Baking method for improving sweetness of tobacco leaves

Abstract

The invention discloses a tobacco leaf baking method for improving sweetness, which comprises the following steps: S1, spraying: spraying a sodium citrate solution to harvested tobacco leaves, and standing for a preset time; s2, baking: prolonging enzyme activity in a yellowing period, protecting sugar in a color fixing period, and directionally regulating and controlling Maillard reaction in a stem drying period; and S3, improving sweetness: when the temperature in the curing barn is reduced to 50 DEG C, injecting aerial fog containing alanine or proline into the curing barn to promote generation of sweet and fragrant substances. The tobacco leaf reducing sugar retention rate and the sweet and fragrant substance content are remarkably improved, and the method is suitable for high-quality cigarette production.

Description

Technical Field

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

[0002] Tobacco leaf baking refers to a drying process in which, by controlling the temperature and humidity conditions in the tobacco loading room, the freshly harvested tobacco leaves are induced to undergo physiological and biochemical transformations, ultimately forming a dried product with specific colors, aromas, and physical properties such as "yellow, bright, soft, and fragrant". The sweet taste of tobacco leaves is an important quality factor of tobacco leaves, referring to the comprehensive sensory experience of sweetness or sweet aroma produced by its chemical components (mainly carbohydrate substances) on the taste and smell during the combustion or smoking process of tobacco leaves, which directly affects the taste of cigarettes and the acceptance of consumers.

[0003] Existing literature (CN104489914B) discloses an additive and method for improving the quality of upper tobacco leaves in the tobacco leaf production process. The additive is an acidic aqueous solution containing monosaccharides. During the growth stage of flue-cured tobacco, after harvesting the middle tobacco leaves and before harvesting the upper tobacco leaves, the additive is added to the surface of the upper tobacco leaves, and then picked and baked according to the normal method. After baking, the appearance quality of the upper tobacco leaves of flue-cured tobacco treated by this method has no obvious change compared with that of the untreated upper tobacco leaves of flue-cured tobacco, but the internal sensory quality has been significantly improved, mainly manifested in the appearance of a caramel-like sweet aroma, the improvement of the rough aroma, the reduction of withered and charred miscellaneous odors, the smoother and more delicate smoke, the reduction of the impact of alkaloids on the throat, and the more comfortable and clean aftertaste, thus significantly improving the usability. This literature mainly improves the sweet taste by spraying an acidic aqueous solution containing monosaccharides on the tobacco leaves before harvesting, and does not make corresponding improvements to the baking process.

[0004] Currently, the intensive baking process of tobacco leaves in China still mainly uses the three-stage baking process. Through the regulation of three stages: the yellowing stage, the color-fixing stage, and the stem-drying stage, the color, aroma, and physical properties of tobacco leaves are optimized. However, if the temperature and humidity are not properly controlled during the yellowing stage (such as too low humidity) in the three-stage baking process, it is easy to cause insufficient activities of amylase and invertase, and low conversion efficiency of starch into reducing sugars; during the high-temperature color-fixing stage (>50 °C), it is easy to cause the decomposition of reducing sugars, and the content of sweet substances (such as fructose and glucose) decreases by 10%-30%. It is necessary to conduct research and improvement on this. Summary of the Invention

[0005] Based on the above, the present invention provides a baking method for improving the sweet taste of tobacco leaves, which significantly improves the sweet taste and sensory comfort of tobacco leaves by controlling the enzyme activity during the yellowing stage, protecting sugars during the color-fixing stage, and regulating the Maillard reaction during the stem-drying stage.

[0006] The technical solution of the present invention is: a baking method for improving the sweet taste of tobacco leaves, comprising:

[0007] S1 Spraying: Spraying a sodium citrate solution on the harvested tobacco leaves and standing for a predetermined time;

[0008] S2 Baking: Curing the tobacco leaves in the baking room according to the following baking process;

