The hygienic consequences of the temperature regimes experienced by perishable product during storage, transport, and display can be assessed by a temperature function integration technique. The technique requires the collection of appropriate temperature histories from product units moving through a process and integration of the histories with respect to suitable models which describe the dependency on temperature of the growth of bacteria of concern. The distributions of the proliferation values obtained are characteristic of each process. However, when the duration of a process is highly variable for individual units passing through it the fundamental characteristics of the process may be difficult to discern from proliferation data. Then, a storage efficiency factor can be calculated from a proliferation value and the duration of each temperature history, and the distributions of those factors used to assess and compare processes. Procedures for the collection and analysis of product temperature history data from product cooling, storage, distribution, and display processes, and the use of such data for process assessment are discussed.