Wax tobacco leaf curing method

Abstract

The invention discloses a waxy tobacco leaf baking method. The waxy tobacco leaf baking method comprises the steps that 1, waxy tobacco leaves are classified and woven into rods; 2, the rod-weaving wax tobacco leaves are put into a Tween-20 solution with the concentration being 0.1%-1%, soaked for 3-5 min and then taken out, and natural air drying is carried out; and 3, the treated waxy tobacco leaves are put into a bulk curing barn to be cured. According to the method, the waxy tobacco leaves are soaked in the Tween-20 solution, in the baking process, on one hand, high-temperature and high-humidity braising baking is matched, so that waxy layers on the surfaces of the tobacco leaves are gradually collapsed, air holes of the tobacco leaves are promoted to be fully opened, normal evaporation and discharge of water are facilitated, coordination of yellowing and water loss of the tobacco leaves is facilitated, and the phenomenon of baking damage caused by unsmooth water loss is avoided; on the other hand, the Tween-20 is gradually decomposed to generate sorbitol and lauric acid, the sorbitol can regulate and control glycometabolism to improve chemical components of the tobacco leaves, the lauric acid optimizes lipid synthesis and aroma precursor substances, and the sensory quality of the tobacco leaves is remarkably improved.

Description

Technical Field

[0001] The present invention relates to a method for baking waxy tobacco leaves, belonging to the technical field of tobacco leaf baking. Background Art

[0002] Waxy tobacco leaves refer to a waxy substance existing on the surface of tobacco leaves. These waxes are mainly composed of various lipophilic compounds, forming a hydrophobic layer on the surface of tobacco leaves, which has an important impact on the water retention performance of tobacco. According to research, the epidermal wax of tobacco leaves is mainly composed of straight-chain alkanes, branched-chain alkanes, triterpenoids, fatty alcohols, etc. The main difference between waxy tobacco leaves and ordinary tobacco leaves lies in the content and composition of the surface wax. The surface wax content of waxy tobacco leaves is relatively high, and the relatively high wax content may affect the moisturizing performance of tobacco leaves, that is, the ability to retain moisture.

[0003] The wax will block the channels for the outward loss of water from tobacco leaves. During the baking process of tobacco leaves, the thin film-like wax layer on the surface of tobacco leaves seriously hinders the evaporation of water from tobacco leaves, resulting in slow water loss during the baking process of tobacco leaves. During the early stage of tobacco leaf baking, the water loss is slow, and the leaves turn yellow slowly. In the later stage, when the temperature rises, it is easy to cause the rupture of the cell wall of tobacco leaves, resulting in a browning reaction and easily occurring phenomena such as ash hanging, etc., which deteriorates the quality of flue-cured tobacco and causes huge economic losses to tobacco farmers.

[0004] The existing literature (CN109924532 B) discloses a method for removing the wax layer of flue-cured tobacco to improve the water loss characteristics of tobacco leaves and its application. This method includes pre-treatment of tobacco leaves, preparation of a dewaxing agent solution, removal of the wax layer of tobacco leaves, re-washing of tobacco leaves, and fishing out and draining. The dewaxing agent solution used in this method is prepared from food-grade sodium carbonate and sodium bicarbonate. It can not only effectively destroy the structure of the wax layer on the surface of tobacco leaves, improve the water loss characteristics of tobacco leaves, reduce the baking cost, but also the baked tobacco leaves are safe, non-toxic, of good quality, and harmless to the human body. Although this method can destroy the structure of the wax layer on the surface of tobacco leaves, the improvement of the baking quality of tobacco leaves is still limited. Summary of the Invention

[0005] Based on the above, the present invention provides a method for baking waxy tobacco leaves, which can not only destroy the structure of the wax layer on the surface of tobacco leaves, but also further improve the baking quality of tobacco leaves.

[0006] The technical solution of the present invention is: a method for baking waxy tobacco leaves, including:

[0007] Step 1: Classify and string the waxy tobacco leaves;

[0008] Step 2: Put the strung waxy tobacco leaves into a Tween-20 solution with a concentration of 0.1% - 1%, soak for 3 - 5 minutes and then take out, and air dry naturally;

[0009] Step 3: Put the treated waxy tobacco leaves into a bulk curing barn for baking.

