Understanding the vital difference between ATP and A3 testing. Helping you to select the best option for your site.

The latest audit data indicates hygiene is one of the leading causes for non-conformities issued against Issue 9 of the BRCGS Global Food Safety Standard. Therefore, it is more important than ever for your site to prioritise hygiene at every level.

Hygiene monitoring is one of the best ways to do this. Instead of leaving your operatives in the dark, validating the quality of your cleans will help you to establish a plan of action – identifying any areas where processes need to be changed and enabling your Hygiene Teams to check the cleanliness of even those hard-to-reach areas.

But what is the best way to do this?

A high number of sites are making the move over to the A3 system – an improved ATP methodology that detects all organic residue and microorganisms on surfaces and in liquids. However, with a lot of sites still relying on conventional ATP swabs, you may be unsure as to the best solution for your factory. In this article, we hope to provide some clarity and will be tackling the following questions. There is valuable content in each section, but you can also use the links below to skip to the answer most relevant to your needs.

You can also follow the link below to watch a webinar on Hygiene Monitoring in High Care Environments. Hosted by Klipspringer Director Alex Carlyon, our in-house A3 specialist Radek Tameczka, and scientific advisor Dr. Stephan Speidel, this webinar explores the limitations of conventional hygiene monitoring methods and provides real-world examples of A3 verification at High Care production sites.

What is ATP and why is it important?

Before we do anything else, it’s important that we run through the basics of what ATP is and why it’s so important to your site.

After all, even a general understanding of the science behind your hygiene testing will make it so much easier for you to identify any areas where your operation could be enhanced. This brief explanation could also help you to make sense of any confusing test results and justify future investment. 

Put simply, what is ATP?

ATP (adenosine triphosphate) is a molecule found in all living cells. Because of this, food and beverage production sites regularly test for ATP when they are trying to determine the overall hygiene levels of a surface and the overall efficiency of a clean. A positive ATP test shows that organic residue is still present on a surface, but it is a common misconception that a negative ATP test proves the inverse. In fact, even with a negative result, adenosine molecules could still be present.

But, how is it possible for a surface to pass an ATP test even when organic residue is present?

ATP is an unstable molecule that degrades during processes such as cooking and fermentation. Under certain conditions it can degrade to become ADP (Adenosine Diphosphate) and AMP (Adenosine Monophosphate). If this happens, a standard ATP test could offer a pass result even if organic residue is still present in the form of ADP or AMP.

What processes cause ATP to degrade to ADP and AMP?

Below are just a few examples of processes that cause ATP to degrade to ADP and AMP. It is likely that a number of them are already taking place at your site.

Cleaning: ATP can be degraded by common cleaning processes such as wiping a surface down with hot water. This is also true of the application of chemicals such as detergents, disinfectants, and sanitisers.

Blanching: this process involves briefly immersing food in boiling water, then plunging it into ice water. During this process, ATP will likely be degraded by its exposure to the high temperature of the boiling water.

Heated foods: Along with blanching, other processes that involve the significant increase of temperature have the potential to degrade ATP. Environments with extremely high temperatures are unfavourable to ATP molecules and could result in them converting to ADP or AMP.

Processed food: ATP is produced by the breakdown of food molecules such as carbohydrates, fats, and proteins. The amount of ATP in processed food can be impacted by a site’s processing methods. As mentioned, heating a product to high temperatures can result in the degradation of ATP. Freezing can also damage the cell membrane and impact the rate of ATP production. Finally, the addition of salt, sugar, and preservatives changes the pH of a product, with this having a knock-on effect on the enzymes involved in ATP production.

Fermentation: Fermentation involves the breakdown of glucose through glycolysis, which yields a limited amount of ATP compared to oxidative phosphorylation. Although high levels of ATP are generally observed towards the start of this process, as fermentation progresses and the availability of fermentable sugars decreases, the metabolic activity of yeasts may slow down, leading to a gradual decrease in ATP levels.

What does the presence of ADP and AMP mean?

ADP and AMP indicates the presence of organic residue. This organic residue is an excellent breeding ground for a new generation of bacteria, and this new generation of bacteria could include ATP. Therefore, it is essential that your Hygiene Monitoring system is capable of detecting adenosine molecules in all three forms. Otherwise, it could pass a surface that has the potential to become a breeding ground for new and undetected ATP.

What are the key differences between an ATP meter and the A3 system?

Seen as a direct response to the limitations of ATP testing and the dangers posed by misleading results, A3 technology allows you to detect not only ATP, but also ADP and AMP. This means that even if ATP degrades during your production process, it will still be possible for your hygiene operatives to accurately test for all organic residue.

Boasting superior sensitivity and stability, A3 can be used for the daily monitoring of environmental contamination at your site. This system detects food residues and organic materials, along with biofilms.

