Effect of malting on the protein and free amino nitrogen composition of sorghum

Abstract

Abstract When sorghum is malted much of the nitrogen in the kernel is transferred to the roots and shoots. Examination of Osborne protein fractions extracted from the kernel reveals that as in the case of barley the prolamins are the major source of the nitrogen transferred. Electrophoretic prolamin bands remained unchanged during malting, indicating that prolamins are degraded directly to small peptides and amino acids. There was a general decline in the number of glutelin proteins whereas some albumin plus globulin proteins increased in quantity while others decreased. In the roots and shoots there was a considerable increase in both protein nitrogen and non‐protein nitrogen as a result of the translocation of the products of storage protein breakdown from the kernel. Several‐fold increases occurred in all of the nine essential amino acids determined. Quantitatively, the two most important free amino acids of sorghum malt appear to be asparagine and glutamine, as in germinated wheat and maize. This is in contrast to barley where proline is the major free amino acid.