A method for improving the quality of difficult-to-bake tobacco leaves

Abstract

The application discloses a kind of improve the roasting method of difficult quality of tobacco leaf, including harvesting, furnace, curing barn high temperature area yellowing control, cold row yellowing control, yellowing later period control, dry tendon period control.The limitation of existing roasting method for the upper leaves of flue-cured tobacco is reduced, thereby effectively improving the proportion of high-quality tobacco after roasting, average price and sensory evaluation and smoking quality of the upper leaves of flue-cured tobacco, improving the quality of tobacco leaf after roasting, significantly reducing the economic loss of tobacco farmers, and improving the utilization rate of tobacco leaf.The application has the characteristics of simple process, easy operation and significant improvement effect.

Description

Technical Field

[0001] This invention relates to the field of roasting technology, and more specifically to a roasting method for improving the quality of difficult-to-roast tobacco leaves. Background Technology

[0002] Discolored tobacco is a common type of spoiled tobacco leaf in flue-cured tobacco production. It not only affects the appearance quality of the tobacco leaves but also seriously impacts their internal quality. According to recent surveys on tobacco production, the incidence of discolored tobacco during the curing process is approximately 25-33%. Discolored tobacco leaves have extremely low commercial value, resulting in a waste of agricultural resources, hindering the supply-side reform of modern tobacco raw materials, and severely restricting the sustainable development of tobacco production.

[0003] Upper tobacco leaves are an important component of tobacco raw materials. Due to their rich and full-bodied texture and intense aroma, good maturity and low levels of off-flavors significantly improve their usability, playing a crucial role in shaping the aroma and quality of cigarettes. However, upper tobacco leaves are denser and thicker, with higher levels of nicotine and starch. Combined with a thicker waxy layer, this makes moisture removal during curing difficult, leading to a prevalence of discolored tobacco. This results in a decline in the appearance quality of the leaves, reduced economic benefits, and an imbalance in the internal chemical composition, severely hindering industrial usability and ultimately impeding the improvement of upper tobacco leaf quality.

[0004] In actual production, due to the unique characteristics of curing the upper tobacco leaves, tobacco farmers typically regulate temperature and humidity over time by observing changes in the tobacco leaves inside the curing barn. However, this method is highly limited and arbitrary, further increasing the risk of damaging the upper tobacco leaves and causing significant economic losses to tobacco farmers.

[0005] Therefore, it is imperative to develop a simple and easy-to-operate baking process that can solve the problem of discolored tobacco in the upper tobacco leaves. Summary of the Invention

[0006] To address the above problems, the purpose of this invention is to provide a curing method for improving the quality of difficult-to-cook tobacco leaves.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for improving the quality of difficult-to-cook tobacco leaves includes the following steps:

[0009] A. Harvesting: Harvest the fresh upper leaves of mature flue-cured tobacco and weave them into poles;

[0010] B. Loading into the oven: Load the woven tobacco leaves into the curing room for curing;

[0011] C. Yellowing control in the high-temperature zone of the drying room: including the early stage of yellowing and the middle stage of yellowing. In the early stage of yellowing, the dry bulb temperature is raised from room temperature to 32-33°C at a heating rate of 1°C / 1-2h, and the wet bulb temperature is adjusted from room temperature to 32-33°C. The dry and wet bulb temperatures are stabilized and the drying is completed after 5-6 hours.

[0012] Then, at a heating rate of 1°C / 2h, raise the dry bulb temperature to 34-35°C and adjust the wet bulb temperature to 35°C. Stable dry and wet bulb temperatures and bake for 12-15h to finish.

[0013] Next, in the middle stage of yellowing, the dry bulb temperature is raised to 38-39°C and the wet bulb temperature is adjusted to 36-36.5°C at a heating rate of 1°C / 2-2.5h. The dry and wet bulb temperatures are stabilized and baked for 18-22h. At the end of the baking, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow and the tobacco leaves in the low-temperature zone are 50% yellow.

[0014] D. Yellowing Control of Cold Bulbs: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to lower the dry bulb temperature to 32-33°C and the wet bulb temperature to 27-30°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 20-24h until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and let the cold air damper be automatically controlled by the curing oven controller. Raise the dry bulb temperature to 34-35°C and the wet bulb temperature to 34-35°C at a heating rate of 1°C / 3h, and stabilize the dry and wet bulb temperatures for 5-6h. Then, raise the dry bulb temperature to 37-38°C and the wet bulb temperature to 34-35°C at a heating rate of 1°C / 3h, and stabilize the dry and wet bulb temperatures for 7-10h until the tips and edges of all the tobacco leaves in the oven curl.

