Variation Of Aroma Characteristics Of Flue-cured Tobacco And Its Relationship With Chemical Components Of Tobacco Leaves

In this study,the overall status and variation characteristics of the aroma characteristics of 232 tobacco leaf samples from different parts of the main tobacco producing areas in China were described and analyzed by variance analysis.The relationship between the aroma characteristics of flue-cured tobacco and the contents of conventional chemical components,neutral aroma substances,petroleum ether extracts,polyphenols and organic acids,clarify was analyzed by using a variety of analytical methods and the corresponding statistical models were created.After that discriminant analysis of the aroma characteristics of different types of tobacco leaves was carried out.The main conclusions are as follows:1 The total score of aroma characteristics of flue-cured tobacco in China was 23.06,the variation amplitude was small,and the coefficient of variation is 7.95%.The average score of aroma quality,aroma quantity and impurity were 5.79,5.77,5.44.All of them were in the middle level,and the average score of diffusiveness was three higher than that of three,which belonged to a strong level.2 The establishment of the aroma characteristic index(ACI)was based on the calculation method of sensory quality index.There was a significant difference in ACI between different parts and grades,and the index in the middle leaf was highest which in a better level.The highest altitude area index was the highest which was obviously higher than the middle and low altitude areas.And there was a significant difference between them.The comparison results of ACI in different tobacco planting areas showed that the ACI of tobacco leaves in south-west and Southeast tobacco areas was obviously superior to other domestic tobacco planting areas.Tobacco leaves in Zimbabwe and Brazil were better than domestic tobacco leaves,and the southwest tobacco planting areas are closer to the two.The ACI of flue-cured tobacco in different provinces had a great relationship with the tobacco growing areas.The index was higher in the southwest and Southeast planting areas,and the index in northern tobacco growing areas was lower.3 The analysis of the relationship between the aroma characteristics of tobacco and the chemical composition of the tobacco showed that there was a significant negative correlation between the total alkaloid,total nitrogen,protein and total volatile alkali and aroma characteristics and a very significant positive correlation between the total sugar,reducing sugar,sugar and alkali ratio,sugar acid ratio and aroma characteristics.The results of regression analysis showed that the relationship between total alkaloid,volatile alkali and protein content and aroma characteristic score was a cubic function,the relationship between total nitrogen content and the total score of aroma characteristics was a quadratic function and reached extremely significant correlation level.The relationship between total sugar and reducing sugar content and the total score of aroma characteristics was a linear function and reached extremely significant correlation level4 The results of grey correlation analysis on aroma characteristics of flue-cured tobacco and neutral aroma compounds showed that all kinds of aroma substances in grey relational order Maillard reaction products>aromatic products>carotenoid degradation products>neophytadiene>degraded by cembrane for aroma quality and quantity,miscellaneous gas,total scores of aroma characteristics.For diffusiveness the grey correlation degree of Maillard reaction product was the highest,followed by aromatic products and the degraded by cembrane was the lowestIn the maillard products,the effects of the aroma characteristics showed that 2-acetyl furan and furfural had a greater correlation to various indexes.Among the aromatic products,the highest degree of association was phenylacetaldehyde and the indole had the least degree of association The effect of all kinds of alcohols on the diffusiveness is higher.The greatest effect on impurity and total score of aroma characteristics was linalool and the influence of indole was the least.Among the carotenoid degradation products,the effects of aroma quality,diffusiveness and total score of aroma characteristics showed that β-damascene had a greater correlation,the dihydroactinidiolide had a greatest effect on aroma quantity and impurity.For the characteristics of each aroma farnesyl acetone’s effect was the leastThe aroma index AI of flue-cured tobacco had a very significant positive correlation with each index of aroma characteristics,and the score of aroma characteristics of flue-cured tobacco increased with the increase of AIThe fitting curves of the BP neural network model of the four types of neutral aroma substances and aroma characteristics showed that the total relationship of the total score of the maillard products and the aroma characteristics showed a parabolic relationship,the same as the degraded by cembrane.With the increase