Have you ever wondered what the froth on top with the pretty design on top of your espresso, often known as "crema," is? Well, I have. And I just discovered Science Friday, a radio show that has a segment on the science of coffee.
The foam found at the top of your cup is "crema" comes from the espresso making process.
Espresso is prepared in a metal contraption, which you pound down and hot water is pumped through at great pressures.
The pressure pushes out the little oils from the coffee beans into the liquid. The oils and the plant carbohydrates from the bean stabilize the bubbles and keep the long lasting foam, or "crema." Crema is, in fact, a type of cream, due to the oils that create fats.
So next time you sip the pretty foam design at the top, you now will know that it is a result of the beautiful science of coffee.