A device for baking tobacco leaves by high frequency combined with air flow modulation and a process method thereof

Abstract

This invention discloses an apparatus and process for conditioning flue-cured tobacco using high-frequency combined airflow. The apparatus includes an airflow-type curing barn and a high-frequency drying device. The high-frequency drying device includes a feed inlet for the initial curing tobacco leaves and a tobacco material conveyor belt. The feed and discharge ends of the tobacco material conveyor belt are respectively equipped with high-frequency electrode feed baffles and high-frequency electrode discharge baffles. The high-frequency drying device is connected to a high-frequency power supply device. The apparatus and process for conditioning flue-cured tobacco using high-frequency combined airflow provided by this invention utilize traditional conditioning methods in the airflow curing barn. The process is mature and easy to master. High-frequency drying conditioning can effectively improve the efficiency of tobacco leaf drying, shorten drying time, achieve low-temperature conditioning, and avoid the aroma decay and quality decline caused by high-temperature baking during the dry-core period of conventional curing. This results in increased filling capacity of the cured tobacco leaves, improved tobacco leaf structure, reduced off-flavors and irritation, improved sensory quality, and enhanced conditioning quality of the initial curing tobacco leaves.

Description

Technical Field

[0001] This invention relates to the field of tobacco curing, conditioning and drying technology, and in particular to an apparatus and process method for conditioning flue-cured tobacco using high-frequency combined airflow. Background Technology

[0002] Conventional airflow drying of tobacco leaves achieves yellowing and fixation of the yellow color, aroma development, and the appearance of fragrance. Simultaneously, complex chemical and biochemical changes occur within the leaf tissue, successfully shaping the internal and external qualities of the tobacco leaf. Currently, there are numerous studies on the impact of temperature during the core drying stage on the aroma and flavor of tobacco leaves. Above 50℃, i.e., in the later stage of color fixation, the leaves are nearly completely dry, the leaf tissue is solidified, and aroma is produced, but there are residual off-flavors. When the temperature reaches 60℃, entering the core drying stage, the off-flavors disappear, and the aroma becomes stronger; at 67℃, the aroma becomes sparse; from 67℃ onwards, with the passage of time, aromatic substances are lost, the aroma becomes increasingly weak, while the spiciness and astringency increase. This indicates a relationship between the maximum temperature of the main vein drying stage and the aroma and flavor of tobacco leaves; high temperatures during the core drying stage cause aroma decay and quality decline in tobacco leaves.

[0003] Therefore, there is an urgent need for a device and process for modulating flue-cured tobacco using high-frequency combined airflow. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and process for modulating flue-cured tobacco using a high-frequency combined airflow, in order to solve the problems in the prior art, effectively improve the efficiency of tobacco drying, achieve low-temperature modulation, avoid the problem of aroma decay and quality decline caused by high-temperature baking during the drying and core-drying stage of conventional baking, and improve the modulation quality of the first-cured tobacco leaves.

[0005] This invention provides an apparatus for regulating flue-cured tobacco using a high-frequency combined airflow, comprising: an airflow-type curing barn and a high-frequency drying device arranged sequentially; wherein the airflow-type curing barn is equipped with tobacco curing equipment for curing partially cured tobacco leaves; the high-frequency drying device includes a partially cured tobacco leaf flat-laying table feed inlet and a tobacco leaf material conveyor belt arranged sequentially; a high-frequency electrode feed baffle is provided at the feed end of the tobacco leaf material conveyor belt, and a high-frequency electrode discharge baffle is provided at the discharge end of the tobacco leaf material conveyor belt; the high-frequency drying device is connected to a high-frequency power supply device for providing a high-frequency oscillating electric field to the high-frequency drying device.

[0006] In the device for regulating tobacco curing with high-frequency combined airflow as described above, preferably, curing doors are rotatably connected to both sides of the airflow curing barn.

[0007] In the apparatus for regulating flue-cured tobacco using high-frequency combined airflow as described above, preferably, a high-frequency drying protective cover is provided above the tobacco material conveyor belt.

[0008] In the apparatus for regulating flue-cured tobacco using high-frequency combined airflow as described above, preferably, a tobacco collection box is connected to the end of the tobacco material conveyor belt between the high-frequency electrode feed baffle and the high-frequency electrode discharge baffle.

[0009] The apparatus for modulating flue-cured tobacco using high-frequency combined airflow as described above, wherein preferably, the high-frequency power supply device includes a high-frequency generator, a transformer cabinet, and a control console.

[0010] The present invention also provides a process method for flue-cured tobacco using high-frequency combined airflow modulation with the above-mentioned device, comprising:

[0011] Based on the quality characteristics of mature fresh tobacco in the field, harvest mature, first-cured tobacco leaves.

[0012] The first-cured tobacco leaves are subjected to airflow curing and conditioning treatment in an airflow curing room: after the tobacco leaves turn yellow and the color-fixing and drying stage, the first-cured tobacco leaves lose 60%-80% of the moisture content of fresh tobacco leaves.

[0013] The pre-cured tobacco leaves, which have undergone the airflow baking and conditioning treatment, are dried using a high-frequency drying device. The moisture content of the tobacco leaves after high-frequency drying is 10%-11%, and the moisture content of the tobacco stems is 11%-12%.

