Abstract
The modified regions of starchy endosperms are strongly coloured when cut or sanded grains are exposed to polyurethane varnish mixed with an oil-soluble stain. Unmodified regions are only faintly coloured, while cracks in the grains, the embryos and the aleurone layers are deeply stained. This technique is a rapid, simple and inexpensive way for detecting the patterns of modification occurring in individual grains and for assessing the uniformity of modification in groups of grains.