Kernel colour changes associated with field weathering of spring wheat

The Canadian wheat-grading system is based on visual assessment to estimate end-use quality, both for assignment to classes and to grades within classes. Extensive training and experience are required to accurately interpret visual indicators of quality. Therefore, breeding programs are attempting to develop instrumental techniques to objectively measure visual characteristics of potential new cultivars. The objective of this research was to examine colour changes associated with field weathering of wheat cultivars from the Canada Western Red Spring, Canada Western Amber Durum, and Canada Prairie Spring Red and White classes of wheat, as measured with a portable colorimeter. The class means exhibited colour differences, although the large variability within classes suggests that, used in isolation, colour measurements would not be a satisfactory means of identifying the class of individual samples. Weathering caused an increase in L* (lightness), a decrease in a* (redness), and a slight increase in b* (yellowness), and the effects were similar for all classes. Severe weathering caused loss of vitreousness in addition to bleaching, and the colour measurements reflect the integrated colour changes associated with both effects. Within each class, although there were cultivar differences for colour, the cultivars responded similarly