EFFECT OF SHEAR ON THE NEMATIC MESOPHASE OF THE WHEAT STORAGE PROTEIN A‐GLIADIN

The nematic mesophase of A‐gliadin exhibits rheopectic properties under oscillatory shear but not under unidirectional shear. The solutions change from a viscous sol to a stable gel after 28 cycles of oscillatory shear at 0.17 Hz, 22°C. The interaction energy between A‐gliadin fibrils is estimated as 10.2 Kcal mole below 35°C and 6.25 Kcal/mole above 35°C with the change in interaction energy coinciding with a known change in the tertiary structure of the molecule. It is suggested that the different response of the solutions to oscillatory shear versus unidirectional shear results from the asymmetric tactoids present in the solutions and that any system which forms nematic tactoidal solutions would exhibit similar properties.