Understanding Kill Steps in Produce Safety

What is a kill step?

Kill steps include high‑heat treatments (cooking, canning, pasteurization, distillation) and other processes that destroy pathogens to safe levels. Any commodity that a farm sends to a processor who will apply a kill step is not covered under the Produce Safety Rule, but only if the processor’s kill step is validated and the farm provides a disclosure statement that indicates “that the food is not processed to adequately reduce the presence of microorganisms of public health significance” and keeps appropriate records. All other produce grown on the farm is still covered under the produce safety rule.

Many common post‑harvest activities — cooling, freezing, slicing, washing or drying — do not kill pathogens and therefore do not fulfill the criteria for the processing exemption. Producers who simply freeze their product must comply with the applicable portions of the Produce Safety Rule because the produce is still considered a raw agricultural commodity that has not been adequately processed to reduce the presence of human pathogens.

Proven kill‑step technologies

Validated kill steps reduce the amount of pathogens through heat or other lethal processes. Validated kill steps kill or inactivate pathogens to reduce the amount present. Some proven examples include:

• Cooking, blanching, or boiling.

• Pasteurization

• Canning

• Distillation, fermenting, and high-pressure processing

For a process to qualify as a kill step it must significantly reduce the presence of pathogens and microorganisms of public health significance, must be scientifically validated, and documentation should be available to prove the process works, and is being executed properly.

Why freezing isn’t a kill step

Freezing preserves the quality of the produce but does not reliably kill or inactivate pathogens. Bacteria, viruses, and parasites in or on the produce become dormant at low temperatures and can survive for months; once the food thaws, they may resume growth. Produce that is contaminated during production or growing, harvesting and packing can reintroduce pathogens after thawing, so good hygiene and sanitation are essential.

By understanding the difference between preserving quality and killing pathogens, farmers can make informed decisions about processing methods and maintain compliance with food safety regulations.

Sources

21 C.F.R. § 1.1310. (2023). Definitions applicable to food traceability subpart. U.S. Government Publishing Office. https://www.law.cornell.edu/cfr/text/21/1.1310

Food Safety News. (2018). Is it time for a “kill step” for pathogens on produce at retail? https://www.food-safety.com/articles/5104-is-it-time-for-a-e2809ckill-stepe2809d-for-pathogens-on-produce-at-retail

UC Agriculture and Natural Resources. (2023). Food safety best practices: Elderberry freezing, storage, and holding. https://ucanr.edu/site/california-elderberries/food-safety-best-practices-elderberry-freezing-storage-and-holding

UMN Extension. (2023). FSMA and the produce safety rule: Does the rule apply to me? https://extension.umn.edu/growing-safe-food/fsma-and-produce-safety-rule-does-rule-apply-me

U.S. Food & Drug Administration. (2024). Exemptions relevant to produce farms under the produce safety rule and the food traceability rule. https://www.fda.gov/food/food-safety-modernization-act-fsma/exemptions-relevant-produce-farms-under-produce-safety-rule-and-food-traceability-rule