Random variability in product thermal properties combined with non-uniformity in the process environment can cause a distribution in product temperature at the end of a heating stage. This unwanted dispersion can affect the integrity and profitability of the operation. The dispersion can be quantified with the statistics of range, minimum or variance. This paper demonstrates how the magnitude of this dispersion is sensitive to the level of processing temperature that is employed. It explains and gives a criterion by which the process environment can be judged as being either uniform or non-uniform. Furthermore the paper demonstrates that using a certain processing time will minimize the variance in product temperature. Using a case study, involving the heat treatment of foods, the strategies that can be employed to control product temperature dispersion, through selection of the process temperature, are outlined.