These **Excel*** workbooks simulate the diminishing survival ratio of targeted bacterial spores during a heat process intended for their elimination **in real time**. These versions of the program simulate the inactivation of spores whose isothermal survival curve follows the **Weibull** (power law) model with a fixed shape factor (power), **n**, and where the temperature dependence of the survival rate parameter, **b(Temp)**, obeys a log logistic relationship. (Explanation of the model can be found in Peleg, M. 2003. (see **References** below). For more information on the concept, its various applications in calculating the efficacy of thermal and non-thermal microbial inactivation processes and biochemical reaction kinetics and its implementation with more complicated survival models, contact Micha Peleg at: http://people.umass.edu/~aew2000/

* Excel is a registered trademark of Microsoft Corporation. You can get more information about Excel by visiting Microsoft's web site at: http://www.microsoft.com/

The demonstration workbooks are available in a file format for Windows Excel 97 through 2007 and MacOS Excel 98 through 2004. If you have a modern web browser you should be able to download a binary Excel file directly by clicking on one of the links below.

Excel binary file (144K) for Windows Excel 97 through 2007 and MacOS Excel 98 through 2004:

Excel binary file (136K) for Windows Excel 97 through 2007 and MacOS Excel 98 through 2004:

Excel binary file (180K) for Windows Excel 97 through 2007 and MacOS Excel 98 through 2004:

Excel binary file (172K) for Windows Excel 97 through 2007 and MacOS Excel 98 through 2004:

Note: Earlier versions were posted here on the web. The first version (dated April 22, 2004) was distributed on CD to Strategic Research Alliance members in May 2004. The February 21, 2006 versions allowed a wider range of values for model parameters **n** and **k** to be used without generation of a runtime error. They also contained other bug fixes, Visual Basic code improvements and pop-up comment note updates. The February 4, 2008 versions add compatibility with Windows Excel 2007 and update several comment notes.

If you have Microsoft Excel installed on your hard drive, you should be able to open either the **RealTimeSterilization.xls** or **RealTimeSterilizationData.xls** workbook file in Excel by double-clicking on its icon. If that doesn't work, open the workbook file by first starting Excel, choosing **Open...** from the **File** menu and then selecting the Excel file that was downloaded and saved on your hard disk. If the file does not appear on the list of file names, set the **Files of type:** pop-up menu to **All Files (*.*)** then select and open the file. If you were unable to open the file by double-clicking on it, use the alternate method just described to open it and once the file has opened in Excel you should immediately save it by choosing **Save** from the **File** menu. This will make it possible to open the file in the future by simply double-clicking on its icon.

When you are shown a dialog box asking about enabling macros, click the **Enable Macros** button. If you are using a recent version of **Excel** for Windows, you may need to reduce the security level in **Tools**>**Macro**>**Security** to **Medium**, then close and reopen the file to enable the macros.

Clicking the **Clear** button will erase the four charts from Sheet1. Clicking the **Solve** button erases the charts before the model is solved so it is not necessary to click **Clear** before clicking **Solve**. **Read the comment notes attached to cells A1 thru A5 for instructions on how to run the worksheet models.** To view or print all of a workbook's comment notes together click on one of the links below.

The Excel files **RealTimeSterilization.xls**, **RealTimeSterilizationData.xls**, **RealTimeSterilization5.xls** and **RealTimeSterilizatonData5.xls** each contain a single worksheet. Sheet1 contains instructions, user input cells, four embedded charts, and two buttons labeled 'Clear' and 'Solve'. **Cells that have a red triangle marker in their upper right corner have a comment note attached to them.** For each of the four workbooks, if you wish to view and/or print all its comment notes together, click on its associated link below.

If a cell contains the name of one or more cells below it, the note explains how those cells are used. In Windows Excel 97, MacOS Excel 98, or newer the note pops up automatically when you use the mouse to point to a marked cell. To edit or change the size of a note, click on a marked cell to select it, then choose

- Peleg, M. and Penchina, C.M. 2000. Modeling microbial survival during exposure to a lethal agent with varying intensity. Crit. Rev. Food Sci. 40:159-172.
- Peleg, M. 2003. Microbial survival curves: Interpretation, mathematical modeling and utilization. Comments on Theoretical Biology 8:357-387.
- Peleg, M., Normand, M.D. and Corradini, M.G. 2005. Generating microbial survival curves during thermal processing in real time. Journal of Applied Microbiology 98:406-417.