Thermophysical properties of cassava during its cooling: Experiment, determination by inverse method, and simulation

Abstract

Minimal processing consists in eliminating inedible parts of agricultural products, through cutting, reducing them to smaller portions, ready for immediate consumption or subsequent preparation. Despite the practicality, this resource is responsible for the first physical alterations in the tissues of food, contributing to its perishability.However, cooling of minimally processed products increases their shelf life. Designing refrigerators and calculating the costs of cooling require that the thermophysical properties of the product be known, making it possible to describe its cooling kinetics. The objective of this study was to present a methodology that includes experimental data and two computer programs for determining these properties referring to cylindrical pieces of cassava. A solver with the solution of the two-dimensional diffusion equation was created for the direct problem, assuming the boundary condition of the third kind. For the inverse problem, an experimental data set of temperature in the center of the cassava pieces during cooling, the solver, and LS Optimizer software were used. The values obtained for thermophysical properties were consistent with those reported in the literature, while the cooling simulation was consistent with the experimental data, with χ 2 = 1.7588 and R 2 = 0.9992. Practical ApplicationsThe main contribution of this article is to present a methodology to determine thermophysical properties of agricultural products, including the uncertainties of these properties, during their cooling. This is a transient process, involving an interval of temperatures, and not one constant temperature, within which thermal properties are usually determined. With the information obtained for the thermal properties of cassava pieces, one can design an efficient refrigerator for the product and reliably calculate the cost for cooling the product during its minimal processing.

Impact of ultrasound pretreatment on banana chip production by convective drying using hot air: Consideration of shrinkage and variable effective mass diffusivity in the process description

“…Classically, the diffusion model based on Fick's second law of diffusion (Crank, 1975) has been applied to explain different types of processes, such as cooling (da Silva et al, 2023; Santos et al, 2022), heating (da Silva et al, 2022), osmotic dehydration (da Silva, de Farias Aires, et al, 2014; da Silva, e Silva, Lins, et al, 2014; Ferreira, Castro, et al, 2020), phytochemical extraction (da Silva et al, 2018), moisture absorption (Pereira et al, 2022), and food drying by moisture gradients (Lima et al, 2022; Pereira et al, 2023; Silva et al, 2008; Srikiatden & Roberts, 2007). Regarding drying, according to the diffusion model, the difference in moisture content within the product is the driving force for moisture transfer (Bird et al, 2001; Crank, 1975; Moran & Higgins, 1970).…”