[0009] Yellowing period: after loading tobacco and closing the door, close the air inlet, start the circulating fan to run idle for 1-2 hours, then slowly raise the temperature of the curing room to 32-33℃ with a small fire, maintain the wet bulb temperature at 32-33℃, and keep it stable for 6-8 hours until the tobacco leaves are fully sweating and the leaf tips are soft; raise the dry bulb temperature to 38℃ at a rate of 1℃ per hour, control the wet bulb temperature at 36-37℃, and keep it stable for 15-20 hours, so that the high-temperature layer of tobacco leaves can reach 70% to 80% yellow; raise the dry bulb temperature to 40℃ at 1℃ / 2h, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 6-10 hours to remove moisture and control water in advance, strengthen the yellowing of tobacco leaves, and the high-temperature layer of tobacco leaves can reach 80% to 90% yellow; raise the dry bulb temperature to 42℃, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 10-16 hours, so that the entire layer of tobacco leaves can complete the yellowing, reaching the yellow leaves and blue veins, the leaves are fully yellowed, withered and collapsed, and the main veins become soft;

[0010] Color fixing period: the dry bulb temperature is raised to 45℃ at 1℃ / 3h, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 6-10h, the ear turns yellow, the branch veins turn white, the leaf tip is dry, and the leaves are fully soft and withered; the dry bulb temperature is raised to 48℃ at 1℃ / 2h, the wet bulb temperature is 37-38℃, and the temperature is kept stable for 6-12h, the yellow leaves with white veins are half dry and small curls are achieved; the temperature is raised to 50℃ at 0.5℃ / h, the wet bulb temperature is controlled at 39℃, and the temperature is kept stable for 6-8 hours, and then the dry bulb is raised to 54℃ at 1℃ / 2h, the wet bulb temperature is 39-40℃, and the temperature is kept stable for 14-16h, until the leaves are dry and large curls;

[0011] Drying period: Raise the temperature to 60℃ at 1℃ / 1h, wet bulb temperature 40℃, keep the temperature steady for 6-8h, balance the front and back sides of the tobacco leaves; Raise the temperature to 62-65℃ at 1℃ / 1h, wet bulb temperature 41℃, keep the temperature steady for 25-30h until the tobacco leaves are completely dry;

[0012] S3 Sweetening: When the temperature in the baking room drops to 50°C, inject aerosol containing alanine or proline into the baking room to promote the production of sweet and fragrant substances.

[0013] Preferably, in step S1, the concentration of the sodium citrate solution is 0.05%-0.1%, and the solution is allowed to stand for 2-4 hours after spraying.

[0014] Preferably, in step S3: the concentration of alanine or proline is 0.1-0.3 g / m 3 , the spraying time is 5-10 hours.

[0015] Preferably, during the yellowing stage at 32 - 38°C, control the dry - wet bulb temperature difference within the range of 0 - 2.0°C. Before heating up to 38°C, adopt closed - humidity - maintaining, that is, shut down the circulating fan; during the 38 - 40°C stage, control the circulating fan through a timer. According to the dry - bulb temperature and the dry - wet difference in the curing barn, determine that the timer controls the circulating fan to run for 5 - 10 minutes per hour to control the humidity and ensure that the actual temperature and humidity match the target temperature and humidity.

[0016] Advantages of the present invention: Through the extension of enzyme activity during the yellowing stage, the protection of sugars during the color - fixing stage, and the directional regulation of the Maillard reaction during the stem - drying stage, the present invention significantly improves the retention rate of reducing sugar and the content of sweet - smelling substances in tobacco leaves, and is particularly suitable for the production of high - quality cigarettes. Specifically, spray sodium citrate on the surface of tobacco leaves before curing to enhance the cell membrane permeability; adopt low - temperature and high - humidity during the yellowing stage to extend the activity window period of amylase and invertase in tobacco leaves and provide sufficient precursors for the formation of sweet - tasting substances; adopt slow temperature increase with small gradients during the color - fixing stage to inhibit the activity of sugar - degrading enzymes and reduce the oxidative loss of sugars; during the stem - drying stage, promote the formation of sweet - smelling substances by adding exogenous amino acids and enhance the volatile components related to the sweet taste of tobacco leaves. Through experiments, compared with the conventional curing process, the present invention can reduce the proportion of green and stiff tobacco leaves after curing, increase the total sugar and reducing sugar content of tobacco leaves after curing, as well as the total sweet smell and sweetness of tobacco leaves, and also shows obvious advantages in terms of the quality, quantity, and concentration of the aroma. Specific embodiments

[0017] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below. Many specific details are set forth in the following description to fully understand 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 departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0018] Example 1

[0019] The verification test was carried out in Fuquan City, Guizhou Province in 2023. The tested flue - cured tobacco variety was Yunyan 87, and the tobacco leaves at the 12th - 13th leaf positions of the middle leaves were used as test materials. The tested tobacco leaves were cultivated and managed according to the local standardized cultivation management of high - quality tobacco leaves. The conventional curing process (Control 1), spraying sodium citrate, injecting proline but without adjusting the process (applying sodium citrate solution and proline solution, according to the conventional curing process) (Control 2) were used as control groups, and the present invention's scheme was used as the treatment group (Treatment 1). After curing, the content of carbohydrate substances in tobacco leaves of different treatments was statistically analyzed, and the sweet - taste score of tobacco leaves after curing was also statistically analyzed. The tested curing barn was a standard intensive large - scale curing barn.