[0014] In the process of flue-cured tobacco using high-frequency combined airflow modulation as described above, preferably, the quality characteristics of the mature fresh tobacco in the field include: yellow leaves with most of the pubescence fallen off, glossy leaves, increased resinous substances, and a sticky feel to the touch; the main vein turns white, and the lateral veins turn white; a separation layer forms at the base of the leaf, making it easy to pick, with a crisp sound when picked, a neat cross-section, and no stem bark; the natural support capacity of the tobacco leaves and the main vein weakens, the leaf tips droop, and the stem-leaf angle increases; yellow-white starch granule maturity spots appear on the middle and upper leaves, the leaf surface wrinkles, the yellowing of the leaf tips increases, or the edges and tips wither and burnt.

[0015] In the process of flue-cured tobacco using high-frequency combined airflow modulation as described above, preferably, the method for determining the rate of moisture loss of fresh tobacco leaves during the airflow-modulated curing process includes:

[0016] In the early stage of yellowing, the leaf tips soften. In the early stage of curing, the tobacco leaves undergo preliminary dehydration, and the leaf tips wilt significantly, while other parts become swollen and hard, losing 10% of the moisture content of fresh tobacco leaves.

[0017] In the middle stage of yellowing, the leaves soften, the leaf tissue and branch veins on both sides of the main vein of the tobacco leaf soften, while the main vein remains swollen and hard, losing 20% ​​of the water content of fresh tobacco leaves.

[0018] In the later stage of yellowing, the main vein softens, the tobacco leaf withers fully, the front side shrinks, the main vein becomes soft and tough, and it is difficult to break. It loses 30% of the water content of fresh tobacco leaves, while preserving the chemical quality that has been formed in the yellowing stage.

[0019] In the early stage of color fixing and drying, the tips and edges of the tobacco leaves are hooked and rolled up. The tobacco leaves are further dehydrated, and a dry band appears between the leaf tips and edges. The leaf tips are clearly hooked, and the front edge of the leaf is rolled up. The rest of the tobacco leaves are still relatively soft, having lost 40% of the moisture content of fresh tobacco leaves.

[0020] During the middle stage of color fixation and leaf drying, the small drum is used to dry more than half of the tobacco leaf area. The leaves on both sides further curl towards the front, losing 50%-60% of the moisture content of the fresh tobacco leaves.

[0021] In the later stages of color fixing and leaf drying, the tobacco leaves are threshed until they are almost completely dry and even more curled up. Only the main veins are basically not dry, losing 70%-80% of the moisture content of fresh tobacco leaves, and the moisture content of the leaves reaches 20%-30%.

[0022] The process of flue-cured tobacco using high-frequency combined airflow modulation as described above, preferably, involves airflow-based curing and modulation of the initially cured tobacco leaves in an airflow-type curing barn: passing through a yellowing stage and a color-fixing and drying stage, causing the initially cured tobacco leaves to lose 60%-80% of the moisture content of fresh tobacco leaves, specifically including:

[0023] In an airflow curing barn, the partially cured tobacco leaves are stalked and placed on a drying rack for further curing, wherein:

[0024] In the early stage of yellowing: turn on the circulating air for 1-2 hours, then slowly raise the temperature to 33-35℃ over low heat, keeping the temperature and humidity stable for 4-6 hours.

[0025] During the middle stage of yellowing, the temperature was increased to 38℃ at a rate of 1℃ / h, and the wet bulb temperature was maintained at 36℃-37℃ for 15-25 hours.

[0026] During the later stage of yellowing, the dry bulb temperature is raised to 42℃ and the wet bulb temperature is 36℃-38℃, and the temperature and humidity are maintained for 20-32 hours.

[0027] In the early stage of color fixation and leaf drying, the temperature is increased to 45℃ at a rate of 1℃ / 3h, with the lower part of the wet bulb at 36℃ and the upper part at 35℃-36℃, and the temperature is maintained for 6h-10h.

[0028] During the mid-stage of color fixation and leaf drying, the temperature was increased to 48℃ at a rate of 1℃ / 3h, the wet bulb temperature was 37℃, and the temperature was maintained for 8h.

[0029] During the later stage of color fixation and leaf drying, the temperature was increased to 54℃ at a rate of 1℃ / 2h, and the wet-bulb temperature was maintained at 38℃-39℃ for 20h-24h.

[0030] The process of flue-cured tobacco using high-frequency combined airflow modulation as described above, preferably, involves high-frequency drying of the initially flue-cured tobacco leaves that have undergone the airflow-modulated curing treatment using a high-frequency drying device, specifically including:

[0031] After passing through the airflow curing barn, the first-cured tobacco leaves enter the high-frequency drying device for high-frequency drying. They then enter the tobacco material conveyor belt 22 through the feed inlet 21 of the first-cured tobacco leaf flat-laying table, and move from the feed end to the discharge end along the tobacco material conveyor belt 22. The width of the tobacco material conveyor belt 22 is 0.9m-1.1m and the length is 20m-25m.

