jacqui{JB} wrote:

> Although there is a chance for error in the analytical process, this
> is the most accurate step in the detection procedure. There are
> several ways of detecting aflatoxin once the sub-sample has been
> obtained. Detection methods range from procedures as simple as visual
> observation of the toxin-producing fungi to complicated chemical
> analyses of the toxins themselves.

See. There ya go. "visual observation of the toxin-producing fungi".
That's a recognized detection method.

In popcorn, it is a black mold (_Aspergillus_) which lives
in the germ of the kernel. Often, the tip of the husk over the
germ of an infected kernel flakes off, so you can see the
blackened germ. This is one of the most common reasons
for me to reject a bad kernel. Sometimes the husk over the
germ remains intact, but you can see visually that the germ
under the husk is blackened. Those are also rejects.
Just to play it safe, I reject any kernel that looks out of the
ordinary. Broken kernels, swollen kernels, kernels with
visible desposits of black crud on them, all get rejected.
(I believe the black deposits are picked up from the corn
handling machinery, which needs to be cleaned.)

When held up to a light, a good kernel is translucent
yellow, with no internal black features.

Bad kernels can pop like good kernels, and those are the
occasional pieces of popcorn that have an off flavor,
which you get if you don't pick out the bad kernels before
making a batch of popcorn.

I avoid them both for the bad flavor and the cancer risk.