[0020] 1.1 Experimental design

[0021] The local main baking process and the process of spraying sodium citrate without adjustment were used as controls, and the "baking method for improving the sweetness of tobacco leaves" was used as the treatment. A comparative experiment was carried out (wherein: the baking method for improving the sweetness of tobacco leaves was used for treatment 1. Before ignition, the harvested tobacco leaves were sprayed with sodium citrate solution (the concentration was 0.06%, and it was evenly sprayed on the surface of the tobacco leaves) and left to stand for 4 hours; after the tobacco leaves were dried and the fire was stopped, when the dry bulb temperature in the baking room dropped to 50°C, a solution containing proline (concentration of 0.2g / m 3 ) of aerosol, the injection time is 8.5 hours); the temperature and humidity parameters are implemented according to Table 1.

[0022] Table 1 Experimental design Unit: °C, h

[0023]

[0024]

[0025] The tobacco leaf baking method for improving sweetness of the present invention comprises the following steps:

[0026] S1 spraying: spray 0.1% sodium citrate solution on the harvested tobacco leaves and let it stand for 4 hours;

[0027] S2 Baking: Curing the tobacco leaves in the baking room according to the following baking process;

[0028] Yellowing period: After loading tobacco and closing the door, close the air inlet, start the circulating fan and run it idle for 2 hours, then slowly raise the temperature of the curing room to 33℃ with a small fire, maintain the wet bulb temperature at 33℃, and keep it stable for 6 hours. At this time, the tobacco leaves are fully sweating and the leaf tips are soft; raise the dry bulb temperature to 38℃ at a rate of 1℃ per hour, control the wet bulb temperature at 37℃, and keep it stable for 18 hours. At this time, the high-temperature layer of tobacco leaves are 70% yellow; raise the dry bulb temperature to 40℃ at a rate of 1℃ / 2h, the wet bulb temperature is 36℃, and the temperature is maintained for 16 hours to drain moisture, drain moisture and control water in advance, strengthen the yellowing of tobacco leaves, and the high-temperature layer of tobacco leaves is 90% yellow; raise the dry bulb to 42℃, the wet bulb is 36℃, and the temperature is maintained for 16 hours. The whole layer of tobacco leaves has completed yellowing, reaching yellow leaves and blue veins, the leaves are fully yellowed, withered and collapsed, and the main veins become soft;

[0029] During the yellowing period, at the 32-38℃ stage, the dry-bulb temperature difference is controlled within the range of 0-2.0℃. Before the temperature rises to 38℃, closed moisturizing is adopted, that is, the circulating fan is shut down; at the 38-40℃ stage, the circulating fan is controlled by a timer. According to the dry-bulb temperature and the dry-wet difference in the baking room, the timer is used to control the circulating fan for 5-10 minutes per hour to control the humidity and ensure that the actual temperature and humidity are consistent with the target temperature and humidity.

[0030] Color fixing period: the dry bulb temperature is raised to 45℃ at 1℃ / 3h, the wet bulb temperature is 37℃, and the temperature is kept stable for 10h, the ear turns yellow, the branch veins turn white, the leaf tip is dry, and the leaves are fully soft and withered; the dry bulb temperature is raised to 48℃ at 1℃ / 2h, the wet bulb temperature is 38℃, and the temperature is kept stable for 6h, until the yellow leaves with white veins are half dry and small curls are achieved; the temperature is raised to 50℃ at 0.5℃ / h, the wet bulb temperature is controlled at 39℃, and the temperature is kept stable for 6 hours, and then the dry bulb is raised to 54℃ at 1℃ / 2h, the wet bulb is 40℃, and the temperature is kept stable for 16h, until the leaves are dry and large curls are achieved;

[0031] Drying period: Raise the temperature to 60℃ at 1℃ / 1h, wet bulb temperature 40℃, keep the temperature steady for 6h, balance the front and back sides of the tobacco leaves; Raise the temperature to 65℃ at 1℃ / 1h, wet bulb temperature 41℃, keep the temperature steady for 25h until the tobacco leaves are completely dry;

[0032] S3 sweetening: When the temperature in the baking room drops to 50°C, inject proline-containing mist into the baking room for 8.5 hours. The concentration of proline is 0.2g / m 3 .

