This study presented the effect of heating temperature on the biochemical changes during thermal sterilization of concentrated cherry juice. Natural convection heating of a viscous liquid (concentrated cherry juice 74° Brix) in a cylindrical can heating from all sides has been simulated and analyzed. The governing equations are solved numerically together with the concentration equations of bacteria and Vitamin C, using the Computational Fluid Dynamics CFD code PHOENICS. Arrhenius equation is introduced to the existing software package using a FORTRAN code to describe the biochemical changes kinetics. The model liquid is assumed to have constant properties except for the viscosity (temperature dependent) and density (Boussinesq approximation). The simulations highlight the formation of the slowest heating zone (SHZ) resulted from different periods of heating. The results showed that the SHZ covers the whole cross sectional area of the can at early stages of heating then migrates during heating and settles at the bottom of the can. The simulation also shows the formation of secondary flow due to the reverse flow, which in turn affect on the shape of the SHZ. It also shows the dependency of the concentration of live bacteria and Vitamin C on both temperature distribution and flow pattern.
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