Cherney Blog: Inside The Petridish

Your blog resource for education, experience, and a good read!

Cherney Blog: Inside The Petridish

Your blog resource for education, experience, and a good read!

Best Sample – Best Result: Environmental Sample Timing

Posted by Matthew Fenske on Jun 12, 2020 10:11:37 AM

During one of my first experiences being audited while working in the food manufacturing world I was asked by the auditor “Is your sanitation program controlling pathogens during the entire production run?”. I immediately responded with a boastful yes! The auditor of course followed up with “Please prove it.” Being relatively new, I temporarily froze as I knew our product results never yielded a positive in my time there but, was fairly certain that was not sufficient proof. Thankfully, I received a quick education as my supervisor presented the auditor with our environmental monitoring results which included pre-operational, operational, and post operational time points. Each sampling time verified something slightly different and was evidence our sanitation program did indeed control pathogens through the entirety of our production runs. The key take-away for me was that an environmental monitoring program must take into consideration when to sample and what each sampling time’s results mean within your Food Safety System.

So when should you take your environmental samples?


Typically, a successful Environmental Monitoring Program (EMP) will have a combination of sampling times based on scenarios that may have changed the sanitation control.

Operating under the FSMA guidance, samples need to be minimally taken at a time which verifies that the Sanitation Preventive Control is effective each time. Commonly this is after sanitation is complete and prior to the start of production. A debated topic that we hear is: Do you sample before or after applying sanitizer? Ideally, the sample would be collected after sanitizer is applied but, you must be cautious not to collect the wet sanitizer on the collection device. This concentrating of sanitizer could kill the target organisms and result in a false negative. Microbiological testing resulting in an absence of pathogens or an acceptable level of indicator organisms suffices as verification of your sanitation preventive control.

Commonly, collection of samples is also done during a production run. A general rule to define “during production” or “operation” is at least three hours after the start of production. If an out of spec or positive result occurs with this testing it can indicate an ingredient, GMP, or biofilm issue could be present and be what is introducing the biological hazard.

To ensure that the biological hazards were controlled through the entirety of the production run samples are commonly collected at the end of the production run or prior to sanitation. Theses samples will quickly indicate if any risk was introduced while the product was being produced. Consistently clean results at this time point can also indicate that you may be ready to test for an extended run time.

While the above time periods are typically routine in an EMP it is very important to sample around non-routine events such as roof leaks, construction/major maintenance events, or in the event of new production equipment or line configuration. The results of this non-routine testing provide data to ensure it is safe to continue or start production. Unfavorable results can lead to the need for specific sanitation to control biological hazards in an area.

The combination of these sampling times lead to a robust program and mitigate the risk of hazards being introduced to the product.

Topics: Food Safety, Environmental Monitoring, Microbiology, FSMA Compliance, Environmental Sampling