[0033] Fuquan conventional baking process includes the following steps:

[0034] Yellowing stage: After loading tobacco, burn a small fire to raise the temperature of the curing room to 34℃, maintain the wet bulb temperature at 34℃, and keep the temperature steady for 8 hours until the tobacco leaves become hot and sweaty; then, raise the dry bulb temperature to 38℃ at 1℃ / h, control the wet bulb temperature at 37℃, keep the temperature steady and keep the moisture for 25 hours, and the tobacco leaves will reach 70% yellow; then, raise the dry bulb temperature to 40℃ at 1℃ / 2h, and the wet bulb temperature at 37℃, keep the temperature steady and drain moisture for 12 hours, and the tobacco leaves will become soft; then, raise the dry bulb temperature to 42℃, and the wet bulb temperature at 36℃, keep the temperature steady for 13 hours, and the tobacco leaves will reach yellow leaves and blue veins (90% yellow), and the main veins will become soft;

[0035] Color fixing period: the dry bulb temperature is raised to 45℃ at a rate of 1℃ / 2h, the wet bulb temperature is 36℃, and the temperature is kept stable for 10h. The ear turns yellow, the branch veins turn white, the leaf tips and edges are dry, the leaves wither, and the main veins are fully softened; then, the dry bulb temperature is raised to 48℃ at a rate of 1℃ / 2h, the wet bulb temperature is 37℃, and the temperature is kept stable for 12h. The main veins turn green and reach the small roll; then, the dry bulb temperature is raised to 51℃ at a rate of 1℃ / 2h, the wet bulb temperature is 38℃, and the temperature is kept stable for 14h. The main veins turn yellow and the leaves are half dry; then, the dry bulb temperature is raised to 54℃ at a rate of 1℃ / 2h, the wet bulb temperature is 38℃, and the temperature is kept stable for 18h. The main veins turn completely yellow, the color difference between the front and back of the tobacco leaves is reduced, the leaves are dry, and the large roll is reached;

[0036] Drying period: Raise the dry-bulb temperature to 60℃ and the wet-bulb temperature to 39℃ at a heating rate of 1℃ / h, keep the temperature steady for 13 hours, and the main veins will turn purple and shrink. Afterwards, raise the dry-bulb temperature to 68℃ and the wet-bulb temperature to 41℃ at a heating rate of 1℃ / h, keep the temperature steady for 27 hours, and the tobacco veins will be completely dry.

[0037] 1.2 Evaluation Method for Flue-cured Tobacco Leaves after Baking

[0038] Randomly select the flue-cured tobacco leaves that have been removed from the curing barn and have been re-moisturized, untie the sticks, mix them evenly, classify them according to the evaluation criteria, calculate the proportion of each type of tobacco leaf based on the weight of each type of leaf after classification, score according to the scoring rules, and summarize the scores of each item to obtain the total score of the appearance quality of the flue-cured tobacco leaves in this curing barn.

[0039] Greenish-yellow Flue-cured Tobacco Leaves (GY): Those with a greenish degree reaching the standard of greenish-yellow tobacco are regarded as greenish-yellow flue-cured, and this item gets 0 points for greenish-yellow flue-cured;

[0040] Mottled Flue-cured Tobacco Leaves (K): Those with a mottled area exceeding 20% are regarded as mottled, and this item gets 0 points for mottled;

[0041] Stiff Structure (S): Leaves with a smooth and stiff area of more than 50% are regarded as having a stiff structure, and those below 50% are regarded as having a loose structure. The score for this item is the proportion of the stiff structure × 0.5;

[0042] Loose Structure: Includes the upper part being moderately loose and slightly dense;

[0043] Good Oiliness of Orange-yellow (F): The color of the freshly flue-cured tobacco is "bright yellow" or above, and the oiliness is "abundant" or above, which is classified into this item, and the score for this item is the proportion;

[0044] Poor Oiliness of Orange-yellow (F): The color of the freshly flue-cured tobacco is "bright yellow" or above, and the oiliness is "slightly" or below, which is classified into this item, and the score for this item is the proportion × 0.8;

