Kill Step

A kill step is a processing step, such as baking, cooking or pasteurizing, that is lethal enough to significantly reduce harmful microorganisms in a food. In baking, the oven is usually the kill step.

  • Food safety
  • Food safety programs

FDA's preventive controls guidance defines a kill step as lethal processing that significantly minimizes biological hazards. Most kill steps are heat treatments such as baking, cooking, boiling or pasteurizing, although the rules also name other processes, such as irradiation. Under 21 CFR 117.135, a facility that relies on a process control like heat treatment must spell out the parameters involved, such as time and temperature, and the minimum or maximum values needed to control the hazard. Steps that only slow microbial growth, such as refrigeration or drying, are not kill steps; FDA calls them non-lethality treatments. Food heat-treated with a kill step is considered fully cooked.

Several common bakery ingredients have no kill step of their own. Most flour is raw, and CDC notes its germs are killed only when it is baked or cooked; raw eggs can carry Salmonella too. The bake is therefore what protects customers, so it needs evidence behind it. A Washington State University study found that brownies baked at 176.7°C (350°F) for at least 40 minutes achieved more than a 5-log (99.999 percent) reduction in Salmonella, and the authors stressed that products with different baking parameters each need their own validation.

Key facts

FDA definition
Lethal processing to significantly minimize biological hazards
Required in writing (21 CFR 117.135)
Process parameters and their minimum or maximum values
Brownie bake validation (WSU)
More than 5-log Salmonella reduction at 176.7°C for at least 40 minutes
Raw flour
Germs are killed only by baking or cooking (CDC)

In a bakery or commercial kitchen

  • Identify the kill step for each product and record its time and temperature limits in your food safety plan
  • Measure end-point internal product temperature, not just the oven setting, to confirm each bake reached its target
  • Validate the kill step for each product and bake profile instead of borrowing results from a different recipe
  • Guard against recontamination after the kill step, a priority area for environmental sampling
  • Treat toppings, glazes and fillings added after baking as having no kill step, and control them separately

For home and cottage bakers

  • Bake dough and batter fully, following the recipe's temperature and time, before anyone eats it
  • Keep raw flour and eggs away from foods that won't be cooked
  • Choose edible dough products labeled for eating unbaked, made with heat-treated flour

Related entries

Sources

Written by VanillaGoods in our own words from these sources. Last reviewed October 17, 2026.

  1. Hazard Analysis and Risk-Based Preventive Controls for Human Food: Draft Guidance for Industry (Introduction and Glossary), U.S. Food and Drug Administration
  2. 21 CFR 117.135: Preventive controls, Electronic Code of Federal Regulations (eCFR)
  3. Raw Flour and Dough, Centers for Disease Control and Prevention
  4. Validation of the baking step for brownies to control Salmonella, Washington State University
  5. Common Questions When Developing an Environmental Monitoring Program for a Food Facility (FST-445NP), Virginia Cooperative Extension