Abstract
The accurate quantification of food allergens is crucial for ensuring consumer safety and compliance with regulatory requirements. A proficiency test (PT) was organised to evaluate the performance of laboratories in quantifying total egg and total milk protein in cookies. The PT involved 20 laboratories, which reported results using mainly commercial ELISA kits and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The findings indicate a satisfactory performance for milk protein determination among the majority of participant laboratories. However, the quantification of egg proteins in heated products remains a challenge, with most laboratories reporting results significantly below the reference value. Several potential factors contributing to this challenge are discussed, including the denaturation of egg proteins during heat treatment, differences in extraction strategies and the antibodies used in ELISA kits, and the lack of standardised methods and conversion factors for LC-MS/MS analysis. These findings underscore the importance of regular PT exercises to evaluate laboratory performance and ensure compliance with WHO/FAO recommendations. The results of this study aim to guide the development of improved analytical methods and strategies for ensuring the accurate quantification of food allergens.