Black lights and aflatoxin: Does it work?

Aspergillus flavus_blogOne of the questions we get a lot is whether using black lights to detect aflatoxin in corn is an accurate method.

The short answer is “not reliably”.

Studies have shown that using black lights to detect aflatoxin in corn produce unreliable results at best. Rather than causing the toxin itself to fluoresce, black lights cause kojic acid (a by-product of Aspergillus flavus, one of the main aflatoxin-producing molds) to fluoresce as bright green-yellow. Additionally, A. flavus can produce this acid without producing aflatoxin and vice versa. The acid also can disperse over time, so a sample that once glowed may not do so later.

Another drawback is the second leading producer of aflatoxin, A. parasiticus, does not produce kojic acid and, therefore, does not glow.

Outside of aflatoxin, most mycotoxins don’t fluoresce at all or fluoresce so little that they are undetected by this method, leaving potentially harmful levels of toxin behind, according to Iowa State University. This method also can produce false positives as non-mycotoxin chemicals or other natural elements (e.g., plant parts, insect parts, etc.) may fluoresce, the University of Nebraska-Lincoln’s Institute of Agriculture and Natural Resources notes.

For more on mycotoxins, check out Neogen’s Mycotoxin Handbook.

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