Is the golden foam of espresso grease or Crema? Is the grease as thick as possible?

Not long ago, in "the oil of espresso is so bitter, why do people still like it?" In the article, Qianjie shared that this layer of golden foam pressed by an Italian coffee machine is called Crema/ grease, so a friend asked backstage: is it Crema or grease?

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

When the espresso machine was first invented, this foam was the main substance that distinguished the espresso machine from other coffee machines. Because only the high pressure of the Italian coffee machine can make coffee with this layer of golden foam! Therefore, people need to give it a new name to distinguish it from other coffees! Because the foam was very thick and smooth when it was first extracted, it looked very much like viscous cream, so people gave it such a name at that time-"Crema". Crema means cream in Spanish.

However, when it spread to China, people misunderstood its meaning because of cultural differences, and everyone thought that Crema was about cream-like texture, so in the end, the name of the bubble was mistakenly changed into "grease". Although the description of grease is not quite right, it has been deeply rooted in the hearts of the people, in case many novice rookies do not understand what Crema is, so Qianjie has been using "grease" to call this layer of foam!

So, the more grease, the better? In the previous article, Qianjie said that the existence of oil makes espresso have more aroma, thicker taste, and add a longer finish! Therefore, many friends will think that the more fat a cup of coffee has, the more delicious it will be!

But this is not the case, the "amount" of oil can not be used to measure the taste of espresso, because it is only concentrated into an icing on the cake, such as adding more layers! But how the concentrated taste or how, will not be affected by the oil! After all, there are many ways to increase the amount of fat, such as deepening the baking degree: the roasting degree of coffee beans affects the thickness of the extracted fat, and the deeper the roasting degree, the looser the structure of the coffee beans. the easier it is to extract the carbon dioxide contained in the body during the extraction, thus forming a rich fat!

Freshness of beans: carbon dioxide is gradually lost from beans over time, so if we want to have a lot of fat, we can't choose beans that have been left for too long (2 months from the baking date) to extract, because a lot of carbon dioxide has been lost. Therefore, in terms of the freshness of beans, it is best to choose fresh beans from the 5th day to 2 months after baking, so that a large amount of oil can be obtained, because beans have the highest carbon dioxide content at this time!

The reason why we do not choose freshly baked beans is that it will bring a negative effect. It is too fresh and the gas is too exuberant. Although there is a lot of fat extracted, it will be very rough and dissipate quickly. And it will drink with the dryness at the end of baking! Change the variety of beans: Arabica is the main variety we use every day. If we pursue the amount of oil instead of taste, we might as well replace the beans with the same baked Robusta, which will extract more abundant oil!

The main reason for this difference is the difference in lipid content between varieties. Arabica coffee beans contain about 14%-18% lipids, while robusta coffee beans contain about 9%-12% lipids. Although it seems that Robusta has less lipids than Arabica, the more lipids actually affect the production of this layer of fat! So Robusta can extract more fat because it contains less fat, but it's just the taste, you can imagine.

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