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Foamy Espresso
What causes foamy espresso and how you can get the consistency just right.
Published December 20, 2021
Johan Hedlund
Coffee experts@The Coffee Lab
If you are like many coffee-drinkers, espresso coffee might be something that you love. Espresso makes you feel more energized and every time you make it, it fills your home with a delicious aroma that instantly makes you feel happier. While espresso should have a thin layer of foam on the top known as crema, if the espresso is too foamy, this can be a sign that something has gone wrong during the brewing process.
What is Espresso Foam?
Espresso foam is often referred to as crema and is a layer of caramel-colored foam that you will find on the top of an espresso shot. While it looks appealing, it will also boost the coffee flavor. When making espresso, it is important to know what crema is, how it is formed, and how you can adjust your brewing process accordingly to reduce the risk of any issues with it to improve quality of the coffee in your cup. If your espresso looks like a bubble bath, something has definitely gone wrong.
How Espresso Foam Forms
Crema is given this name due to being a cream-like substance. When brewing espresso coffee, the water pressure is forced through the coffee grounds, which causes the oils from the beans to be released into your coffee. Along with the plant carbohydrates from the beans, these oils serve the purpose of creating foam and stabilizing bubbles in the liquid. Along with this, the water pressure will dissolve CO2, which is produced by roasting coffee beans. As the coffee is directed into a cup, it will return to its normal atmospheric pressure, and is unable to maintain all this CO2, which leads to small bubbles forming on the surface of the liquid, which then produce foam.
Different Types of Espresso Foam and What They Mean
In order to make sure that you avoid any foam-related issues with your espresso, it is important to first identify the type of espresso foam that you are dealing with and what could be the cause of it. While it can sound quite technical, there’s no need to worry as lots of research has already been done on this, allowing you to get the information that you need to fix the problem.
White with Large Bubbles
If your espresso foam looks like this, it’s quite common and often nothing to worry about. However, it could be a sign that your coffee is over-extracted. This means that you have let your espresso brew for too long. Most commonly anything over thirty seconds will start to over-extract the coffee. During this process, too many soluble flavors are removed from the coffee, which will leave more unpleasant flavors behind. This will leave your espresso not only with a lot of white foam on it, but it will also have a bitter, bland taste. While all espresso coffee should have a little bit of bitterness, it’s too much if the bitterness if overpowering all the other flavors.
Another reason why your espresso might have ended up with a lot of white foam with large bubbles could be that the water you’ve used for brewing it was too hot. When making espresso, always make sure that your coffee brew reaches the right temperature, which is generally considered to be between 195-205 degrees Fahrenheit.
Pale Foam
If your espresso has a layer of foam on the top but this is paler in color than it should be, it’s a sign of the opposite problem to above: under-extracted coffee. Under-extraction happens when the coffee is brewed in a way that means that the flavor is not properly drawn out from the coffee grounds, limiting the flavors that reach your cup and leading to coffee that is watery and weak.
Most of the time, under-extraction is the result of two common reasons; either brewing the coffee for a shorter amount of time than is needed, or not using water that is hot enough for the coffee. To avoid under-extracting your espresso, brew it for between 20-30 seconds.
The coffee grounds being too coarsely ground can also be an issue that leads to pale espresso foam. Since the espresso needs to be brewed quickly to make sure that the water quickly rushes over the grounds and extracts the flavor, the best coffee grounds for espresso are very finely ground. As a result, the coffee grounds are able to dissolve, allowing for their flavors and aromas to be successfully drawn out.
Dark Foam with White in the Middle
If you’re making espresso coffee that comes out with a darker foam than usual but with some white in the middle, this is usually a result of the coffee grounds that you are using. While finely ground coffee is necessary for making the perfect shot of espresso, it is possible to grind them too finely, and when you do, this will be the result.
Foam in the Center of the Cup
If you have made a shot of espresso and there is just some white foam right in the center of the cup, this could mean that you have brewed the espresso for too long. This will also usually mean that the coffee has been over-extracted, and it is likely to also have a bitter and muddy taste. The good news is that you can easily fix this issue with a shorter extraction time in the future.
Different Colors of Espresso Foam
Maybe you have noticed that when making espresso at home, the layer of foam on the top of your coffee is different in color compared to that in espressos made at your local coffee shop. However, before you start to worry, it’s worth bearing in mind that this is not always a sign that you are doing something wrong when you are making the espresso, unless your foam is dark with some white in the middle.
Sometimes, the blend of coffee that you are using will produce a different color to what you are used to, especially if you are using a completely different blend compared to what’s used at your local coffee shop where you normally go to get your espressos. Arabica coffee, for example, will usually produce a reddish-brown colored foam and a pattern known as ‘tiger tail’ on the coffee. On the other hand, if you are using Robusta coffee beans, this will produce a foam that is dark brown in color with some gray.
Which Coffee Beans Produce More Foam?
Another factor to bear in mind when you are making espresso at home is that having a lot of foam is not always a bad thing. Some people like to have more crema on the top of their espresso, and if this sounds like you, you might be glad to hear that you can find some coffee beans that are a better choice for producing foam compared to others.
Along with the type of coffee beans that you use, the way that the beans have been roasted can also have an impact on the quantity and type of espresso foam in your cup. When it comes to choosing coffee beans, there are some things worth knowing when it comes to the type of beans and the foam that they produce.
Freshly roasted beans will increase the amount of foam in your coffee. This is because after the roasting process, the coffee beans will still be releasing gases that have formed inside them during this process.
For an espresso with less foam, darker coffee beans might be a better choice. These beans tend to produce less foam since the coffee bean oils are sometimes rubbed off the beans during handling or packaging. However, this does not always mean that light roasts such as blonde roast will produce more foam, even though there is little to no oil.
For the best foam on your espresso, it’s always ideal to use coffee beans that have been produced naturally and using organic processes. This is because more of their oils are left intact.
Does Coffee Freshness Impact Foam?
You can sometimes tell how fresh the coffee is by checking the foam that it produces on top of an espresso shot. If the coffee is not very fresh, it is more likely to separate easily from the coffee and quickly disappear after brewing. On the other hand, coffee that is fresh tends to look much foamier during the brewing process, before it settles.
If you are getting started with making espresso at home or have been brewing your own espresso for a while and find that you’re often throwing coffee away due to it being too foamy or not foamy enough, there’s no need to worry since most of the common issues that people face with espresso foams are a result of under- or over-extraction, which can, for the most part, be easily fixed. When you know when the foam is showing signs of issues with your coffee, and how to prevent them in future, it’ll be easier for you to enjoy espresso in the best possible way.
About the author
Johan Hedlund
I´m living in Karlstad, Sweden with my family. Been working the last 25 years with several start ups in the tech industry. Coffee has been an integral part, both professionally and privately. Eager to learn new things and happy to be a member of the era of we community.
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