The Cooling and Freezing of Parallelepiped-Shaped Solid: Foundations and Application to Food Product

Abstract

Freezing is a physical treatment commonly used in operations such as drying, conservation and lyophilization of foods. In the processing and potato industries, parameters like dimension and initial moisture content of the product has a great effect on the cooling, freezing and post-freezing kinetics. Therefore, this work presents a transient three-dimensional mathematical modeling including phase change to describe the heat transfer during the process, of cooling and freezing parallelepiped foods. The governing equation was solved numerically using the finite-volume technique and a full implicit formulation. As an application, this methodology was used to describe the freezing process of potato (french-fry). Numerical results of the temperature in the center of the product were compared to the experimental data reported in the literature and a good agreement was obtained. Results of the temperature distribution inside the solid and cooling, freezing and post-freezing kinetics are presented and analyzed. It was verified that, the smaller the dimensions and lower the initial moisture content of the product, the solidification of water inside the solid occurs even faster. The largest temperature gradients were identified in the surface, close to the regions of the borders of the solid.