temperature. Compared with the prior art, the beneficial effects of the present invention are:

[0018] The invention can timely harvest fresh tobacco leaves, reasonably classify and weave tobacco leaves, and load them into a kang, so that the tobacco leaves can be fully yellowed and colored in time, thereby improving the appearance quality of the tobacco leaves after curing.

[0019] Further, in terms of baking process, firstly, airflow descending baking is adopted from the start of ignition in the yellowing period to the end of 38℃ stable temperature baking, which is convenient for ventilation and dehumidification of the baking room and reduces the occurrence of stiff smoke and mildew; secondly, airflow ascending baking is adopted from the end of 38℃ stable temperature baking in the yellowing period to the end of 42℃ stable temperature baking, which is conducive to the full yellowing of the top leaf base and the reduction of the production of green smoke; airflow descending baking is adopted from the end of 42℃ stable temperature baking to the end of 48℃ stable temperature baking in the color fixing period, which is conducive to ventilation and dehumidification of the leaf base, convenient for timely color fixing of tobacco leaves, and the reduction of the production of variegated smoke and ash hanging smoke; airflow ascending baking is adopted from the end of 48℃ stable temperature baking to the end of 54℃ stable temperature baking in the color fixing period, which is conducive to increasing wind resistance, reducing the volatilization of aroma substances on the surface of tobacco leaves, and improving the quality of tobacco leaves after baking. In addition, at the time of each alternation of airflow movement mode, such as when entering the next dry bulb temperature point after the end of 38℃, 42℃ and 48℃ stable temperature baking, the heating rate needs to be reduced to prevent the occurrence of green baking, ash hanging and baking dregs.

[0020] The following advantages can be clearly seen by comparing the baking method of the present invention with conventional baking:

[0021] 1. Significantly improve the appearance quality of flue-cured tobacco leaves;

[0022] 2. Significantly reduce the proportion of green mixed smoke, stiff smoke and moldy cigarettes;

[0023] 3. Significantly improve the grade structure and average price of flue-cured tobacco leaves.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a photo of tobacco leaves after being cured using the conventional curing process;

[0027] Figure 2 This is a photo of tobacco leaves after being roasted using the roasting method of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the tables in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1. A tobacco leaf baking method in a switchable dense baking room with rising and falling airflow:

[0030] 1. A tobacco leaf baking method in a switchable dense baking room with rising and falling airflow, comprising the following steps:

[0031] S1, timely harvesting of fresh tobacco leaves: reduce the maturity of fresh tobacco leaves at the bottom, and the degree of yellowing of leaves during harvesting is 0-10% lower than the normal degree; increase the maturity of fresh tobacco leaves at the middle and upper parts, and the degree of yellowing of leaves during harvesting is 0-10% higher than the normal degree;

[0032] S2, Reasonable classification and arrangement of fresh tobacco leaves: According to the appearance and maturity characteristics of the tobacco leaves, the fresh tobacco leaves are roughly divided into two categories: low maturity and high maturity tobacco leaves. Unripe, overripe and diseased tobacco leaves with no baking value are removed, and classified and arranged into poles. Each pole is arranged with 140 to 160 leaves, and each clip is arranged with 230 to 250 leaves.

[0033] 2. S3, fresh tobacco leaves are reasonably loaded on the kang: classified and layered, and tobacco of the same quality is loaded in the same layer. Low-maturity tobacco leaves are loaded in the middle layer, and high-maturity tobacco leaves are loaded in the lower and top layers; the low maturity in S3 refers to tobacco leaves whose harvest maturity is lower than the conventional harvest maturity or physiologically mature tobacco leaves, and high maturity refers to tobacco leaves whose harvest maturity is higher than the conventional harvest maturity or fully mature tobacco leaves.

[0034] S4, baking: two descending baking processes and two ascending baking processes are used in the yellowing and color fixing stages, and either airflow descending or ascending baking processes are used in the dry rib stage; the operation steps of baking in the yellowing and color fixing stages using two descending baking processes and two ascending baking processes, and either airflow descending or ascending baking processes are used in the dry rib stage are as follows:

