Studies on the Starches of Barley Genotypes. A Comparison of the Starches from Normal and High‐Amylose Barley

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Abstract
Starches have been isolated from two barley genotypes, the normal American variety “Glacier (C. I. 9676)” and a mutant with a low mean‐starch‐granule‐size designated “Glacier (Ac 38)”. Iodine titration has confirmed that the mutant has a starch of high amylose‐content.Both starches have been fractionated to yield their component amylose and amylopectin, and the properties of these fractions examined. The two amylose fractions show very similar properties, but the amylopectin fraction isolated from the starch of “Glacier (Ac 38)” is apparently anomalous with respect to chain‐length, β‐amylolysis limit, and iodine uptake. This behaviour — which is comparable with that exhibited by the amylopectin fractions of the other high amylose‐content starches from pea and maize — has similarly been shown to be due to heterogeneity in the polysaccharide rather than to an increase in the average‐length of the external chains.