The Effect of Water Content on the Compaction Behaviour of Potato Starch

Abstract

AbstractThis study compares treatments of the compaction and stress transmission data obtained for potato starch at different water contents in the range 5‐25% (wet weight basis) compacted in a cylindrical geometry. An increase in water content leads to a greater density for a given pressure, approaching zero porosity at the higher water contents. The limiting gradient of the Heckel plot, which is the reciprocal of a generalised deformation stress, falls with increasing water content due to a plasticisation mechanism. Electron microscopy of granules taken from the compacts revelas greater plastic deformation at the higher water contents. The ratio of transmitted to applied stresses shows irregular variation with water content and degree of compaction. At the higher water contents (> 17%) the stress ratio is however relatively independent of compacted height as predicted by the classical semiparticulate analysis.