[0032] A high-frequency oscillating electric field is provided to the high-frequency drying device through a high-frequency power supply device. The high-frequency drying device controls the transformer cabinet 32 ​​to work through the control console 33, so that the transformer cabinet 32 ​​controls the high-frequency generator 31 to have a high-frequency input power of 39KW-41KW, a high-frequency output power of 29KW-31KW, a high-frequency drying time of 4min-5min, and a frequency of 13.56MHz or 27.12MHz.

[0033] The present invention relates to an apparatus and process for conditioning flue-cured tobacco using high-frequency combined airflow. This method achieves flue-cured tobacco conditioning through high-frequency combined airflow. The initial stage utilizes traditional airflow conditioning methods, which are mature and easy to master. The subsequent high-frequency drying effectively improves the efficiency of tobacco leaf drying, shortens drying time, and achieves low-temperature conditioning. This not only avoids the aroma decay and quality decline caused by high-temperature baking during the dry-core stage of conventional curing, but also increases the filling capacity of the conditioned tobacco leaves, improves their structure, reduces off-flavors and irritation, and significantly improves sensory quality. This greatly enhances the conditioning quality of initially cured tobacco leaves and provides a new method for tobacco curing conditioning, expanding into new fields. Attached Figure Description

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of the control module of the device for modulating flue-cured tobacco with high-frequency combined airflow provided by the present invention;

[0036] Figure 2 This is a flowchart illustrating an embodiment of the process method for flue-cured tobacco using high-frequency combined airflow modulation provided by the present invention.

[0037] Explanation of reference numerals in the attached drawings: 11-Tobacco curing equipment, 12-Curning barn door, 13-Pre-cured tobacco leaves, 21-Pre-cured tobacco leaf flat-laying table feed inlet, 22-Tobacco material conveyor belt, 23-High-frequency electrode feed baffle, 24-High-frequency drying protective cover, 25-High-frequency electrode discharge baffle, 26-Tobacco leaf collection box, 31-High-frequency generator, 32-Transformer cabinet, 33-Control console. Detailed Implementation

[0038] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the present disclosure or its application or use. The present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that the present disclosure will be thorough and complete, and will fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless specifically stated otherwise, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0039] The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Terms such as “including” or “contains” mean that the element preceding the term encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as “above” and “below” are used only to indicate relative positional relationships; when the absolute position of the described object changes, this relative positional relationship may also change accordingly.

[0040] In this disclosure, when a specific component is described as being located between a first component and a second component, an intermediary component may or may not be present between the specific component and the first or second component. When a specific component is described as connecting to other components, the specific component may be directly connected to the other components without having an intermediary component, or it may not be directly connected to the other components but may have an intermediary component.

[0041] All terms used in this disclosure (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as a dictionary, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0042] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0043] like Figure 1As shown, the device for flue-cured tobacco using high-frequency combined airflow modulation provided in this embodiment includes: an airflow-type curing barn and a high-frequency drying device arranged in sequence. The airflow-type curing barn is equipped with a tobacco curing device 11 for curing the initial-cured tobacco leaves 13. The high-frequency drying device includes an initial-cured tobacco leaf flat-laying table feed inlet 21 and a tobacco leaf material conveyor belt 22 arranged in sequence. A high-frequency electrode feed baffle 23 is provided at the feed end of the tobacco leaf material conveyor belt 22, and a high-frequency electrode discharge baffle 25 is provided at the discharge end of the tobacco leaf material conveyor belt 22. The high-frequency drying device is connected to a high-frequency power supply device for providing a high-frequency oscillating electric field to the high-frequency drying device.

[0044] In one embodiment of the present invention, the airflow curing barn is a dense airflow descending curing barn. The internal specifications of the curing barn are as follows: three layers of tobacco are loaded, each layer has two tobacco clips, the length of the curing barn is 9m-11m, for example 10m, the width is 2.8m-3m, for example 2.9m, and the height is 3.5m-3.7m, for example 3.6m.

[0045] Furthermore, the airflow curing barn is rotatably connected to the two sides of the barn door 12, which facilitates the insertion and removal of the first-cured tobacco leaves 13.

[0046] Furthermore, a high-frequency drying protective cover 24, made of stainless steel, is provided above the tobacco material conveyor belt 22. It should be noted that the material of the high-frequency drying protective cover 24 is not specifically limited in this invention. A tobacco collection box 26 is connected to the end of the tobacco material conveyor belt 22 between the high-frequency electrode feed baffle 23 and the high-frequency electrode discharge baffle 25, for collecting the first-cured tobacco leaves 13 after high-frequency drying. In some embodiments of this invention, the width of the tobacco material conveyor belt 22 is 0.9m-1.1m, for example, 1m, and the length is 20m-25m, for example, 22m. It should be noted that the width and length of the tobacco material conveyor belt 22 are not specifically limited in this invention.

