Now, more than ever, food manufacturers are focused on cleaning their facility and ensuring they have a clean and sanitary environment. How can you see if your efforts are working? You can measure the effectiveness of your cleaning process by testing surfaces for Adenosine triphosphate (ATP).
ATP is a molecule found in all living cells and it is responsible for transferring and storing energy. ATP levels act as an indicator of whether your environment has been properly cleaned.
“It can come from bacteria or mold; it can come from food residue, it can come from human skin,” says to Taylor Lecy, a technical service analyst for 3M Food Safety. “It can come from anything that was once living.”
Since it comes from so many different sources, she adds, its presence is very common. The use of ATP for hygiene monitoring provides a measurement of potential risk resulting from the presence of high levels of organic residues, including microorganisms.
Below, Taylor answers some of the most common questions she hears from food processors about ATP.
Why do we need to verify cleaning?
A surface may look clean, but that does not necessarily mean it is clean. Some contamination and debris cannot be seen with the naked eye. Food product is going to be contacting this surface, so it is important to mitigate risk of contamination from that site.
What are the benefits of testing for ATP as a way to verify cleaning?
ATP is a highly efficient way to verify cleaning because it can identify beyond than a visual inspection and provides quick, sensitive and easy quantitative information that verifies that cleaning procedures are working. It also detects food product residues which is important, because if this is not removed from the surface, it can leave behind nutrients that help surviving organisms grow.
How does the 3M™ Clean-Trace™ Hygiene Monitoring and Management System work?
After a surface is cleaned, there may still be ATP on the surface. ATP on the surface can be collected using the 3M™ Clean-Trace™ Surface ATP Test Swab. Once the swab is activated, the ATP will then react with an enzyme and produce light. The 3M™ Clean Trace™ Luminometer will measure the light generated and report it as relative light units or RLUs. We are converting ATP into light and measuring that amount of light production to determine if the surface has been properly cleaned based on predetermined standards. If a sample has an increase in organisms or organic residues, there will be an increase in ATP, and therefore an increase in RLUs.
When should I swab for ATP?
A best practice is to swab after initial cleaning and before sanitation. Sanitizer does not work on a dirty surface and if the result is a failure, sanitizer will be wasted. The cleaning-swab-sanitizer sequence is also ideal to reduce the risk of sanitizer interference with the swab.
3M swabs were designed to be versatile and we understand that not all facilities can conduct ATP swabbing in between cleaning and sanitizing. There is flexibility on when to swab depending on how your cleaning and sanitation programs are established. An AOAC Performance Tested Method (PTM) study (AOAC® Performance TestedSM Certificate #041901) demonstrated actionable results with our swabs even in the presence of residual sanitizers on surfaces.
However, we cannot predict interactions with all the different sanitizers in all situations. So, if you swab after sanitizing, it is important to verify that the sanitizer used will not interfere with the ATP detection.
Can I use ATP to detect viruses on surfaces?
Maintaining a high standard of environmental cleaning and monitoring is core to food safety. Many food processors are taking extra precautions to increase the frequency of cleaning and sanitation in their daily operations and more frequent testing to validate the effectiveness of cleaning. The 3M™ Clean-Trace™ Hygiene Monitoring and Management System is used to rapidly verify cleanliness and hygiene of these food and beverage surfaces.
The 3M Clean-Trace System cannot be used to detect viruses, including coronavirus. Viruses are particles that contain RNA or DNA, but not ATP. The 3M Clean-Trace System does not detect RNA or DNA on surfaces. The absence of ATP does not imply that viruses have been removed from a surface.
Can I correlate Colony-Forming Units (CFU) to RLU?
The 3M Clean Trace System measures total ATP from a variety of sources that contribute to varying amounts of ATP (indicated by RLUs), but microbiological methods such as 3M™ Petrifilm™ Plates detect only viable microbial cells, it is not expected that RLU values will consistently correlate with CFUs for environmental surfaces.
ATP tests verify a surface is clean and microbial tests verify the sanitizer is working. These two methods are providing information about two different things. For cleaning validation, food processors should use microbial tests as part of their validation study. If you have a microbial test that is passing, you can correlate that to the ATP result to decide if this is a clean surface. Microbial tests additionally, should be used with a defined frequency to verify that the sanitation process is being effective.
How do we establish a robust baseline that will determine what is clean (pass) and what is not clean (fail)?
For ATP testing, there is not one pass number that can apply to every facility and every surface. The amount of ATP on a surface after cleaning and the acceptable RLU limits depend on a number of factors. These can include the material of the surface, age of the surface, what has contacted that surface, how often it is cleaned, and the cleaning procedure and its elements (time, temperature, chemicals, etc.).
For example, porous surfaces are more difficult to clean so you may set a higher acceptable ATP level for that surface than a smooth surface. Food manufacturers should develop their own specifications based on what they normally see for each test point site after proper cleaning.
A common starting baseline for many facilities is to set 150 as pass and 300 as fail. Then, intense testing with ATP swabs should be done after a deep cleaning, this will generate data for a defined period of time (for example two to three weeks or 10 to 30 cleaning cycles) and in several pre-selected testing points in order to have an appropriate coverage of the production line or equipment. Then, analyze the results to set a reasonable limit for that surface, and adjust your pass and fail values. We don’t make generalizations for acceptable limits. Each facility should set up pass/fail limits based on their own data and risk tolerance for the surface.
There are additional tools you can use to determine acceptable baseline levels. 3M™ Clean-Trace™ Software includes trending reports, so you can create a histogram and calculate the mean plus 2-3 standard deviations. Remember that the baseline is just a suggested starting point. Adjust your baselines to reflect your internal data and acceptable limits. For continuous improvement, it is always a good practice to review your pass/fail limits on a regular basis and adjust as needed. To learn more about this topic and others that may improve your food safety testing process, access additional resources here.
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