Keeping E. coli O121 Out of Flour

Sampling plans. The validation and ongoing verification of suppliers is a component of a comprehensive food safety program and in keeping with the Food Safety Modernization Act. This program should be established to include an initial, robust testing regime of in-bound ingredients and incorporating skip lot testing as part of on-going supplier qualification programs.

One sampling plan, considered a rule of thumb, is the Association of Official Agricultural Chemists square root of N plus one for sampling lots of wheat, flour, dried fruit, or other bulk agricultural products wherein N equals the lot size. Acceptability limits for each supplier or raw ingredient category and subsequent lot qualification protocols are components of the program. For example, a supplier would be qualified after the initial sampling regime wherein testing of each lot is conducted for a pre-defined period of time or number of inbound lots. The testing is conducted per unit and is performed on an individual sample basis with a criterion of zero defective/out-of-specification results. Once the supplier is qualified, subsequent shipments of inbound goods would be verified with the square root of N plus one testing regime, but using a composite of the units rather than individually tested. Since the organism tested in this case is non-O157 STEC, a pathogen, a standard of 100 percent of the samples must meet the criteria set. Inbound lots can be tested on a skip-lot basis.

Sampling. Once in production, producers should analyze their manufacturing environment and equipment by taking both environmental and in-process product samples. In-process product sampling means that a test and hold program is in place and corrective/preventative actions are established before testing is initiated. In the best-case scenario, product sampling is conducted by an auto-sampler, particularly at the packaging step with each lot tested. Although end product testing is not considered a representative sample, taken together, the testing of inbound raw-ingredients, plant environmental and process equipment sampling, in-line, and finished product testing provide a picture of the microbiological landscape of the process over time. Tracking and then trending the data will provide a depiction of events such as seasonal variations or the effects of supplier or process changes.

Corrective/preventative actions. Out-of-specification responses have the best outcome when they are developed and documented as written programs before testing programs are conducted. In most cases, an out-of-specification result stemming from environmental samples should serve as an early warning or detection mechanism. Often when product is implicated, it is a sign of a condition that has been manifesting for some time. The corrective action/preventative action, or CAPA, program, works to immediately minimize the risk. This will often involve maintaining a hold on the product if a food contact surface or product is involved. If a non-food contact environmental site is involved, the site is immediately spot cleaned, sanitized, and dried. A documented investigative process is then conducted by the HACCP, aka Hazard Analysis and Critical Control Points, team. The multidisciplinary team views the site and looks for root causes. Once a root cause is identified, further corrections and preventative measures can be targeted and then implemented. Although difficult, the process is often a test in patience as it can often span over a multi-week timeframe especially if there are construction events t as part of the corrective/preventative actions.

Using Flour as a Raw Ingredient

During the milling process, flour usually does not undergo a microbial kill-step, but it is expected that further down the production chain, a kill-step is included in the baking process. If a producer has used recalled/implicated flour, demonstrating the use of a validated thermal lethality step may be of importance to reduce the potential or scope of a recalled ingredient. It is, however, incumbent on the ability to demonstrate that a validated thermal lethality has been conducted. To validate an oven, the key processing parameters that should be considered are as follows:

• Using an identified and consistent line speed that is verified;
• Demonstrate uniform heating throughout oven (no cold spots) using thermocouples;
• Inoculate batches with most heat resistant organism that is identified in the Hazard Analysis—if a surrogate is used, provide rationale why the surrogate chosen is relevant to the product;
• Inoculate batches with a mixture (cocktail) of identified strains; and
• Replicate study with at least two, preferably three trials.

Conclusions

Pathogenic organisms continue to surprise us by finding their way into products that we once considered safe. There are processes that can be done to minimize their occurrence once we understand their origin and how they may be cross-contaminated. We may not be able to help mom clean up the kitchen by wiping the bowls clean of raw cookie dough when the rest of the cookies are baking, but we can do our part in helping everyone enjoy safe, quality products.