[0047] Furthermore, the high-frequency power supply device includes a high-frequency generator 31, a transformer cabinet 32, and a control console 33. The control console 33 controls the operation of the transformer cabinet 32, enabling it to control the high-frequency input power of the high-frequency generator 31 to be 39KW-41KW (e.g., 40KW), the high-frequency output power to be 29KW-31KW (e.g., 30KW), the high-frequency drying time to be 4-5 minutes, and the frequency of the high-frequency oscillating electric field generated by the high-frequency generator 31 to be 13.56MHz or 27.12MHz. It should be noted that this invention does not specifically limit the high-frequency input power, high-frequency output power, high-frequency drying time, and frequency of the high-frequency supply device. Simultaneously, the control console 33 can control the conveying speed of the tobacco material conveyor belt 22 according to the amount of tobacco leaves received.

[0048] Conventional airflow drying and conditioning of tobacco leaves achieves yellowing and fixation of the yellow color, aroma development and aroma manifestation. At the same time, complex chemical and biochemical changes occur in the leaf tissue, which can smoothly achieve the formation of the internal and external quality of tobacco leaves. Studies have shown that the temperature during the drying period has a significant impact on the aroma and taste of tobacco leaves.

[0049] High-frequency drying achieves low-temperature water loss based on the principle of dielectric heating. As the electric field frequency increases, the flipping and vibration of dipoles cannot keep up with the changes in the electric field, resulting in hysteresis. The polarizability gradually decreases, i.e., dielectric loss. The hysteresis dipoles rub against each other, causing electrical energy to be converted into heat energy. The material to be dried is placed between high-frequency electrode plates. The heat generated during the drying process mainly comes from the dielectric loss heat effect of the wet material, causing the internal temperature of the material to rise sharply. The water evaporates rapidly, resulting in a significant increase in pressure within the semi-closed cell cavity. A positive pressure gradient with a higher pressure inside and a lower pressure outside is formed inside the material. This gradient is the driving force for the outward migration of water and also removes impurities from the material, reducing irritation. It can also damage the pitted membrane on the cell wall, producing a puffing effect on the material. High-frequency heating also has special biological effects, completely eliminating the occurrence of insect pests at low temperatures. This invention utilizes high-frequency combined airflow to modulate flue-cured tobacco. The conventional airflow drying technology is mature in the early stages, allowing for the fixation of the tobacco leaves' appearance and internal quality. In the later drying stage, high-frequency drying enables low-temperature drying of the tobacco fibers, reducing the decomposition of aroma substances. This fully leverages the advantages of both methods, not only avoiding the aroma decay and quality decline caused by high-temperature drying in conventional curing, but also effectively improving the efficiency of tobacco leaf drying, shortening drying time, achieving low-temperature insect control, increasing the filling capacity of the modified tobacco leaves, reducing off-flavors and irritation, and significantly improving sensory quality. This provides a new method for tobacco curing and modulates, expanding into new fields.

[0050] The apparatus for conditioning flue-cured tobacco using high-frequency combined airflow provided in this invention consists of an airflow curing barn, a high-frequency drying device, and a high-frequency power supply device. It achieves flue-cured tobacco conditioning through high-frequency combined airflow. The initial stage uses traditional airflow conditioning methods, which are mature and easy to master. The later stage involves high-frequency drying, effectively improving the efficiency of tobacco leaf drying, shortening drying time, and achieving low-temperature conditioning. This not only avoids the aroma decay and quality decline caused by high-temperature baking during the dry-core stage of conventional curing, but also increases the filling capacity of the conditioned tobacco leaves, improves the tobacco leaf structure, reduces off-flavors and irritation, and significantly improves sensory quality. This greatly enhances the conditioning quality of the initial-cured tobacco leaves and provides a new method for tobacco curing conditioning, expanding into new fields.

[0051] like Figure 2 As shown, the process of using high-frequency combined airflow to modulate flue-cured tobacco provided in this embodiment specifically includes the following in actual implementation:

[0052] Step S1: Harvest mature, first-cured tobacco leaves based on the characteristics of the mature fresh tobacco in the field.

[0053] The characteristics of mature fresh tobacco leaves in the field include: yellow leaves with most of the pubescence fallen off, glossy leaves, increased resinous substances, and a sticky feel to the touch; the main vein turns white, and the secondary veins turn white; a separation layer forms at the base of the leaf, making it easy to pick, with a crisp sound when picked, a neat cross-section, and no stem bark; the natural support capacity of the tobacco leaves and main veins weakens, the leaf tips droop, and the angle between the stem and leaves increases; yellow-white starch granules appear on the middle and upper leaves, the leaf surface wrinkles, the yellowing of the leaf tips increases, or the edges wither and the tips scorch.

[0054] In one embodiment of the present invention, the flue-cured tobacco varieties are Zhongyan 100 and Yuyan No. 5. The middle tobacco leaves that are uniformly mature are selected, and the fresh tobacco leaves of the tobacco plants that are mainly yellow, with the main vein turning white and shiny, the leaf surface wrinkled, the yellow mature spots on the leaf surface obvious, the veins turning white, and the leaf surface yellow and most of the hairs falling off are harvested when they are at the appropriate maturity.

[0055] Step S2: The first-cured tobacco leaves are subjected to airflow curing and conditioning treatment in an airflow curing chamber: after the tobacco leaves turn yellow and the color-fixing and drying stage, the first-cured tobacco leaves lose 60%-80% of the moisture content of fresh tobacco leaves.

