Matrix-corrected mass spectrometry enables sensitive detection of food allergens and reveals widespread soy contamination of processed foods

Abstract

The frequent use of precautionary food allergen labeling statements such as \"may contain\" poses challenges to allergic individuals who rely on such labeling to determine whether a food is safe to consume. We developed a multiplexed liquid chromatography-mass spectrometry assay targeting 14 common allergens in order to survey how frequently these precautionary statements indicate allergen contamination and to assess whether variations in precautionary phrasing affect the likelihood of allergen contamination. A survey of 84 foods revealed how scheduled multiple reaction monitoring (MRM) transition interference derived from complex and heterogeneous sample matrices hinders sensitive analyte detection. As a solution, we developed MAtrix-Dependent Interference Correction (MADIC), an approach to sensitively detect trace peptide quantities through interference identification and stringent peptide quality control criteria. Applying this method, we find frequent contamination of soy in breads and corn flour, and observe additional instances of food contamination with tree nuts, wheat, milk, and egg. In some of these cases, the food had no precautionary labeling for the offending allergen. We also find that only 10% of warning labels are indicative of contamination, and that products with \"same facility\" precautionary labeling are not necessarily less likely to contain trace amounts of allergens than products labeled \"may contain.\"