CHARACTERIZATION OF RICE COOKING - ISOTHERMAL DIFFERENTIAL SCANNING CALORIMETRY INVESTIGATIONS

Isothermal calorimetry allows rice cooking to be simulated directly at various temperatures in excess water. The signal can be interpreted a s the sum of the thermal effect of the starch gelatinization, which ob eys first-order kinetics, and of a further process that can be tentati vely related to water diffusion. This effect is greatly reduced in gro und rice, as revealed by comparing the behaviour of whole and ground r ice samples. Determinations of water uptake seem to confirm this hypot hesis. The enthalpy of gelatinization drawn from these data can be mat ched with that from non-isothermal DSC investigations carried out at l ow heating rate (<0.5 degrees C min(-1)). Analogous results and conclu sions can be drawn from non-isothermal DSC investigations carried out on partially pregelatinized samples.