What does the espresso extraction process involve from bean to cup?

A balanced espresso depends on every stage of the coffee extraction process beverage chain: resting time, hopper management, grind size, dosing, distributing, tamping, and the final extraction settings. Good beans alone are not enough. Grind size has to be adjusted as the environment changes, and the portafilter basket should be kept at room temperature before the shot is pulled.

Espresso means fast in Italian, describing coffee extracted under high pressure in a short time, and it originated in Italy. The earliest versions tasted bitter with a burnt aroma until the taste and quality were improved in the 1940s. Tamping pressure affects flow rate, so a standard shot means dialing in dose, yield, and time together.

To make a rich, well-balanced espresso at home, good beans alone are not enough. From resting time, hopper management, and fine-tuning the grind size, to each step of dosing, distributing, and tamping, and then to setting the extraction parameters, every stage directly affects the final flavor. Front Street Coffee, drawing on years of production experience, breaks down in detail the key control points in espresso making, including how grind size should be adjusted with environmental changes, why the portafilter basket should be kept at room temperature, the relationship between tamping pressure and flow rate, and the extraction parameters for the sherry barrel blend beans currently used by Front Street, helping coffee enthusiasts systematically master the logic of making a standard Espresso.

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Front Street has always felt that Italy's coffee culture occupies a pivotal position in the entire industry. This coffee tradition, with its long history and deep heritage, has been accepted and loved by people all over the world, and this is truly undeniable. With espresso as the base, many familiar classic drinks have also been derived. Therefore, Front Street holds deep respect for all people and countries that have contributed to the coffee industry. The reason espresso coffee can become a global beverage is inseparable, behind its charm, from a cup of espresso that seems simple but is highly profound. It is a highly condensed essence of coffee, and even if you do not prefer it, this fact cannot be changed—this is the root and continuation of espresso coffee. If you want to understand the birth process of a high-quality espresso, you might as well explore it in depth with Front Street.

The History of Espresso Espresso means "fast" in Italian, referring to coffee extracted under high pressure in a short time. It originated in Italy and is ranked alongside "fashion and food" as one of Italy's three national treasures. The espresso originally invented tasted bitter and also carried a burnt aroma, and it was not until the 1940s that its taste and quality were completely improved and enhanced. In China, various names such as espresso, Italian espresso, and aromatic coffee all actually refer to Espresso.

Next, Front Street will explain one by one how to make an excellent espresso.

First, choose fresh espresso coffee beans that have been rested properly.

Espresso coffee beans generally use a blend, and adding an appropriate proportion of Robusta beans can bring richer crema. What Front Street Coffee (FrontStreet Coffee) uses in production is single-origin sun-dried Yirgacheffe Red Cherry, paired with single-origin Honduras whisky barrel-fermented Sherry. This blend highlights wine aroma and fruity acidity. Freshly roasted coffee beans contain about 2% carbon dioxide by weight. This carbon dioxide will gradually be released depending on the storage environment, equipment, or method, making the pressure inside the packaging higher than one atmosphere, and pressure helps the integration of aromatic substances and oils, allowing all aromatic components in the beans to reach a state that is easy to extract. Resting beans is the process of "gas release," also called awakening, resting, or maturation.

For resting beans, simply keep the original packaging unopened and place it in a cool, dry place, allowing the coffee beans to release gas on their own through the one-way exhaust valve on the bag. If espresso beans are too fresh and degas vigorously, channeling is likely to occur, leading to unstable espresso output. To obtain a stable espresso, espresso coffee beans can be selected from beans rested for about ten days.

1. Refill the hopper

Through experiments, Front Street Coffee (FrontStreet Coffee) found that the amount of coffee beans in the grinder hopper does indeed have a subtle effect on espresso. This effect comes from the gravity of the coffee beans: when the hopper is full, the coffee beans at the burrs are compressed and cut evenly and tightly. As the amount of beans decreases, the weight of beans above the burrs also decreases, making them looser compared with a full hopper, and coffee beans of the same volume are cut fewer times, so the grind size becomes slightly coarser.

2. Clean the grinder

On the one hand, reduce excessive coffee powder residue in the grinder so as not to interfere with the next espresso extraction. On the other hand, in order to make the coffee beans produce more carbon dioxide to withstand the high-pressure environment during espresso machine extraction, a large proportion of espresso coffee beans are roasted relatively dark, which also makes the beans prone to oiling, and the oils remaining in the grinder will likewise affect the coffee taste. Regular maintenance of the grinder can both extend the machine's lifespan and help better ensure consistency in coffee taste.

