Why Are Blended Coffee Beans Used for Espresso?

An espresso blend coffee bean is a mixture of origins roasted specifically for pressure extraction. Not every bean suits an espresso machine: light-roasted lots tend to turn sharply sour when hot water is forced through them at pressure. Blends are assembled to keep flavor and quality stable from shot to shot, unlike single-origin beans that fluctuate with climate, soil and roast.

SOE, or Single Origin Espresso, uses one origin, but those beans are roasted darker than lots meant for pour-over, French press, ice drip or cold brew. In blends, a darker roast supports crema and carbon dioxide release. Common builds include Warm Sun, Specialty, Commercial and Dark Cocoa styles, and freshly roasted beans need resting before use.

Not all coffee beans are suitable for making espresso. Pressure extraction of light-roasted beans tends to amplify acidity, and espresso blends are made precisely for this purpose. From the perspective of Front Street Coffee, this article explains why blends are more suitable for espresso machines than single-origin beans, the difference between SOE and blends, the relationship between deep roasting and crema and carbon dioxide, and introduces in detail the recipes, flavors, and target audiences of Front Street's four blends: Warm Sun, Specialty, Commercial, and Dark Cocoa. It also reminds readers of the necessity of resting freshly roasted beans.

What are blended coffee beans? What are the blending ratios of Front Street's espresso beans? And which beans should be chosen for blended coffee beans?

Recently, a friend asked Front Street Coffee: "Can all coffee beans be used to make espresso?" The answer is no. Not every coffee bean is suitable for pressure extraction, especially light-roasted beans, whose acidity is noticeably amplified during extraction, resulting in a sharply sour taste. So what kind of coffee beans are suitable for making espresso?

When recommending beans for espresso, Front Street Coffee usually suggests choosing espresso blend coffee beans, because this type of bean is tailor-made for espresso machines. Its notable characteristic is a darker roast level than beans used for pour-over, while maximizing the stability of espresso flavor and quality.

Generally speaking, single-origin coffee beans used for pour-over are not suitable for espresso machines. The reason is that single-origin beans cannot ensure consistent output for every cup of espresso. As an agricultural product, even the same coffee bean can show fluctuations in flavor performance due to differences in climate, soil, roasting approach, and daily conditions.

Then how should SOE (Single Origin Espresso) be understood? Although SOE uses single-origin beans to extract espresso, the single-origin beans used for SOE are roasted darker than beans used for pour-over, French press, ice drip, cold brew, and other purposes. Because light-roasted beans often carry noticeable acidity, and when extracted by drip or immersion methods, the acidity may be just right and the coffee may have richer layers.

However, espresso machines use pressure to force hotter water than pour-over to quickly pass through coffee particles, extracting extremely concentrated coffee (the pour-over coffee-to-water ratio is usually 1:13, while the espresso dose-to-yield ratio is 1:2). As a result, the acidity in the beans becomes more prominent, easily producing unpleasant flavors such as sharp sourness and astringency. Light-roasted coffee beans are harder in texture, and soluble substances are not easily released. During pressure extraction, the fast water flow also cannot dissolve mellow substances and can only bring out sweet and sour components, so the final espresso appears thin.

The practice of blending coffee beans emerged precisely because early coffee professionals realized that single-origin beans were difficult to keep flavor-stable over the long term, and not every single-origin bean could extract delicious coffee. So they improved flavor through blending, thereby solving the problem of excessive differences in espresso flavor within the same shop caused by harvest times, differences in roasting approaches, or even a poor harvest of a certain bean. It also reduced output differences caused by different extraction approaches among baristas. In addition to improving flavor and enhancing espresso consistency, there was another key reason—lowering costs.

Most espresso beans use deep roasting. First, it weakens the amplification of acidity by pressure extraction and promotes the release of soluble substances (the darker the roast, the looser the bean texture and the easier it is to extract flavor), thereby increasing the coffee's body. Second, through a longer roasting time, more carbon dioxide accumulates inside the beans, forming a richer espresso crema.

"Ah! What is the relationship between espresso crema and carbon dioxide?" Espresso crema is not all coffee oil! When an espresso machine extracts, it generates more than 9 bar of pressure to "squeeze" the coffee puck. Because the carbon dioxide in the coffee grounds is under excessive pressure, water becomes supersaturated with carbon dioxide, causing the carbon dioxide to be unable to release and instead dissolve directly into the coffee liquid. During extraction, the fats in the coffee are also emulsified, and these fats wrap around the carbon dioxide and are released together. Because oil is lighter than water, golden crema appears on the surface of the extracted espresso.

After reading this, I believe everyone can roughly understand why Front Street Coffee recommends using specially made espresso blend beans when making espresso. So which good espresso blend beans are worth recommending? Front Street currently sells four espresso blend coffee beans, namely:

Warm Sun Blend: Ethiopian natural Red Cherry coffee beans + Honduran coffee beans, with rich fermented aroma, vanilla cream, berry sweet-tartness, and roasted nut flavors. Suitable for friends who like coffee with rich layers.

Specialty Blend: Colombian washed coffee beans + Brazilian semi-washed coffee beans, presenting nut, dark chocolate, and caramel flavors. Suitable for friends who like full-bodied coffee.

Commercial Blend: Robusta washed coffee beans + Colombian washed coffee beans + Brazilian semi-washed coffee, showing nut, cocoa, and caramel flavors. Suitable for friends seeking value for money.

The espresso coffee beans recommended by many baristas—Front Street Dark Cocoa Blend: Yunnan washed small-bean coffee + Brazilian semi-washed coffee beans, with soft fruit acidity, caramel, and nut flavors. Suitable for friends with high demand for everyday coffee.

Everything sold by Front Street is freshly roasted coffee beans shipped within 5 days after the roast date. After receiving espresso beans, do not rush to use them, because excessive carbon dioxide will affect the overall extraction of espresso, easily leading to uneven extraction, longer extraction time, and ultimately unpleasant flavors such as bitterness in the coffee. Although carbon dioxide is key to whether espresso crema is rich, too much carbon dioxide makes the crema very thick. If used to make a hot latte, overly thick crema will affect the integration of milk and coffee, ultimately affecting the formation of latte art and the overall taste performance of the coffee.

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