Differences between Steely and Mealy Barley Samples Associated with Endosperm Modification

Abstract

Structurally, different areas may occur in the endosperm of the barley grain, and they can be visually classi fi ed as either mealy or steely. Barleys with a high proportion of grains that are mostly steely often show uneven physical–chemical modi fi cation of the endosperm during malting. To study the relationship between steeliness and endosperm modi fi cation, two samples of barley cv. Scarlett with con-trasting malting quality were analysed. The proportions of steely grains were 77 and 46% in the two samples, which were then de fi ned as steely sample and mealy sam-ple, respectively. The steely sample showed slower modi fi cation during malting (in terms of b -glucan degradation, friability increase, and Calco fl uor staining), lower hot water extract (HWE) and acrospire growth, and higher extract viscosity. Endosperm permeation to large molecules (tested with the fl uorescein isothiocyanate–dextran conjugate, FITC-D) closely followed cell wall modi fi cation in the steely sample, but this was not so in the mealy sample. Higher steeliness was associated with higher levels of C hordeins in the grain of barley cv. Scarlett. It is proposed that such hordeins can increase the permeability to large molecules (FITC-D) but slow modi fi cation. Like steeliness and the level of C hordeins, permeability to FITC-D appears to be