Development of an UHPLC-Q-Orbitrap HRMS method for simultaneous determination of mycotoxins and isoflavones in soy-based burgers

Soy-based burgers, an option of meatless hamburger-style, are basically made with soy protein, wholegrains and veggies. However, some ingredients, such as cereals and soybean, are particularly susceptible to fungal contamination. Therefore, a fast and simple procedure for the simultaneous determination of isoflavones (n = 12) and mycotoxins (n = 21) in soy-based burgers was developed throughout an acetonitrile-based extraction and UHPLC-Q-Exactive Orbitrap HRMS determination for the first time. The procedure was properly validated in terms of linearity, accuracy (recovery range from 78 to 108%) and precision (RSD < 12%), and the limits of quantitation obtained were at low ng/g range for all studied compounds. The developed method was applied to nineteen soy-based burger samples. Total isoflavones were quantified at a range from 0.40 to 6.39 mg/100g and daidzein was the most abundant aglycone. On the other hand, up to 10 different mycotoxins were found in 94.7% of samples being alternariol monomethyl ether and enniatins the most commonly found at levels of hundreds ng/g. Additionally, co-occurrence of mycotoxins was found in almost all contaminated samples with combinations of up to 6 mycotoxins per sample. These results highlight the importance of implementing analytical tools to control both health-promoting compounds and contaminants in foods particularly in susceptible population groups such as vegetarians.