Analysis on Color Value and Appearance Color Variation of Tobacco Leaves

The experiments were conducted to discover color characteristics of flue-cured tobacco through analyzing changes of L^*, a^*, b^*, C^* and features in each leaf-position. The tobacco cultivars CB-1 and Yunyan 87 ware used in these experiments. Color value, level of appearance color and variation of uniformity were evaluated. The results showed that the trends of changes in color value were similar between different nodes. The clustering results of color value in different nodes agreed with color variation in different stalk portions. With the rising of nodes, the uniformity of brightness decreased and redness increased. The patterns of the uniformity change of yellowness and sensory evaluation at different nodes showed some similarities with the color uniformity of cutters being the highest. A corelation equation between color value of tobacco leaves and the rise in nodes was establelished. The L^* value linearly decreased and the a^* value linearly increased. The changes of the b^* value was a parabola which reached the highest value at the 7th to the 10th nodes. The change of the C^* value was similar to the b^* value. The traditional theory of tobacco grading could be complemented by evaluating color characteristics through L^*a^*b^* color space and sensory evaluation techniques. An objective and quantitative method was provided for appearance color variation of tobacco leaves.