Submitted to: International Gluten Workshop
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 2003
Publication Date: September 10, 2003
Citation: Xu, J., Bietz, J.A., Carriere, C.J. 2003. The viscoelastic properties of vital wheat gliadin and glutenin suspensions [abstract]. International Gluten Workshop. p.168. Technical Abstract: An investigation was undertaken to study the linear and non-linear rheological properties of wheat gliadin and glutenin suspensions. Gliadin suspensions were examined over a range of 150 mg/ml to 350 mg/ml. Below 250 mg/ml and over the measured frequency range of 0.001 to 100 rad/s, the loss moduli (G") of gliadin suspensions were higher than the storage moduli (G') and a plateau was not observed. At 150 mg/ml, G' of the gliadin suspensions were in the range of 0.0002 - 2 Pa and phase shifts were 64 - 83 degrees over the measured frequency range. Above 150 mg/ml up to 250 mg/ml, G" were still greater than G' at the range of the measured frequencies. The values of the moduli increased with the increasing of concentration. This indicated that at 250 mg/ml or below, gliadin suspensions exhibited more viscous properties. However, at 300 mg/ml, G' became higher than G" at lower frequencies and G' exhibited a plateau over the frequency range for 0.001 to 0.01 rad/s. The phase shifts were in the range of 28 - 53 degrees indicating more viscoelastic behavior. These results imply a structure transition between 250 mg/ml and 300 mg/ml of the gliadin suspensions. This transition is coincident with the property shift of gluten suspensions reported earlier. These results also show that gliadin plays important role for the adjustment of the viscoelastic properties of gluten. The glutenin suspensions exhibited strong viscoelastic solid behavior at all measured concentrations. G' had a plateau over the frequency range of 0.001 to 10 rad/s, and G' were greater than G" at all the measured frequencies. The phase shifts were in the same range of 4 - 43 degrees. At 0.1 rad/s, G' of the 100 mg/ml glutenin suspension was 2.5 Pa; while G' of the 150, 200, and 250 mg/ml glutenin suspensions increased to 7.5, 35 and 85 Pa respectively. These results suggested that the glutenin suspensions exhibit more solid-like properties as the concentration increases. The non-linear steady shear measurements of gliadin suspensions exhibited shearing thinning behavior over the shear rate range of 0.001 to 1000 s-1; while glutenin suspensions displayed shear thickening at the lower shear rates between 0.001 to 0.004 s-1 and shear thinning properties at the higher shear rates.