Structure and dynamics of ovalbumin gels .1. Gel induced by high-temperature heat treatment

Dynamic viscoelastic (DVE) measurements are made on seven ovalbumin (OVA) gel samples induced by thermal denaturation of aqueous suspensions of OVA with OVA concentration C ranging from 12 to 45 wt% at 160 degrees C for 5 min and subsequent moulding under pressure, and also on four OVA gels with higher C prepared by slow evaporation of water from the 45 wt% gel. The storage and loss shear moduli, G'(omega) and G ''(omega), of OVA gels with C in the range of 30-59 wt% show angular frequency omega dependence characteristic of the critical gel with the fractal structure, i.e. G'(omega) similar to G ''(omega) similar to omega '' and tan delta = tan(n pi/2) over the whole omega range of 0.14-100 rad s(-1) measured at three temperatures of 5.0, 25.0 and 45.0 degrees C. This finding is confirmed by shear creep and creep recovery measurements as well as dynamic light scattering measurements on the same gels. The critical gel structure, however, is not formed either for gels with C < 25 wt% or for gels with C > 59 wt%.