Comparative development of soluble nitrogen in the malts of barley and sorghum

Abstract

Sorghum variety (KSV 13) and barley variety (Chariot), at similar levels of total nitrogen, showed different patterns of protein breakdown. Changes in molar concentrations of the sodium acetate buffer, pH 5.4, from 0.05 to 0.2 M in the assay procedure produced similar patterns of endopeptidase activities. The protein and amino acid content of brewers’ worts are mainly derived from malted cereals. Protein solubilisation in sorghum was significantly lower than in barley when both cereals were malted at their optimal temperatures of 30 and 17°C. Although the lower solubilisation of protein in sorghum malt was correlated with lower levels of free amino nitrogen and endopeptidase, the peptide levels of sorghum malts were higher than those in the malts of barley. It is possible that the endopeptidases of sorghum malt may have different specificities from those of barley malt, or that the storage proteins (prolamins) of sorghum may be structurally different from those of barley. Peptides seemed to be transferred from the endosperm to the embryo faster in barley than in sorghum malts.