Effect of Different Maturity on the Quality Features of Fresh and Cured Tobacco

In order to explore the quality characteristics of fresh tobacco with different maturity in Guiyang and to reveal indicators for their optimal maturity, using Yunyan 87 as the experimental material, the quality features (water content, pigment and major chemical components) of lower, middle and upper fresh tobaccos with three levels of maturity were investigated. Furthermore, the effects of position and maturity on the quality of cured tobacco were studied. The results showed that with the increase of maturity, the water content of fresh tobacco leaves, veins and whole leaves, as well as the content of chlorophyll a, chlorophyll b, chlorophyll and carotenoid gradually reduced, while the ratio of carotenoid to chlorophyll significantly increased; the content of total sugar, reducing sugar and the total nitrogen gradually increased while the content of nicotine and protein decreased steadily. The comprehensive analysis of the leaf grade structure, average price, appearance quality, content and coordination of chemical components, as well as the sensory evaluation of the cured tobacco turned out that the appropriate maturity of the lower, middle and upper leaves are XM2, CM2 and BM2, respectively. Specifically, the appearance index for the lower leaves with optimal maturity is 60% yellowish green leaf area and 1/3 white main vein at least; the middle leaves can be harvested with 70% yellowish green leaf area and 1/2 white main vein; the upper leaves with appropriate maturity are those with 80% yellowish green leaf area and 2/3 white main vein at least.