Gelatinization kinetic of rice starch studied by non-isothermal calorimetric technique: influence of extraction method, water concentration and heating rate,

Different rice starch samples were obtained varying extraction solution, soaking temperature and length. Gelatinization properties were determined at different water concentrations by differential scanning calorimetry at constant heating rate, revealing no influence by the extraction parameters. Gelatinization kinetics were studied on starch extracted for 6 h with 0.2% NaOH, at 30°C with the aim of comparing some mathematical methods, in order to find whether this technique could be used to estimate the kinetic parameters. Activation energy and order of reaction were calculated at different water:starch ratios and heating rates, to partly simulate the wide variety of conditions for processes where starch gelatinization is involved. Water content influenced both gelatinization enthalpy and Ea, while heating rate influenced the temperature. Non-isothermal DSC was able to characterize the gelatinization process only if the kinetics of the process were already known, since all the tested models well fitted experimental data but gave quite different values of Ea.