Rheological properties of glutenin subfractions in relation to their molecular weight

Gluten extracted from defatted cv. Hereward flour was separated into five different fractions by sequential centrifugation and addition of sodium chloride. The fractions were investigated by dynamic light scattering (DLS), differential scanning calorimetry (DSC) and small deformation rheology. DLS showed a decrease in aggregate size for each subsequent Fraction. Rheology showed a clear transition around 40-50 degrees C, which was not, however, observed by DSC. Time-temperature superposition was possible for the rheological spectra of most fractions, and allowed characterisation of the gluten network in terms of the dynamic rheological spectrum as encountered in network-forming systems: terminal zone, plateau zone and transition zone. The general picture that emerged from our studies is that unheated glutenin fractions show viscous-like behaviour for small concatenations, and gel-like behaviour for larger concatenations. Aggregation occurs upon heating above 40-50 degrees C, which gives the small concatenations more gel-like properties. Therefore, the rheological behav can be related to the aggregate size within the subfraction. (C) 1997 Academic Press Limited.