[0015] E. Yellowing Post-Yellowing Control: Increase the dry-bulb temperature to 40-43°C at a heating rate of 1°C / 1-2h, and adjust the wet-bulb temperature to 35-36°C. Stabilize the dry and wet-bulb temperatures and bake for 12-18h. F. Color Fixing Control: This includes the initial and final stages of color fixing. In the initial stage, after the yellowing period, increase the dry-bulb temperature to 47-48°C at a heating rate of 1°C / 2h, and maintain the wet-bulb temperature at 35-36°C. Stabilize the dry and wet-bulb temperatures and bake for 5-8h.

[0016] Next, in the later stage of color fixation, the dry bulb temperature is raised to 54-56°C and the wet bulb temperature is adjusted to 38-40°C at a heating rate of 1°C / 1-2h, so that the tobacco leaves have a bright color. The dry and wet bulb temperatures are stabilized and the tobacco is baked for 12-24h to finish.

[0017] G. Drying period control: After the color setting period, raise the dry bulb temperature to 65-68°C at a heating rate of 1°C / 1.5-2h, adjust the wet bulb temperature to 40.5°C, stabilize the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten, and then cool and remove from the oven.

[0018] Furthermore, in step A, fresh flue-cured tobacco leaves that have turned white, have thin and elongated leaves that have lost their green color, and have lost most of their downy hairs are harvested.

[0019] Furthermore, the smoke density in step B is 40–45 kg / m³. 3 Furthermore, the tobacco is loaded to more than 95% of the curing barn's volume.

[0020] Furthermore, the room temperature for the dry bulb temperature during the early yellowing stage is 28-30°C, and the room temperature for the wet bulb temperature is 26-27°C.

[0021] Furthermore, the varieties of flue-cured tobacco include Yunnan tobacco series varieties, K326, KRK26, and Honghua Dajinyuan.

[0022] Furthermore, the Yunyan series varieties include Yunyan 99, Yunyan 97, Yunyan 87, and Yunyan 85.

[0023] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0024] This invention addresses the characteristics of upper tobacco leaves by optimizing the combination of temperature, humidity, and baking time during the tobacco curing process. This optimizes the PPO activity of the tobacco leaves during curing, which is polyphenol oxidase. This process alleviates or even avoids the adverse consequences of enzymatic browning of tobacco leaves, which leads to the polymerization of large dark-colored molecules, thus solving the problem of ash accumulation on upper tobacco leaves.

[0025] This invention addresses the issues of excessively thick upper tobacco leaves, excessive dry matter accumulation, high bound water content, and uneven temperatures in the high and low temperature zones of dense curing barns. These factors contribute to difficulties in yellowing the tobacco leaves during the conventional curing process and the occurrence of discoloration during the yellowing stage. The invention incorporates yellowing control in the high-temperature zone and yellowing control in the cold exhaust zone of the curing barn to ensure that the tobacco leaves fully yellow and dehydrate while minimizing the incidence of discolored tobacco.

[0026] This method reduces the limitations of existing curing methods on the curing of the upper leaves of flue-cured tobacco, thereby effectively increasing the proportion of high-grade tobacco, average price, and sensory evaluation quality after curing. This improves the overall quality of the cured tobacco leaves, significantly reduces economic losses for tobacco farmers, and increases the utilization rate of tobacco leaves. It features simple processing, ease of operation, and significant improvement effects. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] Example 1:

[0029] S100: Harvest the upper part of KRK26 tobacco leaves in Ziwu Town, Chuxiong City, where the tobacco veins have turned white, the leaves are thin and long with no green color, and most of the pubescence has fallen off, and then weave them into poles according to the usual method.

[0030] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0031] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 32°C at a rate of 1°C / 1h, and the wet-bulb temperature is adjusted from room temperature to 32°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 5 hours. Then, the dry-bulb temperature is increased to 34°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 12 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 38°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 36°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 18 hours. At the end of the curing, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0032] S400: Yellowing Control of Cold Bulbs: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to reduce the dry bulb temperature to 32°C and the wet bulb temperature to 27°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 20h until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 34°C and adjust the wet bulb temperature to 34°C. Stabilize the dry and wet bulb temperatures and cure for 5h. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 37°C and adjust the wet bulb temperature to 34°C. Stabilize the dry and wet bulb temperatures and cure for 7h until the tips and edges of all the tobacco leaves in the oven curl.

