Glass transition temperatures of a ready to eat breakfast cereal formulation and its main components determined by DSC and DMTA

The effect of water content on the glass transition temperatures of a ready to eat cereal formulation was determined, as well as for its major components, oat flour, rice flour and an oat–rice flour blend, in the same ratio as they are present in the formulation. All samples were compression moulded at high temperature and were moisture conditioned in a 10–22% interval (dry basis). Glass transition temperatures (Tg) were measured by differential scanning calorimetry (DSC) and the main mechanical relaxation temperatures (Tα), measured by dynamic mechanical thermal analysis (DMTA). The relaxation temperatures taken at tan δ peaks, were found 20–30 °C larger than Tg. Besides the plasticizing effect of water adequately described by the Gordon–Taylor equation, no differences of Tg (and Tα) values between the major components were obtained at a constant moisture content. The Tg and Tα values of the RTE formulation were found to be about 30 °C lower than its components, a result which was attributed to the plasticizing effect of the minor components in the formulation (sugar and malt extract).