METHOD AND APPLICATION OF PREPARING SUN-CURED TOBACCO BY IRRADIATION

Abstract

A method for preparing sun-cured tobacco by irradiation, includes the following steps: (1) soaking dried fresh tobacco leaves in water for a period of time and then sun-drying the soaked tobacco leaves; (2) evenly spraying a pretreatment solution on surfaces of the soaked and dried tobacco leaves, sealing, and letting them ferment naturally for a period of time; (3) sun-drying the fermented tobacco leaves again; (4) irradiating the sun-dried tobacco leaves with a certain dose of gamma () rays; and (5) aging and maturing the irradiated tobacco leaves under certain conditions to obtain the sun-cured tobacco. The sun-cured tobacco obtained by the method can be used to improve the smoke quality of cigarettes.

Claims

1. A method for preparing sun-cured tobacco, comprising the following steps: (1) soaking dried fresh tobacco leaves in water for a period of time and then sun-drying the soaked tobacco leaves; (2) preparing a pretreatment solution by: (a) preparing an aqueous ethanol solution with an ethanol concentration of 0.5 to 5.0 wt %; and (b) adding a salt including one or more of sodium chloride, sodium carbonate, sodium lactate, sodium oxalate, sodium alginate, sodium benzoate, potassium citrate, potassium sorbate, methyl lactate, potassium carbonate and potassium phosphate to the ethanol solution at a mass ratio of 0.5 to 5.0 wt % and dissolving the salt in the ethanol solution to obtain the pretreatment solution; (3) spraying the pretreatment solution on surfaces of the soaked and dried tobacco leaves, sealing, and letting the sprayed tobacco leaves ferment naturally for a period of time; (4) sun-drying the fermented tobacco leaves again; (5) irradiating the sun-dried tobacco leaves with a dose of 1.0 to 30.0 kGy of gamma () rays from a .sup.60Co source for an irradiation time of 5 minutes to 120 minutes, wherein the fermented tobacco leaves during irradiation have a moisture content of not less than 12 wt %; and (6) aging and maturing the irradiated tobacco leaves under certain conditions to obtain the sun-cured tobacco.

2. The method according to claim 1, wherein, prior to soaking, the dried fresh tobacco leaves have a moisture content that does not exceed 12 wt %, and the dried fresh tobacco leaves are soaked for a time of 30 to 60 minutes.

3. The method according to claim 1, wherein the sprayed tobacco leaves are naturally fermentation in step (2) includes a temperature of 90 to 100 C., a fermentation time of 2 to 5 days, and a moisture content of the tobacco leaves of not less than 30 wt %.

4. The method according to claim 1, wherein a moisture content of the irradiated tobacco leaves in step (5) during the natural aging and maturation is maintained at 12 to 15 wt %.

5. The method according to claim 1, wherein the natural aging and maturation in step (5) happens in air having a relative humidity of 45% to 55%, at room temperature for a duration of no less than 30 days.

Description

EXAMPLES

[0030] The technical solution of the present invention will be further explained through specific implementation methods below. Those skilled in the art should be aware that the given embodiments are only intended to assist in understanding the present invention and should not be regarded as specific limitations of the present invention. The process, conditions, reagents, experimental methods, etc. of implementation, except for the contents specifically mentioned below, are all common knowledge and common sense in this field. There are no particularly restricted contents in the present invention. For the experimental methods in each embodiment where specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are usually followed. Unless otherwise stated, the meanings of all professional terms and scientific expressions used in this specification are the same as those generally understood by those skilled in the art to which the present invention belongs. However, in case of any conflict, this specification containing the definitions shall prevail.

Example 1

[0031] The steps for preparing the pretreatment solution are as follows: [0032] (A) Preparing an aqueous ethanol solution with an ethanol concentration of 0.5 to 5.0 wt % (specifically, in a ratio of 1 g of ethanol to 97.5 g of water); and [0033] (B) Adding a salt (specifically, sodium chloride) to the ethanol solution in step (A) at a mass ratio of 0.5 to 5.0 wt % (specifically, in a ratio of 1.5 g of sodium chloride to 98.5 g of the ethanol solution), and dissolving the salt in the ethanol solution to obtain the pretreatment solution.

[0034] The method and steps for preparing sun-cured tobacco by irradiation are as follows: [0035] (1) Soaking the sun-dried fresh tobacco leaves (the moisture content of which is reduced to 10 wt %) in water for 40 minutes; [0036] (2) Spraying evenly the tobacco leaves that have been dried and soaked in step (1) with a pretreatment solution and fermenting at 90 C. for 2 days, wherein the moisture content of the tobacco leaves during fermentation is 30 wt %; [0037] (3) Drying the fermented tobacco leaves in the sun for another 10 days, while maintaining the moisture content of the tobacco leaves at 15 wt %; [0038] (4) Irradiating the tobacco leaves after further drying were irradiated with 5 kGy of radiation from a .sup.60Co source for 15 minutes. [0039] (5) The tobacco leaves are sun-dried again, then naturally aged and matured for 30 days, in air at a relative humidity of 50% and a temperature of 30 C. to obtain the aforementioned sun-cured tobacco. [0040] Comparison Example 1: follow the same steps as in Example 1, and the difference is that there is no step (2): spraying the pretreatment solution and natural fermentation. [0041] Comparison Example 2: follow the same steps as in Example 1, but the difference is that there is no irradiation step (4). [0042] Comparison Example 3: follow the same steps as in Example 1, but no pretreatment solution is sprayed in step (2). [0043] Comparison Example 4: follow the same steps as in Example 1, but without the natural aging and maturation in step (5).

