Relationship between Viscoelastic Properties and

This study continues the studies of Noosuk et al. to investigate the properties of four Thai rice starches with different amylose content published in Starch/Stärke (2003, 55, 337–344). The composition, gelatinisation behaviour and paste viscosity of these starches has been discussed previously. Here the amylopectin fine structure, amounts and size of the amylose are reported and discussed with reference to the viscoelastic behavior of the gels. The viscoelastic response was measured for 6 to 15 % (w/w) pastes (607C) and gels (257C) by oscillation (pastes and gels) and creep (gels). Visco-elasticitywas shownby all gels at concentrations.6%and the creep compliance could be represented by a four element Burger model. G ’ from oscillation, the instantaneous elastic modulus and Newtonian viscosity from creep, increased strongly with both starch and amylose concentration. Starch gels (30%, w/w) were monitored over 100 h, by Fourier Transform Infra Red spectroscopy (FTIR) and dynamic oscillatory rheology on storage at 257C. Changes were seen at similar rates, using the Avrami model, for the two high-amylose (.20%) samples, but not for the other starches. Development of crystallinity, at both 25 and 57C, was monitored by X-ray diffraction. Both the kinetics o