A3 vs ATP Hygiene Monitoring – What’s the Difference?

Hygiene monitoring is a fundamental requirement across a wide cross-section of industries. It is especially important in food, beverage, healthcare and pharmaceutical processes, where poor hygiene standards can risk serious consequences. In the simplest possible terms, hygiene monitoring systems measure how clean a surface is. If results exceed a set level, this may indicate that the surface requires further cleaning.

Measurements are normally carried out using a swab-based test to check the effectiveness of cleaning processes, either routinely or as one-off ‘spot checks’. The aim is to ensure that business operations can be carried out without risking consumer safety. In a food production environment, for example, hygiene swabbing is typically carried out once the hygiene team have completed a washdown of an area or equipment, to determine whether it is safe for food production processes to begin.

The most common method associated with hygiene monitoring is measuring ATP, or adenosine triphosphate. Since ATP molecules are found in all living cells, using an ATP meter is a fast and effective option for checking what organic material and microorganisms have been left behind on your surfaces – even if the surface has been cleaned and looks clean to the eye.

The two main components of ATP testing are the ATP measuring unit, and ATP test swabs. ATP swabs are typically used in a zig-zag pattern across your testing surface, 10cm square. The swab is then ‘activated’ by pushing it into the swab housing and shaking the tube. The entire swab tube is then placed into the ATP meter, which uses luminosity to provide a reading of ATP content in the swab sample. This reading is given in RLUs (Relative Light Units), indicating the cleanliness of the surface. The lower the RLU, the cleaner the surface.

As we’ve said, ATP is by the far the most widely used hygiene test and is perfect for applications dealing with very stable processes. However, a key point to remember is that it relies on measuring just one molecule, ATP.

ATP is an unstable molecule which decomposes in certain processes, such as cooking and fermentation. Through these processes, the molecules are participating in biological reactions and losing their energy, resulting in the ATP count decreasing and instead forming ADP (adenosine diphosphate) and AMP (adenosine monophosphate).

With different hygiene monitoring systems using different methods to measure cleanliness, the video shows the difference in sensitivity using the A3 technology compared to a hygiene monitoring system that only measures ATP.

This means that, although an ATP test may not detect high levels of organic residue, it is often still there but just in a different form. The dangerous consequence of this for food safety is that a surface appears ‘clean’ but in fact is still contaminated and requires further cleaning.

Additionally, ATP swabbing alone is not an effective method for allergen testing. Allergens such as milk, nuts, soy and milk are high in proteins and there is limited correlation between protein and ATP test results, making it a questionable approach to allergen management.

Auditors and food safety inspectors are now recognising the A3 system as a more comprehensive and reliable hygiene testing method. The A3 system differs from traditional ATP meters by detecting adenosine molecules in all three forms mentioned above: ATP, ADP and AMP.

Using patented technology, the surface swabbing and measuring process is identical to standard ATP meters, with just one test swab, however the meter gives a combined reading of the levels all three molecules. Regardless of what stage the adenosine molecules are at in their reactions, they will be measured by the A3 system and the resulting RLU reading will be a more accurate reflection of how clean the surface is.

This is particularly noticeable in meat, egg, seafood and nuts, as shown in the graphs below: