Glass transition temperature of starch studied by a high-speed DSC

The glass transition temperature (Tg) of corn starch was measured using a high-speed DSC with heating rate up to 250 °C/min. The high heating rate allows the weak Tg of starch to be visible since the high rate increases the sensitivity of thermal events. For example, the Tg of gelatinized corn starch containing about 13% moisture is too weak to be detected when the heating rate is lower than 50 °C/min, but is clearly visible when the heating rate is higher than 100 °C/min. Specifically, the technique was used to study the Tg of corn starch film with different moisture contents. The true Tg was calculated by the linear regression equation through plotting the results from different heating rates.