What Information Does Espresso Crema Convey? Why Can't the Crema for Latte Art Be Too Thick?

As we all know, Crema is the signature element of espresso. Its presence is what distinguishes espresso from other coffee preparations. However, the state of crema, much like the taste of espresso itself, changes constantly day by day!

Sometimes it's thick, sometimes thin, sometimes so silky and smooth it makes your mouth water, and sometimes so rough it kills your appetite. Often, espresso with unappealing crema doesn't taste very good either. This has led to the belief that "you can tell whether an espresso is good just by looking at its crema." But is this really the case?

The state of crema is actually like the coffee bed in pour-over brewing—the quality of crema doesn't necessarily represent the actual taste of the espresso. To understand why, let's examine the structure of this crema layer.

We all know that "油脂" (oil layer) is actually an informal term—its proper name is Crema, meaning "foam" or "bubble." In fact, it consists of bubbles formed when carbon dioxide is forced into the coffee oils (the natural liquid oils from coffee beans). And like most bubbles, this crema layer also dissipates over time. As the Crema dissipates, the reflective layer floating on the espresso surface reveals the true coffee oils.

The mechanism is quite simple: during espresso extraction, the 9-bar pressure from the espresso machine forces the carbon dioxide released by hot water directly into the coffee oils, which then passes through the portafilter holes and combines with the coffee, creating the golden Crema we see.

What Makes Quality Crema?

Did you know that this crema layer also has varying degrees of quality? According to general consensus, quality crema is rich and delicate, with a standard golden color, good fluidity, and a thick, smooth consistency similar to cream when swirled. Such crema not only stimulates appetite but also provides an excellent base for latte art, allowing baristas to create beautiful patterns more easily. This is naturally why it's called quality espresso crema.

To achieve such quality crema, bean selection is crucial. The carbon dioxide and oil content in coffee beans determine the thickness of the crema. Therefore, medium-dark roasted beans within their optimal flavor period (within two months of roasting) become the first choice. Medium-dark roasted beans contain more oils and carbon dioxide than lightly roasted beans due to longer roasting time. Being within the optimal flavor period ensures that carbon dioxide hasn't been lost due to prolonged storage. Of course, if you don't mind Robusta beans, adding a small amount of Robusta to your blend can yield even richer crema!

The above only covers bean selection. After choosing suitable beans, you still need proper grinding and stable, appropriate extraction to obtain quality crema. The more stable the bean condition, the more stable the crema will be. As mentioned at the beginning, crema extracted sometimes may not be satisfactory due to various factors affecting its stability. So FrontStreet Coffee wants to share what these less-than-ideal crema conditions might be telling us about potential problems.

Too Thick, Coarse, and Clumpy Crema

I believe everyone occasionally extracts this type of crema: although very full and thick, it dissipates extremely quickly. Not only that, but it's also quite rough with poor fluidity. Baristas using it for latte art often complain, "I can't move it! I just can't move it!!"

The cause of this type of crema is quite simple—it's because the coffee beans are too fresh, roasted very recently, and still contain abundant carbon dioxide. As the saying goes, youth is impetuous, and when this vigorous carbon dioxide is forced out, the coffee oils cannot completely encapsulate it. These "irritable" bubbles break through the oil layer, creating the phenomenon of rapid dissipation followed by clumping. Additionally, excessive carbon dioxide can hinder hot water from extracting flavor compounds from the coffee. Therefore, FrontStreet Coffee recommends letting these fresh beans rest for a few days before extraction. This not only makes the crema more stable but also makes it easier to extract delicious espresso!

Too Thin or No Crema (Medium-Dark Roast Beans)

As we can see from the subtitle, this situation is the complete opposite of the previous one. This condition mainly stems from two factors. The first is the coffee bean freshness issue we mentioned earlier.

When coffee beans are very fresh, carbon dioxide content is high. As time passes, it gradually dissipates, making extraction more stable. However, if too much time passes beyond the optimal flavor period (after two months from roasting), the remaining carbon dioxide in the beans becomes minimal. Without sufficient carbon dioxide, the crema naturally cannot be thick. In this situation, without the barrier of carbon dioxide, extraction efficiency increases significantly, making it easy to extract undesirable flavors if you're not careful. Therefore, FrontStreet Coffee recommends purchasing beans in smaller quantities more frequently. This way, you can consume the beans within their optimal flavor period. Alternatively, you can extend the optimal flavor period through airtight storage.

Then there's the second situation: grinding issues! Espresso machines have very strict requirements for coffee grind size. If you don't achieve the required fineness, not only will you fail to extract crema, but the coarse particles will also fail to create effective resistance against water, leading to too fast flow and preventing proper extraction. Therefore, appropriate particle size is extremely important, whether you're pursuing crema or flavor.

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FrontStreet Coffee (FrontStreet Coffee)
No. 10 Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

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Tel:020 38364473