Model of Retrogradation of Extruded Potato Starch

Starch pastes represent unstable systems which tend to retrograde during storage. Starch recrystallisation increases gel hardness and releases entrapped water. This causes undesirable changes in the stability and texture of the whole product. This study aims to analyze the degree and rate of retrogradation. In addition, an attempt is undertaken to fit a retrogradation model for pastes prepared from starches with various granule sizes and subjected to a single or double extrusion process. Pastes prepared from double-extruded starch are characterized by a lower degree of degradation compared to those made of non-extruded and single-extruded starches, and this decrease in degradation extent depends on extrusion process temperature. The degree of starch retrogradation in pastes increases along with greater diameters of starch granules. This is associated with granule size not only because of contents of amylose and amylopectin fractions in the granules but also because of the difference between their mean volumetric diameters.