Evaluation of a Real Time PCR Assay and a ELISA Method for the Detection of Walnuts and Almonds Allergen Traces in Food Products

Food allergens are a well acknowledged issue in food industry and are regulated by legislation. The presence of allergens can either origin from the raw material or due to contamination during production. Allergen information on packaging is mandatory although it cannot be accurate in the case of contamination therefore warnings are used. The purpose of the study is the development and validation of a SYBR Green Real Time Polymerase Chain Reaction method using specific primer pairs based on Jug r 1, Jug r 3, and Jug r 4 allergen-coding sequences to improve the sensitivity of Real Time Polymerase Chain Reaction techniques for detection of walnut and almond traces in commercial food products and its comparison with ELISA methodology in terms of detection ability. A total of 100 samples were collected from local markets and were analyzed by Real Time Polymerase Chain Reaction (RT-PCR) and ELISA methods. The results indicated that 16 samples (16%) were found positive in walnut traces and 18 samples (18%) were found positive in almond traces by Real Time Polymerase Chain Reaction of which Elisa identified 14 samples (14%) positive in walnut traces and 15 samples (15%) positive in almond traces. Among them, 4 samples (25%) that contained walnut traces and 6 samples (33.3%) that contained almond traces had no allergen declaration on their label. The improved accuracy of Real Time Polymerase Chain Reaction underlines the importance of this method for allergen detection and quantification in the food industry