Kristensen, H. & Aastrup, S. Carlsberg Res. Commun. (1986) 51: 509. doi:10.1007/BF02906893
Barley grains are embedded in a block of plastic clay with the Carlsberg Seed Fixation System, abraded to expose a small sector of endosperm and surrounding testa. Staining of the proanthocyanidins in the testa is carried out by immersion into a solution of vanillin in 4.5 N−HCl. Kernels lacking proanthocyanidins are selected, washed and grown to mature plants. Using sodium azide mutagenesis 10 proanthocyanidin-free mutants with anthocyanin pigmentation in the vegetative parts of the plants were obtained among 78,450 M3-kernels amounting to a frequency of 0.013%.