[0010] Tween-20 is a non-ionic surfactant that can effectively reduce the surface tension of liquids, disrupt the hydrophobic structure of the waxy layer, and promote the evaporation of moisture in tobacco leaves; natural air drying after soaking not only avoids the interference of the residual solution on subsequent baking but also retains the effect of the surfactant; meanwhile, it can further improve the quality of tobacco leaves during baking.

[0011] Preferably, the baking of the waxy tobacco leaves includes the following steps:

[0012] S1 Set the temperature and humidity target at 40°C / 40°C. After ignition, raise the temperature to the dry-bulb target temperature of 40°C at a rate of 1°C every 2 - 3 hours. After the wet-bulb temperature rises to 40°C, stop heating, turn off the circulation fan and the cold air inlet damper, and let the tobacco leaves in the loading chamber be in a state of high-temperature and high-humidity baking.

[0013] S2 After the dry-bulb temperature drops to 35°C, reheat the baking room, turn on the circulation fan, heat to the temperature and humidity target of 40°C / 40°C. After the wet-bulb temperature rises to 40°C, stop heating, turn off the circulation fan and the cold air inlet damper, and let the tobacco leaves in the loading chamber be in a state of high-temperature and high-humidity baking.

[0014] S3 Repeat steps S2 and S3 repeatedly until more than 80% of the tobacco leaves turn 30% yellow, the leaves are fully sweating, and the stomata of the tobacco leaves are fully opened.

[0015] S4 Adjust the dry-bulb and wet-bulb temperatures to 38°C / 37 - 38°C, keep the temperature stable for 10 - 15 hours, and bake with humidity until the tobacco leaves are 50% - 60% yellow and the leaves are dehydrated by 10% - 15%.

[0016] S5 Raise the dry-bulb and wet-bulb temperatures to 40°C / 37 - 38°C at a rate of 1°C every 2 - 3 hours, keep the temperature stable for 15 - 20 hours. After the tobacco leaves turn 80% - 90% yellow, adjust the wet-bulb temperature to 36 - 37°C, keep the temperature stable for 6 - 8 hours, and bake until the tobacco leaves are soft.

[0017] S6 Raise the temperature to 42°C / 36 - 37°C at a rate of 1°C every 2 - 3 hours, keep the temperature stable for 16 - 20 hours until the tobacco leaves are fully yellow, 1 / 2 - 2 / 3 of the lateral veins turn white, and the main vein is fully soft.

[0018] S7 Raise the temperature to 44°C / 36 - 37°C at a rate of 1°C every 3 - 4 hours, keep the temperature stable for 6 - 8 hours until the tobacco leaves in the high-temperature layer reach the small roll state and the lateral veins are all white.

[0019] S8 Raise the temperature to 48°C / 37 - 38°C at a rate of 1°C every 3 - 4 hours, keep the temperature stable for 6 - 8 hours until the tobacco leaves in the low-temperature layer reach the small roll state and the lateral veins are all white.

[0020] S9: Raise the temperature to 54℃ / 38-39℃ at a rate of 1℃ / 2-3 hours, and keep the temperature steady for 14-18 hours until the tobacco leaves on the kang reach a large roll and are completely dry;

[0021] S10 was heated to 60℃ / 39-40℃ at a rate of 1℃ / 1-2 hours and kept at this temperature for 6 hours until the main veins of the tobacco leaves turned purple;

[0022] S11: Raise the temperature to 68℃ / 40-41℃ at a rate of 1℃ / 1-2 hours and keep it at a constant temperature for more than 20 hours until the main veins of the tobacco leaves are completely dry;

[0023] S12 stops heating, and the circulating fan continues to be turned on until the dry bulb temperature in the drying room drops below 40°C, then the fan is turned off and the tobacco leaves begin to enter a natural rehumidification state.