of aromatic product content,the aroma characteristic score gradually decreased.The score of aroma characteristics decreased with the increase of carotenoid content.The total score of aroma characteristics increased first and then decreased with the increase of the content of new diene5 The content of petroleum ether extract,aroma quality and aroma characteristics reached very significant positive correlation,respectively.The results of generalized additive model are basically consistent with the results of simple correlation analysis.The petroleum ether extract was linearly and positively correlated with the amount of aroma,indicating that the petroleum ether extract had more influence on the aroma.Petroleum ether extract showed a nonlinear correlation with the aroma quality and total score of aroma characteristics,and the correlation between them was very complex.The relationship between the two shows a positive correlation in general.In addition,the increase in the content of petroleum ether extract of flue-cured tobacco can improve the aroma characteristics of flue-cured tobacco6 Oxalic acid,malic acid,citric acid,malonic acid,succinic acid and succinic acid were negatively correlated with the aroma characteristics and reached a significant level.Palmitic acid,oleic acid,stearic acid and aroma characteristics were significant and very significant positive correlation.Typical correlation results showed that the correlation between oleic acid and flue-cured tobacco was the most,followed by malonic acid,and palmitic acid had the greatest correlation with aroma temperament.Malonic acid with diffusiveness and total score of aroma characteristics showed a nonlinear negative correlation,while palmitic acid was positively correlated with aroma quality and aroma characteristics.The oleic acid with diffusiveness and total score of aroma characteristics showed a nonlinear positive correlation.In general,high fatty acids in organic acids had a great influence on the aroma characteristics,and most of them were positively correlated7 The simple correlation and canonical correlation results showed that chlorogenic acid was positively related to aroma quantity and impurity and it was negatively related to diffusiveness and reaches 0.01 significant levels.scopoletin and aroma quality and quantity,impurity showed a significant negative correlation.Rutin had a significant positive correlation with aroma quality.The correlation of scopoletin and aroma was the greatest,followed by the impurity.The correlation between chlorogenic acid and diffusiveness was the greatestBy the generalized additive model,there was a nonlinear positive relationship between chlorogenic acid and aroma quality,a nonlinear negative relationship between chlorogenic acid and diffusiveness and a linear positive relationship between chlorogenic acid and impurity.There was a nonlinear relation between scopoletin and aroma quantity,impurity and total score of aroma characteristics,a linear negative correlation between scopoletin aroma quantity.The content of rutin had a nonlinear correlation with the total score of aroma characteristics,and showed a positive correlation,totality8 According to the score of aroma characteristics,the aroma characteristics of flue-cured tobacco were divided into three groups:high,medium and low.The variation range of the sample group was small,the whole condition was more stable,and there was significant differences in the scores of various groupsThe total alkaloid in middle group was the highest,but the difference of total alkaloid contents in three groups was not obvious.The total nitrogen,protein and volatile alkali content were the highest in the middle group,and the difference from the low group was not significant,and the difference between the high group and the high group reached 0.05 significant level.In the high,middle and low groups the content of total sugar and reducing sugar and the content of sugar and acid decreased in turnBased on aroma components(neutral aroma substances,organic acids and polyphenols)of flue-cured tobacco,a general discriminant analysis and stepwise discriminant analysis were used to establish tobacco aroma characteristic models.The general discriminant analysis of tobacco leaves was carried out,and three Fisher discriminant functions were constructed,and the accuracy rate was 73.7%and 70.7%respectively.By stepwise discriminant analysis,the aromatic products(X2)and carotenoid degradation products(X3),degraded by cembrane(X4),neophytadiene(X5),polyphenols and organic acids(X6)six variables were kept,and the discriminant function was established,according to the three groups of aroma characteristics Y1=0.113X2+0.179X3-0.233X4+0.077X5+2.536X6+0.389X7-63.645 Y2=0.280X2+0.265X3-0.127X4+0.043X5+2.180X6+0.355X7-55.936 Y3=0.250X2+0.333X3-0.112X4+0.045X5+2.385X6+0.432X7-72.535The accuracy rate was 75.9%and 72.9%respectively,and the discrimination effect was better.It could be used to quantify sensory quality of tobacco leaves and reduce the uncertainty factors in tobacco quality evaluation.