Fast and sensitive electrochemical immunoplatforms for detecting traces of soy in food

Abstract

The prevalence of food allergies has been steadily increasing in developed countries in recent times and is now considered a serious public health problem affecting 2-4% of the population. Soybean is among the most frequent human food allergens, also known as the "big eight", accounting for 90% of all food allergies. Soy allergy has a high prevalence among children (0.5%), probably because soy is widely used as an ingredient in the preparation of many foods, and current EU and US legislations includes soy as one of the major allergens that must appear on the label of food products. Therefore, to protect allergic consumers, regulatory agencies are demanding highly sensitive and selective detection methods. Glycinin and β-conglycinin, accounting for about 70-80% of the total globulin fraction of the seed, are the main allergenic soy proteins. In this communication, the first electrochemical bioplatform for the determination of soy traces in food will be presented. The immunoplatform involves sandwich-type immunoassays using specific antibodies for β-conglycinin and glycinin and carboxylic acid-modified magnetic microbeads (MBs). The determination of both proteins can be carried out in only 1.5 h. It is important to note that, counting since the prepared capture antibody (cAb)-modified MBs, the determination can be performed in a short time as 30 min by direct assaying the food extract. The electrochemical bioplatforms allow their accurate determinations (with results statistically comparable to those provided by ELISA methodologies) in raw cookie dough and baked cookies enriched with soy flour. It is also important to highlight that the results obtained confirm, in a pioneering way with electrochemical biosensors, the possibility of discriminating samples incurred with as little as 0.0005 ppm of a food allergen in model cookie extracts. This level of detection is significantly lower than that achieved with ELISA methodologies using the same immunoreagents (50-500 ppm).