The best-laid plans of mice and men often go awry. This can be the case for even the most experienced processor when lethality or stabilization critical control points are not met. The deviations caused by this failure to meet CCPs can range in severity but will undoubtedly result in a recall if product is passed into commerce before the deviation can be addressed. By learning not only how to limit the number of deviations, but also by preparing for one if it occurs, processors are more able to respond to the threats caused by these deviations.

The most common deviations described here are those that fail to meet the lethality or stabilization parameters outlined by the FSIS Guideline of Appendix A and B. Although these parameters may vary for different products, the overall intent of these guidelines is to limit the number of bacteria growing within a product. When cooked and cooled properly, a product will contain less than 1 log₁₀ colony forming units (CFU) of potentially pathogenic bacteria. For example, the cooling guidelines of Appendix B, also called the Stabilization Guideline, aim to limit the germination of any Clostridium spores that might have survived the cooking process. For this reason, Appendix B has strict time limits for temperature ranges, ensuring that a product will cool faster than the time it takes for bacteria to become dangerous. When a product is cooled more slowly than Appendix B allows, the likelihood of bacterial growth and toxin production increases, and a deviation has occurred.