WHEAT-FLOUR PROTEINS - ISOLATION AND FUNCTIONALITY OF GLIADIN AND HMW-GLUTENIN ENRICHED FRACTIONS

The amount of glutenin subunits of high molecular weight (HMW-glutenin s) appears to be closely related to breadmaking. The relationship of t heir specific functional properties and gluten quality has not been de monstrated. The difficulty in isolating non-denatured HMW-glutenins ex plains largely the lack of information. Investigations have been condu cted to isolate HMW-glutenins without using denaturing agents such as SDS or urea. Using wholemeal treated in mild reducing conditions with Na2SO3, the procedure uses solubilisation in hot aqueous ethanol with the subsequent specific precipitation of HMW-glutenins at low temperat ure. Proteins present in the various extracts were analysed by SDS-PAG E and reverse-phase HPLC. The HMW-glutenins were obtained by precipita tion at low temperature from ethanol extract (purification factor simi lar to 12), whereas the supernatant mainly contained gliadins and LMW- glutenins. After addition of these fractions to meal the modifications of the rheological properties of the resulting dough were investigate d. A model explaining the participation of the different fractions to the structure and the solubility of gluten is suggested. (C) 1998 Soci ety of Chemical Industry.