EFFECTS OF HIGH RATES OF NITROGEN ON NEEPAWA WHEAT GROWN UNDER IRRIGATION. III. PROTEIN QUALITY FOR BREADMAKING AS REFLECTED BY VARIOUS TESTS

Abstract

Eleven samples of hard red spring wheat Triticum aestivum L. em Thell cv. Neepawa, selected from a fertilizer–irrigation study and ranging in protein content from 9.3 to 16.4%, were subjected to various breadmaking quality tests, protein solubility fractionation, amino acid composition analysis and gliadin electrophoresis analysis. Loaf volumes showed a decrease in breadmaking quality with increasing protein for samples at the top of the protein content range. Conversely, the Pelshenke and Zeleny Sedimentation values showed a reverse trend in the same region of protein content. Most of the decreasing rate of change in the loaf volume with protein content at the top of the protein range can be explained by the gradual change in solubility of the glutenin. The gradual decrease in the amount of damaged starch can make a small contribution to the observed loss of quality. Minor quantitative differences (slightly stronger stain intensity for a few bands) were observed in the gliadin electrophoregrams of samples of different protein content. There is no obvious explanation for the increasing rate of change in Pelshenke and Zeleny Sedimentation values with protein content at the top of the protein range.