ISHS Acta Horticulturae 566: II International Symposium on Application of Modelling as an Innovative Technology in the Agri-Food Chain; MODEL-IT
A CFD STUDY ON THERMAL STERILIZATION OF FOOD IN POUCHES |
| Authors: | A.G. Abdul Ghani, M.M. Farid, X.D. Chen |
| Keywords: | temperature distribution; bacteria deactivation; vitamin destruction |
| Abstract:
The objective of this work is to analyze the process of thermal sterilization of liquid food in a three-dimensional pouch and to predict transient temperature, and concentrations of bacteria and vitamins profiles as heating progresses. The migration of the slowest heating zone (SHZ) during natural convection heating in a pouch heated from all sides was simulated and presented. Saturated steam at 121oC was assumed as the heating medium, and the model liquid (carrot-orange soup) was assumed to have constant properties except for the viscosity (temperature dependent) and density (Boussinesq approximation). The governing equations of continuity, momentum and energy equations were solved numerically, together with that of bacteria and vitamins concentration, as expressed by a reaction kinetics model. A computational fluid dynamics (CFD) code PHOENICS was used, which is based on finite volume method of solution. The results of the simulations showed that, natural convection plays an important role in the heat transfer within the liquid food in pouch, but less than what was found in cans, which is due to the small depth of the pouch. The SHZ was found to migrate toward the bottom of the pouch into a region within 30-40% of the pouch height, closest to its deepest end. Sterilization time was found shorter than that required for can having the same volume, which is attributed to the large surface area per unit volume of the pouch. The profiles of the relative bacteria and different vitamin concentrations were also found from the simulation, which maybe used to optimize the industrial sterilization process with respect to sterilization temperature and time. | |
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