|Bietz, Jerold - RETIRED (USDA-ARS-NCAUR)|
Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2000
Publication Date: N/A
Technical Abstract: The linear rheological properties of vital wheat gliadin suspensions were investigated. Semi-concentrated to concentrated gliadin suspensions were studied from 150 mg/ml to 350 mg/ml. Below 300 mg/ml, within the measured frequency range of 0.001 to 1000 rad/s, the loss moduli (G") of gliadin suspensions were higher than the storage moduli (G') and no plateau observed. At 150 mg/ml, the storage moduli (G') of the gliadin were in the range of 0.002-20 dyne/cm**2 and phase shifts were 64-83 deg. This indicated that at 150 mg/ml or below, gliadin's elasticity was very weak and its properties exhibited close to a viscous fluid. Above 150 mg/ml up to below 300 mg/ml, G" were still greater than G' at the range of the measured frequencies. The values of the moduli increased with the increase of the concentrations. However, at 300 mg/ml and above, G' became higher than G" at lower frequencies and there was a plateau of moduli. The phase shifts were in the range of 28-53 deg. This means that above 300 mg/ml wheat gliadin suspensions became viscoelastic fluid. Over a narrow concentration range (250 mg/ml to 300 mg/ml), the properties of gliadin suspensions dramatically changed from viscous to viscoelastic. These results are indicative of structure transition between 250 mg/ml and 300 mg/ml of gliadin suspensions. This transition is coincident with the property shift of gluten suspensions in the same concentration range.