Study On The Difference In Aroma Substances Of Flue-cured Tobacco Leaves Matured At Different Stages

In recent years,flue cured tobacco in some Shandong tobacco areas has suffered from late maturity and long harvesting and roasting period,which affects the quality of tobacco leaf.Taking the flue cured tobacco NC55 in Shandong Province as the research object,this study analyzed the effects of different maturation periods on the chemical substances and aroma content of roasted tobacco,with the aim of finding the optimal maturation time for tobacco quality and providing a theoretical basis for improving the intrinsic quality of flue cured tobacco in Shandong,and determining the feasibility of early maturation measures.The main findings were as follows.There were differences in chemical substance contents in different parts of flue cured tobacco.The nicotine content of the upper leaf was the highest,followed by the middle leaf,and the lower leaf were the lowest.The nicotine content of the lower leaf was lower than that of the upper and middle leaf by 31.38% and 27.9%,respectively,and the differences in nicotine content between different parts were significant.The total Nitrogen content of the upper leaf was higher than that of the middle and lower leaf by 25.2% and 35.1%,respectively,with significant differences between different parts.The total sugar content was the highest in the middle leaf,higher than the upper and lower leaf by 12.2% and 7.8%,respectively,with significant differences between the upper and lower leaf,but not significant between the upper and lower leaf.Reducing sugar content was the highest in the middle leaf,with significant differences between different parts.The sugar to alkali ratio was most suitable in the middle leaf,and the difference between the two sugars in the middle leaf was the smallest,and the ratio of the two sugars was more harmonious and the quality of the tobacco was better.There were differences in the content of aroma components in different parts of flue cured tobacco.In each aroma component,the content of the upper leaf was higher than that of the middle and lower leaf.The content of carotenoids and neophytodienes varied significantly among the three parts,with the content of carotenoids in the upper leaf being 14.5% and33.5% higher than that in the middle and lower leaf,respectively;the content of neophytodienes in the upper leaf was 10.42% and 15.8% higher than that in the middle and lower leaf,respectively.Phenylalanine products and maillard reactants were significantly different in the upper leaf from the middle and lower leaf,respectively,but not significantly different between the middle and lower leaf.The content of phenylalanine metabolites products in the upper leaf was 15.8% and 13% higher than that in the middle and lower leaf,respectively,and maillard reactants in the upper leaf was 16.8% and 14% higher than that in the middle and lower leaf,respectively.There were also differences between different parts of the tobacco leaf for the cembranoid,but the differences were not significant.Different maturation periods had effects on the chemical substances in different parts of the tobacco leaf.The maturation periods had a great influence on the chemical substances in the upper leaf.The maturation time is earlier,and the nicotine content in the upper leaf of flue cured tobacco is lower.The upper leaf matured on September 5 were 2% and 4% lower than those matured on September 15 and 25,respectively,but the differences were not significant and the Nitrogen compounds also showed a decreasing trend.In terms of total sugar content,the upper leaf matured on September 5 were 12.3% and 28.2% higher than the upper leaf matured on September 15 and 25,respectively,with significant differences.In terms of reducing sugar content,22.1% and 33.2% were higher on September 5 compared to 15 and 25,respectively,with significant differences.In contrast,different maturation periods had little effect on the chemical substance content of the middle and lower leaf.Different maturation periods had an effect on the content of aroma components in different parts of the tobacco leaf.The different maturation periods had less effect on the aroma substance content of the middle and lower leaf,and more effect on the aroma substance content of the upper leaf.For the upper leaf,the aroma content of the upper leaf matured on September 5 was significantly higher than that of the tobacco leaf matured on September 15 and 25,in which the content of carotenoid degradation products increased by 32.5% and59.3% on September 5 compared with September 15 and September 25,respectively;the content of phenylalanine,increased by 50% and 67.5% on September 5 compared with September 15 and September 25,respectively;the content of cembranoid increased by 23.3%and 34.3% on September 5 compared to September 15 and September 25,respectively;and the content of Neophytodienes increased by 27.2% and 46.8% on September 5 compared to September 15 and September 25,respectively,with significant differences between these four categories in all three periods.The content of maillard reactants on September 5 differed significantly from that on September 15 and September 25 by 7.6% and 11.1%,respectively,but the difference between September 15 and September 25 was not significant.All components of the aroma of tobacco leaf with early maturity period were improved,which was more conducive to the improvement of the aroma quality of tobacco leaf,thus promoting earlier maturity of tobacco leaf was more conducive to the improvement of the quality of upper tobacco leaf.