Below is a brief video demonstration that shows the higher sensitivity and broader detection ability of the A3 system when compared to conventional ATP tests:

Why are the results of an ATP meter and an A3 system different?

Luciferase is the enzyme that produces light in the presence of ATP. The amount of ATP on a surface can be measured in relation to the intensity of the luminescence emitted. When ATP is in exposed to heat, acids, alkalis, and enzymes, it will try to conserve energy by reducing the amount of luminescence produced – degrading to become ADP, and possibly further, to AMP.

In contrast, an A3 meter introduces recycling enzymes that allow for conversion between all three adenosine molecules. The introduction of the PK Enzyme allows for the conversion of ADP to ATP and the introduction of the PPDK Enzyme allows for the conversion of AMP to ATP. This enables the A3 meter to carry out a simultaneous measurement of ATP, ADP, and AMP.

How different are the results produced by an A3 system and an ATP meter?

The graphs below show the results of an A3 System in comparison to three ATP meters. All four devices are testing for RLU, otherwise known as Relative Light Units. As mentioned above, this is because Luciferase produces light in the presence of ATP.

Even though the devices are testing the same surface, the results differ dramatically, with the A3 System providing high RLU readings and the ATP tests sitting at a much lower level. This demonstrates the importance of measuring AMP, ADP and ATP simultaneously, with the high RLU reading clearly demonstrating the presence of organic food residues that were undetectable to conventional ATP tests.

In contrast, the A3 system uses the PK and PPDK Enzymes to convert ADP and AMP to ATP, generating a much higher and much more accurate reading. Instead of risking the organic residue acting as an excellent breeding ground for new bacteria, hygiene operatives will be able to re-clean the surface until it is free from any soil.

How does an A3 meter eliminate the possibility of False Negative Readings?

Unlike ATP testing, a working A3 meter eliminates the possibility of false negative readings. ATP Meters often display a reading of 0 after swabbing. When this happens, it is understandable that operatives assume an effective clean has taken place and there isn’t any organic residue left on the surface being tested. However, a reading of 0 can also mean a swab has been exposed to high concentration of chemical detergent. Another explanation is that there is a problem with the enzyme in the swab or the swab itself is faulty. An incorrect swabbing procedure can also generate false negative results.

When it comes to traditional ATP testing, false negative results are typically ignored and hardly ever investigated. In contrast, the A3 meter and swab have been designed in a way that means they will always produce a reading (normally between 1-8), even if it is extremely low. In this case, a reading of 0 indicates a potential fault that requires further investigation.

What is the consequence of organic residue still being present on a surface?

As mentioned above, when ATP, ADP, and AMP are detected, they generate a reading for RLU. As you can see in this graph, a high RLU reading indicates the presence of organic residue and a poor clean. You will also see that this directly correlates with the amount of bacteria present on the surface. Put simply, a high RLU reading can be seen as a clear indicator of a high bacterial count.

If a surface passes an ATP test when ADP or AMP is still present, your Hygiene Team will be unable to accurately validate their cleans. Instead of having the opportunity to adapt their processes to achieve better results, they could be handing an area over to production while there is still a chance of organic material contaminating a product. This could result in a failed audit, a product recall, and even the illness or fatality of a consumer.

The McCain Foods Case Study

Here at Klipspringer, we recently published a Case Study with McCain Foods. This study explores the impact of the A3 system on McCain’s Scarborough site. Before switching over to an A3 meter, the Scarborough site found that visibly unclean surfaces were passing traditional ATP swab tests. The swabs were even indicating that potato didn’t contain any ATP once it had been blanched. This was happening because the ATP on these surfaces had degraded to become ADP and AMP. Essentially, organic residue was still present, but the ATP swabs were unable to detect it.

The introduction of an A3 system helped to explain the confusing results previously generated by the ATP tests. Instead of passing visibly unclean surfaces or blanched potatoes, the A3 meter was able to detect the presence of ADP and AMP. This resulted in the following benefits:

  • Increased swabbing reliability in a wide range of testing conditions 
  • Site’s Hygiene Team could update cleaning regime to reflect test results
  • No chance of achieving false-positive readings 
  • Ease-of-use when swabbing (small unit, fast set-up, quick results) 
  • Reduced allergen swabbing requirements, and hence reduced overall costs 

You may have noticed the final point about reduced allergen swabbing requirements. It’s important to stress that an A3 system does not test for allergens and should never be relied upon for this process. However, if a surface is free from organic residue, it follows that there isn’t any residue left to contaminate a non-allergen product. Allergen tests will still need to take place, but A3 technology should help to reduce their frequency.

