Geimori / Coffee Journal
A thick crema looks great in photos. It does not, by itself, prove that an espresso tastes good.
What crema actually is
Crema is the foam that forms when gases from roasted coffee, especially carbon dioxide, expand as pressurized espresso flows into the cup. Coffee compounds help stabilize the tiny bubbles for a short time. The amount and persistence can change with bean age, variety, roast, and how you brew.
You can have a beautiful crema on an unpleasantly bitter shot, or a thin layer on an excellent light-roast espresso. Taste the liquid before treating the foam as a diagnosis.
Why one shot has more foam than another
- Roast and freshness: recently roasted and darker beans may release more gas; very fresh coffee can also be harder to extract evenly.
- Bean variety: some robusta-containing blends create noticeably more foam than an arabica-only light roast.
- Pressure and basket flow: pressure, dose, puck preparation and basket design affect what you see in the cup.
- Cup and timing: foam collapses over time; compare shots immediately after brewing, not minutes apart.
Troubleshoot the flavor, not just the crema
| What you notice | Try this first |
|---|---|
| Shot tastes sharply sour or thin | Check dose and beverage yield, then adjust grind finer in small steps. |
| Shot tastes very harsh or drying | Try a slightly coarser grind or shorter yield; taste again. |
| Fast, spraying or uneven flow | Improve distribution and level tamping; do not chase crema thickness. |
| Good flavor, thin crema | Nothing may need fixing. Bean style and age can explain the appearance. |
A practical espresso starting point
For a conventional double basket, a useful starting experiment is 18 g of coffee to around 36 g of espresso, then adjust by taste. This is not a universal requirement: different coffees and baskets behave differently. Keep the dose and yield fixed while changing grind, and record what improved.
A consistent grinder helps because you can make small repeatable adjustments. If you are switching between espresso and filter beans, note your settings instead of trying to infer them from crema.
When crema is useful
Think of crema as one observation alongside flow, aroma and taste. Sudden differences with the same coffee may suggest a changed grind, bean age or preparation routine. Across different coffees, foam is too variable to serve as a quality score.