[0024] Beneficial effects of the present invention: The present invention soaks waxy tobacco leaves in Tween-20 solution, and on the one hand, cooperates with high temperature and high humidity stewing during baking, so that the wax layer on the surface of the tobacco leaves gradually disintegrates, promotes the full opening of the tobacco leaf pores, facilitates the normal evaporation and discharge of water, and is conducive to the coordination of yellowing and water loss of tobacco leaves, thereby avoiding the phenomenon of baking caused by poor water loss; on the other hand, Tween-20 will gradually decompose and produce sorbitol and lauric acid during the baking process, sorbitol can regulate sugar metabolism to improve the chemical composition of tobacco leaves, and lauric acid optimizes lipid synthesis and aroma precursor substances, significantly improving the sensory quality of tobacco leaves. The present invention effectively solves the problem of waxy tobacco leaves being difficult to lose water and easy to be baked during baking through the collaborative innovation of Tween-20 solution soaking and baking process, improves the chemical composition of tobacco leaves, especially increases the content of aroma substances, and significantly improves the sensory quality of tobacco leaves. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0026] The experiment was conducted in the Weining tobacco-growing area of Bijie in late September 2024 (when the temperature was relatively low and a waxy layer was likely to form on the surface of tobacco leaves). The flue-cured tobacco variety used was Yunyan 87, and the tobacco leaves at the 16th to 18th upper leaf positions were used as experimental materials. Taking the local conventional baking process as the control, treating the tobacco leaves with Tween-20, baking them according to the normal process after cleaning was Treatment 1, treating the tobacco leaves with Tween-20, baking them according to the conventional baking process without cleaning was Treatment 2, and treating the tobacco leaves with Tween-20, baking them according to the optimized process without cleaning using the method of the present invention was Treatment 3. Comparative treatments were carried out to conduct a comparative experiment.

[0027] 1. Control (conventional baking process)

[0028] After the bulk curing barn was filled with tobacco leaves, close the barn door and start baking.

[0029] Yellowing stage:

[0030] After starting the circulation fan and running it idly for 2 h, light a small fire and slowly raise the temperature of the barn to 31 °C, keep the wet-bulb temperature at 31 °C, and keep the temperature stable for 6 h for the tobacco leaves to sweat; then raise the dry-bulb temperature by 1 °C per 1 h to 36 °C, control the wet-bulb temperature at 35 °C, and keep the temperature and humidity stable for 25 h to make 80% of the tobacco leaves in the high-temperature layer turn yellow to five to six tenths; raise the dry-bulb temperature by 1 °C per 2 h to 38 °C, control the wet-bulb temperature at 37 °C, and keep the temperature and humidity stable for 18 h to make the tobacco leaves in the high-temperature layer turn yellow to eight to nine tenths, and gradually exhaust the moisture until the leaves become soft; raise the dry-bulb to 42 °C, wet-bulb 36 °C, and keep the temperature stable for 16 h to make the whole layer of tobacco leaves complete yellowing, reaching yellow leaves with green veins, the leaves are fully yellowed, wilted and collapsed, and the main vein becomes soft;

[0031] Color-fixing stage:

[0032] Raise the dry-bulb temperature by 1 °C every 3 h to 45 °C, wet-bulb temperature 37 °C, keep the temperature stable for 10 h, the branch veins turn white, and the leaves are fully soft and wilted; raise the dry-bulb temperature by 1 °C every 3 h to 48 °C, wet-bulb temperature 38 °C, keep the temperature stable for 8 h to achieve semi-dry yellow leaves with white veins, and most of the tobacco leaves reach small scrolls; raise it by 1 °C every 3 hours to 51 °C, wet-bulb temperature 38 °C, keep the temperature stable for 8 h, and the main vein turns white; then raise the dry-bulb to 54 °C at 1 °C every 2 h, wet-bulb 39 °C, keep the temperature stable for 18 h until the leaves are dried into large scrolls;

[0033] Stem-drying stage:

[0034] Raise the temperature by 1 °C per 1 h to 60 °C, wet-bulb temperature 40 °C, keep the temperature stable for 6 h to balance the tobacco leaves on both sides; raise the temperature by 1 °C per 1 h to 68 °C, wet-bulb temperature 41 °C, keep the temperature stable for more than 25 h until the tobacco stems are completely dry.

