The effect of rain on β-glucan content in barley grains

Abstract

The effect of rain on the viscosity of an acid flour extract and on the acid-soluble, acid-insoluble and total β-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 β-glucan contents. Furthermore, it is concluded that the rain did not alter the structural nature of the acid-soluble β-glucans. The genotype having the lys-3a allele is characterized by such a low extract viscosity and β-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 β-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 β-glucan content were found to decrease from yellow to full ripeness.