Designing Effective Validation Studies for Dried and Fermented Meat Products
By John Scanga, PhD
Process validation is a critical component of food safety systems, particularly in the meat industry, where it serves to evaluate whether a given process applied to a product is sufficient to reduce or eliminate the microbiological risk associated with the product. For thermally processed, heat-treated, and shelf-stable meat products, validation practices are well established and supported by resources such as Food Safety and Inspection Service (FSIS) Appendix A and B, which were recently revised to reflect current scientific understanding.
Historically, HACCP plans for dry and fermented meat products often relied on scientific literature, historical performance data, or assumptions that certain hazards were not reasonably likely to occur. However, outbreaks in 2021 involving Salmonella in this product category1 prompted increased regulatory scrutiny and led to the release of new guidance in 2023: FSIS Ready-to-Eat Fermented, Salt-Cured, and Dried Products Guideline (FSIS-GD-2023-0002)2.
This paper explores key considerations for validating dry and fermented meat products under the updated FSIS guidance, integrating regulatory expectations with practical approaches to ensure product safety and compliance.
New FSIS Guidelines for RTE Fermented, Salt-Cured, and Dried Products
The guideline specifies that processes must demonstrate:
- A 5-log reduction of Salmonella,
- A 5-log reduction of Shiga toxin-producing Escherichia coli (STEC) for beef-containing products,
- A 3-log reduction of Listeria monocytogenes,
- And no outgrowth of Staphylococcus aureus2.
Due to the absence of traditional lethality steps and the potential for extended exposure to temperatures within the bacterial "danger zone" (40–140°F), controlling Staphylococcus aureus is particularly important in these products.
An exception to the standard lethality requirements exists: if robust sampling and testing, such as Blue-Ribbon Task Force protocols, demonstrate the absence of pathogens in raw materials, the required reduction for Salmonella and STEC may be lowered to 2-log. Notably, for comminuted products like salami, sampling must be performed on the finished batter rather than incoming raw materials, due to the increased detectability of pathogens post-grinding.
Critical Steps and Critical Operating Parameters for Dried and Fermented Meat Products
In any manufacturing process, a range of parameters and standard operating procedures influence both product quality and food safety. Some variables affect sensory attributes like texture and flavor, while others are essential for pathogen control. Understanding which parameters serve each purpose, and which serve both, is crucial when designing a validation study.
An overly rigid validation approach that includes too many critical operating parameters can unintentionally create a process that is impractical to replicate in a commercial setting. This can lead to frequent deviations and undermine the reliability of the validation itself.
Therefore, a balanced, pragmatic approach is essential. Manufacturers must identify which aspects of the process are truly critical to food safety, determine how they can be consistently controlled, and establish meaningful ways to measure outcomes.
Fermentation Time, Temperature, and Humidity
Fermentation time, temperature, and humidity are critical parameters in the production of fermented meats. These factors are closely tied to the target endpoint pH, which determines both product safety and quality. The time required to reach this pH is influenced by several interrelated variables.
During fermentation, products are typically exposed to elevated temperatures, often above 20°C, to encourage the growth of beneficial bacteria, particularly starter cultures. These cultures metabolize sugars to produce lactic acid, which lowers the pH and contributes to microbial safety and flavor development. However, it is essential to remain aware that other, potentially undesirable microorganisms can also proliferate under these conditions. Therefore, fermentation must be carefully controlled to stay within safe bounds.
One key concept in managing fermentation is the degree-hour calculation, which helps ensure that the product does not exceed the maximum allowable exposure to elevated temperatures over time. This calculation is especially important when no starter cultures are used, though most commercial fermented meat products fall well within safe limits when cultures are properly applied.
The choice of starter culture plays a significant role in fermentation dynamics. There are thousands of bacterial strains available, each with unique characteristics. While all aim to reduce pH, some do so more gradually, enhancing the product’s flavor and texture. These cultures are often selected not just for safety, but for their contribution to palatability and overall sensory quality.
Additional factors influencing fermentation time include:
- Product characteristics: casing diameter, shape, whole muscle vs. ground or comminuted meat, tied or untied formats.
- Formulation variables: salt and sugar levels, and the inclusion of curing agents like nitrite or nitrate.
Together, these elements must be carefully balanced to achieve a safe, flavorful, and high-quality fermented meat product.
Drying
The drying stage should take strong consideration to the parameters of the drying room temperature and humidity, drying time, and target water activity, whether doing this in a lab, a pilot plant, or the manufacturing facility to ensure understanding of those environmental conditions.
Commercial drying rooms vary widely in scale and sophistication. Some facilities operate large, technologically advanced chambers with precise, automated environmental controls, while others rely on simpler systems with greater variability. Historically, drying was performed in naturally moderated environments, such as underground cellars, where temperature and humidity were largely dictated by ambient conditions.
For validation purposes, documenting not only the target conditions but also the acceptable ranges and natural fluctuations is key. This ensures that laboratory or pilot results can be appropriately translated to commercial production and that the validated parameters reflect the true operating environment.
Low-Temperature Heat Step
Most dried and fermented meat products do not undergo a traditional thermal lethality step. Instead, their safety relies on multiple hurdles—fermentation, drying, salt content, reduced water activity, and extended aging.
