What is coffee crema and what determines its richness?

Coffee crema is the golden layer on top of espresso, and it is made of coffee oils and carbon dioxide, not pure oil. High-pressure extraction emulsifies the fats in the coffee, which wrap around carbon dioxide released from the grounds. Once the crema breaks down and the gas escapes, the thin reflective film left behind is the actual coffee oil. Crema has been treated as a quality marker for espresso since lever machines appeared.

To get a rich crema, choose beans with plenty of oils and enough carbon dioxide. Bean variety and roast level decide oil richness: Robusta generally carries more oils than Arabica, so it is often blended with Arabica to balance flavor. Arabica from the Americas tends to show more oils than African Arabica. Freshly roasted coffee releases carbon dioxide for a limited window, so beans rested but not stale extract better.

Just a few days ago, a customer came to the Front Street Coffee store in Dongshankou, Guangzhou, to drink espresso. Before leaving, they said, "I really love your espresso; the crema is the richest I've ever seen!" Coincidentally, a friend also asked Front Street how to make the crema of espresso even richer. Today, Front Street will share its insights here.

Espresso, as the name suggests, comes from Italy in Europe. The development of espresso was aimed at speeding up coffee making. Originally, espresso referred to a method of making coffee, with "espres" meaning "fast," indicating that a cup of black coffee can be made in a very short time.

The golden layer of crema on espresso is called crema, but calling it oil isn't entirely accurate, because this golden crema is composed of coffee oils and carbon dioxide. Once this crema breaks down and the carbon dioxide dissipates, the thin reflective layer that remains is the actual coffee oil.

However, due to some habitual expressions, this golden crema can also be referred to as espresso crema. Since we know the composition of crema, to extract a rich crema, we need to choose beans with rich oils and sufficient carbon dioxide.

1884In the year, an ItalianAngelo Moriondodesigned the first espresso machine, featuring two independent brewing boilers,1.5barpressure and steam, the extracted coffee liquid is relatively viscous, with a richer taste than drip coffee. As coffee machines were continuously improved, factors like water temperature and pressure were better controlled,1948In the year, a café owner in MilanAchille Gaggiainvented the lever-driven coffee machine, which could generate what we now call crema through high pressure (crema). Since then,cremahas been considered one of the indicators of espresso quality,spressobecame specifically referring to making a highly concentrated coffee with rich crema through pressurized methods.

Some friends rebut that they bought coffee beans roasted abroad and still had oils after more than half a year. First, imported coffee beans use technologies like nitrogen flushing for preservation, but after you open the package, those preservation techniques no longer work, and after 2 months, there's still no flavor.

With sufficient hardware support, it's about the extraction method, such as the coffee-to-water ratio. Some friends think that to get richer oils, they should extract more coffee liquid, so the oils will increase accordingly. But if you observe the coffee extraction process, you should notice that it starts brown-black, then brown-yellow, then golden-yellow, and finally yellow-white.

The above content is compiled by CoffeeHunters, a coffee news website.