SALT SENSITIVITY OF ACETIC ACID-EXTRACTABLE PROTEINS OF WHEAT-FLOUR

The sensitivities of flour proteins to precipitation by NaCl at acid pH were investigated by extraction with 0.05 M acetic acid solution containing varying concentrations of salt and by precipitation of the proteins extractable in acetic acid solution by addition of salt to varying concentrations. Flours of two Canadian hard red spring wheat cultivars (Glenlea and Katepwa) were used because of their different dough strengths. Electrophoresis results showed that as the NaCl concentration was raised, higher M(r) proteins of gliadins and glutenins were less extractable and were more easily precipitated. This tendency was more evident for the proteins of cv. Glenlea than those of cv. Katepwa, indicating that the former (stronger) is more sensitive to NaCl than the latter. SDS-PAGE results indicated that differences in the molecular size and subunit composition (i.e. relative proportion of high:low M(r) glutenin subunits, and relative proportion of x-:y-type high M(r) glutenin subunits) of glutenin polymer contribute to differences in NaCl sensitivity. The differences appear to be related to the baking strength of the flour.