Thermal Inactivation of the Heat-Resistant Pathogens <i>Salmonella</i> Senftenberg 775W and <i>Escherichia coli</i> AW1.7 in Whey Concentrate
2024
Gregor Fiedler | Stefan Nöbel | Sönke Matzen | Meike Samtlebe | Charles M. A. P. Franz
Pasteurized whey concentrate is used as a base for the production of ingredients for various food products. Whey concentrate (30% dry matter) was used to assess the thermal inactivation of <i>Salmonella</i> (<i>S.</i>) <i>enterica</i> serovar Senftenberg 775W (DSM 10062) and <i>Escherichia</i> (<i>E.</i>) <i>coli</i> AW1.7 (DSM 108612) strains in a pilot-scale pasteurizer mimicking industrial heat processing. These strains, chosen for their exceptional heat resistance, represent the most challenging scenario for pasteurization within the context of <i>S. enterica</i> and <i>E. coli</i>. Heat resistance was tested at temperatures of 56, 60, 64, 68, and 72 °C at an average holding time of 17.5 s. These exceptionally heat-resistant strains showed a relatively low reduction in numbers of between 0 and 4.2 log<sub>10</sub> CFU/mL at lower inactivation temperatures of ≤68 °C. A reduction of at least 5 log<sub>10</sub> CFU/mL, as required for adequate heat processing, was achieved for both species after heating at 72 °C for 17.5 s. This study shows that whey concentrate should not lead to contamination of food ingredients and can be considered safe after pasteurization at 72 °C for at least 17.5 s with respect to the pathogens tested.
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