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

The sensitivities of flour proteins to precipitation by NaCl at acid p H were investigated by extraction with 0.05 M acetic acid solution con taining varying concentrations of salt and by precipitation of the pro teins extractable in acetic acid solution by addition of salt to varyi ng concentrations. Flours of two Canadian hard red spring wheat cultiv ars (Glenlea and Katepwa) were used because of their different dough s trengths. Electrophoresis results showed that as the NaCl concentratio n 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, in dicating 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) gl utenin subunits) of glutenin polymer contribute to differences in NaCl sensitivity. The differences appear to be related to the baking stren gth of the flour.