What does acerbic mean in coffee?

Acerbic describes an unpleasant, harsh sourness - the kind that makes you wince rather than brighten. It's distinct from the clean, fruit-like brightness that makes a well-processed washed Ethiopian interesting. That acidity is a positive quality attribute. Acerbic is a fault.

It's a useful diagnostic signal at the cupping table. You taste something sharp and uncomfortable, and the question is where it came from. Common causes include fermentation faults during processing, sour beans in the green lot, or brewing issues like water that's too hot or a contact time that's dragged on too long.

If you're consistently getting acerbic notes from a specific lot across multiple brew methods, the problem usually sits upstream - in the green coffee itself, not your roasting. It's worth pulling a small sample to check the green appearance before writing off the whole lot.