Exposing them, especially after a long dry time, to a sufficient time and temperature to achieve bacterial lethality can introduce very drastic and undesirable product quality attributes, including lipid oxidation, rancidity, fading out, and negative changes to texture and mouthfeel.
As a result, a low‑temperature heat step often does not align with the sensory or identity standards of traditional dried and fermented products.
Validation Study Considerations for Artisan Meat Products
Validating artisan dried and fermented meat products requires navigating a unique balance: preserving traditional, craft‑based production methods while rigorously demonstrating microbial lethality. Because these products involve multiple hurdles rather than a single lethality step, a validation study must accurately replicate the commercial process, capture variability, and quantify the microbial reductions achieved at each stage.
Requirements for Piloting a Validation Study
Effective validation of dried and fermented meat products requires specialized facilities, expertise, and process controls. The following elements are essential for conducting a scientifically robust and commercially relevant validation study:
- Biosafety Level 2 (BSL-2) Facility: Pathogens capable of causing human illness must be handled safely while still supporting the unique needs of a pilot‑scale meat processing environment. These products involve nuanced, artisan‑like processes that require both precision and flexibility.
- Integrated Meat Science and Microbiological Expertise: Successful studies depend on personnel with hands‑on meat processing knowledge in addition to microbiological proficiency. Industry experience has shown that only a limited number of facilities possess the right combination of qualifications and willingness to conduct these complex studies.
- Fermenting, Drying, and Aging Capabilities. Pilot‑scale fermentation and drying units, typically around 100‑kg capacity, must have precise control of temperature, humidity, and airflow. Smaller units often allow tighter control than large commercial systems, enabling researchers to evaluate critical parameters and replicate commercial conditions more accurately.
- Microbiological and Chemical Testing Capabilities. Validation requires comprehensive testing beyond microbiology alone. Facilities must be able to measure key physical and chemical attributes, such as salt content, fat content, pH, and other intrinsic properties, to confirm that pilot‑scale products accurately represent commercial production. These measurements provide a critical proxy for determining whether laboratory-scale outcomes translate effectively to full‑scale operations.
- Facilities to evaluate additional hurdles. A complete validation may require assessing additional interventions—such as antimicrobial treatments, low‑temperature heating, storage, HPP, or other process steps. For example, applying organic acid antimicrobials to raw materials can help reduce initial microbial loads, aligning with “blue ribbon” concepts that reduce the burden the fermentation and drying stages must address.
Inoculation and Sampling
Inoculation and sampling are foundational components of a scientifically defensible validation study. Again, it is important to evaluate the product and the process that it has manufactured under to ensure that the procedures are deliberate and well-justified.
A primary challenge in pathogen validation studies is the limited availability of suitable surrogate organisms that can be safely used at plant scale. Therefore, the inoculation approach must be tailored to both the product and its manufacturing process. The inoculum must be applied at the correct process step to accurately reflect commercial conditions, and at sufficient levels to demonstrate the specified log-reductions and ensure representative pathogen behavior throughout the study.
Pathogen Adaptation
For fermented products, FSIS guidance requires the use of acid‑adapted pathogens, grown in the presence of glucose. Most raw‑material–associated pathogens entering meat plants have not encountered acidic or glucose‑rich environments, so acid adaptation provides a more conservative and protective estimate of their potential survival during fermentation. This ensures that the study does not overestimate lethality.
Conclusion
Validating dried and fermented meat products requires a holistic understanding of how multiple hurdles work together to achieve microbial lethality. No single parameter is sufficient on its own; rather, safety is achieved through the combined and cumulative interaction of these factors. As a result, manufacturers must identify which parameters are truly critical to their specific process, ensure they can be consistently measured and reproduced, and understand how each contributes to the total log reduction achieved.
Because this product category lacks clear stabilization guidance such as Appendix A or B, there remains a knowledge gap in defining standardized time–pH or time–water activity relationships comparable to traditional thermal processing models. As the industry progresses, tools such as meta‑analyses and aggregated datasets may eventually support the development of such resources, helping processors better understand what combinations of intrinsic and extrinsic factors constitute a validated safe process.
Ultimately, validation is an iterative and integrative exercise. If a study does not meet lethality requirements, processors must determine whether the process needs modification, whether more hurdles should be added, or whether the study design itself requires adjustment. By carefully evaluating each component of the process and understanding how these factors collectively drive lethality, manufacturers can continue producing high‑quality artisan products that remain both safe and true to their traditional identity.
Questions on how this information is applicable to your food process?
Additional Resources
Interventions to Achieve Pathogen Lethality Targets and Improve the Safety of Traditional Dried and Fermented SalamiData-Driven Food Safety: E. coli Testing as a Tool for Process Control in Beef Plants
The Four Phases of Onsite Process Validation for Pet Food
References
- USDA-FSIS. Salmonella Outbreaks Linked to Italian-Style Meats – Outbreak Investigation After Action Review. 2022. Available at: https://www.fsis.usda.gov/sites/default/files/media_file/2022-04/FSIS-After-Action-Review-2021-09_2022-01.pdf2022-01 Accessed 05 March 2026.
- USDA-FSIS. FSIS Ready-to-Eat Fermented, Salt-Cured, and Dried Products Guideline. 2023. Available at: https://www.fsis.usda.gov/guidelines/2023-0002 Accessed 05 March 2026.