[0056] In one embodiment of the present invention, the airflow-type curing barn is a dense airflow descending curing barn. The internal specifications of the barn are: three layers of tobacco, each layer with two tobacco clamps; the length of the barn is 9m-11m, for example 10m; the width is 2.8m-3m, for example 2.9m; and the height is 3.5m-3.7m, for example 3.6m. Specifically, in the airflow-type curing barn, the initially cured tobacco leaves are stalked and placed on the curing rack for further curing. In one embodiment of the process method for curing tobacco using high-frequency combined airflow of the present invention, the method for judging the rate of water loss of the fresh tobacco leaves during the airflow curing process specifically includes:

[0057] Step A1: In the early stage of yellowing, the leaf tips soften. In the early stage of curing, the tobacco leaves undergo preliminary dehydration, and the leaf tips wilt significantly, while the other parts become swollen and hard, losing 10% of the moisture content of fresh tobacco leaves.

[0058] Step A2: In the middle of yellowing, the leaves soften, the leaf tissue and branch veins on both sides of the main vein of the tobacco leaf soften, while the main vein remains swollen and hard, losing 20% ​​of the water content of fresh tobacco leaves.

[0059] Step A3: In the later stage of yellowing, the main vein softens, the tobacco leaf fully withers, the front side shrinks, the main vein becomes soft and tough, and it is difficult to break. It loses 30% of the moisture content of fresh tobacco leaves, while preserving the chemical quality that has been formed in the yellowing stage.

[0060] Step A4: In the early stage of color fixation and drying, the tips and edges are hooked and rolled up. The tobacco leaves are further dehydrated, and a dry band appears between the leaf tip and the leaf edge. The leaf tip is obviously hooked, and the leaf edge is rolled up on the front. The rest of the tobacco leaf is still relatively soft, having lost 40% of the moisture content of fresh tobacco leaves.

[0061] Step A5: In the middle stage of color fixation and leaf drying, the tobacco leaves are dried in a small drum, with more than half of the leaf area dried. The leaves on both sides curl further towards the front, losing 50%-60% of the moisture content of the fresh tobacco leaves.

[0062] Step A6: In the later stage of color fixing and leaf drying, the tobacco leaves are threshed in large drums until they are almost completely dry and even more curled up. Only the main veins are basically not dry, losing 70%-80% of the moisture content of fresh tobacco leaves, and the moisture content of the leaves reaches 20%-30%.

[0063] In one embodiment of the process method for modulating flue-cured tobacco using high-frequency combined airflow of the present invention, step S2 may specifically include:

[0064] Step S21: In the early stage of yellowing: turn on the circulating air for 1-2 hours, then slowly heat the fire to 33-35℃, keep the temperature and humidity stable for 4-6 hours.

[0065] Step S22: During the middle stage of yellowing, raise the temperature to 38℃ at a rate of 1℃ / h, maintain the wet bulb temperature at 36℃-37℃, and keep it stable at this temperature for 15-25 hours.

[0066] Step S23: In the later stage of yellowing, raise the dry bulb temperature to 42℃ and the wet bulb temperature to 36℃-38℃, and maintain the temperature and humidity for 20-32 hours.

[0067] Step S24: In the early stage of color fixation and leaf drying, raise the temperature to 45℃ at a rate of 1℃ / 3h, with the lower part of the wet bulb at 36℃ and the upper part at 35℃-36℃, and maintain the temperature for 6h-10h.

[0068] Step S25: During the middle stage of color fixation and leaf drying, raise the temperature to 48℃ at a rate of 1℃ / 3h, keep the wet bulb temperature at 37℃, and maintain the temperature for 8h.

[0069] Step S26: In the later stage of color fixation and leaf drying, the temperature is increased to 54℃ at a rate of 1℃ / 2h, and the wet-bulb temperature is maintained at 38℃-39℃ for 20h-24h.

[0070] Step S3: The pre-cured tobacco leaves that have undergone the airflow baking and conditioning treatment are dried using a high-frequency drying device. The moisture content of the tobacco leaves after high-frequency drying is 10%-11%, and the moisture content of the tobacco stems is 11%-12%.

[0071] After step S3, the initial curing of the tobacco leaves is completed. In one embodiment of the process method for curing tobacco using high-frequency combined airflow of the present invention, step S3 may specifically include:

[0072] Step S31: After passing through the airflow curing barn, the first-cured tobacco leaves 13 enter the high-frequency drying device for high-frequency drying. They enter the tobacco material conveyor belt 22 through the feed inlet 21 of the first-cured tobacco leaf flat-laying table, and move from the feed end to the discharge end with the tobacco material conveyor belt 22. The width of the tobacco material conveyor belt 22 is 0.9m-1.1m and the length is 20m-25m.

[0073] After the initial curing of tobacco leaves 13 has been completed by high-frequency drying, it finally enters the tobacco leaf collection box 26 to collect the tobacco leaves.

[0074] Step S32: A high-frequency oscillating electric field is provided to the high-frequency drying device through a high-frequency power supply device. The high-frequency drying device controls the transformer cabinet 32 ​​to work through the control console 33, so that the transformer cabinet 32 ​​controls the high-frequency generator 31 to have a high-frequency input power of 39KW-41KW, a high-frequency output power of 29KW-31KW, a high-frequency drying time of 4min-5min, and a frequency of 13.56MHz or 27.12MHz.