[0045] Good Oiliness of Lemon-yellow (L): The color of the freshly flue-cured tobacco is "light yellow" or below, and the oiliness is "abundant" or above, which is classified into this item, and the score for this item is the proportion × 0.8;

[0046] Poor Oiliness of Lemon-yellow (L): The color of the freshly flue-cured tobacco is "light yellow" or below, and the oiliness is "slightly" or below, which is classified into this item, and the score for this item is the proportion × 0.6;

[0047] 1.3 Evaluation Results of Flue-cured Tobacco Leaves after Baking

[0048] From Table 2, when comparing the baking method for improving the sweet taste of tobacco leaves (Treatment 1) with the local conventional baking process (Control 1), the proportion of greenish-yellow leaves in the flue-cured tobacco after baking decreased by 2.63 percentage points, the proportion of mottled leaves was comparable, the proportion of stiff leaves decreased by 3.65 percentage points, and the proportion of orange-yellow leaves with good oiliness increased by 13.40 percentage points; although Control 2 increased steps S1 and S3, due to the lack of corresponding adjustment of the baking process, its overall effect was not obvious. Therefore, the overall score of Treatment 1 is higher than that of Control 1 and Control 2.

[0049] Table 2 Evaluation of Flue-cured Tobacco Leaves after Baking in the Baking Process Verification in Fuquan City in 2023

[0050]

[0051] 1.4 Total sugar and reducing sugar contents of flue-cured tobacco leaves after baking

[0052] Table 3 Analysis of conventional chemical component contents of tobacco leaves under different treatments

[0053] Treatment Starch (%) Total sugar (%) Reducing sugar (%) Treatment 1 3.66±0.64 28.15±5.12 24.27±2.14 Control 1 6.34±0.81 24.88±3.15 20.45±1.77 Control 2 4.87±0.65 25.86±2.32 21.31±1.41

[0054] Table 7 shows the starch and disaccharide component contents of tobacco leaves under different processes. It is not difficult to see that the starch content of the baking method for enhancing the sweet taste of tobacco leaves is 3.66%, lower than that of the control process; correspondingly, the total sugar and reducing sugar of the flue-cured tobacco leaves after the baking process for enhancing the sweet taste of tobacco leaves are 28.15% and 24.27% respectively, significantly higher than those of the control baking process, indicating that this method is beneficial to increasing the total sugar and reducing sugar contents of tobacco leaves.

[0055] 1.5 Sensory evaluation quality

[0056] Table 4 Sensory evaluation quality of flue-cured tobacco leaves after baking in the baking process verification in Fuquan City in 2023

[0057]

[0058] Table 8 shows the comparative analysis of the sensory evaluation quality of two different baking processes. It can be seen that the total sweet aroma and sweetness of the flue-cured tobacco leaves after the baking method for enhancing the sweet taste of tobacco leaves reach 3.56 and 6.54 respectively, both significantly higher than those of the control baking process; at the same time, obvious advantages are also shown in terms of the quality of aroma, aroma quantity and concentration.

[0059] Example 2

[0060] The verification test was carried out in Xingyi City, Guizhou Province in 2023. The flue-cured tobacco variety for the test was Yunyan 87, and the tobacco leaves at the 12th - 13th leaf positions of the middle leaves were used as the test materials. The test tobacco leaves were cultivated and managed according to the local standardized cultivation management of high-quality tobacco leaves. The conventional baking process (Control 1), spraying sodium citrate, injecting alanine but without adjusting the process (applying sodium citrate solution and alanine, according to the conventional baking process) (Control 2) were used as the control groups, and the scheme of the present invention was used as the treatment group (Treatment 1). After baking, the sugar substance contents of the tobacco leaves under different treatments were statistically analyzed, and the sweet taste scores of the flue-cured tobacco leaves were also counted. The test curing barn was a standard intensive large curing barn.

[0061] 2.1 Experimental design

[0062] The local main baking process and the process of spraying sodium citrate without adjustment were used as controls, and the "baking method for improving the sweetness of tobacco leaves" was used as the treatment. A comparative test was carried out (wherein: the baking method for improving the sweetness of tobacco leaves, before ignition, spray sodium citrate solution (concentration of 0.07%, spray evenly on the surface of tobacco leaves) on the harvested tobacco leaves and let it stand for 4 hours; after the tobacco leaves were dried and the fire was stopped, when the dry bulb temperature in the baking room dropped to 50℃, inject alanine (concentration of 0.2g / m 3 ) of the aerosol, the injection time is 7.5 hours), the temperature and humidity parameters are implemented according to Table 5, and the rest refer to Example 1. For the Xingyi conventional baking process, except for the parameters in the table, the rest refer to the Fuquan conventional baking process in Example 1.

