Last updated: October 20, 2026
Crema is the reddish-brown layer of tiny gas bubbles and emulsified coffee oils that sits on top of an espresso shot. It forms when hot water under about 9 bar of pressure dissolves carbon dioxide from freshly roasted beans, and the gas escapes as bubbles when the shot reaches normal air pressure. A thick, even layer usually signals fresh beans and a decent pull, but it does not guarantee good flavor. This guide explains what creates crema, how to read it, and how to get more of it at home.
Quick Answer
- Crema needs roughly 9 bar of pressure, a 25 to 30 second extraction and carbon dioxide still trapped in the beans.
- Beans about one to three weeks past their roast date usually give the best foam; very fresh beans (first 3 to 4 days) and beans older than 4 to 5 weeks both disappoint.
- A common target is 2 to 3 mm of fine-bubbled, reddish-brown crema that lasts a couple of minutes.
- A standard starting recipe is 18 g of coffee in and 36 g of liquid out in 25 to 30 seconds.
- Crema is a freshness clue, not a quality score, because robusta and slightly stale coffee can both produce misleading foam.
What You Need
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- Whole beans roasted within the last few weeks, with the roast date printed on the bag
- A burr grinder that can reach a fine espresso setting
- An espresso machine with a portafilter, or a super-automatic or capsule system if you want to compare
- A scale that reads to 0.1 g and a timer
- A clear glass or white cup so you can see the foam
What Creates Crema
Roasting creates carbon dioxide inside the bean. Under espresso pressure, hot water dissolves more of that gas than it could at normal pressure. As the liquid leaves the basket, the gas comes out of solution. Coffee oils, proteins and melanoidins, the brown compounds formed during roasting, stabilize the bubbles into foam. Wikipedia describes the result as emulsified oils turned into a colloid. The term goes back to 1948, when Gaggia coined “caffe crema” for the light brown foam on pressure-brewed espresso.
Several variables push the amount and stability of crema up or down. The table below summarizes what coffee guides report.
| Factor | Effect on crema | Practical note |
|---|---|---|
| Days since roast | Highest CO2 right after roasting; falls as beans sit | Aim for roughly one to three weeks; sources range from 4 to 30 days |
| Beans in first 3-4 days | Large, unstable bubbles that vanish fast | Let the bag rest before judging it |
| Beans past 4-5 weeks | Thin crema whatever else you change | Buy smaller bags more often |
| Pre-ground coffee | Loses most crema-producing gas within days | Grind just before brewing |
| Robusta in the blend | More volume, harsher taste | Evidence on stability is mixed |
| Dark roast | More residual CO2 reported | Surface oils can make foam fade sooner |
| Decaf | Thinner, less stable foam | Process removes some oils |
| Pressurized basket | Foam is mostly aerated liquid | Looks full but is not the same as true crema |
One secondary source reports measured residual CO2 of about 6.3 to 6.7 mg/g in light roasts and 15.4 to 15.6 mg/g in dark roasts. Treat those figures as approximate, since they are summarized from a review rather than checked against the original data.
How to Read Your Crema
Look at color, thickness, bubble size and how fast the layer thins. Guides describe a good shot as 2 to 3 mm of reddish-brown foam with tiny, uniform bubbles that lasts a couple of minutes before thinning. Use the chart below as a starting point rather than a verdict.
| What you see | Likely cause | What to try |
|---|---|---|
| Thick, dark-brown, long-lasting foam | Fresh beans, possibly dark roast or robusta | Taste before you celebrate |
| Pale, thin layer gone in about 20 seconds | Stale beans or under-extraction | Check roast date, then grind finer |
| Large, short-lived bubbles | Beans roasted only a few days ago | Rest the bag a few more days |
| Almost no crema with decaf | Normal for decaf | Judge by taste and flow instead |
| Foam fills the cup but tastes flat | Pressurized basket or capsule system | Compare with a non-pressurized basket |
Tiger striping, the dark and light ripples in the stream from a bottomless portafilter, causes debate. Some barista forums treat early, even striping as a good sign, while a coffee data analysis argues the stripes come from minor channeling. Either way, the cue shows up before the shot reaches the cup and is not a taste guarantee. Early, even striping without sudden pale jets is a reasonable positive, but taste matters more.
How to Get More Crema at Home
- Buy whole beans with a roast date and use them in the first one to three weeks.
- Weigh 18 g of coffee into a double basket and level it with a tap rather than a press.
- Tamp level and firm, with the same pressure each time.
- Lock in the portafilter and start the timer when the pump starts.
- Aim for 36 g of liquid in 25 to 30 seconds; adjust grind size, not dose, to land in that window.
- If the shot runs faster than 25 seconds, grind finer in a small step; if it chokes past 35, grind coarser.
- Store beans in an airtight container away from heat and light.
