Mathematical modeling and thermodynamic properties of rice parboiling

Abstract

Due 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 applications This 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.

Modeling of maceration step of the oat (Avena sativa) malting process

“…Also, there is the energy used to transport water inside oats, which can be associated to the Gibbs free energy (energy needed to perform work). The positive values of Gibbs free energy showed that the maceration of oats is not a spontaneous process, but is influenced by temperature, corroborating with the results obtained in process of hydration of soybean (Borges et al, ) and rice (Balbinoti et al, ).…”

“…The activation energy (E a ) represents the energy required to occur the diffusive mass transfer process during the hydration process. The E a (10-35 C; Table 3) for oat hydration was 17.88 kJÁmol −1 , lower than that found for wheat (Mattioda et al, 2018) and rice (Balbinoti, Jorge, & Jorge, 2018a). However, it was an expected result since some cereals may present different sizes and composition.…”

“…However, it was an expected result since some cereals may present different sizes and composition. The values of enthalpy and entropy (Table 3) increased with temperature rise, as showed in the study of parboiling rice process (Balbinoti et al, 2018a). These phenomena occurred due to the increase in the energy provided by molecular agitation and increase diffusion of water into the grain.…”

Modelling the physical properties change of canned glutinous rice porridge during cooking

“…And the study of the thermodynamic properties made it possible to understand the different forms of energies and phenomena involved in this process. 6 Therefore, in this context, the change tendencies of the moisture content and the hardness of the rice kernels, and shear viscosity of rice porridge during the cooking process at different temperature are investigated. In addition, the exponential models or sigmoidal models are tted to experimental data.…”

Oat hydration kinetics at different temperatures: Evaluation, model, and validation

“…The hydration behavior of grains have been studied and their kinetics mathematically described in several studies to predict the moisture uptake of different grains at different temperatures, such as rice (Balbinoti, Jorge, & Jorge, 2018); sorghum (Kashiri, Daraei Garmakhany, & Dehghani, 2012); wheat (Kashaninejad, Dehghani, & Kashiri, 2009); adzuki beans (Oliveira et al, 2013), among others (Miano, Sabadoti, Pereira, & Augusto, 2017). The hydration studies, however, were mostly conducted at isothermal conditions.…”