Effect of the starch concentration on phase transitions of starch dispersions prepared with a glycerol solution or pure glycerol (original) (raw)

The objective of this work was to study, using a calorimetric method, the effect of the starch concentration on the phase properties of cassava starch dispersions, prepared using a glycerol solution and pure glycerol. Starch dispersions (SD) were prepared with 10-70 g of starch.100 g –1 of SD using either a 20% glycerol solution (GS) or pure glycerol (PG). These dispersions were analyzed with a differential scanning calorimeter. The water activity of these samples was also determined at 25 °C. At low temperatures the glass transition (Tg) was well defined in samples prepared with 10-50% of starch, but was not so for SDs with 70% starch, for both glycerol solutions. For SD prepared with GS, an increase in starch concentration from 10 to 70% caused a reduction in Tg, but for SD with 10-50% starch and prepared with PG, the Tg remained constant, increasing slightly for samples with 70% starch. This behaviour agreed with that of the water activity, which increased when the starch concent...