What are the oils in espresso? Is coffee grease real or fake? What does coffee Crema mean?

"Is the grease I extracted real or fake? "This is a very interesting topic that Qian Jie came across while surfing the Internet in the past two days. I believe that many friends 'first reaction after seeing it was the same as Qian Jie, full of doubts: " Coffee grease can also be true or false? "

With curiosity, Qianjie clicked on a post to find answers. It was found that, to a certain extent, coffee grease can indeed be distinguished between true and false. But to know what "fake grease" is, we first need to understand what "real grease" is. But to be reasonable, the so-called "real" grease is actually not real~

What is coffee grease? Front Street has always shared it, known as the "grease" of the soul of espresso coffee, but it is not essentially the grease in the broad sense of the word we think. In a broad sense, oils refer to chemically defined lipids such as edible oils and animal fats. Although the oil in coffee is called "grease", its main components are carbon dioxide, natural lipids of coffee beans, protein and other substances. It is a foam layer made through a specific extraction method. In other words, it is essentially an emulsion foam, not a pure oil. (PS: There is oil, but the proportion is extremely low, usually less than 1% of the total)

The reason why it is called grease is because the original name "Crema" was mistranslated as grease, and that's all. Crema is an Italian word that originally means "cream." Because the foam on the espresso coffee is very thick and delicate, like cream, it gets this name. We can understand what Crema means here: "creamy foam."

However, such grease can only be produced by pressurized extraction. When hot water is quickly passed through finely ground coffee powder at a high pressure of up to 9 bar, the carbon dioxide in the coffee beans will be quickly released and dissolved in the water, forming micro bubbles. It is then wrapped by other substances such as lipids and proteins from coffee beans to form a stable foam layer. Eventually, when it falls into the cup, it becomes the coffee grease we see.

What is "fake grease"? From the above, we can know that the so-called "real" grease refers to a special product made by pressurized extraction combined with the characteristics of coffee beans. Two conditions are indispensable. Once one of them cannot be met, for example, the extraction method of coffee is not pressurized, or the coffee beans do not have sufficient carbon dioxide or lipids, it is basically impossible to make coffee grease as thick as butter.

However, many friends have found that even if some coffees are made that do not meet these two conditions, they can still produce a rich foam layer, and the thickness of the foam is even much thicker than the oil extracted by the coffee machine. And they are what people call "fake" oils.

(The picture comes from the Internet, for reference only.) These "oils" are not natural, but are just bubbles imitated through manual intervention. For example, by pressurizing air or adding special materials to create foam similar to Crema. Its texture and taste are very different from the real "real" grease made by an espresso machine. Not only is it not as delicate, but also not so smooth, it only has a visual effect. Therefore, people call this foam layer generated by manual intervention "fake grease." So speaking of this, I believe everyone will know the difference between "real" and "fake" oils. However, due to the emergence of "fake oils", many newcomers mistakenly mistake the relatively rough and rich oils extracted from some coffee machines for "fake oils." Because they are neither smooth nor rough, and they are not at all like the rumored "real" grease with a creamy texture, we can often see Xiao Bai's question posts on the Internet: "Is the coffee grease I extracted real or fake? "

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