Role of Starch Granule Characteristics (volume fraction, rigidity, and fractal dimension) on Rheology of Starch Dispersions With and Without Amylose

The link between rheological behavior and morphological‐structural characteristics of gelatinized starch granules has been studied in two starch dispersions (SDs): a cross‐linked waxy maize (CLWM), and tapioca starch, a tuber starch with 19.3 % amylose. Based on the power law relationship between the elastic modulus and volume fraction of the granules predicted by scaling theory, fractal dimension values were obtained for CLWM starch D = 2.81, and tapioca starch D = 2.79, suggesting that both starch granules have highly convoluted surfaces. However, the preexponential coefficient ( G ′ ⊘=1 ) for CLWM SDs was an order of magnitude greater than that for tapioca SDs, in the same range of volume fractions. The G ′ ⊘=1 was mainly dependent on the granule rigidity, and the amylose content in the continuous phase played only a minor role in the rheological behavior.