During a six-to-eight-month trial, the Scarborough site found that if a surface passed an A3 test it would go on to pass a gluten swab and then an ELISA test. In fact, during this period, McCain Foods didn’t have a single allergen fail following an A3 swab pass. This provided an opportunity for the site to reduce the amount of allergen swabs and ELISA tests taking place. This not only resulted in significant savings, but also sped up the process of the Hygiene team releasing lines ready for production.

How does A3 technology relate to audit compliance and BRCGS Issue 9?

Passing an audit isn’t just about keeping your factory up and running, it’s also a sign that you are protecting the people consuming your product – quite literally saving lives on a daily basis. Audit-compliance should be factored into any changes to your site’s processes. It’s important that any developments increase your chance of meeting the relevant requirements and impressing your inspector. With this in mind, we have gathered extracts from four of the clauses featured in Issue 9 of the BRCGS Global Food Safety Standard. As you will see, they all have a direct link to A3 technology:

Clause 4.11.3 - Cleaning and Disinfection

Limits of acceptable and unacceptable cleaning performance shall be defined for food contact surfaces and processing equipment. These limits shall be based on the potential hazards relevant to the product or processing area (e.g. microbiological, allergen, foreign-body, or product-to-product contamination). Therefore, acceptable levels of cleaning may be defined by visual appearance,            ATP bioluminescence techniques, microbiological testing, allergen testing or chemical testing as appropriate.

How does this relate to A3 technology?

Depending on the potential hazards relating to your product, auditors will expect your site to carry out regular hygiene tests – establishing clear pass/fail parameters. ATP bioluminescence techniques are listed as an example of this, with this category including ATP swabbing and the use of an A3 meter. A commitment to allergen testing is also expected.

Clause - Environmental Monitoring

The design of the environmental monitoring programme shall be based on risk, and at a minimum include:

  • Sampling procedures
  • Identification of sample locations
  • Frequency of tests
  • Target organism(s) (e.g. pathogens, spoilage organisms and/ore indicator organisms)
  • Test methods (e.g. settle plates, rapid testing, and swabs)
  • Recording and evaluation of results

How does this relate to A3 technology?

The use of an A3 meter is the perfect example of rapid testing. Evidence of your site carrying out tests with this system could be presented to auditors as a clear sign of your commitment to environmental monitoring.

Clause 5.3.3 - Allergen Management

A documented risk assessment shall be carried out to identify routes of contamination (cross-contact) and establish documented policies, and procedures for handling raw materials and intermediate and finished products, to ensure cross-contamination (cross-contact) is avoided. This assessment shall include:

  • Consideration of the physical state of the allergenic material (e.g. powder, liquid, particulate)
  • Identification of potential points of cross-contamination (cross-contact) through the process flow
  • Assessment of the risk of allergen cross-contamination (cross contact) at each process step
  • Identification of suitable controls to reduce or eliminate the risk of cross-contamination

How does this relate to A3 technology?

Being able to accurately test for the presence or absence of organic residue is an essential part of allergen control. Even with an A3 system at your site, allergen testing will still be essential. However, as evidenced by the McCain Foods Case Study, this technology can enhance your process, whilst saving you a significant amount of money, time, and effort.

When compared to traditional ATP meters, the A3 monitor demonstrates superior sensitivity and stability for the detection of food residues and allergens. The graphs below show the different levels of Luminescence Intensity (RLU) registered by each system when testing the same surface. As you will see the surfaces are being tested for the presence of four out of the fourteen major food allergens:

Clause 5.3.8 - Allergen Management

Equipment or area-cleaning procedures shall be designed to remove or reduce to acceptable levels any potential cross-contamination (cross-contact) by allergens. The cleaning methods shall be validated to ensure they are effective and the effectiveness of the procedure routinely verified. 

How does this relate to A3 technology?

Using A3 technology at your site will allow you to demonstrate a commitment to validating your cleans. If you have made the switch from ATP swabs to the A3 meter, you can use this to impress your auditor – highlighting your determination to eliminate the risk of false negative readings.

How do you use the A3 system?

Introducing any new system to your site can be a daunting prospect, especially if you already have a heavy workload and looming deadlines. The good news is, you won’t have to navigate this process alone. Here at Klipspringer, we provide ongoing support for the implementation of A3 technology. We work closely with a team of micro-biologists to help you establish benchmarks, create a validation document to share with auditors, and train up your operatives. Whether you are evaluating the cleanliness of your production line, carrying out comprehensive hygiene monitoring, or conducting hygiene education for your employees, we will be on hand to guide you through the following steps:

Selecting the right swabs for your site

Here at Klipspringer, we supply Surface Swabs, Pre-moistened Surface Swabs, and Water Swabs. If you are testing a particularly dry area of your site, you will need to use either a pre-moistened surface swab or a dry surface swab that has been momentarily dipped in tap water.

