Peanut traces in packaged food products consumed by allergic individuals: Results of the MIRABEL project

In the frame of the French research project MIRABEL, 899 food samples which contained no peanut ingredients according to the labeling list were analyzed for the presence of peanut allergen traces. Samples covered a broad range of products from ten major food categories. In a stepwise procedure, samples were screened using a sensitive lateral flow assay with a limit of detection of 2 ppm total peanut or 0.5 ppm peanut protein. Positive as well as suspect samples (139/899) were confirmed by real-time PCR with the same sensitivity. Positives in both approaches were quantified by two different commercial ELISA tests. 1% (9/899) out of all samples did contain measurable peanut DNA and protein traces above the detection limit of the applied methods. Six samples had a content of total peanut protein <5 mg/kg, two samples contained between 8 and 10 mg/kg and one sample a maximum of about 20 mg/kg. An excellent correlation was found between Ct-values obtained by PCR and ppm peanut calculated by ELISA. It is concluded that, in the light of future thresholds for labeling of relevant allergens, the methods used for peanut detection in this study are able to detect contaminations as low as 2 ppm.