Can You Judge Espresso Quality by Its Crema? What Exactly is Espresso Crema?

You've probably heard people say, "You can tell if espresso is good just by looking at its crema. The best espresso has fine, rich, golden crema." But can you really judge the quality of espresso by its crema?

To determine if this method is reliable, FrontStreet Coffee just needs to present you with two questions.

Question 1

In the image below, only one cup of espresso tastes good. Please identify the tasty coffee based on the appearance of its crema.

Question 2

In the image below, again only one cup of espresso tastes good. Please identify the tasty coffee based on the appearance of its crema.

The correct answers are: the third cup for Question 1, and the second cup for Question 2. Many of you likely got Question 1 right, while some might have guessed Question 2 correctly.

Looking at espresso crema is like looking at the coffee bed in pour-over coffee - you can't determine whether a coffee tastes good just from appearance. Fine, rich, golden crema doesn't necessarily mean the espresso tastes good. However, you can identify some potential problems from the state of the crema.

What is Espresso Crema?

First, let's talk about what this golden coffee crema actually is. Espresso crema is essentially insoluble oils from coffee beans encapsulating carbon dioxide, both of which originate from the coffee beans. In fact, the golden foam on the surface of pour-over coffee grounds is also oil with a small amount of carbon dioxide.

Due to the high extraction pressure of espresso machines (up to 9 Bar), oils and carbon dioxide are directly forced into the coffee. Since oils don't dissolve in water, they gradually separate to form the golden coffee crema.

Therefore, the quality of coffee crema mainly depends on three factors: the carbon dioxide content in the beans, the grind size, and the roast level of the coffee beans.

What Can Crema Tell Us?

Sometimes, the state of the crema can reflect certain problems. For example, the most common issue is when coffee crema is abundant but has a coarse texture, breaks down quickly, and shows clumping. Espresso with this type of crema often lacks distinctive flavors.

This is because the coffee beans haven't been properly degassed and are too fresh, containing excessive carbon dioxide. As mentioned earlier, the richness of coffee crema is related to carbon dioxide. When coffee beans have abundant carbon dioxide, the extracted crema will naturally be rich. However, too much carbon dioxide can make the crema structure unstable, causing it to break down easily and form large bubbles. When there are many bubbles, they accumulate into clumps with poor fluidity. This state is very similar to milk foam.

Carbon dioxide acts as a protector of flavors, whether it dissipates naturally or is extracted intentionally. Therefore, coffee beans that are too fresh can affect the extraction process, resulting in coffee with no distinct flavors.

Another extreme is when coffee beans are no longer fresh, naturally containing less carbon dioxide, resulting in very thin crema. Coffee beans that aren't fresh will naturally produce espresso that doesn't taste good.

The Impact of Grind Size

Next is the effect of grind size on crema. For example, if the coffee grounds are too coarse, they cannot effectively resist the water pressure, causing the coffee liquid to flow quickly. The crema will be lighter in color with a watery, thin texture. In this case, the espresso will taste sharp and sour with a watery mouthfeel.

Conversely, if the coffee grind is too fine, the coffee puck strongly resists the water pressure, resulting in very rich, thick crema with a dark color. In this case, the espresso will exhibit burnt and bitter flavors.

When Crema Doesn't Tell the Whole Story

We've discussed the factors that can help determine coffee quality from crema appearance. Now, let's look at examples where you can't judge whether coffee tastes good based on crema.

The first example involves extracting espresso from both a dark roast coffee bean and a light roast coffee bean. The espresso from the dark roast will inevitably have richer crema, darker color, and better body than the light roast. However, both espressos have their own characteristics and fall into the category of good-tasting coffee.

The second example is the second question FrontStreet Coffee asked at the beginning. The crema in all three cups looked fine, rich, and golden, but only one performed excellently. This is because FrontStreet Coffee extracted these three espressos using 6 Bar, 9 Bar, and 11 Bar pressures respectively. Coffee crema extracted with this range of pressure variations won't show significant differences, but the tasted flavors have obvious distinctions. The 6 Bar extraction was rather bland, with various flavors not properly expressed. The 11 Bar extraction showed irritating, burnt flavors.

Important Notice :

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