CHARACTERIZATION OF GLUTEN SUBFRACTIONS BY SE-HPLC AND DYNAMIC RHEOLOGICAL ANALYSIS IN SHEAR

Gluten extracted from defatted flour of the wheat cultivar Aubaine was fractionated by sequential extraction with increasing concentrations of dilute hydrochloric acid, providing 12 fractions in total with different proportions of gliadin and glutenin. The protein compositions and polymer characteristics of these fractions were determined by SDS-PAGE and SE-HPLC on Superose 6, respectively. The SE-HPLC patterns of the fractions showed that they differed in their gliadin-glutenin ratios but also in the size distribution of the glutenin polymers. The rheological behaviour of the fractions was analysed by dynamic assay in shear and was found to be typical of transient network structure. Very large differences in storage and loss moduli were observed between the fractions. A very strong correlation was observed between the plateau modulus and the proportion of the largest glutenin polymers (excluded SE-HPLC peak) in the fractions. Glutenin viscoelasticity is determined primarily by the interactions of large concatenations formed by high and low M(r) glutenin subunits.