Computational fluid dynamics analysis on natural convective heating of bottled liquid food during pasteurization: Effect of container orientation

Abstract

The aim of this work was to determine natural convective heat transfer rates in bottled liquid food pasteurized using different container orientations; conventional vertical, inverted vertical, and horizontal bottle positions. For this purpose, a computational fluid dynamic (CFD) model was applied to predict the temperature distribution, flow pattern, and quality changes in non-Newtonian fluid foods for three orientations. The numerically predicted temperatures were successfully validated against experimental data and the model allowed to identify the critical point during the thermal process. Results showed that the fluid flow developed in a horizontal orientation provided a better mixing of liquid food and, hence, a more rapid heating of the slowest heating zone compared to a vertical position. Moreover, the horizontal orientation achieved a 47.2% reduction of processing time and quality losses decreased (45.5–46.4%) with respect to a vertical position. These results suggest that a horizontal position could be considered as an interesting alternative for food processors since processing times can be reduced improving the final quality of the product. Practical Applications: Pasteurization is a heat treatment process applied to a food product with the purpose of destroying disease-producing microorganisms, inactivating spoilage-causing enzymes, and reducing spoilage microorganisms. Overcooking causes detrimental effects in terms of the final product quality. Therefore, providing an adequate process with a desired sterility is one of the challenges to canning industry. In this work, we investigate how to improve, through container orientation modification, the natural convective heat transfer rates during pasteurization of fluid food. These results were obtained by the numerical simulation of the thermal process using CFD analysis which allowed to determine the temperature history and velocity field in the bottled liquid food. From the numerical results, the set of operating conditions that enhance the quality and the safety of the final product was determined, thus minimizing expensive and time-consuming pilot test-runs.