Mycotoxin co-occurrence in rice, oat flakes and wheat noodles used as staple foods in Ecuador

The co-occurrence of aflatoxin B-1 (AFB(1)), B-2 (AFB(2)), G(1) (AFG(1)) and G(2) (AFG(2)), ochratoxin A (OTA), deoxynivalenol (DON), fumonisin B-1 (FB1), zearalenone (ZEN), and HT-2 and T-2 toxins in the main Ecuadorian staple cereals (rice, oat flakes, and yellow and white wheat noodles) was evaluated. A ultra high performance liquid chromatography/time-of-flight mass spectrometry (UHPLC/TOFMS) method was developed and validated to screen for the presence of these mycotoxins in those cereal matrices. Matrix-matched calibration curves were used to compensate for ion suppression and extraction losses and the recovery values were in agreement with the minimum requirements of Regulation 401/2006/EC (70-110%). For most mycotoxins, the LODs obtained allowed detection in compliance with the maximum permitted levels set in Regulation EC/2006/1881, with the exception of OTA in all cereals and AFB1 in yellow noodles. Extra target analysis of OTA in oat flakes and wheat noodles was performed by HPLC with fluorescence detection. High rates of contamination were observed in paddy rice (23% DON, 23% FB1, 7% AFB(1), 2% AFG(1) and 2% AFG(2)), white wheat noodles (33% DON and 5% OTA) and oat flakes (17% DON, 2% OTA and 2% AFB(1)), whereas the rates of contamination were lower in polished rice (2% AFG(1) and 4% HT-2 toxin) and yellow noodles (5% DON). Low rates of co-occurrence of several mycotoxins were observed only for white wheat noodles (5%) and paddy rice (7%). White noodles were contaminated with DON and/or OTA, while combinations of AFG(1), AFB(1), DON and FB1 were found in paddy rice. Yellow noodles were contaminated with DON only; oat flakes contained DON, OTA or AFB(1), and polished rice was contaminated with AFG(1) and HT-2 toxin.