The time evolution of the dynamics of globular protein during the gelation process via aggregation has been studied by time-resolved dynamic light scattering (DLS) for beta-lactoglobulin (beta-LG) in aqueous solutions at pH 2 and 7. The following facts were disclosed: (1) The scattered intensity, QT, started to fluctuate, and the intensity-time correlation function (ITCF) exhibited a power-law behavior (g((2))(tau) - 1 similar to tau(alpha-1)) at the gelation threshold, t(th). (2) The variations of [I](T)'s were different between the two pHs, a gradual increase for pH 2 and a stepwise increase followed by a plateau for pH 7. (3) The exponent a was found to be strongly dependent on pH. The values of a were 0.51 +/- 0.05 for pH 2 and 0.74 +/- 0.05 for pH 7. (4) A strong concentration and pH dependence of t(th) was also observed in both cases. These findings indicate that beta-LG gels formed at pH 2 and pH 7 have different architectures, i.e., loosely tied networks (for pH 2) and fractal aggregates (for pH 7) of protein molecules.