Chromaticity Parameters in Relation to Visual Grades of the Flue-Cured Tobacco
- R. Carotenuto,
- R. Troncone and
- P. Martiniello
The quality of flue-cured tobacco (Nicotiana tabacum L.) depends on field-growth conditions and post-harvest processing, and can be partially determined by the color of the leaves. The objectivesof the investigation were to determine the range of values of chromaticity parameters of visually graded leaves and to evaluate the possibility of utilizing the parameters for electronic screening. The classification of leaves (visually or mechanically) is generally based on the evaluation of chromaticity differences of their color. The success of electronic screening requires an accurate definition of the chromaticity parameters a*, b*, and L*, which were defined mathematically by the International Commission on Illumination. Ten common tobacco cultivars were grown in each of 2 yr. The leaves were harvested four rewings and separated into bottom, lower, upper middle, and top leaves. After flue-curinp, an adequate sample of leaves from each harvest was visually classified into three merit-classes (grade A, B, and C). A colorimeter was used to determine the chromaticity parameters. Leaves from different cultivars and leaf positions on the stalk differed in grades and chromaticity parameters. The cluster technique of the L*, a*, and b* values defined for each merit-class provided a range of chromaticity parameters that can be successfully utilized in electronic screening processing. Four cluster groups for chromaticity parameters L* and a*, and five for b*, were obtained. The range of values of the chromaticity parameters (L*, a*, and b*) obtained from the cluster method were correlated with the grades visually selected.
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