Use of bright greenish yellow fluorescence as a presumptive test for aflatoxin in corn
1981
Shotwell, O.L. | Hesseltine, C.W.
Corn samples from the 1978 crop were examined under UV light (365 nm) for the bright greenish yellow (BGY) fluorescence associated with Aspergillus flavus or A. parasiticus and possibly the aflatoxin produced by these fungi. Two methods were used to test 248 samples for BGY fluorescence. First, whole-kernel samples were examined in a black light viewer, and BGY particles were counted. Then, the corn samples were coarse-ground in a disk mill; BGY particles were counted as the stream from the mill was examined under UV light (365 nm). The counts obtained by the two methods were similar. Particle counts were identical in 61% of the samples and differed by 1 in 20%, 2 in 8%, 3 in 6%, and 4 in only 5%. Tinopal BHS, a compound that is stable to air, can be used as a colour reference standard in the BGY test. In samples of 1978 corn having 1 BGY particle/kg, 92% had <20 ng of total aflatoxin/g, the FDA's action guideline. In 1978 samples having ≥4 particles/kg, only 25% had <20 ng/g. In an examination of 1973 South Carolina corn, 98% of the samples in which no BGY fluorescence was detected had aflatoxin levels <20 ng/g; two samples that were BGY-negative had 21 and 27 ng/g.
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