Measurement of glass transition temperature by mechanical (DMTA), thermal (DSC and MDSC), water diffusion and density methods: A comparison study

Glass transition measured by DMTA from the change in slope in storage modulus was 55 °C, which was 10.5 °C lower than the value measured by tan δ peak. Initial glass transition measured by DSC, increased exponentially and reached a constant value of 55 °C at or higher heating rate of 30 °C/min. Transition temperature, measured by MDSC, remained constant up to heating rate 15 °C/min and then decreased. The glass transition values determined from reversible heat flow was 60 °C. The break in diffusivity and density (i.e. volume) was observed at 50 °C below the glass transition temperature measured by thermal and mechanical methods.

Measurement of glass transition is important in determining the stability of foods during storage. Glass transition can be measured by different methods. It is difficult to find any work which measured glass transition by five methods for a material to see their variations. This Letter presents results of five measurement methods and analyzed their variations with explanation based on physico-chemical reasons. Spaghetti was considered as a model system.