2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Quantitative contributions of glutenin subunits to the viscoelastic behavior of wheat starch-protein systems could improve our understanding of these important functional polypeptides. The influence of glutenin (0.5-4%) extracted from hard red winter wheat, Jagger cv, flour on the dynamic rheological properties of wheat starch dispersions (3-6%) were studied. The starch/glutenin mixtures were preheated in a water bath for 5 min at 70°C before loaded on the Rheometer. Storage modulus (G'), loss modulus (G"), loss tangent delta(d) and complex viscosity (n*) were recorded on a small deformation oscillation test with temperature ramps during heating (60-90°C) and cooling (90-25°C). When glutenin extract was added to starch slurries, the elastic behavior G' increased 5 to 90 times and tan delta(d) decreased up to 9 times after heating and cooling, compared to starch alone. G' of 4 to 6% starch increased up to several thousand times compared to the G' of 3% starch after cooling. Tan delta(d) of 3% starch (1.26) and 4% starch (1.44) described a more viscous behavior compared to 3% starch + 4% glutenin (0.16), 4% starch +1% glutenin (0.16), 5% starch (0.14), or 6% starch slurries (0.09). Small tan delta(d) indicated a decreased energy loss per cycle and more structured and/or elastic gels formed after heating and cooling. The results suggests that the wider range of G' offers more flexibility in interpreting structural contributions of glutenin-starch interactions.