Development of a Flow Cytometry Bead-Based Immunoassay for the Simultaneous Detection of Food Allergens

Introduction:  Food allergy prevalence has increased (up to 7%) over the last decades. Efficient monitoring of allergens in food is required to ensure safety of consumers facing this health problem. Most of current analytical methods for food allergens are based on immunological reactions (ELISA and immunostrips) or PCR. Classical immunoassays are, generally, suitable for detecting, only, one single allergen at a time, or are limited to few targets. In contrast, multiplexed PCR tests are available; but, for some major allergens, like milk or egg, this technique lacks in sufficient performance.

Purpose:  Flow Cytometry bead-based Immunoassays (FCIA) present all the advantages of immunological tests (sensitivity, specificity, high-throughput) and, additionally, provide great multiplexing capacity. Different immunoassays developed using individually encoded, fluorescent microparticles can be combined in a final test to broaden the compounds detected. The aim of this work was to explore the potential of FCIA for the simultaneous analysis of four major food allergens; milk, egg, peanut, and soya.

Methods:  Individual competitive bead-suspension assays have been developed for milk (β-lactoglobulin and casein), egg, peanut, and soya. The tests have been combined in a five-plex assay to detect all of the allergens in a single analysis.

Results: The performance of the assay was evaluated in diverse food matrices: speculoos, cookies, ice-cream, spices, chocolate, and tomato sauce. Upon extraction of the fortified matrices, the allergens were detected at concentrations as low as 0.2, 0.3, 0.6, 1, and 2 µg g^–1 (protein content) for β-lactoglobulin, casein, egg, peanut, and soya, respectively, in all food commodities tested.

Significance: The results, presented herein, pointed out the interest of FCIA for food allergen determination as applied in routine quality control, by food industries and official entities. Further work is ongoing to expand the application of the test to other allergens and matrices.