[0033] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 40°C and the wet-bulb temperature to 35°C at a heating rate of 1°C / 1h, and bake at stable dry and wet-bulb temperatures for 12 hours. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 47°C at a heating rate of 1°C / 2h, and maintain the wet-bulb temperature at 35°C, and bake at stable dry and wet-bulb temperatures for 5 hours. Then, in the later stage of color fixing, increase the dry-bulb temperature to 54°C at a heating rate of 1°C / 1h, and adjust the wet-bulb temperature to 38°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 12 hours.

[0034] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 65°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 1.5h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0035] Example 2:

[0036] S100: The upper leaves of KRK26 flue-cured tobacco, which have turned white, have thin and elongated leaves that have lost their green color and have lost most of their downy hairs, are harvested in Ziwu Town, Chuxiong City, and then bundled into poles according to conventional methods.

[0037] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0038] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 32°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted from room temperature to 32°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 6 hours. Then, the dry-bulb temperature is increased to 35.5°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 14 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 38.5°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 36.5°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 20 hours. At the end of the curing process, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0039] S400: Yellowing Control of Cold Bulbs: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to lower the dry bulb temperature to 32°C and the wet bulb temperature to 28°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 20-24 hours, until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 35°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 5.5 hours. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 37.5°C and adjust the wet bulb temperature to 34°C. Stabilize the dry and wet bulb temperatures for 9 hours, until the tips and edges of all the tobacco leaves in the oven curl.

[0040] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 42°C and the wet-bulb temperature to 35°C at a heating rate of 1°C / 1h, and bake at stable dry and wet-bulb temperatures for 16h. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 48°C at a heating rate of 1°C / 2h, and maintain the wet-bulb temperature at 35°C, and bake at stable dry and wet-bulb temperatures for 8h. Then, in the later stage of color fixing, increase the dry-bulb temperature to 55°C at a heating rate of 1°C / 1.5h, and adjust the wet-bulb temperature to 39°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 18h.

[0041] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 66°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 1.5h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0042] Example 3:

[0043] S100: The upper leaves of KRK26 flue-cured tobacco, which have turned white, have thin and elongated leaves that have lost their green color and have lost most of their downy hairs, are harvested in Ziwu Town, Chuxiong City, and then bundled into poles according to conventional methods.

[0044] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0045] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 33°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted from room temperature to 33°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 6 hours. Then, the dry-bulb temperature is increased to 35°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 15 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 39°C at a rate of 1°C / 2.5h, and the wet-bulb temperature is adjusted to 36.5°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 22 hours. At the end of the curing process, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0046] S400: Cold Bulb Yellowing Control: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to reduce the dry bulb temperature to 33°C and the wet bulb temperature to 30°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 24h until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 35°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 6h. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 38°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 10h until the tips and edges of all the tobacco leaves in the oven curl.

[0047] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 43°C at a rate of 1°C / 2h, adjust the wet-bulb temperature to 36°C, and bake at stable dry and wet-bulb temperatures for 18h. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 48°C at a rate of 1°C / 2h, maintain the wet-bulb temperature at 36°C, and bake at stable dry and wet-bulb temperatures for 5-8h. Then, in the later stage of color fixing, increase the dry-bulb temperature to 56°C at a rate of 1°C / 2h, adjust the wet-bulb temperature to 0°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 24h.

[0048] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 68°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 2h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0049] Experimental Example 1:

[0050] Using conventional curing methods, the tobacco leaves harvested in Examples 1, 2, and 3 were respectively cured, and the resulting flue-cured tobacco was designated as Control Group 1, Control Group 2, and Control Group 3. Then, various post-curing indicators of the tobacco leaves from the Examples and the Control Groups were measured, and the results are shown in Tables 1 and 2.

[0051] Table 1. Curing quality of KRK26 flue-cured tobacco leaves in Ziwu Town, Chuxiong City

[0052]

[0053] As shown in Table 1, the proportion of superior tobacco, the proportion of mixed-color tobacco, the average price, and the grade index of Examples 1-3 are all better than those of the corresponding control groups.

