Aspergillus flavus infection and aflatoxin production in mixtures of high-moisture and dry maize

High-moisture (26·6–27·9% m.c.) and dry (9·8% m.c.) fractions of white and yellow maize were examined for fungal development and aflatoxin production during an 8-week incubation at 25°C. Treatment procedures included blending of either high-moisture white with dry yellow or high-moisture yellow with dry white maize fractions (average moisture in blend, 14%) and inoculation of some test maizes with A. flavus spores. At sampling time white and yellow components of maize blends were manually separated and all of the maize samples were analyzed for levels of moisture, fungal infection and aflatoxin. Moisture levels in maize blends equilibrated rapidly during the initial 2–4 days of incubation; neither dry yellow nor dry white exceeded 13% moisture during the trial period. Only a limited incidence of A. flavus was observed on uninoculated maize. but in samples treated with A. flavus spores a high infection rate developed; from 58 to 98% of the kernels in dry fractions of inoculated blends were infected with A. flavus during the trial. Aflatoxin was detected in high-moisture maize and in both high-moisture and dry fractions of inoculated maize blends. Up to 500 μg aflatoxin B₁/kg of corn was found after the 8-week incubation in a dry fraction of inoculated maize blends.