Dielectric processes of wet and well-dried wheat starch

The influences on polymer dynamics due to the presence of water molecules in dried wheat starch were studied by means of dielectric relaxation spectroscopy. The dominant relaxation process in the low temperature range due to a local motion of chain segments via the glycosidic linkages largely affected by the introduction of water molecules. Two relaxation processes called as β- and βwet- in polymeric system in wet wheat starch were observed while no βwet-relaxation was observed in well-dried wheat starch. We observed a higher dc contribution in presence of water molecules in the system. The shape and the intensity of β-relaxation were largely affected by introducing excess water molecules in wheat starch (wet state) in comparison with well dried sample. The activation energy of β-relaxation was increased in wet sample. An excess transition was observed in wet sample at ca. 30 °C. Such transition may be an inter-crystalline transition.