Tracer microrheology of γ-dodecalactone induced gelation of aqueous starch dispersions

We have studied the rheological properties of the natural biopolymer system starch in the presence of the gelation inducing flavor compound γ-dodecalactone. From optical microrheology, based on the multiple scattering of laser light (DWS), we deduce the frequency-dependent moduli G′(ω) and G″(ω) of the gelling sample over the full frequency range. Our measurements demonstrate the inherent advantages of optical microrheology over classical mechanical experiments such as non-invasive sample access, extremely fast data acquisition time and an extended range of accessible frequencies. This enables us to study the critical power law scaling of G′(ω) and G″(ω) of these weak physical gels in a single experimental run despite the fact that the gelation time is only of the order of a few minutes.