Cereal Chem 65:463-470   |  VIEW ARTICLE

Gamma Irradiation of Hulless Barley: Effect on Grain Composition, Beta-Glucans and Starch.

R. S. Bhatty and A. W. MacGregor. Copyright 1988 by the American Association of Cereal Chemists, Inc. 

Scout hulless barley with gamma irradiated to 10 Mrad (100 kGy) with cobalt-60. Irradiation had no major, apparent effect on grain composition, except for starch and beta-glucans. Total nitrogen, nonprotein nitrogen, and amino acid composition of nonirradiated and irradiated barleys were identical. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of the two barleys were also identical. However, protein bands corresponding to 45 and 94 kDa showed reducing staining. Irradiated barley completely lost viscoamylogram properties and had reduced endosperm cell wall fluorescence but higher (75%) soluble beta-glucans. Irradiated barley starch contained lower molecular weight amylose and amylopectin compared to the nonirradiated barley starch. However, the two starches showed similar endothermic properties (differential scanning calorimetry) and gelatinization temperatures. The starch granules appeared to be normal externally but were fractured internally. This was particularly evident during the later stages of gelatinization. Irradiation increased the susceptibility of barley starch to alpha- and beta-amylase hydrolysis. Irradiated barley had lower in vivo dry matter (2.6%), starch (1.0%), and protein 5.2%) digestibilities as determined by mouse-feeding experiments.