Effects of moisture content, molecular weight, and crystallinity on the glass transition temperature of inulin

Effects of moisture content, molecular weight (MW), and crystallinity on the glass transition temperature (Tg) and freeze-concentrated glass-like transition temperature ( T ′ g ) of a fructan (inulin) were investigated using differential scanning calorimetry. The Tg of inulin samples decreased with increasing moisture content. The Tg of semi-crystal inulin was higher than that of amorphous inulin. These results were fitted to the Gordon–Taylor equation, and k values, reflecting the sensitivity to the water plasticizing effect, were obtained. The k value was plotted against anhydrous Tg, and the relationship of amorphous inulin was described with a linear function. Tg of anhydrous inulin samples and T ′ g of inulin–water mixtures increased with increasing MW, and the results were described empirically by a stretched exponential equation. These results will help to predict Tg and T ′ g of inulin, depending on the moisture content, MW, and crystallinity.