[0063] Table 5 Experimental design Unit: °C, h

[0064]

[0065]

[0066] 2.2 Evaluation method of flue-cured tobacco leaves

[0067] Randomly select the moistened tobacco leaves from the hot spring, unstem them, mix them evenly, and then classify them according to the evaluation criteria. After classification, calculate the proportion of each type of tobacco leaf according to the weight of each type of leaf, and give scores according to the scoring rules. The summary of each score is the total score of the appearance quality of the tobacco leaves after curing.

[0068] Flue-cured green tobacco leaves (GY): Green tobacco leaves that have reached the green-yellow tobacco standard are considered flue-cured green, and 0 points are awarded for this item;

[0069] Flue-cured mixed tobacco leaves (K): leaves with mixed areas exceeding 20% ​​are considered flue-cured mixed tobacco leaves, and will receive 0 points for this item;

[0070] Structural stiffness (S): Leaves with smooth and stiff area of ​​more than 50% are considered to have structural stiffness, and leaves with smooth and stiff area of ​​less than 50% are considered to have loose structure. The score for this item is calculated by the percentage of structural stiffness × 0.5;

[0071] Loose structure: including the upper part which is still loose and the upper part which is slightly dense;

[0072] Orange (F) Good oil content: The color of the first-cured tobacco is "pure yellow" or above, and the oil content is "some" or above, which is classified into this item, and the percentage is the score of this item;

[0073] Orange (F) Oil content difference: the color of the first-cured tobacco is "pure yellow" or above, and the oil content is "slightly" or below, which is classified into this item and the score of this item is calculated by multiplying the proportion by 0.8.

[0074] Lemon color (L) good oil content: the color of the first-cured tobacco is "light yellow" or below, and the oil content is "yes" or above, which is classified into this item, and the score of this item is calculated by the percentage × 0.8;

[0075] Lemon color (L) oil difference: For the initial flue-cured tobacco with a color of "light yellow" or below and an oil content of "slightly" or below, it is classified into this item, and the score for this item is the percentage × 0.6.

[0076] 2.3 Evaluation results of flue-cured tobacco leaves after baking

[0077] As can be seen from Table 6, when comparing the baking method for enhancing the sweet taste of tobacco leaves (Treatment 1) with the local conventional baking process (Control 1), the proportion of green tobacco leaves after baking decreased by 3.17 percentage points, the proportion of mottled tobacco leaves decreased by 0.64 percentage points, the proportion of rigid tobacco leaves decreased by 5.4 percentage points, and the proportion of orange-yellow tobacco leaves with good oil content increased by 12.46 percentage points. Although Control 2 added steps S1 and S3, due to the lack of corresponding adjustment of the baking process, its overall effect was not obvious. Therefore, the overall score of Treatment 1 is higher than that of Control 1 and Control 2.

[0078] Table 6 Evaluation of flue-cured tobacco leaves after baking in the baking process verification in Xingyi City in 2023

[0079]

[0080]

[0081] 2.4 Total sugar and reducing sugar content of flue-cured tobacco leaves after baking

[0082] Table 7 Analysis of the content of conventional chemical components in tobacco leaves under different treatments

[0083] Treatment Starch (%) Total sugar (%) Reducing sugar (%) Treatment 1 3.96±0.62 32.46±3.21 27.73±2.34 Control 1 6.84±0.74 28.96±2.32 24.48±2.21 Control 2 5.53±0.58 29.38±2.74 25.65±2.74

[0084] Table 3 shows the starch and disaccharide component contents of tobacco leaves under different processes. It is not difficult to see that the starch content of the baking process for enhancing the sweet taste of tobacco leaves is 3.96%, which is lower than that of the control process; correspondingly, the total sugar and reducing sugar of the flue-cured tobacco leaves after the baking process for enhancing the sweet taste of tobacco leaves are 32.46% and 27.73% respectively, which are significantly higher than those of the control baking process, indicating that this process is beneficial to increasing the total sugar and reducing sugar content of tobacco leaves.

