初烤烟叶主脉不同区段色度及Fisher最优分割法分析

  目的  分析初烤烟叶主脉不同区段色度值的变化，为烟梗的差异化加工和分类使用提供参考依据。  方法  以云烟87 B3F、C3F初烤烟叶为试验对象，将每片烟叶中的主脉平均分成6段，采用色差计测定每个区段烟梗粉末的色度值L*（明度值）、a*（红度值）、b*（黄度值）和E（总色差值），利用单因素方差分析和回归分析分别研究不同区段烟梗色度值的差异性及变化趋势，并通过Fisher最优分割法分析2种烟叶主脉最佳的分段比例。  结果  ① 同一烟叶主脉不同区段烟梗的色度值L*、a*、b*、E总体均存在显著差异；B3F和C3F烟叶主脉相同区段的色度值对比，L*值为C3F > B3F，a*、b*、E值为B3F > C3F。②从主脉基部到尖部，L*值呈先降低后升高的抛物线形变化趋势，a*、E值呈先升高后降低的抛物线形变化趋势，b*值呈逐渐升高的线性变化趋势。③从梗基到梗尖，B3F烟叶主脉最佳分段比例可分为1/6、3/6、1/6、1/6，C3F烟叶主脉最佳分段比例可分为4/6、1/6、1/6。  结论  烟叶主脉不同区段的色度存在较大差异和规律性变化趋势，叶基和叶中部分的烟梗更适宜作为制梗丝的原料。 

Chromatic value of different segments of main vein of flue-cured tobacco and analysis by Fisher optimal segmentation method

  Objective  This study aims to analyze the changes in the chromatic values of different segments of main vein of flue-cured tobacco leaves so as to provide references for the differentiated processing and classification of tobacco stems.  Methods  The main veins in Yunyan87 B3F and C3F cured tobacco leaves were equally divided into 6 segments. The chromatic values L* (lightness value), a* (redness value), b* (yellowness value) and E (total color difference value) of the tobacco stem powder of each segment were measured by a colorimeter. Single factor analysis of variance and regression analysis were carried out to study the difference and change trend of the chromatic values of tobacco stems at different segments. Finally, the optimal segmentation ratio of the main veins of the two types of tobacco leaves was analyzed by Fisher optimal segmentation method.  Results  1) There were significant differences in chromatic values L*, a*, b* and E values of tobacco stems at different segments of main vein for the same tobacco leaf. Through comparison of chromatic values of the same segment in main veins of B3F and C3F tobacco leaves, it was found that the L* value was C3F > B3F, and a*, b*, E values were B3F > C3F. 2) From stem base to stem tip, the best segment ratio of the main vein of B3F tobacco can be divided into 1/6, 3/6, 1/6, 1/6, and the best segment ratio of C3F tobacco can be divided into 4/6, 1/6, 1/6.  Conclusion  There are significant differences and regular trends in the chromatic values of different segments of tobacco main vein. The tobacco stems in the leaf base and the middle part of the leaf are more ideal raw materials for stem cutting.