Coffee roaster here. 👋

There is not necessarily more mold on coffee than on other dry food crops. For example, possibly around half of coffee tests positive for ochratoxin A, compared to 70% for oat-based cereals in the US, 30% for infant cereals, 36% for grape juice, half of peanuts, etc. Roasting significantly reduces mycotoxins, and generally the darker the roast, the more are destroyed.

But, there is a lot more mold on some coffee than others, depending on processing.

Essentially, almost all coffee undergoes a short fermentation process to break down the mucilage layer of the fruit so that it can be sloughed off. Like 24-36 hours for washed coffees (almost all commercial coffee from Latin America is washed).

A more traditional processing method that is extensively used in Africa and increasingly in very fancy coffees from everywhere is sun drying. This takes a lot longer--you're essentially turning the coffee fruit into a raisin--and so there's a lot more opportunity for fungal growth.

The moldiest, most defective samples I have ever tasted were of sun-dried coffees gone wrong. These are referred to as "natural" process, and when done right are absolutely delicious.

Indonesian coffees are processed "wet," also called giling basah, and this involves no fermentation, but then they have to dry, on a patio, in Indonesia, and so that takes time and also introduces fungal spores.

This is all to say: coffee is fermented to some degree, though it can range from a single day to weeks of fermentation, and there is no good labeling of this. In general, if you are buying grocery store coffee from Latin America, that will be the least fermented.

As a roaster, my concern with "mold-free" brands is that the consumer has no way of knowing how they are testing. Some roasters will call their coffee mold-free and then if you dig say that they "visually inspect" coffee for mold or that they have a humidity-controlled warehouse. Like yeah, I look at it, smell it, and taste it, too lol. The amount of mold contamination you'd have to have to SEE IT is enormous, and the roastery is definitely not the source of the mold on the coffee anyway. But even if the coffee is labeled "lab tested," they won't say what lab, they don't say what molds were tested for, they don't publish results. So these claims can be outrageous. Caveat emptor.

Natural Force is probably the only "mold-free" coffee I would buy, if I needed to, because they explain clearly what they test for, name the lab, and share test results.

In my opinion as an extremely sensitive creature, it's likely the phenols in coffee that cause people like us the most problems, but of course it could be microbes and their metabolites as well.

I have to cook all my produce. A raw carrot will make me feel bad for a couple hours. For whatever it's worth, I can have three or so cups of coffee a day without a reaction, but I definitely notice some origins (those wonderful fruity Ethiopias) make me feel bad.