Top Tips for Better Process Validation

Back in 1994, Russell Cross, head of the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA FSIS) who helped shepherd the nation’s “War on Pathogens” plan in response to the 1993 Jack in the Box E. coli outbreak, recommended that all federally inspected meat and poultry plants be required to implement Hazard Analysis and Critical Control Points (HACCP). “We believe that the HACCP system, coupled with strong risk assessment programs is the food safety system of the future … and the future is now,” Cross stated.

Thirty years later, that sentiment remains as true as the day Cross uttered it. Verification and validation have been an integral element of the HACCP model since the introduction of the seven principles of HACCP in 1997 by the National Advisory Committee on Microbiological Criteria for Foods. Of these, validation is arguably among the top elements of HACCP, propelling the success of food safety systems in the future-forward present.

The enactment of the Food Safety Modernization Act (FSMA) in 2011, which includes the Preventive Controls for Human Food (PCHF) rule, served to emphasize the importance of validation as it galvanized food processors to validate not only critical control points (CCPs) but also preventive controls such as those for allergen management and cleaning and sanitizing (CFR 2011). The passage of the regulation also prompted companies to expand the risk assessments being conducted to include not only each step in the process but all ingredients, raw materials, and packaging. Today, proponents of the ISO 22000 standard, Food Safety Management Systems—Requirements for Any Organization in the Food Chain, also want to see validation data for all preventive controls.

Validation means obtaining and evaluating scientific and technical evidence that a control measure, combination of control measures, or the food safety plan as a whole, when properly implemented, is capable of effectively controlling the identified hazards. The bottom line is that validation is the science behind the preventive control or critical control point (CCP). So, what can processors do to ensure that processes are validated? First, let’s look at the different types of processes that require validation.

Processes Requiring Validation

The first real mandate for validation targeted low-acid canned foods, which has been expanded to include aseptic products such as shelf-stable milk and beverages from nuts and grains, puddings, and other foods. The target organism is Clostridium botulinum. The U.S. Food and Drug Administration (FDA) mandates that processes must be developed by a process authority and filed with the agency. For a new canned low-acid product (i.e., one for which there is no history), the processes to gather the necessary data are complex and may include challenge studies using thermal death time studies, heat penetration studies in canned products, and inoculated pack studies using a nontoxic surrogate. With aseptic processes, not only must the time and temperature to produce a commercially sterile product be established but the parameters to sterilize both the packaging and the filling area need to be established.

Another FDA mandate focuses on acidified foods. Acidified foods are defined as low-acid foods to which acid(s) or acid food(s) are added. These foods include, but are not limited to, beans, cucumbers, cabbage, artichokes, cauliflower, puddings, peppers, tropical fruits, and fish, singly or in any combination. They have a water activity (aw) greater than 0.85 and have a finished equilibrium pH of 4.6 or below. Products that are acidified to a final equilibrium pH of 4.6 or below will inhibit the growth of Clostridium botulinum. As with low-acid foods, processes for acidified foods must be submitted to the FDA for review. These two product categories took a HACCP-like approach in the early 1970s to ensure safety but focused solely on control of Clostridium botulinum.

What is unique about traditional canned foods is that they involve processes that focus on the container. Once the process is delivered, the food is safe within the container, whether that container is a can, plastic cup, or laminated paper box. There may be occasional spoilage due to leakage (i.e., post-process contamination), but it is rare, and the spoilage organisms are almost always not pathogenic. There are, however, many products that are cooked using steam, hot air, bake ovens, direct flames, or hot oil and packaged after the process. The same is true with some of the nontraditional processes such as microwave heating and pulsed light. The products are processed and packaged. It is up to the processor to not only gather the necessary data to validate these processes but to establish post-process handling procedures to ensure that the process product is not contaminated. The preventive controls for these examples that require validation in this manner are the traditional CCPs.

