Effect of processing on fumonisin concentration in corn flakes

The stability of fumonisin B1 and fumonisin B2 during processing of corn flakes was investigated with three different methods for analysis of the naturally contaminated raw material (corn flour), intermediate product (extruded, but not roasted corn flakes), and final product (roasted corn flakes). Only one method, using immunoaffinity column clean-up, provided reliable results in the determination of fumonisins in corn flake samples at the intermediate and final steps of processing. About 60 to 70% of the initial amount of fumonisins were lost during the entire cycle of corn flake processing, with less than 30% losses occurring during the intermediate extrusion step (70 to 170 degrees C for 2 to 5 min). The effect of different additives commonly present in commercial products (sodium chloride, sucrose, and ferrous sulfate heptahydrate) on the reliability of fumonisin analysis has also been investigated. The presence of sodium chloride strongly reduced fumonisin recovery when strong anion-exchange (SAX) columns were used for the clean-up step, whereas the other additives appeared to have little or no effect on the accuracy of fumonisin analysis. The use of reliable analytical methods that are effective for both raw materials and processed products is of paramount relevance for studying the effect of food processing on mycotoxin-contaminated commodities. Despite the fact that some effective fumonisin decontamination occurring during corn flake processing has been shown, more work is needed to identify the thermal breakdown products of fumonisins and their relevant toxicity.