Glass Transition Temperatures Determined using a Temperature‐Cycling Differential Scanning Calorimeter

Abstract

ABSTRACT Glass transition temperatures, T g , of polystyrene, polyvinylpyrrolidone, polydextrose, gelatin, corn flakes, pasta, and aqueous glucose/glycine solutions were determined using a differential scanning calorimeter which cycled the temperature while the net temperature increased at a constant rate. Operating conditions of the modulated differential scanning calorimeter (tm) (MDSC (tm) ) for optimizing the endothermic baseline shift associated with the glass transition were a scan rate of 5°C/min with an amplitude of ± 1°C over a modulation period of 60 or 100 sec. The MDSC successfully separated the glass transition from other irreversible thermal changes in simple food ingredients. While the MDSC did not distinctly determine T g of complex food systems at low moisture contents, glass transitions were observed for solutions and food systems at higher moisture contents. T g values from MDSC were reproducible and similar to those from standard DSC.