The Italian Espresso National Institute standard cited by Wikipedia gives water at 88 plus or minus 2 C at the exit, 9 plus or minus 1 bar and 25 plus or minus 5 seconds, with 25 plus or minus 2.5 ml in the cup including crema. Home machines will not match it exactly, but the numbers show where the target sits. Before you chase foam, confirm the basket type. Pressurized baskets add back pressure mechanically, so they create a foamy layer even from older or coarser grounds, and that layer is not the same as crema from a puck.
Why Some Shots Have No Crema
A flat, crema-free shot usually traces back to one of a few causes. Work through them in this order, since the early ones are the most common.
- Stale beans or grounds: if the bag is more than four to five weeks past roast, or you used pre-ground coffee, the gas that builds foam is largely gone.
- Grind too coarse: when water runs through in roughly 10 to 15 seconds, the shot tastes thin and sour and carries little foam.
- Dose too low or uneven: a thin or uneven puck lets water take the easy path, so level the grounds before tamping.
- Decaf beans: thinner foam is normal because processing removes some oils.
- Brewing method: filter coffee and French press apply far less pressure than an espresso pump, so they do not produce true crema.
Super-automatic machines and capsule systems add another wrinkle. Some build foam with their own mechanisms, such as the spinning capsule used by Vertuo, so a thick layer there does not tell you the same thing it would on a portafilter machine.
Diagnose Your Crema in Five Shots
| Shot | What to change | What to watch |
|---|---|---|
| 1 | Nothing; use 18 g in, 36 g out | Time, color and thickness as the baseline |
| 2 | Grind one step finer | Does flow slow and foam thicken? |
| 3 | Back to the baseline grind; use a fresher bag if you have one | Foam stability with newer beans |
| 4 | Level and tamp more carefully | Even flow without pale streaks |
| 5 | Swap in a non-pressurized basket if you have one | Whether foam looks different |
Change one variable per shot and keep notes. Three or four shots are usually enough to see which factor is holding you back.
Gear That Helps
Baratza Encore ESP – Why It Helps
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Crema depends on a fine, consistent grind, and this grinder is aimed at espresso. It uses a 40 mm conical steel burr and has 40 settings, with the finer steps (1 to 20) intended for espresso and the coarser steps for filter coffee. Baratza suggests starting near setting 15 for an 18 g dose of medium roast. Hopper capacity figures differ between retailers, so confirm on listing. It will not solve stale beans, and you still need a scale and a way to tamp.
Fellow Atmos Vacuum Canister – Why It Helps
Since freshness drives crema, storage matters. The 0.7 L Atmos holds about 11 oz of beans and uses a twist-lid pump to remove air. Fellow recommends whole beans only, because fine grounds can clog the valve, and suggests twisting every 4 to 5 days to maintain the seal. The company claims coffee stays fresh up to twice as long, but reviewers report mixed results, so treat that as a claim rather than a guarantee. It slows staling; it cannot restore a bag that has already passed its window.
Common Mistakes
- Judging a bag in its first 3 to 4 days, when excess gas makes unstable bubbles.
- Using pre-ground coffee and expecting thick foam.
- Treating a thick layer as proof of flavor, even though robusta and dark roasts produce plenty.
- Changing grind, dose and tamp all at once, which hides the cause.
- Leaving beans in a clear jar next to the stove.
- Comparing a pressurized-basket shot with a puck-based one as if they were equal.
Questions
Why does my Nespresso Vertuo make so much foam?
Vertuo machines spin the capsule at about 7,000 rpm and a barcode sets the spin profile. The foam comes from centrifugal mixing rather than 9 bar of pump pressure, so it is thicker and more foam-like than classic crema.
Should I skim crema off my espresso?
There is no authoritative rule. Some drinkers stir it in, others spoon it off. Try the same shot both ways and keep whatever tastes better to you.
How long should crema last?
A fine-bubbled layer should hold for a couple of minutes before thinning. If a pale layer disappears in about 20 seconds, beans may be stale or the shot under-extracted.
Does decaf make crema?
Usually less. Decaffeination removes some of the oils and disrupts CO2 retention, so thinner foam is normal and not a defect.
Is more crema always better?
No. Robusta, dark roasts and pressurized baskets can produce a lot of foam without improving taste. Use it as a freshness clue and let the cup decide.
Update History
- October 20, 2026 – Updated with specification checks and a revised product comparison.
- Check the product page for current specifications and availability before buying.
Sources
- Wikipedia entries on espresso and caffe crema
- Talk About Coffee article on the science of espresso crema
- Coffee-science guides on CO2, bean freshness and robusta versus arabica foam
- Home-Barista and other discussion pages on tiger striping and channeling
- Breville guidance on pressurized versus non-pressurized baskets
- Retailer and manufacturer pages for the Baratza Encore ESP and Fellow Atmos
- Guides to the Nespresso Vertuo centrifusion process