[0035] S4-1, yellowing period: after ignition, the curing room adopts airflow descent, and the dry bulb temperature is raised to 32℃ and the wet bulb temperature is 32℃ at a rate of 1℃ / h, and the temperature is kept constant for 4 hours; then, the dry bulb temperature is raised to 35℃ and the wet bulb temperature is 34℃ at a rate of 1℃ / h, and the temperature is kept constant for 6 hours, until the top layer of tobacco leaves turns 10% to 20% yellow; then, the dry bulb temperature is raised to 38℃ and the wet bulb temperature is 35℃ at a rate of 1℃ / h, and the temperature is kept constant for 35 hours, until the top layer of tobacco leaves turns 10% to 20% yellow. The leaves turn 70% to 80% yellow and become soft, and the bottom tobacco leaves turn 50% to 60% yellow; then, the curing room adopts airflow rising, and the dry bulb temperature is raised to 40℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 36℃, and the temperature is kept constant for 12h, until the bottom tobacco leaves turn 80% to 90% yellow; then, the dry bulb temperature is raised to 42℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 35℃, and the temperature is kept constant for 15h, until the whole tobacco leaves turn yellow, blue veins appear, and the base is slightly green and the frame collapses;

[0036] S4-2, color fixing period: the curing room adopts airflow descending type, and the dry bulb temperature is raised to 45℃ at a rate of 1℃ / 3~4h, the wet bulb temperature is 35℃, and the temperature is kept constant for 10h, until the small tendons of the whole kang tobacco leaves turn white, and the main tendons of the leaf tips turn white; then, the dry bulb temperature is raised to 48℃ at a rate of 1℃ / 2~3h, the wet bulb temperature is 36, and the temperature is kept constant until more than 96% of the main tendons of the whole kang tobacco leaves turn white and the leaves are more than 1 / 2 dry; then, the curing room adopts airflow ascending type, and the dry bulb temperature is raised to 50℃ at a rate of 1℃ / 3~4h, the wet bulb temperature is 38℃℃, and the temperature is kept constant for 5h, until the main tendons of the whole kang tobacco leaves are basically completely white, and the main veins are more than 2 / 3 dry; then, the airflow ascending type is maintained, and the dry bulb temperature is raised to 54℃ at a rate of 1℃ / 2~3h, the wet bulb temperature is 38℃℃, and the temperature is kept constant for 15h, until the leaves of the whole kang tobacco leaves are completely dry and the main veins are more than 1 / 3 dry;

[0037] S4-3, drying period: The flue-curing room can adopt either descending or ascending airflow, and the dry bulb temperature can be raised to 65℃ and the wet bulb temperature to 40℃ at a heating rate of 1℃ / h, and the tobacco leaves can be baked at a steady temperature until they are completely dry.

[0038] Example 2. A tobacco leaf baking method in a flue-curing room with switchable intensive airflow rising and falling comprises the following steps:

[0039] S1, timely harvesting of fresh tobacco leaves: reduce the maturity of fresh tobacco leaves at the bottom, and the degree of yellowing of leaves during harvesting is 0-10% lower than the normal degree; increase the maturity of fresh tobacco leaves at the middle and upper parts, and the degree of yellowing of leaves during harvesting is 0-10% higher than the normal degree;

[0040] S2, Reasonable classification and arrangement of fresh tobacco leaves: According to the appearance and maturity characteristics of the tobacco leaves, the fresh tobacco leaves are roughly divided into two categories: low maturity and high maturity tobacco leaves. Unripe, overripe and diseased tobacco leaves with no baking value are removed, and classified and arranged into poles. Each pole is arranged with 140 to 160 leaves, and each clip is arranged with 230 to 250 leaves.

[0041] S3, fresh tobacco leaves are reasonably loaded on the kang: classified and layered, and tobacco of the same quality is loaded in the same layer. Low-maturity tobacco leaves are loaded in the middle layer, and high-maturity tobacco leaves are loaded in the lower and top layers; the low maturity in S3 refers to tobacco leaves whose harvest maturity is lower than the conventional harvest maturity or physiologically mature tobacco leaves, and high maturity refers to tobacco leaves whose harvest maturity is higher than the conventional harvest maturity or fully mature tobacco leaves.

[0042] S4, baking: two descending baking processes and two ascending baking processes are used in the yellowing and color fixing stages, and either airflow descending or ascending baking processes are used in the dry rib stage; the operation steps of baking in the yellowing and color fixing stages using two descending baking processes and two ascending baking processes, and either airflow descending or ascending baking processes are used in the dry rib stage are as follows:

[0043] S4-1, yellowing period: after ignition, the curing room adopts airflow descent, and the dry bulb temperature is raised to 32-33℃ at a rate of 1℃ / h, the wet bulb temperature is 32℃, and the temperature is kept constant for 3 hours; then, the dry bulb temperature is raised to 35℃ at a rate of 1℃ / h, the wet bulb temperature is 35℃, and the temperature is kept constant for 5-6 hours, until the top layer of tobacco leaves turns 10% to 20% yellow; then, the dry bulb temperature is raised to 38℃ at a rate of 1℃ / h, the wet bulb temperature is 37℃, and the temperature is kept constant for 27 hours, until the top layer of tobacco leaves turns 10% to 20% yellow. The top layer of tobacco leaves turn 70% to 80% yellow and become soft, and the bottom layer of tobacco leaves turn 50% to 60% yellow; then, the curing room adopts airflow rising, and the dry bulb temperature is raised to 40℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 37℃, and the temperature is kept constant for 10h, until the bottom layer of tobacco leaves turn 80% to 90% yellow; then, the dry bulb temperature is raised to 42℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 37℃, and the temperature is kept constant for 103h, until the whole bed of tobacco leaves turn yellow, blue veins appear, the base is slightly green, and the frame collapses;

[0044] S4-2, color fixing period: the curing room adopts airflow descending type, and the dry bulb temperature is raised to 45℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 36℃, and the temperature is kept constant for 8h until the small tendons of the whole kang tobacco leaves turn white, and the main tendons of the leaf tips turn white; then, the dry bulb temperature is raised to 48℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 37℃, and the temperature is kept constant until more than 96% of the main tendons of the whole kang tobacco leaves turn white and more than 1 / 2 of the leaves are dry; then, the curing room adopts Airflow rising method, raise the dry bulb temperature to 50-51℃ at a heating rate of 1℃ / 3-4h, and the wet bulb temperature to 38℃7℃, and bake at a steady temperature for 4h, until the main tendons of the whole kang tobacco leaves are basically completely white and the main veins are more than 2 / 3 dry; then, keep the airflow rising method, raise the dry bulb temperature to 54℃ at a heating rate of 1℃ / 2-3h, and the wet bulb temperature to 38℃℃, and bake at a steady temperature for 13h, until the leaves of the whole kang tobacco leaves are completely dry and the main veins are more than 1 / 3 dry;

[0045] S4-3, drying period: The flue-curing room can adopt either descending or ascending airflow, and the dry bulb temperature can be raised to 66℃ and the wet bulb temperature to 40℃ at a heating rate of 1℃ / h, and the tobacco leaves can be baked at a steady temperature until they are completely dry.

[0046] Embodiment 3. A tobacco leaf baking method in a flue-curing room with switchable intensive airflow rising and falling, comprising the following steps:

[0047] S1, timely harvesting of fresh tobacco leaves: reduce the maturity of fresh tobacco leaves at the bottom, and the degree of yellowing of leaves during harvesting is 0-10% lower than the normal degree; increase the maturity of fresh tobacco leaves at the middle and upper parts, and the degree of yellowing of leaves during harvesting is 0-10% higher than the normal degree;

[0048] S2, Reasonable classification and arrangement of fresh tobacco leaves: According to the appearance and maturity characteristics of the tobacco leaves, the fresh tobacco leaves are roughly divided into two categories: low maturity and high maturity tobacco leaves. Unripe, overripe and diseased tobacco leaves with no baking value are removed, and classified and arranged into poles. Each pole is arranged with 140 to 160 leaves, and each clip is arranged with 230 to 250 leaves.

[0049] S3, fresh tobacco leaves are reasonably loaded on the kang: classified and layered, and tobacco of the same quality is loaded in the same layer. Low-maturity tobacco leaves are loaded in the middle layer, and high-maturity tobacco leaves are loaded in the lower and top layers; the low maturity in S3 refers to tobacco leaves whose harvest maturity is lower than the conventional harvest maturity or physiologically mature tobacco leaves, and high maturity refers to tobacco leaves whose harvest maturity is higher than the conventional harvest maturity or fully mature tobacco leaves.

[0050] S4, baking: two descending baking processes and two ascending baking processes are used in the yellowing and color fixing stages, and either airflow descending or ascending baking processes are used in the dry rib stage; the operation steps of baking in the yellowing and color fixing stages using two descending baking processes and two ascending baking processes, and either airflow descending or ascending baking processes are used in the dry rib stage are as follows:

[0051] S4-1, Yellowing period: After ignition, the curing room adopts airflow descent, and the dry bulb temperature is raised to 33℃ and the wet bulb temperature is 32℃ at a rate of 1℃ / h, and the temperature is kept constant for 2 hours; then, the dry bulb temperature is raised to 36℃ and the wet bulb temperature is 35℃ at a rate of 1℃ / h, and the temperature is kept constant for 5 hours, until the top layer of tobacco leaves turns 10% to 20% yellow; then, the dry bulb temperature is raised to 38℃ and the wet bulb temperature is 37℃ at a rate of 1℃ / h, and the temperature is kept constant for 20 hours, until the top layer of tobacco leaves turns 10% to 20% yellow. The leaves turn 70% to 80% yellow and become soft, and the bottom tobacco leaves turn 50% to 60% yellow; then, the curing room adopts airflow rising, and the dry bulb temperature is raised to 40℃ at a rate of 1℃ / 3~4h, and the wet bulb temperature is 37℃, and the temperature is kept constant for 8h, until the bottom tobacco leaves turn 80% to 90% yellow; then, the dry bulb temperature is raised to 42℃ at a rate of 1℃ / 2~3h, and the wet bulb temperature is 37℃, and the temperature is kept constant for 10h, until the whole tobacco leaves turn yellow, with blue veins, and the base is slightly green and collapsed;

