The University of Wisconsin-Madison Meat Science & Animal Biologics Discovery (MSABD) team is rolling out the Hydrated Surface Lethality (HSL) Calculator.  

Developed by Dr. Jeff Sindelar’s research group at UW-Madison MSABD, the web-based HSL tool enables processors, food safety professionals and regulators the ability to input time–temperature data collected from a thermal process, apply validated D- and z-values to estimate process lethality at the surface and the core of a product, and generate an integrated report to confirm a process achieves the required log reduction for the microorganism of concern.  Internal/core lethality determination is based on the highly regarded and longtime used Meat Institute Foundation’s Process Lethality Spreadsheet. 

Surface lethality is calculated with a similar approach following the premise that pathogenic bacteria are destroyed when the surface is wet (aka. hydrated) and when lethal temperatures exist.  

The HSL tool supports several critical industry needs including providing a transparent, science-based method for evaluating whether a given process delivers sufficient lethality and an alternative approach to the humidity options listed in USDA, FSIS Appendix A.  It can also be used to help identify gaps in marginal processes before they become regulatory or food safety concerns.

The HSL calculator, along with “how to” instructions (written and video format) can be found at https://meatsciences.cals.wisc.edu/hsl-calculator/ and is free to use.

Source: University of Wisconsin-Madison Meat Science & Animal Biologics Discovery