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 (γ) 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.

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 (γ) rays from a  60 Co 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.