Mathematical modeling and thermodynamic properties of rice parboiling

Abstract

AbstractDue to the importance of hydration stage for parboiling, related studies are insufficiently addressed in the literature. The objective of this study was to model the moisture absorption kinetics of paddy rice, as well as estimate the thermodynamic properties involved in the hydration. The observed mass transfer in the process was directly influenced by the temperature of the system, showing changes in absorption capacity over time. The models addressed allowed satisfactorily describing the moisture gain under various thermal conditions. Particularly, the model based on Fick's second law best represented the experimental data. The effective diffusion coefficient was adjusted to an Arrhenius equation and a new model was generated, capable of describing hydration. The coefficient presented positive dependence with the temperature increase and allowed the determination of different forms of process energy. It was concluded that the hydration of the rice in the parboiling process is nonspontaneous and exothermic.Practical applicationsThis study allowed characterizing the moisture transfer in the hydration stage of the parboiling process, exploring the time and temperature relationship. From these data, mathematical modeling was used as a quality tool, guaranteeing for the parboiling industries control and optimization of the process in a cheap and easy way. In addition, this study presented relevant information on the thermodynamic properties, which made it possible to understand the different forms of energies and phenomena involved. This information can help, in a practical way, in the elaboration of industrial projects aimed at the parboiling of rice.