Water during the extraction process is under a lot of pressure, prompting it to release carbon dioxide.
When mixed with the coffee grounds, hot water then emulsifies the oils in the coffee, resulting in a foamy bubble layer.
For the simple coffee drinker, the crema is not that important.
It doesn’t even affect the taste.
However, the crema indicates the freshness and quality of coffee beans and the barista’s skill to the trained eye.
Baristas and other professionals have different opinions regarding the “perfect crema.”
Nonetheless, the goal here is that the crema should not have been too thick nor too thin.
Plus, it should remain for at least two minutes.
Here are some facts that you should remember about the crema:
- The grind’s coarseness and extraction process can affect the crema.
- Too much crema results in less espresso. As such, most baristas aim to have one-tenth of crema in a cup of espresso.
- If the crema disappears less than a minute, then you extracted it too quickly, or the roast you used was too light.