A Preliminary Study on the Color Variation and Classification of Tobacco Strips Separated from Different Threshing and Pneumatic Separation Units

PurposeThe differences and classification of color values of tobacco strips separated from different pneumatic separation outlets in threshing process were investigated in order to provide reference for differentiated redrying and aging of different quality tobacco strips after threshing and further improve the modularization, homogenization and purification level of tobacco raw materials.

MethodThe flue-cured tobacco of Yunyan87 C3F in Kunming, Yunnan Province in 2019 was taken as the research materials. Under the condition of stable production in threshing process, tobacco strips separated from different threshing and pneumatic separation outlets were sampled many times and their CIE-L^*a^*b^* color space values (lightness value L^*, redness value a^*, yellowness value b^* and total color difference value ΔE) were determined by colorimeter. The differences of color values of tobacco strips separated from different pneumatic separation outlets were analyzed by one way ANOVA. Fisher optimal segmentation method was used to divide the eleven pneumatic separation outlets based on the standardized color values matrix.

Results(1) For the same grade of flue-cured tobacco in the threshing process, there were significant differences and regular trends in color values of the tobacco strips separated from different pneumatic separation outlets. (2) With the increase of pneumatic separation stage in the first and second stage threshing units, the L^* value gradually decreased, while the values of a^*, b^* and ΔE gradually increased. With the increase of pneumatic separation stage in the third and fourth stage threshing units, the L^* was generally increasing, while the values of a^*, b^* and ΔE were decreasing. (3) Based on the variations of color values of tobacco strips, the eleven pneumatic separation outlets were divided into four segments in sequence using Fisher optimal segmentation method, and there were significant differences in the overall color values of tobacco strips among the segments.

ConclusionThere was difference in tobacco strips quality separated from different threshing and pneumatic separation outlets. Through technological modification, differential redrying and utilization of different segments strips after threshing was of great significance for regulating the quality of tobacco leaves and controlling the quality of cigarettes.