[0044] The sun-cured tobaccos obtained from Example 1 and the Comparison Examples 14 were made into cigarettes, and a 9-point evaluation method was used for evaluation of smoking sensation. The results of the smoking sensation evaluation are shown in Table 1.

TABLE-US-00001 TABLE 1 Smoking evaluation; Results of different sun-cured tobaccos Aroma Unpleasant Concentration Strength Pungent After- Examples content (9) taste (9) (9) (9) (9) taste (9) Total Example 1 8.5 8.0 8.0 7.5 8.5 8.5 49.0 Comparison 1 6.5 5.5 6.0 7.0 5.0 6.5 36.5 Comparison 2 6.9 5.0 6.5 7.0 7.0 5.0 38.5 Comparison 3 7.0 6.0 7.5 7.5 6.5 6.0 40.5 Comparison 4 7.5 7.0 7.5 7.5 7.0 7.0 43.5

[0045] From the evaluation results in Table 1, it can be seen that the sensory quality of the sun-cured tobacco obtained in Example 1 is the best, with a better aroma, especially featuring a sweet and mellow aroma and a roasting aroma, which is more intense. The sun-cured tobacco obtained in Example 1 has less impurities, rich aroma, good concentration, moderate intensity, a relatively pure and comfortable aftertaste, a purer smoke flavor, and a higher sense of satisfaction. The tobacco from Comparison Example 1 without spraying the pretreatment solution or the natural fermentation step has a relatively high impurity and irritation, and the concentration is insufficient. The tobacco from Comparison Example 2 without the irradiation step has very obvious impurities, a prominent pungent sensation, and the worst aftertaste. The tobacco from Comparison Example 3 without spraying the pretreatment solution has some unpleasant taste, pungent and relatively poor aftertaste. The tobacco from Comparison Example 4 without aging and maturation steps is also relatively good, but the mellow and sweet aroma of the tobacco is insufficient, and the unpleasant taste and aftertaste are not as good as those of the sun-cured tobacco obtained with the natural aging and maturation steps.

[0046] The water-soluble sugar, total nitrogen, total alkaloids, potassium, chloride, nitrate and other chemical component indicators of the tobacco leaves obtained in Example 1 and Comparison Examples 14 were determined. The testing methods and basis are shown in Table 2, and the test results are shown in Table 3.

TABLE-US-00002 TABLE 2 Testing Items and Basis for the Intrinsic Chemical Components of Tobacco Leaves Testing Items Standard (Method) Name and Code followed by the tests Water- Tobacco and tobacco products - Determination of water- soluble soluble sugars - Continuous flow method (YC/T159-2002) sugar Total Tobacco and tobacco products - Determination of total Nitrogen Nitrogen-Continuous flow method (YC/T16l-2002) Total Tobacco and tobacco products-Determination of total alkaloids alkaloids-Continuous flow (potassium thiocyanate) method (YC/T468-2013) Chloride Tobacco and tobacco products - Determination of Chloride- Continuous flow method (YC/FFl62-2011) Potassium Determination of potassium in tobacco and tobacco products - Flame photometry (YC/T173-2003) Nitrate Tobacco and tobacco products - Determination of Nitrate Content-Continuous flow method (YC/T 296-2009)

TABLE-US-00003 TABLE 3 Content of Intrinsic Chemical Components in Tobacco Leaves Total Total Water- Nitrogen alkaloids soluble Potassium Chloride Examples % % sugar % % % Example 1 3.07 2.21 3.08 2.24 0.73 Comparison 1 3.65 3.67 3.03 2.91 0.71 Comparison 2 4.14 4.59 1.63 2.88 0.78 Comparison 3 3.79 3.15 2.38 2.76 0.74 Comparison 4 3.37 3.23 2.59 2.83 0.77

[0047] As can be seen from Table 3, the water-soluble sugar content of the tobacco leaves after irradiation treatment increased significantly, reaching up to 89% at the highest, while there was no significant difference in the contents of total nitrogen, alkaloids, potassium and chlorine before and after irradiation. This indicates that after irradiation, the sugar-base ratio significantly increases, making the tobacco taste more mellow, reducing pungent, and significantly decreasing the green unpleasant taste, thereby improving the smoking experience.

[0048] The total nitrogen of the tobacco leaves obtained in Example 1 and Comparison Examples 1-4 was tested, and the results are shown in Table 4.

TABLE-US-00004 TABLE 4 Results of tobacco specific N-nitrosamines (TSNAs) Content Test 4-(N-methyl- nitrosamine)-1- N-nitroso (3-pyridinyl)-1- N-nitroso N-nitroso Total nicotine butanone neonicotinoids pseudolignin TSNAs Examples (NNN) (g/g) (NNK) (g/g) (NAT) (g/g) (NAB) (g/g) (g/g) Example 1 0.06 0.16 0.13 0.36 Comparison 1 0.09 0.22 0.18 0.50 Comparison 2 0.11 0.41 0.30 0.01 0.83 Comparison 3 0.08 0.17 0.21 0.47 Comparison 4 0.06 0.20 0.16 0.43

[0049] It can be seen from the conclusion of Table 4 that the TSNA content of the tobacco leaves in Example 1 after irradiation treatment and those in Comparison Examples 1, 3 and 4 is lower than that of the tobacco leaves in Comparison Example 2 without irradiation treatment. Among them, the degradation rate of TSNAs in Example 1 compared with the Comparison Example 2 of tobacco leaves without irradiation treatment reached 57%, and the degradation rate of NNK reached 61%. Therefore, the effect of the present invention on reducing nitrogen-containing harmful components by using irradiation to make sun-cured tobacco is obvious.

[0050] The embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can be modified and changed in various ways. Any modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.