[0035] Moisture regain:

[0036] Cease fire. Keep the circulation fan running until the temperature drops below 40°C, then stop the fan, open the curing barn door slightly, and enter the natural conditioning stage.

[0037] 2. Treatment 1 (Treat the tobacco leaves with Tween-20, wash them, and then bake them according to the conventional baking process)

[0038] Step 1: Classify and string the waxy tobacco leaves on poles.

[0039] Step 2: Add Tween-20 to deionized water and gently stir or shake to prepare a 0.3% Tween-20 solution. Place the strung waxy tobacco leaves into the Tween-20 solution, soak for 4 minutes, then take them out and gently rinse 3 - 5 times with deionized water, and air dry naturally.

[0040] Step 3: Load the treated waxy tobacco leaves into a bulk curing barn and bake them according to the above control (conventional baking process).

[0041] 3. Treatment 2 (Treat the tobacco leaves with Tween-20, do not wash them, and bake them according to the conventional baking process as Treatment 2)

[0042] Step 1: Classify and string the waxy tobacco leaves on poles.

[0043] Step 2: Add Tween-20 to deionized water and gently stir or shake to prepare a 0.3% Tween-20 solution. Place the strung waxy tobacco leaves into the Tween-20 solution, soak for 4 minutes, then take them out and air dry naturally.

[0044] Step 3: Load the treated waxy tobacco leaves into a bulk curing barn and bake them according to the above control (conventional baking process).

[0045] 4. Treatment 3 (Treat the tobacco leaves with Tween-20, do not wash them, and bake them according to the optimized process)

[0046] Step 1: Classify and string the waxy tobacco leaves on poles.

[0047] Step 2: Add Tween-20 to deionized water and gently stir or shake to prepare a 0.3% Tween-20 solution. Place the strung waxy tobacco leaves into the Tween-20 solution, soak for 4 minutes, then take them out and air dry naturally.

[0048] Step 3: Load the treated waxy tobacco leaves into a bulk curing barn and bake them according to the following process:

[0049] Set the temperature and humidity target at 40°C / 40°C. After ignition, raise the temperature by 1°C every 3 hours until the dry-bulb target temperature reaches 40°C. When the wet-bulb temperature reaches 40°C, stop heating, turn off the circulation fan and the cold air inlet damper, and let the tobacco leaves in the loading chamber be in a state of high-temperature and high-humidity baking;

[0050] S2 After the dry-bulb temperature drops to 35°C, heat the curing barn again, turn on the circulation fan, and heat to the temperature and humidity target of 40°C / 40°C. When the wet-bulb temperature reaches 40°C, stop heating, turn off the circulation fan and the cold air inlet damper, and let the tobacco leaves in the loading chamber be in a state of high-temperature and high-humidity baking;

[0051] S3 Repeat steps S2 and S3 repeatedly until more than 80% of the tobacco leaves turn 30% yellow, the leaves sweat sufficiently, and the stomata of the tobacco leaves open fully;

[0052] S4 Adjust the dry-bulb and wet-bulb temperatures to 38°C / 37°C, keep the temperature stable for 12 hours, and bake with humidity control until the tobacco leaves turn 50%-60% yellow and the leaves dehydrate by 10%-15%;

[0053] S5 Raise the dry-bulb and wet-bulb temperatures to 40°C / 37°C at a rate of 1°C every 2 hours, keep the temperature stable for 20 hours. After the tobacco leaves turn 80%-90% yellow, adjust the wet-bulb temperature to 36°C, keep the temperature stable for 8 hours, and bake until the tobacco leaves become soft;

[0054] S6 Raise the temperature to 42°C / 36°C at a rate of 1°C every 2 hours, keep the temperature stable for 18 hours until the tobacco leaves are fully yellow, 1 / 2 - 2 / 3 of the lateral veins turn white, and the main vein becomes sufficiently soft;

[0055] S7 Raise the temperature to 44°C / 36°C at a rate of 1°C every 3 hours, keep the temperature stable for 8 hours until the tobacco leaves in the high-temperature layer reach the small scroll state and the lateral veins are all white;