When making this decision, many sites opt for pre-moistened swabs in an attempt to save time and effort. Some sites are also concerned that tap water could impact the results of the A3 system.

Although this is technically correct, tap water will only impact the reading up to 30 RLU, so not to a significant extent. Another point to consider is that, unlike surface swabs dipped in tap water, pre-moistened swabs can leave a slight residue – something that a lot of hygiene teams want to avoid.

If you are unsure about the best fit for your site, this is an area where Klipspringer, along with our team of microbiologists, can help you to make the right decision.

Evaluating the cleanliness of your production line

Determine the test locations. Identify the areas that are most likely to remain contaminated. This could be surfaces that have come into direct contact with products or raw materials e.g. the surface of your conveyor belts. It could also be the hard-to-reach areas that are likely to missed during a clean e.g. the valves of a tank outlet or pipe-coupling packings.

Decide on the Benchmark values for each location. These values should reflect the condition of a surface, the type of product that has been in contact with it, and the risk management level of the area. It is recommended that you conduct self-validation to establish your own benchmark values. We can help you with this decision, but as a general rule:

  • 200 RLU or lower: smooth, direct contact, or easy-to-clean surfaces (e.g. stainless steel, glass)
  • 500 RLU or lower: textured, indirect contact, or hard-to-clean surfaces (e.g. resin)

Determine the swabbing method of each location. Again, we can help you with this decision, but general guidance suggests:

  • Large sample: swab a 10cm square area vertically and horizontally about ten times in each direction
  • Small sample: swab the entire area thoroughly

Preventing secondary contamination through hygiene monitoring

Determine the test locations. Identify the areas that are difficult to wash and most likely to remain contaminated. It could also be the areas that have come into contact with unsterilised (raw) food.

Decide on the Benchmark values for each location. This will be the same as the approach listed for evaluating the cleanliness of your production line.

Determine the swabbing method of each location. This will be the same as the approach listed for evaluating the cleanliness of your production line.

Conducting hygiene education for your employees

Decide when to carry out the testing. After hand washing, but before using disinfectants.

Decide on the Benchmark values for each location.

  • 2000 RLU or lower: entire palm, including fingertips and between fingers. 90% of people can achieve this level when they conduct an A3 test after hand washing.

How do I store and access my results?

The Lumitester App can be used to store the data gathered through your A3 testing.

The app is capable of sophisticated data analysis, with inspection pass rates automatically turned into graphs. There is also the option of downloading the data onto Microsoft Excel – presenting it in your desired format. This will allow you to track trends and identify any areas in need of improvement.

In addition to this, the app will make it easier for you to motivate and manage your operatives. Small wins can be celebrated and oversites can be met with accountability, with every test recorded alongside the date it took place and the name of the operative responsible. Cooperation will also be made easier, as you will be able to share data between different individuals and sites. This data can be stored in the cloud, making it accessible at any time, from anywhere in the world.


  • Upload results to the cloud via Bluetooth
  • Set test points and benchmark values
  • Display time-series data for each test
  • Track overall inspection scores, with graphs
  • Access results 24/7 – from any device, anywhere.

Which industries will benefit the most from A3 technology?

A3 testing is particularly useful for sites that handle both allergen and non-allergen products. It is also suited to factories that handle products with a high number of potential hazards. After all, standards of hygiene and cleanliness will be much higher if you are producing an item that could pose serious risk to the consumer. A3 technology has also proved successful in specific areas of the industry. Below are just a few examples:

Get started with your A3 System

That brings us to the end of our guide to ATP and A3 Testing. Hopefully we have left you with a comprehensive understanding of the two different methods, along with the reasons behind so many sites switching over to the A3 system. From increased accuracy and the elimination of false negatives to lower costs and a faster Hygiene Window, A3 technology has the potential to enhance your operation at every level.

In the interest of being honest and open, Klipspringer is a proud supplier of the A3 Hygiene Monitor. However, we can guarantee that our interest in promoting this technology comes from a genuine belief in its ability to improve hygiene standards across your site and further protect consumers. Our Case Study with McCain Foods helps to put weight behind these words – a real-life example of A3 meters helping a site to secure success, supported by undeniable evidence and compelling testimonials.

With around 22 years supporting over 4,000 food and beverage sites across the UK and Ireland, we are always happy to share our honest feedback and findings, determined to assist you in making the best decision for your site. We are also on hand to help with your enquiries, you can contact us on 01473 461800 or sales@klipspringer.com.  Alternatively, you can fill out the contact form below and one of our friendly team members will be in touch. 

If you would like further guidance relating to A3 testing, the Klipspringer team would be happy to help. Share your details below to arrange a free consultation.