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Italy is a country of coffee culture. The espresso that has spread across the globe is the soul of coffee and a treasure Italy has given to the world. Espresso, as its name suggests, is a coffee with a short preparation time, a short drinking time, and a strong flavor and mouthfeel. It is a pure cup that concentrates the essence of coffee.

Making espresso, however, is not simple, because many parameters need to be calibrated. These include the coffee grind size, water temperature, extraction time, extraction ratio, and so on, all of which are key to determining espresso quality. The extraction ratio is also a parameter that requires precision. Today, Front Street will share with everyone the extraction ratio for espresso and explore the secrets behind the ratio.

Dose-to-Yield Ratio

There is actually no completely fixed parameter for the extraction ratio; it needs to be adjusted according to the situation. However, every industry has unwritten rules, using respected in-industry standards as common values and forming benchmarks within the industry. For regular espresso, the extraction ratio is controlled between 1:1.5 and 1:2.5. Front Street stores use a 1:2 ratio.

The extraction ratio includes the dose and the weight of extracted coffee liquid. In China, the extraction ratio for single and double shots is based on the portafilter basket configured with the coffee machine. A single shot is 8-9 g, and a double shot is 18-20 g, extracting 28-30 g of espresso liquid for a single shot and 30-40 g for a double shot within 25-30 s. The coffee machine at Front Street stores is equipped with a 20 g double basket. When serving, 20 g of coffee grounds are used to extract 40 g of coffee liquid, then adjusted up or down according to that day's espresso extraction status.

Increasing or decreasing the dose can change the compactness of the coffee puck, thereby determining the flow rate of the espresso liquid. The firmer the puck, the slower the coffee liquid flow rate, the longer the time required to extract the same amount of coffee liquid, and accordingly the stronger the coffee liquid and the higher the extraction yield. Normally, it is necessary to judge based on the flow rate and flavor to decide how to make tiny increases or decreases.

Grind Size Coarseness

In most cases, a cup of espresso can be extracted in just a few dozen seconds. In such a short extraction time, to fully extract the coffee's aroma, the coffee grounds need to be ground finer and more evenly, which requires a dedicated electric grinder used for espresso extraction.

Because espresso extraction amplifies coffee flavors, the requirements for grind size are very strict. It is difficult for us to judge the coarseness of the grind with the naked eye; it generally shows up in the flow rate and flavor of the espresso. If the grind is too coarse, the coffee particles are larger, the puck is looser, and water passes through the coffee grounds in less time, making under-extraction easy, with weak and sour coffee flavor. If the grind particles are too fine, the coffee is prone to over-extraction, with a bitter taste and sharp mouthfeel. In addition, because the fineness of espresso grinding is far higher than grind sizes for methods such as pour-over, adjustments should not be too large, as this can easily cause excessive variable changes and make extraction more unstable.

How to Adjust Extraction Parameters

Espresso extraction changes with air humidity under weather influences and the condition of the coffee beans. For example, rainy days are more humid than sunny days, and coffee grounds easily absorb more moisture, thereby affecting subsequent extraction. When we extract espresso, the water temperature and pressure rarely change easily and are usually set at fixed parameters. For example, the coffee machine at Front Street stores uses 9Bar and a water temperature of 94 degrees Celsius. Generally, the coffee in the cup is dialed in by adjusting three parameters: grind size, dose, and coffee liquid weight.

For example, the extraction parameters Front Street used the day before were: 19.8 g coffee grounds, 38 g coffee liquid, time 29 seconds. Extracting with the same dose yielded 38 g of espresso liquid, but the time changed to 26 seconds, indicating that the flow rate became faster.

At this point, Front Street would first change the flow rate by increasing the dose by 0.1 g each time. When Front Street used 20 g of coffee grounds and extracted the same liquid weight, the time became 29 seconds. Tasting the espresso liquid, there was no strange bitterness, but the aroma was slightly flat, indicating that the coffee was under-extracted. This shows that increasing the dose was not effective enough, and the grind size needs to be changed. Here it should be adjusted finer so that the particles are smaller and fully release flavor substances. Conversely, if the flow rate becomes slower, it is necessary to first speed up the flow by reducing the dose. If reducing the dose does not achieve the effect, then adjust the grind coarser. The direction of parameter adjustment is flexible. As long as we are familiar with the characteristics of the coffee beans and the coffee machine, quickly dialing in a delicious espresso is not difficult.

In addition, espresso extraction is also related to the roast level of the coffee beans. The lighter the roast, the harder the coffee bean texture, and the worse the water absorption effect when ground into coffee powder. During extraction, this can easily cause channeling and spraying, so the coffee taste will be under-extracted. For this reason, if you want espresso to achieve stable extraction, Front Street Coffee recommends prioritizing medium roast, medium-dark roast, and dark roast coffee beans. Below, Front Street lists several espresso blend coffee beans according to different tastes. Everyone can purchase according to preference and needs:

"Front Street Specialty Blend Coffee Beans" 75 yuan/454g: Colombian washed coffee beans + Brazilian semi-dry coffee beans, with flavor notes of nuts, dark chocolate, and caramel.

"Front Street Classic Blend Coffee Beans" 33 yuan/100g; Brazilian semi-dry coffee beans + Indonesian Mandheling coffee beans + Vietnamese coffee beans, with rich coffee crema and a mellow mouthfeel;

"Front Street Strawberry Candy Espresso" 43 yuan/100g; Costa Rican coffee beans + Panamanian coffee beans + Ethiopian coffee beans, with aromas of roses, strawberry candy, and glucose, a prominent fruity sweet-and-sour sensation, and a pleasant taste.

After adjustment, Front Street serves a normal cup of espresso here for everyone to reference. Front Street uses its own roasted "Front Street Sunflower Warm Sun Blend Coffee Beans," blended from 30% Yirgacheffe natural and Honduras.

Front Street uses 20 g of coffee grounds, follows a 1:2 dose-to-yield ratio, and extracts 40 g of coffee liquid under 9 bar of pressure, with the time controlled at 30 seconds.

The flavor of the espresso has rich vanilla and cocoa notes, with the acidic aroma of berries. As the temperature drops slightly, creamy flavors begin to emerge, with a dark chocolate finish. The overall cup is balanced, with a rich and smooth mouthfeel.

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