Functional properties of wheat gliadins. II. Effects on dynamic rheological properties of wheat gluten

The effects of addition of purified total gliadin and its subgroups (alpha-, beta-, gamma- and omega-gliadins) on the dynamic rheology of gluten were investigated. The frequency sweeps of gluten with added alpha-, beta-, gamma-and omega2-gliadins showed unexpected increases in the magnitude of G' and G", suggesting stiffening of the native gluten. Conversely, a reduction in the magnitude of G' and G" occurred upon addition of the total gliadin fraction and the omega1-gliadin, implying softening of the gluten. Addition of individual gliadin fractions increased the values of slope log G' vs log frequency, suggesting increased concentrations of uncrossed-linked material compared with the native gluten. There were significant differences in the slope values for individual gliadin fractions. The increasing order of slopes for different gliadins was: beta- >gamma- >alpha- = omega1>omega2, indicating that glutens containing omega- and alpha- gliadins arc relatively less crossed-linked than those containing beta- and gamma-gliadins. The dynamic moduli, G' and G", of cv. Hereward gluten showed significant positive relationships with Mixograph parameter peak dough resistance (PDR), and loaf volume for gliadin subgroups added to cv. Hereward flour. (C) 2002 Elsevier Science Ltd.