When one of the managers at the cafe I worked at first taught me about crema, all I remember thinking afterwards was that he sounded so pretentious. It wasn’t even that he was saying anything particularly arrogant; sure, he was a nagging plague sometimes, but this time he was simply giving me facts.
Maybe it was the sound of the word “crema” and how it seemed to inherently possess a sense of grandeur, or maybe it was just the air of “let me educate you about coffee” I was getting from my manager. Whatever it was, at least he left me with one vital impression: that crema is very important.
As you might already know, crema is the golden-brown layer of foam that forms over the surface of your espresso, and is known as the Holy Grail of espressos. Explaining crema can get very technical, but here, I’ll break it down into easier blocks of information so you can get a general idea of what it really is.
What is crema?
In short, crema is the result of a chain of chemical reactions that occur between the water (which is forced out with extremely high pressure), coffee grounds, oils, and CO2 and other gases. It not only acts as a sort of lid on top of the coffee underneath, safely trapping the precious gases that make the drink all the more delicious, but it also contains important gases itself — more, in fact, than the liquid itself. To borrow the words of one of my trusty coffee bibles, The Blue Bottle Craft of Coffee:
The crema on top of an espresso is made of emulsified oils, sugars, and proteins that form a network of tiny spheres. Each of those holds a precious bit of sensory information — much more information per cubic milliliter than the coffee alone.
Recognizing good crema
A well-extracted espresso will bear the medal of a beautiful, even layer of crema that is mottled with dark brown dots or “tiger stripes.” The crema should cover the entire surface, be consistent in its thickness throughout, and be neither too light nor dark in color, indicators of under-extraction and over-extraction, respectively.
But the mere presence of crema in your espresso does not guarantee good flavor. With that said, it does tell us if the coffee is fresh, in which case the shot will appear as though it is entirely formed of crema during its extraction stage before rising to the surface. It also reveals how fully the espresso has been extracted, which you can tell by examining the crema’s color.
Just by knowing these few things about crema, you’ll be able to tell a masterfully extracted espresso from a badly brewed one, and know what to aim for if you make your own espressos at home.
As simple as crema may look in your cup, there’s actually quite a lot going on in its myriad of minuscule bubbles. If you want a more in-depth look into crema, I recommend this article from CoffeeGeek, which you can read while sipping on your favorite drink. Get ready to delve deeper into the world of this wonderful element of espresso.