Microbead-based simultaneous fluorometric detection of three nut allergens

A microbead-based method is developed for the detection of three nut allergens that can occur in food. The bead array constitutes of a suspension of spectrally distinct fluorescent polystyrene microbeads and has been applied for the simultaneous detection of three main and serious allergens (hazelnut, peanut and walnut). The method is based on the simultaneous identification of specific DNA sequences after PCR. The PCR products are biotinylated and hybridized to nut-specific oligonucleotide probes attached to the microbeads. The hybrids are finally detected by a streptavidin-phycoerythrin conjugate and flow cytometric analysis. As low as 0.01% content of the three nuts in processed food (cookies) can be detected by this method.