Effects of different extrusion conditions on the chemical and toxicological fate of fumonisin B1 in maize: a short review

Fumonisin B-1 (FB1) is a common mycotoxin found in maize and maize-based food products. Although FB1 is relatively heat stable and survives most thermal processes, extrusion cooking has been shown to be effective at reducing levels of the toxin in contaminated maize. This review summarises studies on the chemical and toxicological fate of FB1 in maize extruded under different conditions. Overall, these studies indicate that stability of FB1 depends on the extrusion conditions, e. g. temperature and screw speed, and that the presence of reducing sugars augment apparent loss of the toxin. The chemical fate of FB1 was investigated by measuring FB1, hydrolysed FB1, and N-substituted FB1 compounds with a mass balance approach while the relative toxicity was determined by rat feeding trials. FB1 in contaminated grits was reduced by 21-37% and 77-87% in the absence and presence of 10% (w/w) glucose, respectively, during single-screw extrusion. Greater reductions of 64-72% and 89-94% were achieved by twin-screw extrusion. Mass balance analysis showed that most of the FB1 in grits extruded without glucose was recovered as FB1, whereas the FB1-glucose reaction product, N-(deoxy-D-fructos-1-yl)-fumonisin B-1 was the prevalent form after extrusion with glucose. 23 to 38% of FB1 in extruded grits with and without added glucose was bound to component(s) of the maize grits. Only 37-46% of FB1 present in unextruded grits could be recovered as one of the fumonisin species (hydrolysed FB1, N-substituted FB1 compounds) or as matrix-bound forms in extruded grits. Reduced FB1 concentrations in extruded grits and the even lower concentrations in grits extruded with glucose resulted in a dose-dependent reduction of toxicity as shown by the less severe apoptotic lesions and sphingolipid effects that were found in the kidneys of rats. In summary, extrusion processing, especially with glucose supplementation, is potentially useful to reduce FB1 concentrations and toxicity of contaminated maize.