[0075] High-frequency drying typically uses frequencies of 6.78MHz, 13.56MHz, and 27.12MHz, with 13.56MHz or 27.12MHz being the most common. 6.78MHz is generally used for heating structural materials with larger cross-sectional dimensions. The high-frequency oscillating electric field used in this invention has a frequency of 13.56MHz or 27.12MHz. High-frequency drying equipment requires highly standardized operation and a high level of expertise. Generally, when the moisture content is high, the penetration is weak, and energy consumption is high. Drying efficiency is low when the initial moisture content of the tobacco leaves is high. High-frequency drying can achieve rapid and high-quality drying when the moisture content is 20%-30%.

[0076] In some embodiments of the present invention, conventional airflow baking tests, airflow baking + high-frequency drying tests in the later stage of color fixing and leaf drying, airflow baking + high-frequency drying tests during the dry rib stage, and high-frequency drying tests after airflow baking were conducted. The specific test procedures are as follows:

[0077] Conventional airflow curing test: 100 kg of tobacco leaves of the same grade were taken at the mid-stage and late-stage of color-fixing and drying, and the experiment was repeated three times. The sampling grade was C3F. Treatment 1 (T1) was airflow curing + high-frequency drying in the late-stage of color-fixing and drying, repeated three times to obtain samples T11, T12, and T13. Treatment 2 (T2) was airflow curing + high-frequency drying during the dry-core stage, repeated three times to obtain samples T21, T22, and T23. The control group (CK) consisted of tobacco leaves cured by airflow curing. 100 kg of tobacco leaves with a moisture content of 20%-30% after airflow curing were fed onto a 1 m wide and 20-25 m long tobacco material conveyor belt 22 for high-frequency drying. Finally, the moisture content of the tobacco leaves dried by the combined high-frequency and airflow drying reached 10-11%, meeting the tobacco leaf quality and moisture content requirements.

[0078] Specifically, the test conditions for the airflow drying + high-frequency drying test of the color-fixing dried leaves are as follows: the airflow drying process is completed in the middle of the color-fixing dried leaf stage, and the moisture content of the fresh tobacco leaves is reduced by 50%-60%. The temperature is raised to 48°C at a rate of 1°C / 3h, the wet bulb temperature is 37°C, and the temperature is maintained for 8h. After the airflow drying, the high-frequency drying stage is then entered.

[0079] The experimental conditions for the airflow drying + high-frequency drying test during the leaf drying stage were as follows: the airflow drying process was completed in the later stage of color fixing and leaf drying. When 70-80% of the moisture content of the fresh tobacco leaves was lost, the moisture content of the leaves was 25%-30%, and the moisture content of the main vein was 55%-60%. In the later stage of color fixing and leaf drying, the temperature was increased to 54℃ at a rate of 1℃ / 2h, the wet bulb temperature was 38℃-39℃, and the temperature was stabilized for 20h-24h. After airflow drying, the high-frequency drying stage was then entered.

[0080] After the experiment, the appearance quality, sensory evaluation quality, and physical properties of each flue-cured tobacco sample modulated by high-frequency combined airflow were evaluated. The optimal control scheme for high-frequency combined airflow modulation of flue-cured tobacco was selected through the evaluation of the appearance quality, sensory quality, and physical properties of the cured tobacco leaves. The specific evaluation criteria and results are as follows:

[0081] (I) Appearance Quality Evaluation

[0082] The appearance quality evaluation adopted a visual assessment method to qualitatively evaluate each sample's indicators. The appearance quality evaluation indicators included: identity, color, oil content, fullness, uniformity, brightness, and aroma. Specifically, identity was divided into: thick, slightly thick, medium, slightly thin, and thin; color was divided into eight grades: pale yellow, earthy yellow, true yellow, golden yellow, deep yellow, light orange-red, orange-red, and reddish-brown; oil content was divided into four grades: abundant, present, slightly present, and scarce; fullness was divided into three grades: full, fairly full, and not full; uniformity was divided into three grades: uniform, fairly uniform, and mottled; and brightness was divided into four grades: bright, bright, slightly dark, and dark. The specific evaluation results are shown in Table 1.

[0083] Table 1. Comparison of appearance quality of smoke after baking under different baking methods

[0084]

[0085] As shown in Table 1, compared with the control group (CK), the appearance quality of tobacco leaves after high-frequency combined airflow modulation curing (T1 and T2) improved from slightly thick to medium in thickness, with a looser structure and improved texture. The color was mainly orange-yellow, with less red tobacco leaves, increased oil content, stronger color, more mellow and prominent aroma, and a significantly reduced proportion of veins and flakes. Overall, the appearance quality of the tobacco leaves improved, and the appearance quality of airflow curing + mid-term high-frequency drying of color-fixed dried leaves (T1) was better than that of airflow curing + late-term high-frequency drying of color-fixed dried leaves (T2).

