Presence of soy in cereals and cereal products: validation of an ELISA technique and monitoring of products from the Italian market

Soybean (Glycine max) is an edible legume belonging to the Fabaceae family. Soybean is a protein source and can be included as ingredient in a wide variety of processed foods. Soy and soy protein formulas can potentially induce food allergies, even though severe and/or fatal anaphylaxis reactions are rare. Soy is also widely consumed by children (soy-based formulas have been introduced in infant nutrition). Furthermore, soy can also be detected in food as an occult contaminant due to cross contamination processes. The aim of the research has been to evaluate the presence of this allergen in products belonging to the category of cereal-based foods, not-declaring presence of soy, using a validated method and proposing an internal quality control material that can be used in the context of control activities. A total of 65 samples belonging to the category of cereals and cereal-based foods (wheat flour, semolina, spelt, rice and pasta): 23 samples for the validation and 42 sample for monitoring were collected at retail stores in the metropolitan Rome area in Italy. Presence of soy in food samples was measured by an immunoenzymatic technique (Enzyme-linked Immunosorbent Assay, ELISA). The method used was preliminarily verified and validated in accordance with the main harmonized standards. A material for internal quality control was preliminarily designed. Validation confirmed the suitability of the method for official control. Only 3 samples out of a total of 42 (about 7%) were positive in terms of soybean presence. Moreover, a material for internal quality control has been characterized and preliminary results have been encouraging in terms of recovery and repeatability.