Studies on Various Light Sources Concerning the Evaluation and Differentiation of Red Wine Color. I

¹ Department of Viticulture and Enology University of California, Davis

The ability of a panel to differentiate wines as to color has been tested, and it has been shown that extremely small differences in color characteristics as determined by tristimulus data can be differentiated by the panel. Definition of the McAdam unit was found to be erroneous under the conditions of this test. This is explainable by the fact that the color was from reflected and transmitted light rather than just reflected light as the McAdam units were originally designed to compare.

Three light sources have been compared. It was found that fluorescent light of the type tested was significantly better than the daylight source for differentiation, while no significant differences were found between incandescent and fluorescent or incandescent and daylight sources.

In testing for color preference changes with various light sources, if was found that the fluorescent light showed a one blend preference shift from the other two sources.

Further studies are planned to study the effects of changes in percent brightness and percent purity without dominant wave length change, and the converse of this. Also, studies pertaining to the Webner-Fechner law will be made.