Effect of Processing Conditions on Thermal Properties of Parboiled Rice

Abstract

Differential scanning calorimetry (DSC) was used to determine the thermal properties of parboiled rice, and these properties, i.e, gelatinization parameters, namely, peak temperature (Tp) and residual gelatinization enthalpy (ΔH) were evaluated. The Tp increased and ΔH decreased with increase in the severity of heat treatment during the parboiling process. The physical property of color value correlated positively with the Tp and the degree of starch gelatinization correlated positively with the hardness of the parboiled rice. The Tp, which represents half the conversion temperature of the sample melting, is believed to be a suitable indicator to identify the severity of heat treatment in the parboiling process. The quantitative Tp values of 77.4 to 79.2°C corresponding to the processing conditions of 90°C-30 min and 100°C-15 min are viewed as an index for better quality of the rice. The thermal properties thus can be utilized to understand the cooking behavior of parboiled rice.