Search

A feasibility interlaboratory comparison (ILC) was organised by the European Commission’s (EC) Joint Research Centre (JRC) on the determination of the mass fraction of total cow’s milk protein in baked cookies. The ILC was organised to support Commission Regulation (EU) 1169/2011 on the provision of food information to consumers, including the mandatory allergen food labelling and the harmonisation of measurement procedures used for food allergen analysis. An incurred baked cookie was prepared at the JRC and samples were sent to participants for analysis. The laboratories were asked to report their results as “mass fraction of total cow’s milk protein in baked cookies”. This common well-defined measurand was used for the first time in such an ILC to assess the equivalence of measurement results. Homogeneity and stability of the test material were demonstrated to be adequate. An indicative assigned value was established using the JRC single-laboratory validated method based on liquid chromatography coupled to mass spectrometry (LC–MS), independently from the results reported by the participants. Twenty-three laboratories from the European Network of Food Allergen Detection Laboratories (ENFADL), representing 20 European Union (EU) Member States, reported results. Their laboratory performance was assessed using the percent difference Di score. The participating laboratories applied either enzyme-linked immunosorbent assays (ELISA) or LC–MS. Even though the majority of the laboratories used commercially available ELISA test kits, a significant scatter of all the reported results was observed. This indicates that further harmonisation is required for measurement procedures aiming to determine potentially allergenic constituents in food.

The establishment of a reference method for the determination of the allergen protein content in a processed food material has been explored. An analytical approach was developed to enable the comparability of food allergen measurement results expressed in a decision-relevant manner. A proof of concept is here presented, resulting in quantity values for the common measurand, namely ‘mass of total allergen protein per mass of food’. The quantities are determined with SI traceability to enable the comparability of reported results. A method for the quantification of total milk protein content in an incurred baked food at a concentration level clinically relevant is presented. The strategy on how to obtain the final analytical result is outlined. Challenges associated with this method are discussed, in particular the optimal extraction of the marker proteins, the complete digestion and release of the peptides in an equimolar fashion, the use of conversion factors to translate the amount of measured proteins into total milk protein and the estimation of the uncertainty contributions as well as of the combined uncertainty of the final result. The implementation of such a reference method for the determination of the total allergen content in a processed food is an important step, which will provide comparable measurement data of relevance to risk assessors.