Depending on the operation, a processor may or may not be able to properly validate these post-process handling steps. Post-process handling steps include the physical separation of raw and cooked sides of the facility, operation of the facility under positive pressure filtered air, installing minimum efficiency reporting value (MERV) 13 filtered air cooling systems, and ensuring that all seasonings are pathogen-free for operations such as fried snacks. And, yes, potato chips have been implicated in food poisoning outbreaks. The cause of the outbreak was traced to seasonings containing paprika that were contaminated with Salmonella. So, for any product that is seasoned after processing, the processor must mandate that the supplier provide pathogen-free seasonings and a certificate of analysis (COA) that supports this. It is also recommended that the processor verify the COA at least once a year by testing random samples for pathogens.

There are some products on the market that are not only bacteriostatic (i.e., inhibitory to microorganisms) but bactericidal (i.e., lethal to microorganisms). Examples of such products include soy sauce, soft drinks, many syrups, condiments, and alcohol-based flavors. If processors believe their products have such characteristics, they should conduct challenge studies using a range of pathogens and spoilage organisms. This provides validation data on the safety of the products and will clearly demonstrate that the product will not support pathogen growth. It has another benefit: there is no need for environmental monitoring according to 21 CFR Part 117.130 (c) (ii): “The hazard evaluation required by paragraph (c)(1)(i) of this section must include an evaluation of environmental pathogens whenever a ready-to-eat food is exposed to the environment prior to packaging and the packaged food does not receive a treatment or otherwise include a control measure (such as a formulation lethal to the pathogen) that would significantly minimize the pathogen.”

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Don’t Forget Allergens

Another preventive control that food processors should validate is allergen cleaning. The definition for validation when referring to cleaning is to “determine whether or not the plan is sufficient to ensure clean equipment and environment using visibly clean criteria and quantifiable methods.” The plan refers to the documented procedure for cleaning and sanitizing.

When validating a cleaning plan for efficacy in removing allergens, the processor should utilize a quantifiable test to ensure that the allergen is successfully removed. Industry best practices (ILSI Europe 2022) recommend that processors use lateral flow devices (LFDs) together with ELISA test kits to determine whether the allergen has been eliminated from the surface of the equipment. The test that is selected should be the specific test for the most prominent allergenic food residue in the product that was manufactured. Users should also ensure that the selected LFD and/or ELISA kits can detect the form of the allergenic food that is present on the uncleaned equipment as processing unit operations and variations in ingredient forms of allergenic foods can affect detectability.

When validating the cleaning method, the food processor should successfully complete three changeovers and document that no residues of the allergenic food were detectable after use of the cleaning method. The procedure should be revalidated every year. Processors should also test the first product through the system after cleaning for the allergen in question. For example, this can be quite a challenge for a beverage producer. A beverage processor wishing to validate the cleaning plan for a 40-head filler should swab each of the heads and repeat the cleaning three times. Equipment that is difficult to clean demands a more conservative approach to validation. However, there are companies that still utilize a visually clean standard with no testing. Visual examination can be quite useful in situations where particulate allergens are likely to occur but may not consistently be present in samples obtained for quantitative ELISA kit testing.

Validate the Plan

Validations should be conducted prior to implementation of the food safety plan. The PCHF rule under FSMA as outlined in 21 CFR Part 117.160 allows extensions of up to 90 days to complete the validation work. It is hard to imagine that the food safety team would be very comfortable running their facilities without proper validation of preventive controls or CCPs. Validations must be done under the supervision of a Preventive Controls Qualified Individual (PCQI), but that does not imply that all PCQIs are able to conduct validation work. The PCQI will utilize in-house expertise when they have an in-house process authority, or a process authority who works with a contract laboratory or as an independent professional.

One of the keys to ensuring safety of foods is properly validating procedures to address potential hazards determined through risk assessment, whether these hazards are biological, chemical, or physical. Gathering the scientific data to control these risks should be done in advance of the rollout on the production floor. In other words, get it done before you start processing.ft