Technical Abstract: Inactivation rates of a cocktail of Salmonella spp. in sous-vide cooked beef exposed to varied heating rates of 1 to 3 h from 10 C to the process- ing temperature of 58 C were determined. The primary thermotolerance response of the organism, as a result of increasing cooking times to the target temperature, was a switch to non-linear inactivation kinetics, resulting in the presence of shoulders (lag time) in the survival curves. From the survival curves obtained in this study, values for two parameters: the asymptotic D-value and the "lag" time, were estimated. The computa- tions for the non-linear curves suggested that the treatment affects the initial cell resistance (lag time), but that once this initial period is past, the heat resistance, as measured by the asymptotic D-value, is not affected by rate of cooking. At 58 C, the asymptotic D-value was estimated to be between 5.2-7.4 minutes. These findings should have substantial practical importance to food processors in sous-vide cooked beef that are processed by slow heating rate/long come-up times and low heating temperatures.