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ATP is a rapid microbial test to measure the effectiveness of cleaning on food-contact surfaces such as mixers, tanks, conveyors and piping.

ATP

Also known as microbial ATP bioluminescence assay or rapid hygiene monitoring

What is ATP?

ATP, or adenosine 5’-triphosphate assay, is a rapid microbial test based on bioluminescence. It is used to measure the effectiveness of cleaning activities and SSOPs performed on food-contact surfaces such as:

  • Mixers
  • Tanks
  • Conveyors
  • Piping1,2

Food production facilities rely on the ATP test to see if food-contact surfaces are cleaned properly. Also, it shows if surfaces are free from unsafe microbial loads that could compromise the safety and quality of the products. The ATP test lets food companies detect, identify, and correct potential microbial hazards in their processing lines and finished products before they are released from the plant.

How does it work?

The ATP test measures the presence of adenosine triphosphate (ATP) — life’s energy carrying molecule within cells. The reaction of ATP with a luciferin-luciferase complex allows the estimation of the microbial load of food samples, equipment and surfaces in direct contact with the products. Food residues, proteins and cells are rich in ATP. They undergo bioluminescence process when in contact with luciferin–luciferase where oxidation of luciferin results in light emission.1,2,3

The intensity of the emitted light is measured with a device called luminometer. The intensity is proportional to the amount of ATP produced and the level of microorganisms on the swabbed food surface. The ATP content of the sample correlates with the number of microorganisms present because all living cells have a specific amount of ATP.1,3

Application

To perform an ATP test, gather a pre-moistened swab, a food-contact surface, and an automated palm-sized bioluminescence device. Steps needed to complete an ATP assay are:

  1. Remove swab from device
  2. Swab a representative portion/area of a food-contact surface (or equipment)
  3. Reinsert swab into body and screw down
  4. Shake liquid down into bottom of clear tube and mix 2-3 times
  5. Insert pocket swab into the instrument or device
  6. Select swab site and press the run button to execute the counting or measurement

The following block diagram helps explain how the ATP test interacts with food safety systems and sanitation procedures in place in food processing facilities.

How the ATP test interacts with food safety systems and sanitation procedures in place in food processing facilities.

Advantages Disadvantages
  • Quick and reliable results.
  • Less labor intensive than traditional culture or agar plate-based methods.
  • Relatively inexpensive.
  • Provides “overall” cleanliness reading that helps food safety managers make decisions regarding SSOPs, HACCP plan, cleaning programs.
  • ATP may not detect the presence of mature biofilms. This is because bacterial cells are usually hidden inside the thick outer layer of biofilm.
  • Assay is not specific to the source of ATP. The test cannot be used to confirm the presence of a specific protein (allergen) or pathogen, merely the presence/absence and the relative quantities of microbial-based soil.
  • Traditional methods such as agar plates are used to confirm the presence of a specific pathogen.
  • Cleaning compound residues can quench the light reaction to prevent proper response from the assay system. Commercial ATP kits contain neutralizers to combat the effect of detergents/sanitizers.
  • The ATP test is somewhat ineffective in bakeries where considerable buildup of milk solids or wheat flour residues exist on product-contact surfaces. For example, mixers and makeup equipment.

References

  1. Marriott, N.G., Schilling, M.W., and Gravani, R.B. “The Relationship of Microorganisms to Sanitation.” Principles of Food Sanitation, 6th edition, Springer International Publishing AG, 2018, pp. 33–72.
  2. Cramer, M.M. “Verification of Sanitation.” Food Plant Sanitation. Design, Maintenance, and Good Manufacturing Practices, 2nd edition, CRC Press, Taylor & Francis Group, LLC, 2013, pp. 167–201.
  3. Loughney, C.F., and Brown, S.R. “Plant sanitation.” Gracey’s Meat Hygiene, 11th Edition, John Wiley & Sons, Ltd, 2015, pp. 89–112.

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