Determination of Peanut Traces in Food by a Commercially-available ELISA Test

Peanuts are one of the most important food allergens. The unintended ingestion of peanut has caused severe allergic reactions and even deaths in sensitive individuals. Specific methods with sensitivities in the low ppm range are necessary to check whether a food contains relevant amounts of peanut protein. Based on a commercially-available ELISA test, a test protocol was established for the detection and semi-quantitative determination of peanut traces in a wide range of products, including chocolate and chocolate confectionery, ice cream and bakery goods. The test was rendered semi-quantitative by including a standard curve prepared from different peanut materials and by adapting the extraction procedure. Using the extraction buffer supplied with the kit, only 2-3% of peanut protein added to dark chocolate could be recovered. By using a fish gelatine containing extraction buffer, recoveries of 60-90% and a detection limit of 2 mg peanut protein kg-1 product were achieved for this matrix. Comparable results were established for other products with similar values for extraction with or without fish gelatine. No false positive results were observed. With this a sensitive method is available for the determination of peanut traces in a wide range of raw materials and finished products. The detection limit of 2 mg peanut protein kg-1 product is satisfactory if compared to the lowest tolerable dose of peanut protein as determined in recent challenge studies.