[0054] The tobacco leaves obtained from the final processing in Examples 1-3 and Control Groups 1-3 were evaluated and scored. An evaluation panel of five people, including five provincial-level tobacco tasters, was formed. The intrinsic sensory quality evaluations of Examples 1-3 and the Control Group are shown in Table 2 below.

[0055] Table 2. Scoring table of intrinsic sensory quality of tobacco leaves obtained by curing method

[0056]

[0057] As shown in the table above, the smoking quality of tobacco leaves prepared using the method of this invention is significantly improved compared to the control group. The tobacco leaves prepared according to this invention have a good aroma, sufficient aroma quantity, less off-flavors, less irritation, stronger strength, and a comfortable aftertaste, which can fully meet the needs of the cigarette industry and solve the problem of upper leaf curing.

[0058] Example 4:

[0059] S100: The upper part of the 'Honghua Dajinyuan' tobacco leaves, which have turned white, have thin and long leaves that have lost their green color and have lost most of their downy hairs, are harvested in Jiuxi Town, Yuxi, and then woven into poles according to conventional methods.

[0060] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0061] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 32°C at a rate of 1°C / 1h, and the wet-bulb temperature is adjusted from room temperature to 32°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 5 hours. Then, the dry-bulb temperature is increased to 34°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 12 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 3°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 36°C. The dry and wet-bulb temperatures are stabilized and the curing is completed after 18 hours. At the end of the curing, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0062] S400: Yellowing Control of Cold Bulbs: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to lower the dry bulb temperature to 32°C and the wet bulb temperature to 27°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 20h until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 34°C and adjust the wet bulb temperature to 3°C. Stabilize the dry and wet bulb temperatures and cure for 5h. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 37°C and adjust the wet bulb temperature to 34°C. Stabilize the dry and wet bulb temperatures and cure for 7h until the tips and edges of all the tobacco leaves in the oven curl.

[0063] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 40°C and the wet-bulb temperature to 35°C at a heating rate of 1°C / 1h, and bake at stable dry and wet-bulb temperatures for 12 hours. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 47°C at a heating rate of 1°C / 2h, and maintain the wet-bulb temperature at 35°C, and bake at stable dry and wet-bulb temperatures for 5 hours. Then, in the later stage of color fixing, increase the dry-bulb temperature to 5°C at a heating rate of 1°C / 1h, and adjust the wet-bulb temperature to 38°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 12 hours.

[0064] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 65°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 1.5h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0065] Example 5:

[0066] S100: The upper part of the 'Honghua Dajinyuan' tobacco leaves, which have turned white, have thin and long leaves that have lost their green color and have lost most of their downy hairs, are harvested in Jiuxi Town, Yuxi, and then woven into poles according to conventional methods.

[0067] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0068] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 32°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted from room temperature to 32°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 6 hours. Then, the dry-bulb temperature is increased to 35.5°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 14 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 38.5°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 36.5°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 20 hours. At the end of the curing process, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0069] S400: Yellowing Control of Cold Bulbs: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to lower the dry bulb temperature to 32°C and the wet bulb temperature to 28°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 20-24 hours, until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 35°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 5.5 hours. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 37.5°C and adjust the wet bulb temperature to 34°C. Stabilize the dry and wet bulb temperatures for 9 hours, until the tips and edges of all the tobacco leaves in the oven curl.

[0070] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 42°C and the wet-bulb temperature to 35°C at a heating rate of 1°C / 1h, and bake at stable dry and wet-bulb temperatures for 16h. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 48°C at a heating rate of 1°C / 2h, and maintain the wet-bulb temperature at 35°C, and bake at stable dry and wet-bulb temperatures for 8h. Then, in the later stage of color fixing, increase the dry-bulb temperature to 55°C at a heating rate of 1°C / 1.5h, and adjust the wet-bulb temperature to 39°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 18h.

[0071] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 66°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 1.5h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0072] Example 6:

[0073] S100: The upper part of the 'Honghua Dajinyuan' tobacco leaves, which have turned white, have thin and long leaves that have lost their green color and have lost most of their downy hairs, are harvested in Jiuxi Town, Yuxi, and then woven into poles according to conventional methods.

[0074] S200: The already bundled tobacco leaves are processed at 43.5 kg / m 3 The tobacco loading density is such that the tobacco is loaded to more than 95% of the volume of the airflow descending dense drying room, ready for drying.

