Development of three real-time PCR assays to detect peanut allergen residue in processed food products

Hypersensitivity to peanut is a public health problem, since the ingestion of even low amounts of peanut can trigger severe allergic reactions. Allergic consumers rely on the information provided on the label of foodstuffs to identify products that might endanger their health. In order to protect the allergic consumer methods are required for the detection of allergenic ingredients. For this purpose we have developed three real-time polymerase chain reaction (PCR) assays, based on TaqMan chemistry, that are capable of detecting peanut specific DNA sequences in food products. The peanut specific sequence targeted for detection is located within the gene family of the allergen Ara h 3. The occurrence of multiple Ara h 3 sequences in the peanut genome increases the chance to achieve a good sensitivity. DNA extraction is also known to affect detection by PCR, therefore the efficiency of several different DNA extraction methods was compared. The methods reported here are capable of detecting 2.5 pg peanut DNA (less than one copy of peanut genome equivalent) and all three assays were successfully applied to detect peanut traces in a model food product where they could detect 10 mg kg⁻¹ peanut.