A CALORIMETRIC INVESTIGATION OF THE INFLUENCE OF SUCROSE ON THE GELATINIZATION OF STARCH

The gelatinization of starch in the presence of low levels of water and high levels of sucrose was studied. The gelatinization temperature was found to increase in the presence of sucrose, whereas the gelatinization enthalpy was unaffected. The gelatinization temperature range was not as broad in the presence of sucrose as without sucrose. Furthermore, the shape of the gelatinization 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 although at a higher temperature. To obtain this change in the shape of endotherm more sucrose was needed for a waxymaize starch than for maize starch or potato starch. The effect of sucrose, thus, seemed to be both to restrict the gelatinization and to make the gelatinization occur more easily. The first effect (temperature) was related to the discussion in the literature on the glass transition of starch. The second effect (shape of the endotherm) may be due to a lower local viscosity in the presence of sucrose, resulting in a shorter time interval necessary for the transitions to occur.