The crema is a thick foam that sits on top of the espresso. It has a hazelnut color, almost golden and is very relevant for the complete tasting experience. It is the result of an alchemy between four elements: coffee, water, pressure and temperature.
The crema’s function is to preserve the aromas and prevent the drink from losing temperature. It is formed by the highly pressurized preparation process generated in an espresso machine that adds flavor and body to the coffee.
Crema is formed when hot water comes into contact with coffee powder. The water emulsifies the oils present in the coffee, which becomes supersaturated with carbon dioxide, creating a layer of creamy foam on the espresso.
The importance of crema emerged in Italy in 1938, when Achille Gaggia invented the first espresso machine that used high pressure to prepare coffee.
Using high pressure for preparation was a new concept that produced the “crema”, exclusive to espresso coffee. This is where the concept that a good crema is necessary for a great espresso comes from.
The chemistry of crema and how it forms
During coffee roasting, the beans retain the CO2 generated as a by-product, which is completely released, ideally within 48 to 72 hours, when the beans “rest”. During the crema formation phase, when extracting the espresso, the water comes into contact with the ground coffee at a pressure of 9 bar, which generates a supersaturation of CO2 in the water, which moves to the surface in the form of bubbles.
It is the protein fractions and polysaccharides extracted from roasted coffee that promote the foamability and stability of the crema.
Cream is rich in natural sugar, coming from the coffee fruit itself. The formation of the crema occurs when the fruit is nourished while still attached to the plant, in combination with roasting and water pressure during extraction (which ends up emulsifying the coffee's natural oil). The quality of the crema then derives from reactions between compounds and the melanoidin in the coffee itself.
What is the Perfect Cream like?
This velvety foam adds body, complexity and persistent flavor to your espresso.
Most baristas agree that the perfect crema should make up about 1/10th of the espresso shot and remain on top of your coffee for about 2 minutes.
Espresso crema acts as the first impression of your coffee, and if it's too gritty, too thin, or too dark, it usually indicates that the coffee doesn't taste good either.
What are the aspects that contribute to the perfect foam in your espresso coffee?
Coffee Freshness
The ideal timeline for brewing coffee is 7 to 21 days after the roast date. If you try to brew coffee that has been roasted for more than 21 days, crema will be more difficult to achieve. This occurs because the gases responsible for the crema have, at this point, already left the coffee beans.
Likewise, if the coffee was roasted less than 7 days ago, the gases produced during roasting have not yet settled. Wait at least 3 to 5 days after roasting to obtain the ideal crema.
Milling
The perfect crema is impossible to achieve without a correctly adjusted grind. If the grind is too fine, the resulting crema will be too dark and the coffee will taste overly extracted and bitter.
If the grind is too coarse, the resulting drink will have a light, thin, or no crema and a very sour flavor.
Revenue
Following the correct recipe will optimize the result in your cup. Measuring the ratio between grains and yield, and optimizing the preparation process to around 30 seconds, will guarantee the best crema.
Leveling
The coffee beans need to be compacted with the correct pressure. Too much pressure will result in the preparation process being prolonged, and a crema that will be very dark. As well as insufficient pressure will produce insufficient crema.
Machine Temperature
A disappointing crema can also be caused by your machine being too cold. Keeping your espresso machine at around 90 to 96°C will give you the best chance of creating a good crema.
The color of the crema is influenced by the roast and the type of beans you are using. In general, if the crema in your espresso is very dark, this usually indicates that the shot has been over-extracted and will taste bitter. On the other hand, a very light crema indicates underextraction.
Baristas often talk about the desired "brindle spots" of the crema, which ensure the good quality of the coffee beans and the ideal flavor of the espresso.
Although the crema should not be too thin, too much crema is also not ideal and indicates excessive extraction.
But there are other aspects that influence the quantity of crema, and which are not directly related to the quality of the drink.
In addition to essential steps such as the freshness of the beans, correct compression, or the temperature of the espresso machine, there are other attributes that influence the crema:
Darker roasts have less crema because more oils evaporate during the brewing process
Naturally processed coffee produces more crema than washed coffee beans
Robusta coffee produces more crema than Arabica coffee
Coffee beans used when still very fresh, less than 7 days after roasting, will produce more crema, but this will be less balanced.
Let's understand the difference between cremas:
Super Extracted Espresso
Basically, it is possible to notice the darker espresso crema around the cup, that is, on the sides of it. Furthermore, it is common for a very obvious white spot to appear only in the center of the cup. Generally, espresso coffees that show this stain very clearly have undergone over extraction.
Then, it is possible to notice flavor characteristics. The aroma is quite specific from these visual aspects. For example: burnt flavor and aroma, astringency and loss of sweetness. In this sense, even if the coffee has a lighter roast , when over-extraction occurs, it will present these sensorial characteristics.
Here are some causes of this common error, so you can avoid them in preparation:
Excessive use of coffee
Very fine coffee grind
Excessive tamper force
Machine temperature is too high
The machine pressure is unregulated
Sub Extracted Espresso
The espresso crema breaks easily, receding towards the edges of the cup.
In this case, you may notice that the aroma of the coffee becomes weak and lacks intensity. And the taste is uninteresting.
The causes of this error can be:
The coffee grind is too coarse
Light compression
Little coffee
And it is worth mentioning that oxidized coffee may appear under-extracted. Be careful when storing your coffee.
Well Extracted Espresso
Color standardization around the cup;
The crema becomes thicker and does not break easily like the extracted sub;
Darker spots characteristic of what we call espresso brindle ;
Pleasant aroma. Just by approaching the cup you will be able to perceive the sweetness through the smell;
When tasting, you will identify all the basic characteristics of sweetness, acidity and intensity present in the coffee you are using;
Pleasant aftertaste.
Now just follow these guidelines and I'm sure your espresso experience will be even more complete.
When drinking your espresso, it is recommended that you stir the liquid to mix the aroma with the essential oils and fully appreciate the characteristics and sensations that the espresso provides.
And even stirring, the crema will not dissolve. In general, a good crema sticks to the walls of the dishes and remains at the bottom even after the coffee is finished. The denser and longer lasting, the better the quality of the extraction and grain used.
And for a perfect crema, an excellent machine is also very important. Click on the link below to see a post about the 10 most technological espresso machines that will provide you with a unique experience when drinking your coffee.
And you, do you like Espresso with or without crema? Comment here.
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