DETERMINATION OF THE TEMPERATURE OF GELATINIZATION AND ENERGY OF TRANSFORMATION OF STARCH BY DIELECTRIC DISSIPATION INDUCED CHANGES

In this work we present a new method which allows to determine the str uctural changes of starches subjected to a thermal process. Using that method, the initial and final gelatinization temperatures and the amo unt of energy required to induce the thermal changes can be deduced. T he method takes the advantage of the dielectric dissipation of electri cal energy in the system consisting of a mixture of starch grains and water enclosed in a specially designed sealed cell. AC electrical powe r at a fixed voltage and frequency is applied to the material to be st udied. The magnitude of the electric current is then monitored as the temperature is raised (by Joule effect) up to temperatures of 120 degr ees C. The plots of the electric current Vs temperature in all the sam ples studied yield two distinct extreme values: the onset and the endi ng temperatures of the gelatinization of the processed samples. Analyz ing the current Vs time plots during the gelatinization of starch, we are able to determine the energy required for the transformation proce ss. The method as such, demonstrates to be a useful technique to deter mine the basic parameters during starch gelatinization and it is much simpler then those known in the field.