Is the Golden Foam of Espresso Actually Coffee Oils or Crema? Are Thicker Oils Better?

Recently, in the article "Why do people still like espresso when the crema is so bitter?", FrontStreet Coffee shared that this layer of golden foam extracted by espresso machines is called Crema. This led some friends to ask in the comments: Is it Crema or "oils"?

We can first look at this full picture of espresso, which is mainly divided into two parts: the coffee liquid and the golden foam floating on the surface!

The Origin of the Term "Crema"

When espresso machines were first invented, this foam was the main substance that distinguished espresso machines from other coffee machines. Only the high pressure of espresso machines could produce coffee with this layer of golden foam! Therefore, people needed to give it a completely new name to distinguish it from other coffees! Because this foam was quite thick when first extracted and had a certain smoothness, looking very much like thick cream that was about to be whipped, people at the time gave it such a name—'Crema', which means 'cream' in Spanish.

Why "Crema" Became "Oils" in Chinese

However, when it was introduced to China, cultural differences led people to misunderstand its meaning. Everyone thought that Crema referred to cream-like textured oils, so ultimately, through a series of misunderstandings, the name of this foam mistakenly became 'oils' (油脂). Although the description 'oils' isn't quite accurate, it has become deeply ingrained in people's minds. To prevent many beginners from not understanding what Crema is, FrontStreet Coffee has continued to use 'oils' to refer to this foam!

Is More Crema Always Better?

So, is more crema always better? In a previous article, FrontStreet Coffee mentioned that the presence of crema gives espresso a richer aroma, a thicker mouthfeel, and adds a longer aftertaste! Therefore, many friends might think that a coffee with more crema must be more delicious!

But that's not actually the case. The 'quantity' of crema cannot be used to measure the taste of espresso, because it only serves as an enhancement to the espresso, for example, adding more layers! However, the taste of the espresso remains what it is and is not affected by the crema! After all, there are many ways to increase the amount of crema, such as:

Deeper Roast Level

The roast level of coffee beans affects the thickness of the extracted crema. When the roast level is deeper, the structure of the coffee beans becomes looser, making it easier to extract the carbon dioxide contained within during extraction, thus forming rich crema!

Bean Freshness

Carbon dioxide gradually escapes from the beans over time, so if we want to have rich crema, we cannot choose beans that have been stored for too long (from 2 months after the roast date) for extraction, because the carbon dioxide has already been significantly lost. Therefore, in terms of bean freshness, it's best to choose fresh beans from the 5th day to 2 months after roasting for extraction, as this will yield a large amount of crema, because this is when the beans have the highest carbon dioxide content!

Bean Variety

The reason we don't choose freshly roasted beans is because they bring a negative effect - too fresh, too much gas. Although the extracted crema quantity is high, it will be quite rough, dissipate quickly, and when consumed, it will have a dry feeling from the end of roasting! Changing the bean variety: Arabica is the main variety we use daily. If we don't pursue taste but pursue the amount of crema, we might as well switch to Robusta beans with the same roast level, which will extract more abundant crema!

The main reason for this difference is the different lipid content between varieties. Arabica coffee beans have about 14%-18% lipid content, while Robusta coffee beans have about 9%-12% lipid content. Although Robusta appears to have less lipid content than Arabica, actually more lipids反而 affect the formation of this layer of crema! So Robusta, due to its lower lipid content, can extract richer crema, but as for the taste, well, you can imagine~

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