Sensitive and specific detection of almond (Prunus dulcis) in commercial food products by real-time PCR

Almond has been widely used in all sorts of food products, mostly due to its pleasant flavor and health benefits. However almonds can become an important health problem since they are responsible for triggering adverse immune responses in allergic individuals, and since they are present in many processed foods they are considered as a potential hidden allergen. Consequently, it's important for food processors and regulatory agencies to be able to ensure accurate labeling of foods to protect the safety of the public and to avoid expensive recalls. We propose a simple and highly sensitive approach to detect almond in a wide range of processed foods. The method consists of a real-time PCR assay targeting the gene encoding for the ITS1 in almond, using a nuclease (TaqMan) probe labeled with FAM and BBQ. Sensitivity of real time PCR was determined by analysis of raw and heat treated almond-wheat flour mixtures with a range of detection of 0.1–100,000 mg/kg. The assay was successfully trialed on a total of 214 commercial foodstuffs allowing the detection of trace amounts of almond down to the level of 0.1 mg/kg, and is therefore proposed as a ready-to-use analytical tool to trace almond allergens in foods.