Food Processing: Keep It Clean

Environmental considerations may come into play when choosing a chemical disinfectant. Wastewater discharge requirements, the level of wastewater treatment capacity at the facility, pH, water temperature, and water chemistry management may factor into the decision.

Deciding between so many possible disinfectants might seem difficult unless sanitation is your full-time job, but there are plenty of suppliers that can help you identify the right product type and the most appropriate level for your water type, pH, temperature, and equipment type.

Verification with ATP

After cleaning and sanitizing is complete, how do company personnel know equipment and other surfaces are indeed clean and sanitary? Verification is absolutely the most critical part of a sanitation plan and should never be skipped, no matter how small the operation. In fact, small operations are at higher risk for bacterial contamination of equipment, which can affect the product and be passed on to the consumer. A company can be ruined if a product is recalled or, worse yet, people get sick from a foodborne illness.

First, start with a visual inspection immediately after cleaning. Surface contamination must be removed along with the residual cleaner. Lighting in some facilities is not always optimal, so visual inspection should be performed with a flashlight, a spotlight, or even a black light. This serves as a daily “check.”

Periodically, a rapid chemical test using adenosine triphosphate (ATP) bioluminescence should be performed to verify clean conditions prior to sanitizing. This commercially available rapid swab test measures the amount of organic matter remaining on a surface by detecting the amount of ATP in the organic matter. ATP is a vital energy source that microbes easily store and utilize for cellular functions. The amount of ATP—and where it is located—alerts company personnel to possible trouble spots that might need to be re-sanitized before starting the next production cycle.

Once the testing swab has been swiped across the surface of interest, the swab is placed in a solution and undergoes a reaction, producing light. The swab is then placed in a luminometer, which measures the light intensity produced in “relative light units” (RLUs). The light intensity is directly related to the amount of ATP on the surface, and therefore is an indicator of the amount of organic matter remaining on the surface. High remaining organic residual levels may render a sanitizer ineffective.

How often to do ATP testing? That depends on a lot of factors. Depending on the size of an operation, a company might have 50 different sampling sites and test five of them a week.

Microbial Assays. ATP test results, however, do not correlate to microbial count. The high RLU might result from food residue, not from potentially harmful bacteria. For that reason, ATP testing is complemented by conducting microbial testing on the surface and in the air and/or in the water rinsed through equipment, both before and after sanitizing. Microbial testing can determine what microorganisms are contaminating the production area, which can help identify the source.

These microbial assays generally include testing for aerobic plate count, or APC, which indicates bacterial populations that grow and proliferate in the presence of oxygen (aerobic conditions) and in some instances, may involve more sophisticated testing for genus of bacteria which include potential pathogens such as Listeria spp. Salmonella spp., and/or E.coli spp. These microbial test methods utilize sterile agar plates, swab techniques, or petrifilm to verify the effectiveness of the sanitizing practices utilized in the food processing facility.