[0075] S300: Yellowing control in the high-temperature zone of the curing barn: This includes the early and middle stages of yellowing. In the early stage, the dry-bulb temperature is increased from room temperature to 33°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted from room temperature to 33°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 6 hours. Then, the dry-bulb temperature is increased to 35°C at a rate of 1°C / 2h, and the wet-bulb temperature is adjusted to 35°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 15 hours. Next, in the middle stage of yellowing, the dry-bulb temperature is increased to 39°C at a rate of 1°C / 2.5h, and the wet-bulb temperature is adjusted to 36.5°C. The dry and wet-bulb temperatures are stabilized and the curing process is completed after 22 hours. At the end of the curing process, the tobacco leaves in the high-temperature zone of the curing barn are fully yellow, and the tobacco leaves in the low-temperature zone are 50% yellow.

[0076] S400: Cold Bulb Yellowing Control: Set the dense curing oven fan to high speed, manually open the cold air inlet of the curing oven, and set the curing oven to a cooling rate of 1°C / 4h to reduce the dry bulb temperature to 33°C and the wet bulb temperature to 30°C to reduce discoloration and ash accumulation in the tobacco leaves. Curing time is 24h until the entire oven turns yellow with white veins. Then, set the curing oven fan to low speed, and the cold air damper is automatically controlled by the curing oven controller. At a heating rate of 1°C / 3h, raise the dry bulb temperature to 35°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 6h. Then, at a heating rate of 1°C / 3h, raise the dry bulb temperature to 38°C and adjust the wet bulb temperature to 35°C. Stabilize the dry and wet bulb temperatures for 10h until the tips and edges of all the tobacco leaves in the oven curl.

[0077] S500: Yellowing Stage Control: Increase the dry-bulb temperature to 43°C at a rate of 1°C / 2h, adjust the wet-bulb temperature to 36°C, and bake at stable dry and wet-bulb temperatures for 18h. S600: Color Fixing Stage Control: Includes the initial and later stages of color fixing. In the initial stage, after the yellowing stage, increase the dry-bulb temperature to 48°C at a rate of 1°C / 2h, maintain the wet-bulb temperature at 36°C, and bake at stable dry and wet-bulb temperatures for 5-8h. Then, in the later stage of color fixing, increase the dry-bulb temperature to 56°C at a rate of 1°C / 2h, adjust the wet-bulb temperature to 0°C to achieve a bright tobacco leaf color, and bake at stable dry and wet-bulb temperatures for 24h.

[0078] S700: Drying period control: After the color setting period, raise the dry bulb temperature to 68°C and adjust the wet bulb temperature to 40.5°C at a heating rate of 1°C / 2h. After stabilizing the dry and wet bulb temperatures, bake for 32h to dry the entire batch of gluten and then cool it out of the oven.

[0079] Experiment Example 2

[0080] Using conventional curing methods, the tobacco leaves harvested in Examples 1, 2, and 3 were respectively cured, and the resulting flue-cured tobacco was designated as Control Group 1, Control Group 2, and Control Group 3. Then, various post-curing indicators of the tobacco leaves from the Examples and the Control Groups were measured, and the results are shown in Tables 3 and 4.

[0081] Table 3. Curing quality of safflower and ginseng tobacco leaves in Jiuxi Town, Yuxi

[0082]

[0083] As shown in Table 3, the proportion of superior tobacco, the proportion of mixed-color tobacco, the average price, and the grade index of Examples 4-6 are all better than those of the corresponding control groups.

[0084] The tobacco leaves obtained from the final processing in Examples 4-6 and Control Groups 4-6 were evaluated and scored. An evaluation panel of five people, including five provincial-level tobacco tasters, was formed. The intrinsic sensory quality evaluations of Examples 4-6 and the Control Group are shown in Table 4 below.

[0085] Table 4. Intrinsic sensory quality rating table of tobacco leaves obtained by curing method

[0086]

[0087] As shown in the table above, the smoking quality of tobacco leaves prepared using the method of this invention is significantly improved compared to the control group. The tobacco leaves prepared according to this invention have a good aroma, sufficient aroma quantity, less off-flavors, less irritation, stronger strength, and a comfortable aftertaste, which can fully meet the needs of the cigarette industry and solve the problem of upper leaf curing.

