Fig. 5.

Survival (log CFU/ml) of exponentially growing cells in UHT-processed whole milk after 15 s at 72°C for Listeria monocytogenes LO28 wild type and 10 isolated heat-resistant variants. For LO28 WT, no cells could be detected after the heat treatment (n.d.). The first 7 heat-resistant variants are the ctsR variants. The dotted line indicates the initial level of cells (9 log CFU/ml). The solid line shows the standard 5 log reduction after 15 s at 72°C as used in the industry and advised by the FDA. Each inactivation experiment was conducted at least two times on different days. The error bars show one standard deviation. Results in white bars are statistically different from the results for the wild type.