[0052] S4-2, color fixing period: the curing room adopts airflow descending mode, and the dry bulb temperature is raised to 45℃ and the wet bulb temperature is 37℃ at a rate of 1℃ / 3~4h, and the temperature is kept constant for 6h until the small tendons of the whole kang tobacco leaves turn white and the main tendons at the leaf tips turn white; then, the dry bulb temperature is raised to 48℃ and the wet bulb temperature is 38℃ at a rate of 1℃ / 2~3h, and the temperature is kept constant until more than 96% of the main tendons of the whole kang tobacco leaves turn white and the leaves are more than 1 / 2 dry; then, the curing room adopts airflow ascending mode, and the dry bulb temperature is raised to 51℃ and the wet bulb temperature is 39℃ at a rate of 1℃ / 3~4h, and the temperature is kept constant for 3h, until the main tendons of the whole kang tobacco leaves are basically completely white and the main veins are more than 2 / 3 dry; then, the airflow ascending mode is maintained, and the dry bulb temperature is raised to 54℃ and the wet bulb temperature is 39℃ at a rate of 1℃ / 2~3h, and the temperature is kept constant for 10, until the leaves of the whole kang tobacco leaves are completely dry and the main veins are more than 1 / 3 dry;

[0053] S4-3, drying period: The flue-curing room can adopt either descending or ascending airflow, and the dry-bulb temperature can be raised to 67°C and the wet-bulb temperature to 41°C at a heating rate of 1°C / h, and the tobacco leaves can be baked at a steady temperature until they are completely dry.

[0054] In order to prove the advantages of the tobacco leaf baking method in the airflow rising and falling switchable dense curing room, the tobacco leaf baking method in the airflow rising and falling switchable dense curing room in the embodiment is compared with the conventional "three-stage" baking process of tobacco leaves, such as Figure 1 and Figure 2 As shown, it can be seen that 1. the appearance quality of the flue-cured tobacco leaves is significantly improved; 2. the proportion of green mixed tobacco, stiff tobacco and moldy tobacco ends is significantly reduced; 3. the grade structure and average price of the flue-cured tobacco leaves are significantly improved.

[0055] At the same time, a batch of middle tobacco leaves were collected for testing, and the results are shown in the following table.

[0056] Table 1 Effects of different treatments on the appearance quality of flue-cured tobacco leaves

[0057]

[0058]

[0059] Table 2 Effects of different treatments on the proportion of green mixed tobacco, stiff tobacco and moldy tobacco after curing (%)

[0060]

[0061] Note: Different lowercase letters indicate significant differences among treatments.

[0062] Table 3 Effects of different treatments on grade structure and average price of flue-cured tobacco leaves

[0063]

[0064] Tables 1 to 3 show that the analytical data of the middle tobacco leaves after curing were obtained by using the tobacco leaf baking method in a switchable intensive flue-curing room with rising and falling airflow. The results show that the new baking technology significantly improves the appearance quality of the tobacco leaves after curing, significantly reduces the proportion of green tobacco, stiff tobacco, and moldy tobacco, and significantly improves the grade structure and average price of the tobacco leaves after curing.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A tobacco leaf baking method in a switchable dense baking room with rising and falling airflow, characterized in that: include: S1, timely harvesting of fresh tobacco leaves: reduce the maturity of fresh tobacco leaves at the bottom, and the degree of yellowing of leaves during harvesting is 0-10% lower than the normal level; increase the maturity of fresh tobacco leaves at the middle and upper parts, and the degree of yellowing of leaves during harvesting is 0-10% higher than the normal level; S2, Reasonable classification and arrangement of fresh tobacco leaves: fresh tobacco leaves are roughly divided into two categories according to the appearance and maturity characteristics of tobacco leaves: low maturity and high maturity tobacco leaves. Unripe, overripe and diseased tobacco leaves with no baking value are removed, and classified and arranged into poles. Each pole is arranged with 140-160 leaves, and each clip is arranged with 230-250 leaves. S3, fresh tobacco leaves are properly loaded on the kang: classified and layered, with tobacco of the same quality loaded on the same layer, low-maturity tobacco leaves loaded on the middle layer, and high-maturity tobacco leaves loaded on the lower and top layers; S4, Baking: Two-descending baking processes and two-ascending baking processes are adopted in the yellowing period and the color fixing period, and either airflow descending or ascending baking processes can be adopted in the dry tendon period; the two-descending baking process refers to airflow descending baking from the start of ignition to the end of 38°C steady-temperature baking in the yellowing period, and from the end of 42°C steady-temperature baking to the end of 48°C steady-temperature baking in the color fixing period, and the two-ascending baking process refers to airflow ascending baking from the end of 38°C steady-temperature baking to the end of 42°C steady-temperature baking in the yellowing period, and from the end of 48°C steady-temperature baking to the end of 54°C steady-temperature baking in the color fixing period.

