A vanillin-HCl staining has been used to locate the proanthocyanidins in mature barley grains. These flavanoids were found to be concentrated in the seed coat (testa) just outside the aleurone layer in the 7 varieties with yellow coloured grains investigated. The seed coats of 10 proanthocyanidin-free barley mutants belonging to 4 different gene loci did not stain with vanillin-HC1.

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The effect of rain on the viscosity of an acid flour extract and on the acid-soluble, acid-insoluble and total ~-glucan contents of barley flour has been investigated. Four commercial varieties and two high lysine genotypes were studied. In the commercial varieties rain induces a decrease in the viscosity of the acid flour extract which is paralleled by decreases in soluble and total ~-glucan contents. Furthermore, it is concluded that the rain did not alter the structural nature of the acid-soluble ~,-glucans. The genotype having the lys-3a allele is characterized by such a low extract viscosity and ~-glucan content that the rain had no effect on these parameters. The rain had a very unexpected effect on the genotype having the lys allele, namely, a marked decrease in extract viscosity that was not accompanied by a decrease in ~-glucan contents. Similar analyses on pure endosperm demonstrated that the rain effect is not a result of an altered 1000-grain weight. In addition, the extract viscosity and the soluble I~-glucan content were found to decrease from yellow to full ripeness.

The relationship between the viscosity of an acid flour extract and the acid-soluble, acid-insoluble and total [~-glucan content of barley flour has been investigated. The extract viscosity was found to be closely related (R2 = 0.99, S.E.E. = 0.19) to the content of soluble ~,-glucan. It is concluded that the acid-soluble [~-glucans from 14 of the 18 different genotypes studied have a similar structural nature. Genotypes containing the lys-3a allele were found to have very low extract viscosities and [~-glucan contents. Quick and accurate methods are described for measuring viscosities of acid extracts made from flour derived from grains of a single plant and flour derived from a single grain. These methods can be used to screen plants for their soluble (3-glucan content in a plant breeding program.