Theoretical consideration of the general validity of the Equivalent Point Method in thermal process evaluation

Abstract

The general validity of the Equivalent Point Method as an evaluation technique in thermal processing is considered. An analysis, based on analytical expressions for the impact of a heat treatment on food quality attributes indicates that the basic assumption of the methodology, i.e. a unique intersection point for a series of thermal reduction relationships, is only warranted theoretically for isothermal heating processes. Under time-variable temperature conditions, the difference between the impact on a target quality attribute calculated from the equivalent point and the impact evaluated directly from the temperature profile increases with increasing deviation from the isothermal heating. This conclusion is proven for process evaluation, based on both the Arrhenius concept and the Thermal Death Time model.