Quantitation of surface color of flue-cured tobacco leaves and its relationship with carotenoid
In order to reveal the possible causes about the color difference among flue-cured tobacco leaves of different growing areas in China, the surface color of tobacco leaves, C3F, from 60 counties in 11 provinces were measured, analyzed and characterized with Lab* uniform color space. The relationship between surface color spatial distribution characteristics of and carotenoid content in leaves was investigated. The results showed that: 1) The surface color spatial distribution indexes, L* (brightness), a* (red chroma), b* (yellow chroma), c* (color saturation), and carotenoid content were obviously different among leaves from different areas. The L*, b*, c* and carotenoid content in tobacco leaves from the southeast tobacco belt were lower, while a* and lutein proportion were higher; for tobacco leaves from the upper and middle reaches of the Yangtze River and the southwest tobacco belts, L*, b*, c* and carotenoid content were higher, while a* was relatively lower; L* of tobacco leaves from the northern tobacco belt was relatively higher, while c* and carotenoid content were relatively lower. 2) The carotenoid content in tobacco leaves closely correlated to leaf’s surface color spatial distribution indexes. With the increase of carotenoid content, a*, b*, and c* increased significantly, however the ratio of L* to b* decreased significantly.