Detecting Contamination: Beer Brewing & ATP Testing

by Laura Eisan

Fireflies use their light-up butts to communicate gender, species and health status during mating season. This 'cold light' that they produce is caused by a chemical reaction featuring the bio-luminescence enzyme luciferase. When it mixes with the organic compounds luciferin and ATP, the result is the glow of bio-luminescence - exactly what we see in fireflies.

How did we get from fireflies to detecting contamination? The link is ATP - adenosine triphosphate.

What is ATP?

ATP is the energy molecule that fuels all living things on Earth. It is sometimes referred to as 'cellular currency' because all cells need it to exist. Wherever there is ATP, there are cells. This makes ATP a great indicator of organic contamination on surfaces, and a direct measurement of cleanliness. This indicator of cleanliness is often used to food and beverage production, clinical environments, environmental testing and various other applications. Today, we are focusing on how and where to test for ATP when brewing beer - both on large and small scales.


Here's a look at the beast you're hunting for:

How does it work?
ATP testing systems contain 3 main parts - sample collection swabs, a luminometer and software to analyze the data output.

Sample collection swabs are used to swab down surfaces or collect water samples. These pen sized swabs contain bioluminescent reagents that react with the ATP in the sample to emit light.

That light is measured inside the portable, handheld luminometer - the amount of light emitted is directly proportional to the amount of ATP in the sample, and is measured in Relative Light Units (RLU). The more ATP on the swab, the more photons (light) is created.

The RLU measurement can be analyzed and archived to help establish acceptable baseline ATP readings, pass/fail thresholds, and to provide insights into sanitation processes. If RLU exceeds specifications, it instantly alerts you that the surface must be cleaned and swabbed again until the RLU is in an acceptable range.

Cool, but how does that impact beer brewing?

Precision brewing is key to quality beer production. Particularly if you're a home brewer, lingering residue due to improper sanitation could compromise entire batches. While brewing on a larger scale, it is imperative to ensure new product rungs aren't contaminated by the last run, and biofilm development is a real concern in hard to reach places.

ATP testing tells you if the tools, detergents and techniques being used to remove product residue and prevent cross-contamination are working well for you. While swabbing and culturing can give you accurate and reliable results, it can be costly and time consuming. ATP testing gives you a rapid result and is a great place to start concerning environmental cleanliness. This answers the question of "Can I fill this tank/carboy right now?" instantly.

ATP testing is a method outlined by The American Society of Brewing Chemists Methods of Analysis Standards, and is a foundation part of any quality control/assurance program.

To start ATP testing, first complete a full Clean-in-Place cycle, and swab your surfaces to create a baseline ATP reading. This sets the expectations for pass/fail tolerances. Once these baseline parameters are set, its time to go into search and destroy mode. It is reccommended that you select hard to reach sites, where automated systems or humans have a hard time reaching as ATP sample sites - this way the hardest to clean sites are consistently being addressed.

If you're using municipal water source, you may want to consider ATP testing the water as an assurance that the water supply is relatively clean, and not contributing any detrimental contamination.

ATP testing to verify sanitation protocols, and monitoring for any unexpected contaminants in the water supply instills confidence that your product has not been contaminated during production.

What should I know?

Setting tolerances, or critical limits, for ATP residue in a sample is fundamental in establishing a sanitation monitoring program. Results greater than the upper limit indicate corrective action, such as re-cleaning, should occur.  Like the rest of the food and beverage manufacturing industry, brewers use industry accepted critical limits of 10 & 30 RLU.

<10 RLU = Pass : Surface was cleaned thoroughly

10-30 = Caution : Surface may require targeted re-cleaning, especially for higher risk surfaces

30+ = Fail : Cleaning process failure. Sanitation should be repeated and samples retested until a Pass score is achieved.

Examples of areas to test:

  • Tanks
  • Hoses
  • Brew Kettle
  • Ports
  • Mash tun 
  • Lauter tun 
  • Inside manway door 
  • Racking arm & head
  • Gaskets



Join us next week for Sanitation Basics!

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