Differential scanning calorimetry: gelatinisation of sago starch in the presence of sucrose and sodium chloride

The effect of sucrose and sodium chloride (NaCl) on sage starch gelatinisation was investigated by differential scanning calorimetry (DSC). The gelatinisation of starch in the presence of low levels of water and high levels of sucrose was studied. The gelatinisation temperature was found to increase in the presence of sucrose, whereas the gelatinisation enthalpy was unaffected. The gelatinisation temperature range was not as broad in the presence of sucrose as without sucrose. Furthermore, the shape of the gelatinisation endotherm was changed by the addition of sucrose. The double endotherm obtained in limited water-starch systems was changed into a single endotherm, similar to the endotherm obtained in excess water-starch systems at higher temperature. DSC was also used to examine the effects of water and NaCl content on the phase transitions of sage starch. Samples were adjusted to starch-water weight ratios of 2:3 and 3:2 in NaCl concentrations from 1 to 5 M. The gelatinisation temperature of sage starch increased and then decreased as the NaCl concentration increased. NaCl created similar effects on the endotherms with excess water content and on the first endotherm with limited water content. (C) 1999 Society of Chemical Industry.