Fractal analysis of the elasticity of BSA and beta-lactoglobulin gels

The fractal structure of aggregates in heat-induced BSA and beta-lactoglobulin gels prepared with and without CaCl2 was examined. From the concentration dependence of the gel elasticity determined from a uniaxial compression test of the gel, the fractal dimensions D-f of the aggregates in the gels were evaluated, using the theory of Shih et al. It was confirmed that the gels with and without CaCl2 showed weak- and strong-link behavior, as defined in the theory of Shih et al., respectively. The obtained values of D-f were about 2 for strong-link gels and about 2.7 for weak-link gels. In addition, for the beta-lactoglobulin gels containing CaCl2 (weak-link type), from the analysis of the gel image obtained with confocal scanning laser microscopy of the gels, the fractal dimensions were also evaluated, the value being close to that found from the gel elasticity measurements. These results indicate that the elastic behavior of the aggregate gels is a reflection of the fractal structure of the aggregates in the gels.