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Comparison of creep recovery test from gluten and dough: Effects of HMW-GS composition
Z. HERNÁNDEZ ESTRADA (1), P. Rayas-Duarte (1), J. Figueroa Cárdenas (2) (1) Oklahoma State University, Stillwater, OK, U.S.A.; (2) Cinvestav, Querétaro, Querétaro, Mexico.

Effects of high molecular weight glutenin subunits (HMW-GS) on gluten and dough rheology, as well as mixing, extensibility and bread-making parameters of 19 hard red winter wheat flours were studied. Viscoelasticity was evaluated by creep recovery test using rheometer, with parallel plate geometry, 100 Pa of shear stress was imposed and holding by 100 sec, recovery also recorded by 100 sec. Data was fitted to a 6-element Kelvin-Voigt model (<i>R</i>2=0.99). <i>Glu-D1</i> 5+10 samples had higher loaf volume, resistance to extensibility and values of elastic moduli and viscosity coefficients compared with 2+12. Differences in elasticity <i>G1</i> or <i>G2 </i>and viscosity <i>?1 </i>or <i>?2</i> by glutenins attributed to entanglement of short-chain and large-chain sizes, respectively were correlated with quality. Also, <i>?2</i> explained more the variability in loaf volume, as indicated by <i>r</i>=0.57; <i>P</i><0.0001 compared to <i>?1</i> <i>r</i>=0.45; <i>P</i><0.01 in gluten. Elastic moduli <i>G1</i> and <i>G2</i> showed differences among poor and good quality samples. Gluten samples were on average 5.5, 3.1 and 1.6 times less stiff than their respective dough when comparing <i>G0</i>, <i>G1</i> and <i>G2</i>, respectively. These differences suggest that the non-gluten components have high influence in the instantaneous and first Kelvin elements of the model and they are manifested faster compared to gluten components.