If you have ever roasted a coffee that looked great but tasted bitter, smoky, or harsh, you are not alone. This is one of the most common problems home roasters run into, especially as they start pushing roasts darker or trying to get more body.
Let’s start with a simple example.
Imagine two roasts of the same coffee. Both hit first crack at about the same time. One finishes smoothly and tastes balanced, with sweetness and body. The other tastes sharp and bitter, with a dry finish that lingers on the tongue. The difference often comes down to what happened after first crack.
What is First Crack?
First crack is when the coffee starts releasing energy and expanding. At this point, the sugars that were built earlier in the roast are fragile. If too much heat is applied after first crack, those sugars begin to break down. Instead of sweetness, you get bitterness and a burnt or ashy character.
Another common scenario is stretching the roast too long at the end. This often happens when chasing a darker color. The coffee may look even and well developed, but the extra time combined with steady heat can strip away sweetness and leave the cup tasting hollow and dry.
A good fix is to think of the end of the roast as a gentle landing, not a sprint. Reducing heat slightly as the coffee enters first crack helps slow things down. You want the roast to keep moving, but calmly. This allows the coffee to finish cleanly, keeping bitterness in check while preserving body and balance.
If bitterness is showing up in your roasts, try one small change at a time. Ease off the heat after first crack. Finish the roast a little earlier. Pay attention to aroma, not just color. These small adjustments often make the biggest difference.