No abstract

The endosperm cell walls of barley are degraded extensively during malting whilst those of sorghum are not. Malting barley produced endo-β-1,3:1,4-glucanase, endo-β-1,3-glucanase and pentosanase in large quantities. In contrast, malting sorghum developed mainly endo-β-1,3-glucanase and pentosanase. Although the limited break-down of the endosperm cell walls of sorghum may reflect sub-optimal activities of β-glucanases, such as endo-β-1,3:1,4-glucanases, it is possible that the highly intractable nature of the cell walls and their high protein content (approx. 60%) may contribute to the low susceptibility of sorghum endosperm cell walls to enzymic degradation during malting.

Mercuric chloride was used to selectively inhibit the sulphydryl function of p-amylase, enabling the dextrinizing activities of a-amylase and the Diastatic Power (total reducing power activity) to be calculated from a single extract of molt by one assay method. Using commercial malts, there was a 98% and 96% correlation between results obtained by this method and the recommended methods of the Institute of Brewing (IOB) for the determination of Diastatic Power (DP) and Dextrinizing Unit (DU).