[0085] 2.5 Sensory evaluation quality

[0086] Table 8 Sensory evaluation quality of flue-cured tobacco leaves after baking in the baking process verification in Fuquan County in 2023

[0087]

[0088] Table 4 is a comparative analysis of the sensory evaluation quality of two different baking processes. It can be seen that the total sweet aroma and sweetness of the flue-cured tobacco leaves after the baking method for enhancing the sweet taste of tobacco leaves reach 3.62 and 6.64 respectively, which are significantly higher than those of the control baking process; at the same time, obvious advantages are also shown in terms of the quality and quantity of aroma.

[0089] The above-described embodiments merely represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent for 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 fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. A baking method for improving the sweet taste of tobacco leaves, characterized in that, include: S1 spraying: spraying sodium citrate solution on the harvested tobacco leaves and leaving them for a predetermined time; S2 Baking: Curing the tobacco leaves in the baking room according to the following baking process; Yellowing period: after loading tobacco and closing the door, close the air inlet, start the circulating fan to run idle for 1-2 hours, then slowly raise the temperature of the curing room to 32-33℃ with a small fire, maintain the wet bulb temperature at 32-33℃, and keep it stable for 6-8 hours until the tobacco leaves are fully sweating and the leaf tips are soft; raise the dry bulb temperature to 38℃ at a rate of 1℃ every 2 hours, control the wet bulb temperature at 36-37℃, and keep it stable for 15-20 hours, so that the high-temperature layer of tobacco leaves can reach 70% to 80% yellow; raise the dry bulb temperature to 40℃ at 1℃ / 2h, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 6-10 hours to remove moisture and control water in advance, strengthen the yellowing of tobacco leaves, and the high-temperature layer of tobacco leaves can reach 80% to 90% yellow; raise the dry bulb temperature to 42℃, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 10-16 hours, so that the entire layer of tobacco leaves can complete the yellowing, reaching the yellow leaves and blue veins, the leaves are fully yellowed, withered and collapsed, and the main veins become soft; Color fixing period: the dry bulb temperature is raised to 45℃ at 1℃ / 3h, the wet bulb temperature is 36-37℃, and the temperature is kept stable for 6-10h, the ear turns yellow, the branch veins turn white, the leaf tip is dry, and the leaves are fully soft and withered; the dry bulb temperature is raised to 48℃ at 1℃ / 2h, the wet bulb temperature is 37-38℃, and the temperature is kept stable for 6-12h, the yellow leaves with white veins are half dry and small curls are achieved; the temperature is raised to 50℃ at 0.5℃ / h, the wet bulb temperature is controlled at 39℃, and the temperature is kept stable for 6-8 hours, and then the dry bulb is raised to 54℃ at 1℃ / 2h, the wet bulb temperature is 39-40℃, and the temperature is kept stable for 14-16h, until the leaves are dry and large curls; Drying period: Raise the temperature to 60℃ at 1℃ / 1h, wet bulb temperature 40℃, keep the temperature steady for 6-8h, balance the front and back sides of the tobacco leaves; Raise the temperature to 62-65℃ at 1℃ / 1h, wet bulb temperature 41℃, keep the temperature steady for 25-30h until the tobacco leaves are completely dry; S3 Sweetening: When the temperature in the baking room drops to 50°C, inject aerosol containing alanine or proline into the baking room to promote the production of sweet and fragrant substances.

2. The baking method for improving the sweet taste of tobacco leaves according to claim 1, wherein In step S1, the concentration of the sodium citrate solution is 0.05%-0.1%, and the solution is left to stand for 2-4 hours after spraying.

3. The baking method for improving the sweet taste of tobacco leaves according to claim 1, wherein The concentration of alanine or proline is 0.1 - 0.3 g / m 3 , and the spraying time is 3 - 5 hours.

4. The baking method for improving the sweet taste of tobacco leaves according to claim 1, characterized in that, During the yellowing period at 36-38℃, the dry-bulb temperature difference is controlled within the range of 0-2.0℃. Before the temperature rises to 38℃, closed moisturizing is adopted, that is, the circulating fan is turned off. In the 38-40℃ stage, the circulating fan is controlled by a timer. According to the dry-bulb temperature and the dry-wet difference in the baking room, the timer is used to control the circulating fan for 5-10 minutes per hour to control the humidity and ensure that the actual temperature and humidity are consistent with the target temperature and humidity.

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