[0056] S8 Raise the temperature to 48°C / 37°C at a rate of 1°C every 3 hours, keep the temperature stable for 8 hours until the tobacco leaves in the low-temperature layer reach the small scroll state and the lateral veins are all white;

[0057] S9 Raise the temperature to 54°C / 39°C at a rate of 1°C every 2 hours, keep the temperature stable for 16 hours until the whole batch of tobacco leaves reaches the large scroll state and the leaves are completely dry;

[0058] S10 Raise the temperature to 60°C / 39°C at a rate of 1°C per hour, keep the temperature stable for 6 hours until the main vein of the tobacco leaves turns purple;

[0059] S11 Raise the temperature to 68°C / 40°C at a rate of 1°C per hour, keep the temperature stable for more than 20 hours until the main vein of the tobacco leaves is completely dry;

[0060] S12 Stop heating. Keep the circulation fan running until the dry-bulb temperature of the curing barn drops below 40°C, then turn off the fan, and the tobacco leaves start to enter the natural rewetting state.

[0061] The following describes the effects of different treatments on the classification and evaluation of flue-cured tobacco leaves after baking, the appearance quality of tobacco leaves, the content of main aroma components, and the sensory evaluation quality, etc.

[0062] 1.1 Classification and evaluation results of flue-cured tobacco leaves after baking

[0063] Take 10 poles of tobacco leaves at the same position in the loading chambers of 4 curing barns respectively, and classify and statistically analyze the weight of the initially cured tobacco leaves according to ash-hung tobacco leaves (including mild ash-hung and severe ash-hung), normal tobacco leaves, and green-cured tobacco leaves (including green veins, green slices, and mechanical damage). The results show that the occurrence ratio of ash-hung tobacco leaves in the initially cured tobacco leaves under the control baking process is as high as 22.91%, while in Comparative Treatments 1, 2, and 3, the ash-hung ratio of tobacco leaves can be effectively reduced. At the same time, all three treatment methods can significantly reduce the ratio of green-cured tobacco leaves, indicating that the yellowing of tobacco leaves can be effectively promoted after treatment with tween-20. The control effects on the ash-hung and yellowing of tobacco leaves are very obvious.

[0064] Table 1 Comparative analysis of the baking effects of different baking processes

[0065]

[0066] 1.2 Comparative analysis of the appearance quality of flue-cured tobacco leaves after baking

[0067] For the above comparative verification test, take the normal tobacco leaves among them, and conduct an appearance quality identification of the flue-cured tobacco leaves B2F after baking according to the national standard GB2635-1992. The results are shown in Table 2.

[0068] Table 2 Effects of baking processes on the appearance quality of the upper tobacco leaves

[0069]

[0070]

[0071] As can be seen from the above table, even for the same normal flue-cured tobacco leaves after baking, there are differences in the appearance quality of the flue-cured tobacco leaves under the two baking processes. The structure and identity of the flue-cured tobacco leaves under the comparative treatment process are slightly better than those of the control process. Therefore, it can be said that the appearance quality of the flue-cured tobacco leaves under the comparative process is better than that of the control process.

[0072] 1.3 Content of main aroma components of flue-cured tobacco leaves after baking

[0073] Table 3 Content of main aroma components of flue-cured tobacco leaves after baking in the baking process verification in 2024 (ng / g)

[0074]

[0075]

[0076] The aroma components of tobacco leaves are important quality substances of tobacco leaves and play a key role in the aroma of tobacco leaves. The above table shows the contents of the main aroma-forming substances in tobacco leaves treated by different processes. It can be seen that the total amount of aroma-forming substances in the control tobacco leaves is 9325.69 ng / g, while the contents of aroma-forming substances in Treatment 1 and Treatment 2 are slightly higher than that of the control. The content of aroma-forming substances in the tobacco leaves treated by the solution of the present invention (Treatment 3) is the highest, reaching 11459.05 ng / g, which is significantly higher than that of the control, as well as Treatment 1 and Treatment 2.

