Espresso is a precious beverage Italy has gifted to the world. It may seem to require only a few dozen seconds of extraction, but behind it lies a precise coordination of grinding degree, water temperature, dose, liquid yield, and a series of other parameters. Starting from the freshness and roast level of coffee beans, this article explains the impact of different roast levels on extraction stability, and introduces the flavor characteristics and suitable scenarios of several Front Street Coffee espresso blends. It then delves into how brew ratio, dose adjustments, grind size, and humidity changes affect flow rate and flavor. Combined with actual parameter-tuning cases from Front Street Coffee shops, it demonstrates how to achieve an ideal balance among aroma, acidity, and body through fine-tuning dose and grind size.
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Italy is a country of coffee culture. The espresso that has spread worldwide is the soul of coffee and a treasure Italy has given to the world. Espresso, as the name suggests, is a coffee with a short preparation time, a short drinking time, and a strong flavor and mouthfeel—a pure concentration of coffee's essence.
Making espresso, however, is not simple, because many parameters need to be calibrated, such as grind size, water temperature, extraction time, and brew ratio. These are all key factors affecting the quality of espresso.
A perfect espresso is inseparable from freshly roasted coffee beans, which not only bring layered coffee aromas but also present a dense and rich crema. Front Street Coffee has always adhered to the most important point—the freshness of coffee beans. Therefore, Front Street Coffee beans are all roasted within 5 days, support 24-hour shipping, and achieve all-around freshness.
Espresso extraction is related to the roast level of the coffee beans. The lighter the roast, the harder the bean texture, and the worse the ground coffee's water absorption, making it prone to channeling and splattering during extraction, resulting in under-extracted coffee flavor. For this reason, if you want stable espresso extraction, it is recommended to prioritize medium-roast, medium-dark roast, or dark roast espresso beans. You can purchase according to your preferences and needs:
Creamy Nutty Aroma Blend — Front Street Coffee Specialty Blend : Colombian washed coffee beans + Brazilian semi-washed coffee beans, with nutty, dark chocolate, and caramel flavor notes. It can also be used for moka pot coffee extraction, suitable for home use and commercial coffee shops.
Crema Explosion Blend — Front Street Coffee Classic Blend : Brazilian semi-washed coffee beans + Indonesian Mandheling coffee beans + Vietnamese coffee beans, with rich crema and a full-bodied mouthfeel. Suitable for home or commercial espresso machines, and can also extract rich moka pot coffee.
Fruity Gummy Candy Blend — Front Street Strawberry Candy Espresso : Costa Rican coffee beans + Panamanian coffee beans + Ethiopian coffee beans, with aromas of roses, strawberry candy, and grapes. The fruity sweet-and-sour notes stand out, with a pleasant taste.
For the extraction parameters of the above espresso blends, Front Street uses 20 grams of coffee powder, follows a 1:2 brew ratio, and extracts 40 grams of coffee liquid under 9 bar of pressure, with the time controlled at 30 seconds.
The flavor of espresso has rich vanilla and cocoa notes, with a berry-like acidic aroma. As the temperature drops slightly, creamy flavors begin to emerge, with a dark chocolate finish. Overall it is well-balanced, with a rich and smooth mouthfeel.
Brew Ratio
There is actually no completely fixed parameter for brew ratio; it needs to be adjusted according to circumstances. However, there is an unwritten rule in the industry: use the value recognized by industry authorities as a universal figure, forming a benchmark in the industry. For regular espresso, the brew ratio is controlled between 1:1.5 and 1:2.5. Front Street shops use a 1:2 ratio.
The brew 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 capacity of the portafilter basket configured with the espresso machine: single shots at 8–9 g, double shots at 18–20 g, extracting 28–30 g for a single shot and 30–40 g for a double shot within 25–30 s. The espresso machines at Front Street shops are equipped with a 20-gram double basket. When serving, 20 grams of coffee powder are used to extract 40 g of coffee liquid, and adjustments are made up or down based on the 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. The more compact the puck, the slower the coffee liquid flow rate, and the longer it takes to extract the same amount of coffee liquid. Correspondingly, the coffee liquid will be more concentrated, and the extraction yield will be higher. Normally, you need to judge based on flow rate and flavor to decide how to make small adjustments up or down.
Grind Size Coarseness
In most cases, an 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 powder needs to be ground finer and more evenly—that is, a dedicated electric grinder for espresso extraction is required.
Because espresso extraction amplifies coffee flavors, the requirements for grind size are extremely strict. It is difficult to judge grind size coarseness with the naked eye; it usually manifests in the flow rate and flavor of the espresso. If the grind is too coarse, the coffee particles are larger, the puck is looser, water passes through the coffee powder in less time, and under-extraction is likely, resulting in weak, sour coffee flavor. If the grind is 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 that of pour-over and other methods, adjustments should not be too large, as this can easily cause excessive variation and make extraction more unstable.
How to Adjust Extraction Parameters
Espresso extraction changes with air humidity under weather influence and the condition of the coffee beans. For example, rainy days are more humid than sunny days, and coffee powder easily absorbs more moisture, affecting subsequent extraction. When we extract espresso, water temperature and pressure are rarely changed easily; they are usually set at fixed parameters. For example, the espresso machines at Front Street shops use 9 bar and 94°C water temperature. 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 previous day were: 19.8 grams of coffee powder, 38 grams of coffee liquid, time 29 seconds. Extracting with the same dose yields 38 grams of espresso, but the time becomes 26 seconds, indicating the flow rate has become faster.
At this point, Front Street will first change the flow rate by increasing the dose by 0.1 grams each time. When Front Street uses 20 grams of coffee powder and extracts the same liquid weight, the time becomes 29 seconds. Tasting the espresso shows no strange bitterness, but the aroma is slightly flat, indicating under-extraction. This shows that increasing the dose is 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 compounds. Conversely, if the flow rate becomes slower, you need to first reduce the dose to speed up the flow rate. 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 espresso machine, quickly dialing in a delicious espresso is not difficult.
The above content is compiled by CoffeeHunters, a coffee news website.