[0086] (II) Sensory Quality Evaluation

[0087] Sensory quality evaluation indicators include aroma quality, aroma quantity, concentration, smoothness, aftertaste, off-flavors, irritation, and strength. In practice, 11 professional smokers conduct sensory quality evaluations according to "YC / T138-1988·Sensory Evaluation Method for Tobacco and Tobacco Products". Each sensory indicator is evaluated on a 9-point scale, and the total sensory quality evaluation score is the sum of the actual scores of each indicator multiplied by their respective weights.

[0088] The formula for calculating the total score of sensory quality evaluation is as follows:

[0089] T = (A+B)×2.0+(C+D)×1.5+E+F+G+H, where T is the total score of sensory quality evaluation, A is the aroma quality score, B is the aroma quantity score, C is the concentration score, D is the smoothness score, E is the aftertaste score, F is the off-flavor score, G is the irritation score, and H is the strength score. The sensory quality evaluation results are shown in Table 2.

[0090] Table 2 Sensory Quality Evaluation Table

[0091]

[0092] As shown in Table 2, the sensory quality scores of the high-frequency combined airflow-modulated tobacco leaves were significantly higher than those of the control group. The aroma quality was improved to varying degrees, the aroma quantity was significantly increased, the smoothness and aftertaste were improved, and the irritation of off-flavors was reduced. The sensory quality scores of the high-frequency combined airflow-modulated tobacco leaves were higher than those of the control group. Furthermore, the total sensory quality score of the airflow-modulated tobacco leaves cured by high-frequency drying in the middle stage of color-fixing and drying (T1) was higher than that of the airflow-modulated tobacco leaves cured by high-frequency drying in the later stage of color-fixing and drying (T2).

[0093] (III): Evaluation of physical indicators

[0094] Physical properties include: thickness (mm), leaf density (g / m³)2 ), equilibrium moisture content (%), tensile strength (%), elongation (%), and filler content (cm). 3 The physical index evaluation results are shown in Table 3.

[0095] Table 3 Evaluation Table of Physical Properties of Tobacco Leaves

[0096]

[0097] As shown in Table 3, compared with the control group, the high-frequency combined airflow modulation of tobacco leaves has a moderate thickness, improved leaf density, increased tensile strength, increased filling value, and significantly better physical properties than the control group. Furthermore, the physical properties of the airflow baking + mid-term high-frequency drying of color-fixed dried leaves (T1) treatment are better than those of the airflow baking + late-term high-frequency drying of color-fixed dried leaves (T2).

[0098] The evaluation results in Tables 1-3 show that the flue-cured tobacco leaves obtained by the high-frequency combined airflow modulation treatment of the present invention maintain a good maturity state, increase the proportion of orange-yellow leaves, loosen the leaf structure, thinner the leaf body, maintain a good color, have more oil content, stronger color, and significantly reduce the proportion of veins and leaves. The overall appearance quality of the tobacco leaves is improved, the physical properties of elasticity and tensile strength are enhanced, the sensory quality is improved, the aroma is increased, the off-flavors and irritation are reduced, the aroma is full and rounded, and the taste is comfortable and the aftertaste is pure.

[0099] The present invention provides a process for conditioning flue-cured tobacco using high-frequency combined airflow. This process achieves conditioning by utilizing high-frequency combined airflow. The initial stage employs traditional airflow conditioning methods, which are mature and easy to master. The subsequent high-frequency drying effectively improves the efficiency of tobacco leaf drying, shortens drying time, and achieves low-temperature conditioning. This not only avoids the aroma decay and quality decline caused by high-temperature baking during the dry-core stage of conventional curing, but also increases the filling capacity of the conditioned tobacco leaves, improves their structure, reduces off-flavors and irritation, and significantly improves sensory quality. This greatly enhances the conditioning quality of initially cured tobacco leaves and provides a new method for tobacco curing conditioning, expanding into new fields.