3. Adjust the grind size

Properly adjusting the grinder helps with the stability of espresso output. As for espresso grind size, it is not simply a matter of setting it to a certain mark and being done with it. It is affected by air temperature, air pressure, temperature, storage time, and, when replacing old beans with new ones, different roasting times, different bean batches, and different resting times, resulting in different extraction conditions. There is also another point: continuous brewing and extraction of espresso will also bring changes in grind size, so making espresso requires appropriately adjusting the grind according to the extraction condition. The finer the espresso grind particles, the longer the extraction time, the more burnt and bitter the taste, and the easier it is to over-extract, so it is recommended to adjust coarser; conversely, the coarser the grind particles, the shorter the extraction time, the more sour the taste, and the easier it is to under-extract, so it is recommended to adjust finer.

Front Street reminds you here of one point: when the grinder runs continuously for more than 3 minutes, the burrs will overheat due to prolonged operation, and overheated burrs will affect the flavor of the ground coffee beans; at the same time, long operation will generate a large amount of static electricity, which also affects grind uniformity. At this point, the grinder should be stopped for 1 minute to give the burrs time to cool down.

4. The portafilter basket must be at room temperature!

Through experiments, Front Street believes that when the portafilter basket is at room temperature, the extraction degree of espresso can well reach the standards for concentration and extraction yield. A high-temperature portafilter basket will accelerate the volatilization rate of flavor molecules in the coffee grounds and greatly reduce the extractable flavor substances. In daily production, locking in the portafilter and extracting immediately is also to reduce the high temperature of the group head accelerating the volatilization of flavor molecules in the puck. But if the portafilter basket is at a low temperature, low temperature will cause the flavor substances in the coffee to be unable to extract evenly, and the concentration and extraction yield will instead be lower.

4. Dosing

After the espresso coffee beans have been adjusted, keep distributing the grounds at a constant speed while rotating the handle at a constant speed. Do not underestimate the dosing step—uneven dosing will cause great misleading and impact on the subsequent distribution step; uneven density distribution of the coffee bed will lead to inconsistent puck thickness, and during extraction the hot water will pass through different positions at different speeds. A slight lack of attention can easily cause perforation, resulting in part of the puck being under-extracted and part being over-extracted, and the coffee taste will be unstable every time. If you have paid attention to how coffee grounds fall, you will probably find that coffee grounds do not fall completely vertically. Under the influence of lateral acceleration, the coffee bed will show a certain degree of deviation. At this time, we need to distribute the grounds at a constant speed while rotating the handle at a constant speed.

5. Distribution Common distribution tools usually have adjustable height. Before distributing, determine the appropriate height according to the dose. If the distribution tool is too far from the surface of the coffee bed, it will touch the raised parts and distribute them into the hollows; if it is too close, it will press into the coffee bed, and such pressure is not necessarily even.

6. Tamping The direction of tamping: vertically downward. The direction of tamping may be a little more complicated than we imagine: vertically downward. If tamped at an angle, the high-temperature, high-pressure hot water coming from the group head will seek the layer with the least resistance to penetrate, causing uneven extraction.

The force of tamping needs to be determined according to the coarseness or fineness of the coffee grounds, with the reference basis being the coffee flow rate during extraction (extraction time 25±3 seconds). If the flow rate is too fast, it means the tamping force is too light; if the flow rate is too slow, it means the tamping force is too heavy. These will directly affect the finished espresso and the coffee's mouthfeel. In order to reduce instability in espresso caused by different tamping force each time, Front Street Coffee (FrontStreet Coffee) recommends using a calibrated tamper for tamping.

7. Extracting the coffee liquid

The generally reasonable extraction time range is 20~30 seconds (without first considering extraction extended by other factors). The time to stop extraction is also an important factor determining the final taste of a cup of espresso. A relatively standard espresso should achieve balance among the flavors, with a smooth mouthfeel, a sweet and mellow entry rather than bitterness, moderate acidity, bitterness, and sweetness, as well as a solid rich aroma.

Front Street Coffee (FrontStreet Coffee) currently uses a blend of sherry barrel-processed coffee beans and sun-dried Yirgacheffe Red Cherry Plan coffee beans to make espresso. Sixty percent Honduras sherry barrel coffee beans provide flavor and body for this blend, while forty percent sun-dried Yirgacheffe provides more aroma and acidity.

Front Street espresso extraction parameters:

Grinder: Flying Horse 900N

Grind size: 1.6

Pressure: 9 bar

Temperature: 90.5~96 degrees Celsius

Time: 20~30 sec

Dose: 20g (double espresso)

Extraction yield: 40ml

Extracted espresso flavor: smooth mouthfeel, medium body, noticeable fruity acidity on the entry, accompanied by faint berry aroma, whisky aroma, and rich chocolate flavor, with a clear sweet aftertaste.

To get more specialty coffee knowledge, welcome to follow Front Street Coffee (Frontsteet Coffee).

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