The ATP Process

The ATP ‘process’ is widely used around the world in any situation where an ‘immediate’ contaminant measurement is required – for example it is used in virtually all food processing, drinks manufacturing, water processing plants etc, when a start up reading is mandated prior to the commencement of production. Whilst the size of the machine used for testing purposes may vary, the principle is totally accepted and Quality Assurance technicians around the world are very familiar with both the technology and the process.

What is ATP?

ATP (adenosine triphosphate) is present in all organic material and is the universal unit of energy used in all living cells. ATP is produced and/or broken down in metabolic processes in all living systems. Processes such as photosynthesis in plants, muscle contraction in humans, respiration in fungi and fermentation in yeast are all driven by ATP. Therefore, most foods and microbial cells will contain some level of naturally occurring ATP. A typical luminometer uses bioluminescence to detect residual ATP as an indicator of surface cleanliness.

How is ATP detected by the ATP device?

Snap swabs are moistened with a buffer that aids in the removal of any biological material (ATP) on either wet or dry surfaces, while also penetrating through any biofilm to expose underlying cells. The ATP from microbiological cells, in addition to free ATP from any food residue, is collected from the sample surface with the swab, and is then available to react with the unique liquid-stable reagent contained in the device. This reagent is derived from a naturally-occurring enzyme (called luciferase) found in fireflies. When this enzyme reacts with ATP on the swab, a low-level of light is produced that can be detected and quantified by the luminometer. The amount of light detected is directly proportional to the amount of ATP on the sample, thus giving a quantitative measure of the cleanliness of the surface where the sample was taken.

Atp swab
 

What does the number result on the luminometer mean?

The luminometer displays results in RLU (Relative Light Unit) values. The light produced from the reaction between ATP and the enzyme in the snap device reagent is emitted in the form of photons. The luminometer detects these photons, quantifies them, and displays them as an RLU value. This RLU value and the ATP on a surface are in a 1:1 ratio. Therefore, more ATP present on a surface means more light is emitted in the snap reaction, giving a greater RLU number detected by the luminometer. The accepted scale adopted for use in food / beverage processing environments, is shown on the side and a typical ATP device is shown above.

0-30 Considered Food Safe
31-100 Considered Clean
101-200 Caution!
201-500 Contaminated
501-1000 High Risk of Infection
1000+ Extreme Risk of Infection