Do all ATP systems rise to the challenge?

By 3M Food Safety Technical Team

The use of adenosine triphosphate (ATP) as an indicator of cleanliness is a widely recognized practice in the global food and beverage industry. ATP rapid hygiene monitoring has been available to the UK market for decades and during this time, manufacturers of ATP tests have been advancing their solutions to meet their customers’ requirements.

“ATP hygiene monitoring systems should be simple and easy to use, with minimal operative training required.”
-3M Food Safety Team

Today's market offers a number of ATP systems varying in sensitivity, repeatability and, of course, price. All food and beverage processors using ATP to monitor hygiene will want to ensure they are using the most reliable and efficient system available to them to help avoid any costly food contamination incidents. It is therefore important to understand that not all systems are the same.

Much has already been written about the criteria to be assessed when choosing an ATP system, including a recent International Food Hygiene article titled "Choosing the correct luminometer" by Professor Chris Griffith, Head of Food Research & Consultancy Unit, Cardiff School of Health Sciences, University of Wales Institute, Cardiff.

Areas such as repeatability, sensitivity, use of extractants to break microbial cell walls and aid detection of biofilms, and even the type of device used to detect the light reaction, are all critical factors which require consideration.

What is ATP hygiene monitoring?

When ATP (the energy molecule found in all living cells) is present on a surface, organic residues - in the form of food or other cellular material - must be present. The presence of these organic residues creates a breeding ground for microbes, giving rise to the potential for contamination of products during the manufacturing process. ATP-based rapid hygiene tests seek to measure the amount of ATP present at the critical points of a production line, thereby giving an indication of the hygienic status in less than a minute.

The technology typically involves a sample being taken using a surface swab or water sampling device. The test is activated, leading to a bioluminescence reaction taking place. The light produced by the test is measured in a luminometer and converted into Relative Light Units (RLU) for easy interpretation. The greater the RLU the more ATP present and therefore potential contamination risk. By setting Pass, Caution and Fail limits for each critical control point, the user can then immediately determine if the point tested is clean or if further re-cleaning is needed prior to production commencing.

Such rapid technology offers many benefits; ATP tests deliver results in seconds, giving real-time hygiene information that a manufacturer can act on. Tests are simple to use and provide clear results, allowing all operatives to perform the testing with no specialist personnel or laboratory required. Records can be kept to show due diligence and to demonstrate that an effective cleaning regime is in place as part of the company's HACCP system. It enables companies to not only quickly identify a hygiene trouble spot but also to take immediate corrective action to ensure the critical area is within the required hygienic status and ready for production again. Rapid hygiene testing is also an excellent training tool - enabling personnel to see a clear and immediate link between good hygiene practices and the hygiene test results.

Data Trending Software

Some ATP systems allow regular analysis of hygiene monitoring results through the use of data trending software. This enables food processors to monitor the hygiene status of their operations at all times by providing information on performance over time. This ongoing benefit of ATP hygiene monitoring helps to identify problem areas and measures the effectiveness of remedial action while allowing managers to keep a close eye on the standards of cleaning by all operatives. It also helps manufacturers refocus and refine their cleaning regimes, concentrating their time and effort on the areas which really count. Some companies have even used the technology to modify their production lines, by identifying production areas which are difficult to clean and feeding that information back to their production line equipment suppliers.

Audit Requirements

The value of a good ATP rapid hygiene monitoring system is no more apparent than when meeting audit requirements, whether internal or external. Hygiene data can quickly be presented to the auditor through the use of sophisticated data filtering. In the case of a retest following re-cleaning, clear audit trails allow easy identification of the steps taken, by whom and when. Data trending also allows the production of hygiene reports without spending valuable time manipulating data, with graphical representations generated easily for reporting needs.

ATP hygiene monitoring systems should be simple and easy to use, with minimal operative training required. Tests should be reliable and repeatable to ensure consistency of results. The system should be portable and robust, with swabs being easily identified by color or metal-detectable properties in case of loss in the production area.

Maximum Return

To get the maximum return on your ATP investment, the system should include an advanced data trending software to allow easy, yet thorough analysis of hygiene data.

Ultimately, the use of an effective ATP hygiene monitoring system can help reduce product reject and recall levels, in turn protecting the consumer, the brand and retail relationships.

Studies by independent companies such as Cara Technology Limited 1, 2 and Hygiene Assured 3, 4, 5, 6 have highlighted marked differences between systems currently available on the market. In order to be sure which system will be the most effective for your facilities, valuable independent information can be enhanced by conducting your own in-house system comparison study.

This route of in-house evaluation is becoming increasingly popular and some manufacturers of ATP test systems are actively promoting these studies. 3M is currently running an ATP challenge, encouraging users of ATP systems to compare the 3M Clean-Trace ATP system with the user's current system in place. The scheme demonstrates the high level of confidence 3M has in the performance of the Clean-Trace ATP system when compared to others.

When conducting such a study, the two key performance metrics are Sensitivity and Repeatability. It is important to understand that sensitivity and repeatability are very much inter-related. Sensitivity is a measure of the smallest amount of ATP that can be detected by an ATP system and is a function of how much the test signal is greater than the background signal. Repeatability is the ability of the system to provide the same result when presented with the same sample repeatedly. In this regard, Repeatability is more important than absolute Sensitivity... if you have no confidence that the reading is repeatable, any sensitivity claims are irrelevant. Confidence in test results can only really be achieved when an ATP system provides both these factors.

The 3M ATP Challenge focuses on these two parameters, and those who have already taken up the challenge have found that the 3M Clean-Trace ATP System has produced favorable results.

If you would like further information, visit the 3M website at www.3M.com/foodsafety

References
1. Protocol for assessing the sensitivity of hygiene test systems for live microorganisms and food residues. WJ Simpson, JL Archibald & CJ Giles, Cara Technology Limited. Report 120906, 13 October 2006.
2. Repeatability of hygiene test systems in measurement of low levels of ATP. WJ Simpson, JL Archibald & CJ Giles, Cara Technology Limited. Report 30606, 27 July 2006.
3. Comparative trial of two leading ATP hygiene monitoring systems - bakery high care and low risk areas. J Brewster, Hygiene Assured. February 2008.
4. Comparative trial of two leading ATP hygiene monitoring systems - prepared salad production. J Brewster, Hygiene Assured. December 2007.
5. Comparative trial of two leading ATP hygiene monitoring systems - cheese cutting and packing operation. J Brewster, Hygiene Assured. October 2007.
6. Comparative trial of two leading ATP hygiene monitoring systems - cultured dairy products. J Brewster, Hygiene Assured. October 2007.