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Cheese Thermization

Overview

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

Disclaimers

  • Temperature must be taken at the coldest point of the system.
  • Milk must be stirred/agitated during thermization to ensure each particle is heated.
  • Time output is for hold time and does not include integrated lethality for come-up and cool down times.
  • Values are valid for bovine milk with typical fat content 5% fat or less. Milk of higher fat content may require greater thermization.
  • Data derived from D- and z-values from experiments Engstrom & Glass 2021, J. Dairy Science.


The Food Research Institute’s Cheese Thermization Software (the “Software”) is made available at no cost and provided “as is” as an informational reference for cheesemakers in connection with the University of Wisconsin-Madison’s education and outreach missions. The Software may give inaccurate results due to the insertion of inaccurate data by the user, by a technical error within the server at the moment of calculation, or other unforeseen circumstances. Users accept all risk associated with use of the Software, and remain responsible for compliance with all regulatory and other requirements related to their cheesemaking activities, including but not limited to all requirements related to food safety.

THE UNIVERSITY OF WISCONSIN-MADISON EXPRESSLY DISCLAIMS ANY AND ALL WARRANTIES IN CONNECTION WITH THE SOFTWARE, INCLUDING BUT NOT LIMITED TO WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, WARRANTIES OF MERCHANTABILITY, AND WARRANTIES OF NON-INFRINGEMENT.

By using the Software you acknowledge and agree to the foregoing and waive any and all claims of any kind and description against the Board of Regents of the University of Wisconsin System, its officers, employees and agents, in connection with your use of the Software and any decisions you may make as a result of using the Software.
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