[0077] 1.4 Sensory evaluation quality

[0078] Table 4. Sensory evaluation quality of flue-cured tobacco leaves after baking process verification in 2024

[0079]

[0080]

[0081] The above table shows the comparative analysis of the sensory evaluation quality of 4 different flue-curing processes. It can be seen that the total score of the sensory evaluation quality of the flue-cured tobacco leaves after Treatment 3 baking treatment reaches 73.04 points, which is significantly higher than that of the control, Treatment 1 and Treatment 2, especially in terms of the aroma quality, aroma quantity and aftertaste of the flue-cured tobacco leaves.

[0082] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A waxy tobacco leaf baking method, characterized in that: include: Step 1: Classify the waxy tobacco leaves and weave them into poles; Step 2: Place the braided waxy tobacco leaves into a Tween-20 solution with a concentration of 0.1% to 1%, soak for 3-5 minutes, then take them out and air dry them naturally; Step 3: Load the processed waxy tobacco leaves into a dense curing room for baking.

2. The waxy tobacco leaf baking method according to claim 1, characterized in that: The baking of the waxy tobacco leaves comprises the following steps: S1 sets the temperature and humidity target at 40℃ / 40℃. After ignition, the temperature is raised to the dry-bulb target temperature of 40℃ at 1℃ / 2-3 hours. When the wet-bulb temperature rises to 40℃, the heating is stopped, and the circulating fan and cold air inlet door are closed to keep the tobacco leaves in the smoke chamber in a high-temperature and high-humidity roasting state. S2 After the dry-bulb temperature drops to 35°C, heat the curing room again, turn on the circulating fan, and heat to the temperature and humidity target of 40°C / 40°C. When the wet-bulb temperature rises to 40°C, stop heating, close the circulating fan and the cold air inlet door, and keep the tobacco leaves in the loading room in a high-temperature and high-humidity state; S3 repeatedly repeats steps S2 and S3 until more than 80% of the tobacco leaves are 30% yellow, the leaves are fully sweating, and the stomata of the tobacco leaves are fully opened; S4 adjusts the dry-bulb and wet-bulb temperatures to 38°C / 37-38°C, keeps the temperature constant for 10-15 hours, and bakes the tobacco leaves until they are 50% to 60% yellow, and the leaves are dehydrated by 10-15%; S5 raises the dry-bulb and wet-bulb temperatures to 40℃ / 37-38℃ at a rate of 1℃ / 2-3 hours, and keeps the temperature steady for 15-20 hours. When the tobacco leaves are 80%-90% yellow, the wet-bulb temperature is adjusted to 36-37℃, and kept steady for 6-8 hours, until the tobacco leaves become soft. S6: Raise the temperature to 42℃ / 36-37℃ at a rate of 1℃ / 2-3 hours and keep it at a constant temperature for 16-20 hours until the tobacco leaves turn completely yellow, 1 / 2-2 / 3 of the side veins turn white, and the main veins become fully soft; S7 is heated to 44℃ / 36-37℃ at a rate of 1℃ / 3-4 hours, and kept at a constant temperature for 6-8 hours until the high-temperature layer tobacco leaves reach a small roll state and the side veins are completely white; S8 is heated to 48℃ / 37-38℃ at a rate of 1℃ / 3-4 hours, and kept at a constant temperature for 6-8 hours until the tobacco leaves in the low temperature layer reach a small roll state and the side veins are completely white; S9: Raise the temperature to 54℃ / 38-39℃ at a rate of 1℃ / 2-3 hours, and keep the temperature steady for 14-18 hours until the tobacco leaves on the kang reach a large roll and are completely dry; S10 was heated to 60℃ / 39-40℃ at a rate of 1℃ / 1-2 hours and kept at a constant temperature for 6 hours, and the main veins of the tobacco leaves turned purple; S11: Raise the temperature to 62-65℃ / 40-41℃ at a rate of 1℃ / 1-2 hours and keep the temperature constant for more than 20 hours until the main veins of the tobacco leaves are completely dry; S12 stops heating, and the circulating fan continues to be turned on until the dry bulb temperature in the drying room drops below 40°C, then the fan is turned off and the tobacco leaves begin to enter a natural rehumidification state.

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