Evaluation of citrus flavonoids against Aspergillus parasiticus in maize: Aflatoxins reduction and ultrastructure alterations

In this study, the effects of citrus flavonoids naringin (NAR), neohesperidin (NEO) and quercetin (QUER) on aflatoxins accumulation by a selected Aspergillus parasiticus strain in maize at 0.95 a(w) were studied by response surface methodology using a Box-Behnken design. Multiple response optimization was applied to simultaneously minimize the contamination with aflatoxins (AFs) B1, G1, B2 and G2. The application of the optimal mixture in maize at 0.95 a(w) (0.39 mM NAR, 0.24 mM NEO and 0.40 mM QUER) reduced from 85% to 100% AFs accumulation. The same mixture at 0.98 a(w), led to a reduction in AFs accumulation that ranged from 93% to 98%. Ultrastructure alterations of cellular membranes and walls in A. parasiticus, evidenced by transmission electron microscopy images, were severe and depended on the type of flavonoid and their combination. Flavonoid mixtures may provide an environmentally friendly alternative for decreasing AFs accumulation in stored maize, replacing synthetic compounds.