What Causes Clumping in Espresso Crema? Pay Attention to These Details When Extracting Espresso!

The "golden armor" worn by espresso, the crema, is a wonderful product unique to pressurized extraction. Its presence not only provides an excellent canvas for latte art but also makes the coffee's texture more mellow. Of course, as FrontStreet Coffee often says, the prerequisite is that the quality of that crema must be up to standard. When the crema is too thick or too thin, its benefits are significantly diminished.

Recently, FrontStreet Coffee has received many inquiries from friends who find that the espresso crema they use for milk coffee is thick but lacks fluidity, much like whipped cream, appearing overall very stiff. Such crema not only affects the drinking experience but also creates obstacles when making latte art. This situation is likely caused by the following factors.

1. Operational Issues

Operational issues are one of the more common causes. After extraction is complete, the crema and coffee liquid remain closely integrated for a period of time. We can observe this clearly by gently shaking the cup: the crema flows with the movement of the coffee liquid, very smoothly. At this point, the espresso is best suited to drinking and to making other espresso-based drinks.

If we do not use the espresso immediately after extraction but instead start doing other things, this layer of crema will not only dissipate over time but also separate from the coffee liquid. When we shake the cup then, we can observe the phenomenon: the coffee liquid moves while the crema stays still. Although the coffee at the bottom rotates with the shaking, most of the crema on top remains stationary, except for the thinner parts that may jiggle slightly. Crema in this state is not well suited to making hot milk coffee, because it is too stiff for light milk foam to push aside, making it impossible to create beautiful latte art. We should therefore use the espresso immediately after extraction is complete. Of course, if other delays cause us to miss that golden window and the crema hardens, we need to stir it at that point to reconnect the crema with the coffee liquid and give it better fluidity.

2. Material Issues

What materials do we need to make a cup of espresso?

That is right: coffee beans and water. When certain substances in these two materials are excessive, the extracted crema becomes too hard and lacks fluidity.

FrontStreet Coffee has discussed coffee beans many times, so sharp readers can probably guess the root of the problem: the beans are too fresh.

When beans are too fresh, they contain enormous amounts of carbon dioxide. Carbon dioxide and the lipids in coffee beans are the main components that form crema. When there is too much carbon dioxide, the lipids cannot encapsulate it for long. Within a short time after extraction, then, the crema quickly ruptures because of the carbon dioxide's activity, forming clumps that lack fluidity. In such cases, FrontStreet Coffee recommends solving the problem through pre-grinding: grind the coffee in advance and let it sit for a short period to degas, just a few minutes. Once ground into powder, coffee beans degas more strongly because of the increased surface area, quickly releasing carbon dioxide to solve the overly hard crema caused by rapid foam collapse. It is important to note, though, that you cannot let it sit too long, since the rate of gas loss after grinding is truly unimaginable.

Then there is the water used in the coffee machine. In the article "Preparing Coffee Water," FrontStreet Coffee explained why tap water cannot be used in coffee machines: it contains too many minerals, which places a certain burden on the machine. Beyond that, another reason not to use tap water, also caused by minerals, is that tap water has too high a KH value.

The KH value refers to the concentration of bicarbonate, HCO3-, in water, and bicarbonate is a very important buffering substance in water quality. Important as it is, moderation is key in everything. When the KH value in water is too high, the carbon dioxide in the coffee powder is extracted more easily, as are other substances. If you happen to be using beans rich in carbon dioxide at that time, the result will match what was described above: the crema may be abundant, but it breaks more easily. Water quality also has a certain impact on the taste of the espresso itself. In such cases, FrontStreet Coffee recommends installing a filtration system for the coffee machine water or changing the water source.

3. Parameter Issues

To give coffee more possibilities, we often use different parameters to extract espresso, giving the coffee a deliciousness that differs from the conventional. Water temperature, pressure, output volume, and grind are all adjustable parameters for espresso. Short-extracted Ristretto, long-extracted Lungo, and variable-pressure or over-extracted espresso are all delicious coffees made through parameter adjustments. If, when adjusting these parameters, we make their extraction efficiency too prominent, it causes large amounts of carbon dioxide to be extracted in a short time. Because the structure of the crema is then unstable, the problems of excessive hardness and clumping described above can easily occur.

The taste of the coffee itself is not problematic, but the presence of the crema brings certain negative effects. In such cases, beyond stirring, friends making Americano can also remove some of the crema using filter paper or a filter screen for a cleaner taste. For those making latte art who encounter harder crema, FrontStreet Coffee recommends pre-mixing to obtain a high-fluidity coffee base: add a little milk before mixing, then shake it evenly to give the crema more fluidity. That way you can solve the problem of difficult latte art caused by overly hard crema.

FrontStreet Coffee Recommendation

Good crema starts with the bean, and for anyone learning latte art, the blend matters as much as the technique. FrontStreet Classic Blend is the place to begin. It is a medium-dark espresso formula built from three origins, inspired by the old "Mamba" combination of Mandheling and Brazil, with a small amount of Robusta added to boost aroma and crema. Extracted, it gives off distinct butter, toasted bread, and caramel-cookie aromas with a strong flavor, solid body, and fine crema that pulls in a very stable way. It is the essential home coffee for a beginner.

If you prefer a nutty, rich profile, choose FrontStreet Premium Blend. Also a medium-dark espresso bean, it pairs washed Colombian coffee with semi-washed Brazilian coffee, bringing nut, dark chocolate, and caramel notes to espresso. Whether you make an Americano or milk drinks such as a latte or flat white, it highlights cream, almond, and cocoa with a smooth aroma, and its crema is fully the equal of a cafe's, more than enough for practicing latte art, which makes it ideal for anyone planning to open a shop or learn at home.

If FrontStreet Premium Blend and Classic Blend are made for beginners, FrontStreet Commercial Blend is tailored for those about to open a store. It takes Premium Blend as its base and adds a small amount of Robusta in a traditional Italian recipe, producing more fine dark-brown crema and a heavier body. Whether you make an Americano, latte, or mocha, it carries nut, cocoa, and caramel flavors and makes latte art noticeably easier.