During hydrothermal treatment of starch suspension, the starch granules swell with kinetics depending on temperature evolution. Variability of swelling characteristics between starch granules was also observed. A semi-mechanistic and semistochastic model for individual starch granule swelling was developed and coupled with a discrete element (DEM) model. The DEM model takes into account the normal elastic forces exerted between the granules when they come in contact and optimally occupy the available volume. The evolution of particle volume fractions, size dispersion, the fraction of overlap volume and elastic energy per unit volume were analysed in the case of chemically modified waxy maize starch. It appears that for this particular starch all the jamming indicators increase rapidly for a volume fraction of about 0.65.