PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Soaking is a crucial step in the parboiling process that directly impacts the overall quality of parboiled rice. The aim of this study was to investigate the impact of soaking time and temperature on the kinetics of colour, dimensions, and hardness of parboiled rice MR297. In this study, MR297 paddy was soaked at different temperatures (50 °C, 60 °C, and 70 °C) for 1, 2, 3, 4, and 5 hours. Kinetic models assessed for quality changes in parboiled rice included the zero-order, first-order, and second-order models. The data showed that the total colour change (6.95–15.09), chroma (30.46–36.94), browning index (61.59–90.05), length (9.61–10.38 mm), width (2.06–2.37 mm), and thickness (1.80–2.11 mm) increased. Whereas the Hue angle (77.21–74.14) and hardness (3576.61–3167.4) decreased as the temperature (50 °C–70 °C) and time (1–5 hours) of soaking increased. The alterations in colour, dimensions, and hardness were satisfactorily explained by the kinetic models (zero, first, and second-order). Most of the reaction rate constant (k) of the change greatly depended on the soaking temperature. The kinetic models for colour (total colour change, chroma, hue, and browning index), dimensional (length, width, and thickness), and hardness alterations followed the Arrhenius equation. Hence, the fitted kinetic models of the quality alteration can be employed to forecast the immersion procedure of parboiled rice MR297. The significance of this study lies in providing predictive models that can optimise the parboiling process for the MR297 rice variety, enabling producers to better control product quality while potentially reducing processing time and energy consumption. These findings contribute to the scientific understanding of rice parboiling and can be valuable for industrial applications in the rice processing industry.