2. The tobacco leaf baking method in a dense baking room with switchable rising and falling airflow according to claim 1 is characterized in that: The S3 low maturity refers to tobacco leaves harvested at a maturity lower than the conventional harvest maturity or physiologically mature tobacco leaves, and the high maturity refers to tobacco leaves harvested at a maturity higher than the conventional harvest maturity or fully mature tobacco leaves.

3. The tobacco leaf baking method in a dense baking room with switchable rising and falling airflow according to claim 1 is characterized in that: The yellowing and color fixing stages use two descending baking processes and two ascending baking processes, and the drying stage uses airflow descending or ascending baking. The operation steps are as follows: S4-1, yellowing period: after ignition, the curing room adopts airflow descent, and the dry bulb temperature is raised to 32~33℃ and the wet bulb temperature is 32℃ at a rate of 1℃ / h, and the temperature is kept constant for 2~4 hours; then, the dry bulb temperature is raised to 35℃~36℃ and the wet bulb temperature is 34℃~35℃ at a rate of 1℃ / h, and the temperature is kept constant for 5~6 hours, until the top layer of tobacco leaves turns 10%~20% yellow; then, the dry bulb temperature is raised to 38℃ and the wet bulb temperature is 35℃~37℃ at a rate of 1℃ / h, and the temperature is kept constant for 20~35 hours, until the top layer of tobacco leaves turns 70%~80% yellow and softens, and the bottom layer of tobacco leaves turns 50%~60% yellow; then, the curing room adopts airflow ascending, and the dry bulb temperature is raised to 40℃ and the wet bulb temperature is 36℃~37℃ at a rate of 1℃ / 3~4 hours, and the temperature is kept constant for 8~12 hours, until the bottom layer of tobacco leaves turns 80%~90% yellow; then, the temperature is raised to 1℃ / 2~3 hours, and the temperature is kept constant for 10~20 hours. h, raise the dry bulb temperature to 42℃, wet bulb temperature to 35~37℃, and bake at a steady temperature for 10~15 h, until the whole tobacco leaves are yellow, blue veins, slightly green at the base and collapsed; S4-2, color fixing period: the curing room adopts airflow descending mode, and the dry bulb temperature is raised to 45℃ at a rate of 1℃ / 3~4 h, and the wet bulb temperature is 35℃~37℃, and the temperature is kept constant for 6~10 hours until the small tendons of the whole tobacco leaves turn white, and the main tendons at the leaf tips turn white; then, the dry bulb temperature is raised to 48℃ at a rate of 1℃ / 2~3 h, and the wet bulb temperature is 36~38℃, and the temperature is kept constant until more than 96% of the main tendons of the whole tobacco leaves turn white and the leaves are more than 1 / 2 dry; then, the curing room adopts airflow ascending mode, and the dry bulb temperature is raised to 50~51℃ at a rate of 1℃ / 3~4 h, and the wet bulb temperature is 38℃~39℃, and the temperature is kept constant for 3~5 hours, until the main tendons of the whole tobacco leaves are basically completely white and the main veins are more than 2 / 3 dry; then, the airflow is kept rising mode, and the temperature is kept rising mode at 1℃ / 2~3 h. The dry-bulb temperature is raised to 54℃ and the wet-bulb temperature is 38℃~39℃ at a heating rate of 10~15 hours, until the tobacco leaves are completely dry and the main veins are more than 1 / 3 dry. S4-3, drying period: The flue-curing room can adopt either descending or ascending airflow, and the dry-bulb temperature can be raised to 65℃~67℃ and the wet-bulb temperature to 40℃~41℃ at a heating rate of 1℃ / h, and the tobacco leaves can be baked at a steady temperature until they are completely dry.

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