How to Make Rich Crema on Espresso? What Substances Compose Crema?

Understanding Rich Crema in Espresso Coffee

Just a few days ago, a customer visited FrontStreet Coffee's Guangzhou Dongshankou store for an espresso coffee. Before leaving, they remarked, "I absolutely love your espresso! The crema is the richest I've ever seen!" Coincidentally, some friends have also asked FrontStreet Coffee how to make espresso crema richer. Today, FrontStreet Coffee will share their insights on this topic.

What is Espresso?

Espresso, as the name suggests, originates from Italy in Europe. The development of espresso was aimed at increasing the speed of coffee preparation. Initially, espresso referred to a method of making coffee, with "espres" meaning "fast" - signifying that a black coffee could be prepared in a very short time.

Understanding Crema

The golden layer on top of espresso is called Crema. However, calling it "oil" isn't entirely accurate, as this golden crema consists of coffee oils combined with carbon dioxide. When this crema breaks down and the carbon dioxide dissipates, what remains is a thin reflective layer of actual coffee oils.

Nevertheless, due to common usage, this golden crema layer can be referred to as espresso crema. Now that we understand crema's composition, to extract rich crema, we need to select coffee beans with abundant oils and sufficient carbon dioxide.

The Evolution of Espresso Machines

In 1884, Italian Angelo Moriondo designed the first espresso machine, featuring two independent brewing boilers with 1.5 bar pressure and steam. The extracted coffee liquid was relatively viscous, with a richer taste compared to drip coffee. As coffee machines were continuously improved, factors like water temperature and pressure became better regulated. In 1948, Achille Gaggia, a café owner in Milan, invented a lever-driven machine capable of producing what we now call crema through high pressure. Since then, crema has been considered one of the quality indicators for espresso, and espresso became specifically defined as a high-concentration coffee made through pressurization containing rich crema.

Coffee Bean Selection for Rich Crema

The richness of coffee oils primarily depends on the bean variety and roast level. Generally, Robusta beans have richer oils than Arabica, but their flavor isn't as good as Arabica. Therefore, Robusta beans are typically blended with Arabica to achieve balance. For example, FrontStreet Coffee's commercial blend series contains 10% Robusta beans to enhance coffee oils while balancing flavor. Meanwhile, American Arabica beans perform better in terms of oil content compared to African varieties. For instance, the Sunflower Warm Blend used at FrontStreet Coffee stores contains 70% Honduras Sherry coffee beans, providing rich oils.

The roast level also affects the richness of extracted oils. Typically, the darker the roast, the better the coffee oil expression. Therefore, to achieve good crema, espresso beans are usually medium to dark roast. Some friends pursue acidity in espresso and use medium-light roast beans, but naturally, the crema expression won't be as good.

The Importance of Freshness

Next is the carbon dioxide content, which essentially means freshness. Carbon dioxide is produced during roasting and gradually released from the beans over time. Generally, espresso beans completely release their carbon dioxide in about 45-60 days. However, when the carbon dioxide is completely released, the coffee's flavor is also nearly depleted (meaning it's no longer fresh). The extracted coffee will have thin crema and only the bitterness of the coffee itself. Some friends ask FrontStreet Coffee why their extracted espresso has no crema, and when asked about the roast date, it turns out the beans were roasted six months ago... When stored for too long, the resulting coffee lacks aroma, let alone crema. This is why FrontStreet Coffee has always emphasized the importance of fresh roasting over the years.

Some friends argue that they've purchased imported coffee beans from abroad that still have crema after more than half a year. First, imported coffee beans often use preservation technologies like nitrogen flushing. However, once you open the package, these preservation techniques become ineffective, and after two months, the flavor will be gone regardless.

Secondly, it's not that espresso beans are better the fresher they are. Without a 7-12 day degassing period, the abundant carbon dioxide in the beans will be pressed into the crema, forming very thick crema. However, this crema is coarse and unstable, breaking down quickly, and the coffee flavor will be relatively weak. Some friends who just bought espresso beans ask FrontStreet Coffee why the coffee flavor tastes different from before. FrontStreet Coffee tells them to let the beans rest for 5 days before trying again. After 5 days, they confirm it tastes like it should.

Extraction Techniques for Rich Crema

After selecting suitable coffee beans, the next consideration is extraction. To achieve rich golden crema, the extraction pressure should be maintained at 9 Bar. Some small home machines using vibration pumps struggle to maintain stable pressure throughout the extraction process, which is another reason for lacking crema.

With adequate hardware support, the extraction method becomes crucial. For instance, some friends believe that to get richer crema, they should extract more coffee liquid, thinking the crema will increase accordingly. However, if you observe the coffee extraction process, you'll notice that initially, the liquid is dark brown, then brownish-yellow, followed by golden yellow, and finally yellowish-white.

This represents the process of crema changing from rich to pale. The further into the extraction, the thinner the crema becomes, and the lighter its color, which actually affects the overall quality of the espresso. FrontStreet Coffee's espresso typically uses a powder-to-liquid ratio between 1:1.8-2, rarely exceeding a 1:2 ratio. For example, today's parameters were 20 grams of coffee powder extracted for 30 seconds to yield 40 grams of coffee liquid.

Important Notice :

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