Technique

Crema is the reddish-brown, foamy layer that sits on top of a freshly pulled espresso shot. It forms when CO₂ dissolved in the coffee bean is released during high-pressure extraction and emulsifies with the coffee’s natural oils. Crema is unique to espresso — it requires 9 bars of pressure to form. You won’t get real crema from a moka pot, French press, or drip coffee. Why Crema Forms Coffee beans contain dissolved CO₂ from the roasting process. When you force hot water through finely-ground coffee at 9 bars of pressure, two things happen simultaneously: ...

The espresso ratio is the relationship between how much dry coffee you use (dose) and how much liquid espresso you get out (yield). Expressed as dose:yield, the standard espresso ratio is 1:2 — 18g of coffee in produces 36g of espresso out. Understanding espresso ratios is the fastest way to improve your shots and troubleshoot problems. Once you know the ratio framework, you can adjust any variable with confidence instead of guessing. ...