Gelation and retrogradation of concentrated starch systems: 2. Retrogradation

Concentrated starch gels were prepared by heating starch suspensions at rest. Large deformation properties of these gels were studied by compressing cylindrical samples between parallel plates. It was observed that the properties of concentrated starch gels at large deformations depend on the age of the gels and the type of starch. The mechanical properties of the gels are related to their structure, consisting of partly swollen, irregularly shaped granules with a thin amylose matrix gel between them. Observed changes in the Young's modulus, and in the fracture stress and strain during storage are ascribed primarily to the increase in stiffness of the swollen granules. The rate at which the mechanical properties change during storage is at least partly affected by the number of entanglements between the starch molecules or the number of chemical cross-links present. © Oxford University Press.