This application allows the user to determine the milk hold time and temperature necessary for log-reductions of 2 foodborne pathogens pertinent to cheeses made with unpasteurized bovine milk. Please read all disclaimers before use. Cheeses made using milk with higher fat or solids content (e.g. sheep’s milk) are outside the scope of this application. Use of time / temperatures treatments does not negate requirements for manufacturing cheeses under Good Manufacturing Practices.
Use the drop-down menus to select your bacteria of choice (Listeria monocytogenes or Shiga-toxin producing Escherichia coli) and your desired log-reduction of the chosen bacteria (3-, 4-, 5-, or 6-log kill). To make selections, hover over the “Bacteria” or “Reduction” field, click, and highlight your selection. Repeat for the second field.
A temperature range of 140°F to 155°F in whole degree increments is included in the application. To make selections for temperature, hover over the gray circle located at 140°F (by default). Click and hold the gray circle and slide it along the temperature axis, releasing when at your desired temperature . Alternatively, click a temperature along the axis to select. Outputs to the right of the application (“Hold Time”, in seconds, and log-reduction of unselected pathogen) will change in real-time according to the temperature selected.
E.g. Selecting Shiga-toxin producing Escherichia coli and 3-log kill requires a hold time of 22 seconds at 150°F; a 1.25-log reduction of Listeria monocytogenes is anticipated with this same treatment.
For additional information, please reference Determination and Validation of D-Values for Listeria monocytogenes and Shiga Toxin-Producing Escherichia coli in Cheesemilk, Journal of Dairy Science, 2021, https://doi.org/10.3168/jds.2021-20350 by S. K. Engstrom, M. F. Mays, and K. A. Glass.
This research was funded by the National Dairy Council, the Robert H. and Carol L. Deibel Distinguished Graduate Fellowship in Food Safety Research (University of Wisconsin–Madison), and by unrestricted gifts from the industry to the Food Research Institute, University of Wisconsin–Madison