[0088] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of the disclosure and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A curing method for improving the quality of difficult-to-cure tobacco leaves, characterized by: The method comprises the following steps: A, harvesting: harvesting the ripe fresh tobacco leaves of flue-cured tobacco and pole; B, loading: loading the pole of the tobacco leaves into the curing barn for baking; C, high-temperature zone yellowing control in the curing barn: including the early stage of yellowing and the middle stage of yellowing, in the early stage of yellowing, the dry ball temperature is increased to 32-33 DEG C from room temperature at a rate of 1 DEG C / 1-2 h, the wet ball temperature is adjusted to 32-33 DEG C from room temperature, the dry ball temperature and the wet ball temperature are stabilized for 5-6 h, and then the dry ball temperature is increased to 34-35 DEG C at a rate of 1 DEG C / 2 h, the wet ball temperature is adjusted to 35 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 12-15 h, and then the middle stage of yellowing is entered, the dry ball temperature is increased to 38-39 DEG C at a rate of 1 DEG C / 2-2.5 h, the wet ball temperature is adjusted to 36-36.5 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 18-22 h, and when the baking is finished, the full yellowing of the tobacco leaves in the high-temperature zone of the curing barn and the 5% yellowing of the tobacco leaves in the low-temperature zone are ensured; D, cold row yellowing control: the fan of the dense curing barn is adjusted to the high-speed gear, the cold air inlet of the curing barn is manually opened, the curing barn is set to decrease the dry ball temperature to 32-33 DEG C at a rate of 1 DEG C / 4 h, the wet ball temperature is adjusted to 27-30 DEG C, the color and the ash of the tobacco leaves are reduced, the baking is performed for 20-24 h, the yellowing white muscle of the full furnace is baked, then the fan of the curing barn is adjusted to the low-speed gear, the cold air door is automatically controlled by the curing barn controller, the dry ball temperature is increased to 34-35 DEG C at a rate of 1 DEG C / 3 h, the wet ball temperature is adjusted to 34-35 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 5-6 h, then the dry ball temperature is increased to 37-38 DEG C at a rate of 1 DEG C / 3 h, the wet ball temperature is adjusted to 34-35 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 7-10 h, and the tobacco leaves in the full furnace are curled and hooked until the tobacco leaves in the full furnace are curled and hooked; E, yellowing later stage control: the dry ball temperature is increased to 40-43 DEG C at a rate of 1 DEG C / 1-2 h, the wet ball temperature is adjusted to 35-36 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 12-18 h, and the baking is finished; F, color fixing period control: including the early stage of color fixing and the later stage of color fixing, in the early stage of color fixing, the dry ball temperature is increased to 47-48 DEG C at a rate of 1 DEG C / 2 h after the yellowing period, the wet ball temperature is adjusted to 35-36 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 5-8 h, and the baking is finished; then the later stage of color fixing is entered, the dry ball temperature is increased to 54-56 DEG C at a rate of 1 DEG C / 1-2 h, the wet ball temperature is adjusted to 38-40 DEG C, the color of the tobacco leaves is bright, the dry ball temperature and the wet ball temperature are stabilized for 12-24 h, and the baking is finished; G, dry muscle period control: after the color fixing period, the dry ball temperature is increased to 65-68 DEG C at a rate of 1 DEG C / 1.5-2 h, the wet ball temperature is adjusted to 40.5 DEG C, the dry ball temperature and the wet ball temperature are stabilized for 32 h, the dry muscle of the full furnace is baked, and the tobacco leaves are cooled and taken out of the furnace. The fresh tobacco leaves of the A step are the tobacco leaves with white muscle, slender and green leaves and most of the hair fallen off. The room temperature of the dry ball temperature in the early stage of yellowing is 28-30 DEG C, and the room temperature of the wet ball temperature is 26-27 DEG C.

2. The curing method for improving the quality of difficult-to-cure tobacco leaves according to claim 1, characterized in that: The variety of the flue-cured tobacco includes KRK26 and Honghua Dajinyuan.

3. The curing method for improving the quality of difficult-to-cure tobacco leaves according to claim 1, characterized in that: The loading density in the B step is 40-45 kg / m 3 and loading to 95% or more of the barn volume.

4. The curing method for improving the quality of difficult-to-cure tobacco leaves according to claim 1, characterized in that: ​ 5. The curing method for improving the quality of difficult-to-cure tobacco leaves according to claim 1, characterized in that: ​

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