[0100] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0101] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. A process for modulating flue-cured tobacco using high-frequency combined airflow, characterized in that, The apparatus includes a sequentially arranged airflow curing barn and a high-frequency drying device. The airflow curing barn is a dense airflow descending type, and it contains tobacco curing equipment for curing partially cured tobacco leaves. The high-frequency drying device includes a partially cured tobacco leaf flat-laying table feed inlet and a tobacco leaf material conveyor belt, arranged sequentially. A high-frequency electrode feed baffle is installed at the feed end of the tobacco leaf material conveyor belt, and a high-frequency electrode discharge baffle is installed at the discharge end of the tobacco leaf material conveyor belt. The high-frequency drying device is connected to a high-frequency electrical supply device to provide a high-frequency oscillating electric field to the high-frequency drying device. The process includes the following steps: Based on the quality characteristics of mature fresh tobacco in the field, harvest mature, first-cured tobacco leaves. The first-cured tobacco leaves are subjected to airflow curing and conditioning treatment in an airflow curing barn: after the tobacco leaves turn yellow and the color-fixing and drying stage, the first-cured tobacco leaves lose 60%-80% of the moisture content of fresh tobacco leaves; The pre-cured tobacco leaves, after undergoing the aforementioned airflow baking and conditioning process, are dried using a high-frequency drying device. The resulting tobacco leaves have a moisture content of 10%-11%, and the tobacco stems have a moisture content of 11%-12%. The process involves airflow-type curing in a curing barn to cure the initially cured tobacco leaves. This includes a yellowing stage and a color-fixing and drying stage, causing the initially cured tobacco leaves to lose 60%-80% of their fresh tobacco leaf moisture content. Specifically, this includes: In an airflow curing barn, the partially cured tobacco leaves are stalked and placed on a drying rack for further curing, wherein: In the early stage of yellowing: turn on the circulating air for 1-2 hours, then slowly raise the temperature to 33-35℃ over low heat, keeping the temperature and humidity stable for 4-6 hours. During the middle stage of yellowing, the temperature was increased to 38℃ at a rate of 1℃ / h, and the wet bulb temperature was maintained at 36℃-37℃ for 15-25 hours. During the later stage of yellowing, the dry bulb temperature is raised to 42℃ and the wet bulb temperature is 36℃-38℃, and the temperature and humidity are maintained for 20-32 hours. In the early stage of color fixation and leaf drying, the temperature is increased to 45℃ at a rate of 1℃ / 3h, with the lower part of the wet bulb at 36℃ and the upper part at 35℃-36℃, and the temperature is maintained for 6h-10h. During the mid-stage of color fixation and leaf drying, the temperature was increased to 48℃ at a rate of 1℃ / 3h, the wet bulb temperature was 37℃, and the temperature was maintained for 8h. During the later stages of color fixation and leaf drying, the temperature was increased to 54℃ at a rate of 1℃ / 2h, and the wet-bulb temperature was maintained at 38℃-39℃ for 20-24 hours. The high-frequency drying of the pre-cured tobacco leaves, which have undergone the airflow baking and modulation treatment, using a high-frequency drying device specifically includes: After passing through the airflow curing barn, the first-cured tobacco leaves enter the high-frequency drying device for high-frequency drying. They then enter the tobacco material conveyor belt (22) through the feed inlet (21) of the first-cured tobacco leaf flat-laying table. The first-cured tobacco leaves move from the feed end to the discharge end along the tobacco material conveyor belt (22). The width of the tobacco material conveyor belt (22) is 0.9m-1.1m and the length is 20m-25m. A high-frequency oscillating electric field is provided to the high-frequency drying device through a high-frequency power supply device. The high-frequency drying device controls the transformer cabinet (32) to work through the control console (33), so that the transformer cabinet (32) controls the high-frequency generator (31) to have a high-frequency input power of 39KW-41KW, a high-frequency output power of 29KW-31KW, a high-frequency drying time of 4min-5min, and a frequency of 13.56MHz or 27.12MHz.

2. The process method for modulating flue-cured tobacco using high-frequency combined airflow according to claim 1, characterized in that, The quality characteristics of mature fresh tobacco in the field include: yellow leaves with most of the pubescence fallen off, glossy leaves, increased resinous substances, and a sticky feel to the touch; the main vein turns white, and the lateral veins turn white; a separation layer forms at the base of the leaf, making it easy to pick, with a crisp sound when picked, a neat cross-section, and no stem bark; the natural support capacity of the tobacco leaves and the main vein weakens, the leaf tips droop, and the angle between the stem and leaves increases; yellow-white starch granules appear on the middle and upper leaves, the leaf surface wrinkles, the yellowing of the leaf tips increases, or the edges wither and the tips scorch.

3. The process method for modulating flue-cured tobacco using high-frequency combined airflow according to claim 1, characterized in that, The method for determining the rate of moisture loss of fresh tobacco leaves during the airflow baking and conditioning process includes: In the early stage of yellowing, the leaf tips soften. In the early stage of curing, the tobacco leaves undergo preliminary dehydration, and the leaf tips wilt significantly, while the other parts become swollen and hard, losing 10% of the moisture content of fresh tobacco leaves. In the middle stage of yellowing, the leaves soften, and the leaf tissue and branch veins on both sides of the main vein of the tobacco leaf soften, while the main vein remains swollen and hard, losing 20% ​​of the water content of fresh tobacco leaves; In the later stage of yellowing, the main vein softens, the tobacco leaf withers fully, the front side shrinks, the main vein becomes soft and tough, and it is difficult to break. It loses 30% of the water content of fresh tobacco leaves, while preserving the chemical quality that has been formed in the yellowing stage. In the early stage of color fixing and leaf drying, the tips and edges of the tobacco leaves curl as the leaves further dehydrate. A dry band appears between the leaf tips and edges, the leaf tips are clearly hooked, and the front edges of the leaf edges curl up. The rest of the tobacco leaf is still relatively soft, having lost 40% of the moisture content of fresh tobacco leaves. During the middle stage of color fixing and leaf drying, the tobacco leaves are thawed in small drums, and more than half of the tobacco leaf area is dried. The leaves on both sides further curl towards the front, losing 50%-60% of the moisture content of fresh tobacco leaves. In the later stages of color fixing and leaf drying, the tobacco leaves are threshed until they are almost completely dry and even more curled up. Only the main veins are basically not dry, losing 70%-80% of the moisture content of fresh tobacco leaves, and the moisture content of the leaves reaches 20%-30%.

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