Temperature evolution inside liquids during reciprocal agitated processing: influence of food matrix rheology on thermal inactivation

The influence of food product viscosity on the temperature evolution inside distilled water and a high-viscosity liquid food model system during agitated retort processing (i.e., Shaka process) was investigated by simulations via a previously developed mathematical model. On the one hand, the volume average temperature increased at a faster rate in the high-viscosity liquid than in the water due to its lower specific heat. On the other hand, temperature distribution was rather uniform in the water, while a significant heterogeneity was observed in the high-viscosity liquid. Since significant thermal inactivation of bacteria occurs in local high- temperature zones, it would be beneficial to take simulated temperature profiles into account for bacterial inactivation predictions in future studies.