What is an espresso Crema? The more coffee fat, the better?

Speaking of espresso, I have to mention its soul-Crema. A qualified espresso, rich and delicate Crema is an important criterion.

Crema, also known as coffee fat, this unique and rich layer of Crema can only be made by an Italian coffee machine, and the key lies in the extraction pressure.

When the Italian coffee machine is working, it will produce a 9bar water pressure to "squeeze" the coffee pressed powder. Because the carbon dioxide in the coffee powder is under too much pressure, the water is supersaturated for the carbon dioxide, so the carbon dioxide can not be released, so it is directly integrated into the coffee liquid. And in the process of extraction will emulsify the fat in the coffee, these fat will be wrapped in carbon dioxide, because it is lighter than water, all will gradually delaminate, golden oil will appear on the surface, very beautiful.

So this golden and delicate coffee oil is formed by the insoluble oil of coffee wrapped in carbon dioxide. The oil richness of espresso is not only related to the pressure at the time of production, but also related to coffee beans. In pursuit of rich oil, Italians add 20% or less robusta coffee beans to Arabica coffee beans. But the flavor of Luodou itself is not as good as that of Arabica, so even Italians who love espresso will not use it all.

Although Crema is the indispensable soul of espresso, it is not the more the better. We pay more attention to the quality of Crema than quantity. As described above, the appearance of Crema, the color to show golden yellow, too light color is generally relatively thin, difficult to improve the taste, but also have astringent negative effects. If the color is too dark, it is generally thought that the extraction is not complete (only the first part of the extraction), and such grease will dissipate quickly. For the thickness of Crema, too thin is naturally inappropriate, but very thick is not a good state. Usually a very thick Crema layer, very prone to caking, when shaking espresso, the Crema layer barely moves, and may be very dense at first, and after tens of seconds, very rough bubbles appear, showing a "pimple" shape on the surface. The most likely cause of this problem is that the espresso beans used are too fresh.

In fact, too rich Crema is not suitable for making lattes. Too thick Crema will make it more difficult for milk foam to blend with oil and make the liquid surface less fluidity. If the fat is too thick because the beans are fresh, the foam will also disintegrate quickly because of the instability of the oil.