Detection of moulds producing aflatoxins in maize and peanuts by an immunoassay

An enzyme-linked immunosorbent assay (ELISA) was developed to detect moulds producing aflatoxins in maize and peanuts by an antibody produced to extracellular antigen from Aspergillus parasiticus. This antibody recognized species with phenotypic similarities to A. parasiticus, A. flavus and the domesticated species A. sojae and A. oryzae. For maize samples that were naturally contaminated with aflatoxins, low and high levels of aflatoxin corresponded with low and high ELISA readings for mould antigens, respectively. Maize and peanuts inoculated with 10(2) spores ml(-1) of A. parasiticus and incubated at 15 degrees C for 18 days or 21 degrees C for 7 days were analyzed for mould antigens and aflatoxin levels. At 15 degrees C, mould antigens were detected by day 4 in maize when 0.16 ng g(-1) of aflatoxin was detected by ELISA but not by thin layer chromatography (TLC). Antigens were detected in peanuts by day 4 before aflatoxin was found. Likewise, at 21 degrees C, antigens were detected by day 4 in maize when less than 1 ng g(-1) of aflatoxin was detected by ELISA but not by TLC, but by day 2 in peanuts when no aflatoxin was detected. A. parasiticus could be detected before it could produce aflatoxins. Therefore, this ELISA shows potential as an early detection method for moulds that produce aflatoxins.