关键词: 烤烟, 烟叶分切, 聚类分析, 正交偏最小二乘判别分析, 差异挥发性物质, 感官质量

Abstract: To explore the longitudinal distribution law of volatile compounds in upper tobacco leaves from Yunnan Province，Tobacco leaves of cultivar Yunyan 100 at grade B2F，collected from Luoping County，Qujing City，Yunnan Province，were used as the research object，and evenly divided into 10 segments（Q1—Q10）along the longitudinal direction of the main vein. Gas chromatography⁃mass spectrometry（GC⁃MS） was employed to determine the contents of volatile compounds.Subsequently，hierarchical cluster analysis was performed for differential grouping of these sections，and orthogonal partial least squares discriminant analysis（OPLS⁃DA）was used to screen for differential aroma⁃active compounds among the groups. The results showed that 145 volatile compounds（predominantly hydrocarbons，alcohols and ketones）were identified in 10 segments. The total content exhibited a trend of increasing first，then decreasing and increasing again along the direction from leaf tip to leaf base（Q1 to Q10）.The total amount of Q7 was the highest（129.66 μg/g）and the total amount of Q9 was the lowest（48.11 μg/g）.Hierarchical clustering divided tobacco leaves into three characteristic sections：upper section（Q1—Q4），middle section（Q5—Q7）and lower section（Q8—Q10）.Based on the OPLS⁃DA model，39 differential volatile compounds（variable importance projection≥1，difference multiple≥2 or difference multiple≤0.5，p<0.05）were further screened.Among them，the number of up⁃regulated compounds in the middle section was significantly higher than that in the upper and lower sections，including solanone，damascenone，dihydroactinidiolide and other key aroma compounds.Sensory evaluation revealed that the middle section of tobacco leaves was significantly superior to the upper and lower segments of tobacco leaves in terms of aroma intensity，aroma quality，aftertaste，and comprehensive score，and this result was consistent with the distribution pattern of volatile compounds.In conclusion，this study clarified the gradient distribution pattern of volatile compounds along the longitudinal axis of tobacco leaves，especially revealed the superiority of the middle section of tobacco leaves in aroma quality，providing a scientific basis for the refined grading of tobacco leaves and the high⁃value utilization of tobacco resources.

Key words: Flue?cured tobacco, Tobacco leaf slicing, Cluster analysis, Orthogonal partial least squares discriminant analysis, Differential volatile compound, Sensory quality