| This paper mainly studies the free sterols in tobacco leaves,determines the content of free sterols in tobacco leaves,understands its variation law,and analyzes the reasons for the difference of the content of free sterols.Based on the reported methods and experiments,the characteristics of chemical component analysis of tobacco,the contents of 5 free sterols(stigmasterol,β-sitosterol,campesterol,cholesterol,ergosterol)in 65 tobacco samples which includes domestic fiue-cured tobacco,sun-cured tobacco,cigars were determined by UPLC-MS method in this paper.The differences of the content of free sterols in different types,varieties,planting areas,stalk positions and harvesting methods were studied,and the reasons for the difference in the content of free sterols in tobacco leaves were discussed preliminarily.These studies and discusses provide theoretical reference for cigarette formulation regulation and subsequent research in cigarette enterprises.The research results are as follows:1.Based on the comprehensive consideration of various literature reporting methods and industry standard methods,the original analytical conditions were improved by UPLC-MS methods in this study,and the analytical method was verified from the aspects of detection limit,recovery rate and precision.2.The results of experimental analysis showed that the detection limit of five free-state sterols was from 0.13 to 1.36(g/mL),the standard-added recovery range was from 94.16%to 103.18%,and the range of RSD was from 1.04%to 3.75%.The results showed that the detection limit was low,the recovery rate was good,and the relative standard deviation was small,which indicated that the method had high accuracy,precision and repeatability,and it was suitable for the analysis and determination of free sterols in tobacco.3.This paper investigated the content changes of free sterols in domestic flue-cured tobacco,sun-cured tobacco and cigar.The results showed:① the total content of free sterols in 3 types of tobacco leaves showed certain regularity,among which cigar was the highest,followed by sun-cured tobacco and flue-cured tobacco.② The total content of fragrance-type flue-cured tobacco was higher than that of fragrance type flue-cured tobacco in different types of flue-cured tobacco,while the content of stigmasterol in fragrance type flue-cured tobacco was higher than that of β-sitosterol,whereas the fragrance-type was the opposite.The content of stigmasterol,β-sitosterol,campesterol,cholesterol in different varieties and different producing areas of flue-cured tobacco is different,the total content of free sterols is also different.The variation of total content of free sterols in flue-cured tobacco in different parts:lower>upper>middle.The changes of free sterols content in the three parts of flue-cured tobacco were consistent,as follows:stigmasterol>β-sitosterol>campesterol>cholesterol>ergosterol.③The content of free sterols in red sun-cured tobacoo was higher than that of yellow sun-cured tobacco in different types of sun-cured tobacco,while the content of campesterol in red sun-cured tobacco was higher than that of β-sitosterol,whereas that of yellow sun-cured tobacco was the opposite.The variation of total content of free sterols in different parts of sun-cured tobacco:lower>upper>middle.The changes of free sterols content in different parts of sun-cured tobacco were consistent,as follows:stigmasterol>β-sitosterol>campesterol>cholesterol.④ Different varieties of cigar flue-cured tobacco had different total contents of free sterols,and the different content of stigmasterol,β-sitosterol,campesterol and cholesterol.The variation of total content of free sterols in different parts of cigar:upper>middle>lower.The changes of free sterols in upper and middle tobacco leaves were the same:stigmasterol>campesterol>β-sitosterol>cholesterol>ergosterol.while the variation regulation of free sterols content in the lower tobacco leaves of cigars:stigmasterol>β-sitosterol>campesterol>cholesterol>ergosterol.At the end of drying,the contents of total free sterols and any free sterols increased under the different harvesting methods.Compared with leaf-by-leaf tobacco,the total content of free sterols collected by stem was higher than that of leaf-by-leaf tobacco.The contents of stigmasterol,β-sitosterol,campesterol and cholesterol in different harvesting modes showed different changes during drying process.4.By analyzing the variation rule and difference of free sterols content in flue-cured tobacco,sun-burned tobacco and cigars and 5 free sterols,combined with the genetic factors,external environment factors,drying conditions and other influencing factors,the reasons for the difference of free sterols content in tobacco were preliminarily discussed.Therefore,the research work of this paper provides an important reference and guidance for promoting tobacco quality improvement and cigarette coke reduction and harm reduction research. |
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