SMALL-ANGLE NEUTRON-SCATTERING AND VISCOELASTICITY STUDY OF THE COLLOIDAL STRUCTURE OF AQUEOUS-SOLUTIONS AND GELS OF A GLOBULAR PROTEIN

Small-angle neutron scattering and viscoelasticity measurements were p erformed on beta-lactoglobulin solutions and heat-set gels at pH 9 and low ionic strength. The rheological properties of the solutions were characterized by antithixotropy and viscoelasticity. In the case of ag gregates and gels, a peak in the scattering curves was observed; q(max ) varied as C-0.5. This correlation peak vanished with increasing ioni c strength. The dilution of the aggregates showed that the correlation s were lost and that the aggregates displayed the same internal struct ure as the gels. Gels formed at low ionic strength indicated a liquid type viscoelastic behaviour. At high ionic strength, fractal structure s of the aggregates would be observed between 400 and 40 Angstrom with d(f) = 1.3 at low protein concentration and 1.75 at a higher concentr ation. Subsequent dilution did not change the fractal dimension of the se structures.