Recently at dotCross, we’ve been having problems with the coffee we’ve been roasting. We have a tiny little home roaster that we use to explore the art of roasting and it’s been a real fun journey. Aaron does most of the roasting and I, unfortunately, do most of the criticizing. But in a constructive manner! At least I think so.

More specifically though, we were having issues with the Sumatran we have. We roasted it thrice, the first time was great, the second time was awful and the most recent one was passable. We spoke with some people about why there was so much variation and got a couple of reasons which we’ll incorporate with our next roasts.

But it got me thinking, what does defects in coffee mean? We’ve been working on understanding good coffee, or figuring out how to attain it, but there is a tremendous gap in our knowledge as to how to spot a defect. We won’t be able to point to what is wrong if we have no idea what we’re talking about.

It was just a terrible coincidence that cupping today at Counter Culture was done with defective beans for the express purpose of showcasing defects. Specifically, coffee with the presence of phenol compounds and faded coffee. I thought I’d just share with you guys what they actually are like, because as consumers of coffee, defective coffee is something that just doesn’t get into our cups, but I do think its terribly interesting.

Presence of phenolic compounds:
Phenolic compounds appear as a byproduct of contaminated coffee, due to storage issues or fermentation issues. Certain fungi, for example, cause the breakdown of green coffee beans into phenolic compounds. And it’s almost impossible to identify such tainted coffee beans before roasting them.

As far as I could taste, the taste of phenol was just bad. Imagine opening a fresh bandaid, and there’s that medicinal smell that comes out. Not bitter, but a little rancid. Imagine weak old rancid cooking oil, with the taste of plastic. It creates this “roundness” in the mouth, the kind of feeling you get when you bite into semi raw garlic.

Faded coffee:
So this is coffee that’s been left a little too long. It’s old coffee, or green coffee that hasn’t been stored properly before roasting. There’s a lack of flavor, a muteness as the compounds disappear and get broken down.

In terms of flavor and taste, this was a little more of a muted-ness. Every flavor is there like how it should, but the volume was just at 2 instead of at the usual 5. In particular though, there was a flavor of plywood, and just a general staleness about it (bread, biscuits). And this is attributed to the cellulose that’s in the bean: most of the bean is just cellulose at this point instead of the favors, giving it that cardboard woody flavor, perhaps also close the the rind of pith of certain fruits.

There’s plenty more defects to go around, and its always unfortunate that any batch is defective. But it does provide indications of where we can improve on coffee processes, and improve quality down the chain.