Effect Of Harvest Time,curing Method And Fermentation Conditions On The Quality Of Sun-cured Tobacco In Wanyuan

There are many problems in sun-cured tobacco production in Wanyuan area,such as insufficient maturity of tobacco leaves,single curing method,too fast dehydration of tobacco leaves,and easy mildew of tobacco stems during tobacco fermentation.To solve these problems,field experiments were carried out to investigate the effect of harvest time,curing method and fermentation conditions on the quality of sun-cured tobacco from 2016~2017 in Wanyuan,Sichuan.The main results are as follows:1.With the delay of harvest time,the filling ability of tobacco leaves decreased first and then increased,the leaf density and the single leaf weight gradually increased,and the percentage stem was first increased and then decreased.The content of total nitrogen and nicotine gradually increased with the delay of harvest time,and the content of reducing sugar,total sugar,the ratio of total sugar to nicotine and potassium to chlorine decreased continuously.The total content of neutral aroma substances first decreased and then increased with the harvest time postponed.The difference of neophytadiene was extremely significant.The content of 25 d after topping is up to the highest.The total aroma substances,except for neophytadiene,decreased first and then increased,the difference between them was significant.The total amount of amino acids in tobacco leaves increased first and then decreased with the increase of maturity,and the difference of aspartic acid content was very significant.The content of TSNAs in tobacco leaves decreased first and then increased with the harvest time postponed.When the leaf maturity was too low or too high,the content of TSNAs increased significantly.The content of alkaloids and nitrate increased continuously with the delay of harvest.The total score of 30 d after topping was the highest,the smoking quality was the best.2.The curing method has little influence on the physical characteristics of tobacco leaves.After sun-cured,reducing sugar and total sugar content was significantly higher than that of air-cured in the same harvest time.It's 1.37 and 1.33 times the air-cured,respectively.The total nitrogen and nicotine content was higher than that of air-cured,but there were not significant changes.The trend of total sugar to nicotine proportion is contrary to potassium to chlorine.The ratio of total sugar to nicotine is higher after sun-cured,and is lower after air-cured.The total amount of neutral aroma substances in air-cured tobacco leaves is generally higher than that of the sun-cured tobacco,and the difference of 25 d harvest after topping is significant.The total amount of amino acids in tobacco leaves was little influenced by the curing method,but the content of aspartic acid in the sun-cured tobacco leaves was significantly higher than that in the air-cured level.The content of TSNAs,alkaloid and nitrate in the air-cured tobacco leaves was significantly higher than that of the sun-cured when the leaf maturity was too low or too high.The curing method has little effect on the sensory quality of tobacco leaves,and it has not reached a significant level.3.After fermentation,all indexes of tobacco increased significantly.Content of reducing sugar,total sugar and nicotine decreased significantly.The content of aroma components increased.The contents of nitrate and alkaloids decreased significantly,and transformed into TSNAs,resulting in a significant increase in their contents.After fermentation,the quality of smoking was generally improved,with strong aroma,moderate strength,little irritation and comfortable aftertaste.The content of neutral aroma components increased firstly and then decreased with the increase of fermentation temperature and increased with the increase of humidity.The content of TSNAs is greatly influenced by the change of temperature and humidity.With the increase of temperature,the content of TSNAs in tobacco leaves increased significantly,while the increase of humidity inhibited it.The quality of the senses is greatly influenced by the humidity of the fermentation.The aroma,concentration,miscellaneous gas,irritation and aftertaste of tobacco leaves were better when they were fermented at high humidity.4.The results of the study show that harvest the upper leaves at 35 d after topping and harvest the middle leaves at 39 d after topping,then take the sun-cured method,fermentation at 45 centigrade and humidity 90%,such the quality of tobacco leaves is the best,with coordinated chemical composition,good aroma components,high safety,and the best quality of suction,meet the requirements of high quality tobacco production requirements.