Effective cleaning is usually identified as a prerequisite for most Good Manufacturing Practices (GMPs) and Hazard Analysis and Critical Control Points (HAACP) plans in the food industry, and cleaning is often considered a CCP for allergen control. Cleaning is designed to remove food residues that contain many common components, such as adenosine triphosphate (ATP), protein and sugars, and some foods may contain allergens. The more effective the cleaning procedure, the lower the amount of food residues and the lower the risk. Using the most sensitive detection methods gives the greatest assurance of cleaning efficacy.

The principle of broad-spectrum monitoring methods together with indicators and specific detection methods is well established in monitoring and managing risk, for example, in microbiology, total bacteria counts, coliforms and Listeria spp. are used as indicators and then specific tests for specific pathogens are used as required. Here we describe a similar combined approach of prevalidation and monitoring of cleaning for allergen management using a combination of three high sensitivity detection methods.

Detection Methods
ATP bioluminescence provides a direct objective test of cleaning efficacy that has been well established for more than 30 years and detects a very broad range of foodstuffs. Recent developments in ATP bioluminescence have improved detection capabilities and sensitivity and at this level, it is capable of detecting food residues below the limit of detection of specific allergen tests.

The new EnSURE instrument and SuperSnap reagent swab from Hygiena both provide additional sensitivity with low background noise and low variation for precise accurate and consistent results. This means that this system is 10 times more sensitive than Hygiena SystemSURE Plus with UltraSnap swabs and 100 times more sensitive than other ATP systems (Table 1). The results are quantitative and give a linear response to increasing amounts of food residue. SuperSnap is also more robust and tolerant of harsh materials at extremes of pH; in the presence of sanitizer, it is unaffected by 1000 ppm hypochlorite.

Allergens are glycoproteins that can be detected by simple protein test (e.g., the biuret method, AllerSnap); however, this non-specific protein test cannot differentiate non-allergen protein from allergens. This protein test can detect allergenic foodstuffs, but for maximum sensitive (1–3 μg protein), the test must be run at elevated time and temperature combinations such as  37 °C for 30 min. The results are semi-quantitative and the scope and sensitivity of the protein test is limited to 10–100 ppm for certain allergenic foods.

Specific allergen tests such as lateral flow dipstick formats were originally designed to detect the presence of the allergens in foodstuffs, and certain extraction procedures are required for optimal performance. This technology has been extended for surface hygiene testing for cleaning validation where the limit of detection is claimed to be 1–20 μg or ppm; however, studies have shown that they only achieve 4–27% recovery and give a qualitative presence/absence result.

Table 2 demonstrates shows results from a factory trial where high sensitivity ATP and protein tests provided effective monitoring tools as part of the allergen management program. Before cleaning, all test results were positive; after cleaning, most tests were negative. The ATP test detects residues below that of protein tests and allergen were not detected, thus confirming the highest level of cleaning has been achieved and allergens were absent.

Detecting Allergens in a Ready Meal Factory
A production facility manufacturing ready meals and vegetable dishes for major supermarket retailers but also makes a nut product on a less frequent basis. The site needs to ensure that its cleaning has been effective to remove nut allergens after the manufacturing of nut products and before releasing the production area back to general manufacturing. The products contained three different tree nuts, but for the sake of completeness, nine nut allergens were tested in the cleaning validation exercise, and all nine nut allergens need to be shown to be absent before release of the lines and equipment.

An off-site contract laboratory was used to conduct specific enzyme-linked immunosorbent assay (ELISA)-based allergen tests with a turnaround time of 10 working days during which the production facility could not be used thus losing valuable production time. A minimum of 10 different samples were taken at various points of the production facility and each sample was test for nine tree nut allergens at considerable cost.

Previous cleaning validation exercises using only the specific allergen tests had not always passed first time, thus requiring repeat testing and the production line out of use for further 10 days. This was an extremely costly exercise, and the facility needed a faster, more reliable and cost-effective way to validate the cleaning.

The EnSURE luminometer with SuperSnap gives a high sensitivity ATP test to a sensitivity level of 0.1 fmol ATP, and results were obtained in 15 seconds to give immediate feedback and corrective action. Surfaces that failed at greater than 10 relative light units were cleaned again and retested.

When all surfaces passed with SuperSnap, the surfaces were then swabbed with AllerSnap protein detection swabs and incubated in a portable incubator for 30 minutes. When the protein test gave negative results, the more expensive specific allergen tests were employed. Subsequently all the specific allergen tests were shown to be negative and the line was released back to production.

The staff felt extremely confident that the specific allergen tests would come back negative following the initial prevalidation using the SuperSnap and AllerSnap tests.

Prevalidation screening enabled the site to make significant savings by avoiding repeat testing and further lost production. The hygiene manager commented that the combined method approach was very beneficial in releasing the nut production are back into general production and that  “This process gave me confidence that we would get it right first time with the allergen swabs. This not only saved on cost but more importantly guaranteed food safety. All our allergen swabs came back clear and the area was released back to general production on plan. I would definitely employ this process again.”

The regular use of high sensitivity ATP and protein tests enable high standards of cleaning to be maintained that can be supplemented with specific allergen tests less frequently and as required.

Summary
Cleaning is one the CCPs for allergen control, and a variety of detection methods are available to validate the cleaning processes. Specific allergen tests have their limitations and are expensive whereas met other methods have sensitivity but lack specificity.

A combination of three high sensitivity detection methods (ATP, protein and specific allergen tests) provides a more comprehensive, sensitive and rapid result to deliver a timely and cost-effective solution.

Martin Easter, Hygiena. For more information visit www.hygiena.net