CFD Simulation of Heat Conduction in Curry Paste during Sterilization

Abstract

Curry paste is a popular food product in Thailand, made of many fresh and dry spices that are finely ground to a solid-like homogeneous blend. The four types of curry paste KangSom (KS), GreenCurry (GC), PadPed (PP) and MasMan (MM) were used as 100 g samples in glass bottles. A water-spray with pressure-balance retort was run at 116°C to thermally sterilize by eliminating pathogenic microorganisms, and to extend the shelf-life of curry paste. Time profile of temperature at the slowest heating zone (SHZ) during thermal treatment is important for estimating the sterilization value (F0). A high quality mesh discretization was use in numerical simulations. This study used CFD simulations of heat conduction in curry paste during sterilization to get the SHZ(sim), which was compared with the experimental SHZ(exp). Thermal diffusivity (α) of each curry paste was adjusted for best fit of SHZ(sim) with SHZ(exp) according to the coefficient of determination R². The results were for KS (α=1.55x10^-7 m²/s, R²=0.9990), GC (α=1.55x10^-7 m²/s, R²=0.9989), PP (α=1.65x10^-7 m²/s, R²=0.9996) and MM (α=1.45x10^-7 m²/s, R²=0.9993). The sterilization values F0(sim) from simulation and F0(exp) from experiments were approximately equal, and so were the processing times required. In summary, CFD simulation of heat conduction can be used to describe the heat transfer in an actual food product that is solid-like and homogeneous. This study can be used as a template for guiding thermal process design by numerical simulations.