Extraction

Coffee beans are made up of 28 to 30% soluble material. The rest is cellulose, which doesn’t dissolve in water. Extraction determines how much of that soluble material ends up in your cup.

An ideal extraction sits between 18 and 22%. Too little extraction — under-extraction — tastes sour and thin. Too much extraction — over-extraction — makes coffee bitter and dry.

Four variables control extraction:

1. Grind size: A finer grind increases surface area. More surface area means faster extraction.
2. Water temperature: Hotter water extracts more, and faster. Cooler water extracts less.
3. Contact time: The longer water and coffee stay in contact, the more extracts.
4. Brew ratio: More water per gram of coffee pulls out more soluble material.

You control extraction through these four variables, always. Change one at a time — otherwise you won’t know what actually made the difference.

Frequently Asked Questions

How do I know if my coffee is extracted correctly?

Taste it. Sour, sharp, or thin flavors point to under-extraction. Bitter, dry, or woody flavors point to over-extraction. A well-extracted coffee is balanced — sweetness, acidity, and body in proportion. Want to measure it? Use a TDS meter and calculate the extraction percentage.

What’s the easiest fix if my coffee tastes too bitter?

Grind coarser. This reduces surface area and slows extraction down. It’s the fastest, most direct fix. After that, you can look at lowering water temperature or shortening contact time. Change one variable at a time.

Why does espresso extract differently than drip coffee?

Espresso uses pressure (9 bars) to force water through coffee. That speeds up extraction enormously, which is why the contact time is short (25–30 seconds) and the grind is finer. Drip coffee is pressureless extraction driven by gravity, which needs a coarser grind and longer contact time. Same principle, different parameters.