Analysis of allergens on work surfaces: “cotton cheats”

28 Apr 2017

Have you ever wondered if the cleaning that you do is really effective? The answer is especially important when we talk about cross-contamination through food allergens.

People who are allergic to foods may suffer a reaction in the presence of very small amounts of the allergen (in the order of parts per million or ppm). This reaction can be mild like a hive or very serious as is the case of the dreaded anaphylactic shock.

In recent years, due to the growing importance of this problem, the food industry is making an effort to improve the information on the content of food allergens in products offered to the consumer. However, there are still many products where the reference “may contain…” appears on the label, theoretically the result of the impossibility of controlling cross-contamination with ingredients of other products that are manufactured in the same facility.

This labelling generates confusion and reduce the range of foods available for allergic consumers (DunnGalvin et al., 2015;) Marchisotto et al., 2016; Muraro et al., 2014). As well as the increase in the number of alert notifications RASFF shows them the threat posed to their health food allergens present in products that do not appear on the labelling.

As we discussed in our blog, in order to reduces the use of the words «may contain» and reduce the presence of non- intentional allergens, it is important that all members of the food industry consider allergens as a danger and are integrated within a HACCP system.

An effective tool to confirm that the practices of handling and cleaning are being done correctly is the control of allergens on work surfaces and analytical tools. But don’t forget that to make useful application of analytical techniques the user has to have information in order to understand what the applicability and scope of the test being performed is.

For this reason ZEULAB in collaboration with the University of Zaragoza and Madrid’s Hortaleza District Health Department, has conducted a study to demonstrate the analytical conditions for the realization of this type of analysis.

The work that has been published recently in the journal Food Control shows the development of a method that combines the recovery of material allergen of surfaces through the use of swabs and further analysis both qualitatively, with a rapid strip, and quantitatively through a test ELISA (Galan-Malo et al., 2017).

The objective of this work has been to develop a method that is both as simple as possible without losing technical performance and has initially focused on the analysis of residues of milk and egg.

Three important aspects of the method have been evaluated in the study: swab material, composition of the extraction solution, and temperature and time of removal before the trial. Swabs made of five different materials were analyzed and of these selected the higher yield was obtained. The results indicated that cotton was the material that worst captures the remains of milk and egg. So, that famous phrase saying «cotton does not deceive» does not apply in this context.

Therefore, it is very important that the material supplied or recommended by the manufacturer is used for analysis of allergens on surfaces and that swabs from another source, are not used since they could compromise the results of the analysis.

In this work, the analysis of allergens in two types of surfaces were evaluated namely melamine and stainless steel. These two types of surface are located in the facilities of the food industry or in the kitchens of canteens and of which there was not much information available about the effectiveness of the methods of analysis.

The results showed that the ELISA test is able to detect levels as low as 0.04 µg of egg and 0.2 µg of milk. The rapid tests put their detection limit at 0.07 µg of egg and 0.6 µg of milk depending on the analyzed surface.

From a practical point of view, the rapid tests are very useful and have proven their validity for the routine check after cleaning of equipment and facilities. In a few minutes they let you verify if the cleaning procedure has been correctly carried out and whether the measures of containment against cross-contamination are adequate and effective.

On the other hand, the ELISA tests due to its greater sensitivity and especially to provide quantitative results, are a very useful tool for the validation of cleaning procedures.

This type of testing should be conducted periodically or after the introduction of relevant changes in the cleaning procedure. A proper use of these tools will improve allergy risk management plans and reduce the indiscriminate use of preventive labeling.