How does a semi-automatic coffee maker actually extract espresso?

Espresso comes from pushing hot water at roughly 92 degrees Celsius through a finely ground, compacted puck under high pressure. That extraction yields a concentrated shot with more caffeine per unit volume than most other coffee drinks, and it forms the base of every Italian-style drink: Americano, latte, cappuccino, flat white, and mocha.

Dose, yield, and time are the core parameters to dial in, and a seven-step routine covers grinding, distribution, tamping, and the pull itself. To make americano, either dilute the shot with hot water or brew with a drip coffee maker, the route American households adopted first. Front Street offers four espresso blend options to match different milk and straight-shot uses.

Espresso is the foundation of all Italian-style drinks; Americano, latte, cappuccino, flat white, and mocha are all derived from it. This article starts from the practical store operations of Front Street Coffee and systematically sorts out the logic of using a semi-automatic espresso machine: first clarify the high-pressure extraction principle of espresso, then compare the historical origins and flavor differences between Italian-style and American-style coffee, followed by a detailed explanation of the positioning of Front Street’s four espresso blend beans, and finally provide the core extraction parameters such as dose, yield, and time, along with a seven-step operating process. Whether you are a beginner who has just come into contact with a semi-automatic machine or a coffee enthusiast looking to optimize your output, you can find practical reference solutions here.

Although most people who come to Front Street for pour-over coffee are in the majority, the customers willing to order espresso drinks are also quite considerable. Everyone clearly knows that espresso forms the base of all kinds of Italian-style drinks—Americano, latte, cappuccino, flat white, mocha, without exception.

As Front Street understands it, espresso is called “espresso” abroad, and its caffeine content per unit volume is also higher than that of most coffee drinks. Espresso is obtained by extraction with an espresso machine. The principle is to use a high-pressure environment to let hot water (at a temperature of roughly around 92°C) pass through a finely ground and compacted layer of coffee grounds. In this process, solids and soluble components are extracted, and the liquid formed is espresso. Espresso is certainly the starting point of all coffee drinks, but it is also itself an independent coffee drink. Many people also regard espresso as the representative of Italian-style coffee and compare it with Americano. So where exactly is the difference between Italian-style coffee and American-style coffee?

There are two ways to make Americano. One is a drink extracted with an American drip coffee maker, and the other is made by diluting espresso with water. To understand the difference, one can start with the historical evolution of Americano. American drip coffee makers first became popular in American households, and Americans had long been accustomed to the taste produced by drip machines—coffee flavor on the lighter side, thin taste, and an obvious watery feel. During World War II, the coffee American officers drank in Europe was almost all espresso, with a strong and stimulating taste.

In order to replicate the flavor of drip coffee maker coffee, they added hot water to the espresso liquid. In this way, the coffee’s flavor became much softer and much smoother to drink. Because at that time no other people in Europe drank coffee this way, this drink was given the name “Americano.” In fact, this name carried a bit of mockery behind it; it was the locals’ teasing of Americans for not being used to drinking espresso. The French even privately called “Americano” “sock coffee” to describe how bad its taste was.

The Americano at FrontStreet Coffee is made by adding water to espresso, and the vast majority of coffee shops on the market also use this method. Generally speaking, the water-to-espresso ratio of Americano is between 1:4 and 1:9, and different coffee shops each have their own standards. Front Street’s hot Americano has a ratio of water to coffee liquid of 1:4.5. This was determined by taking into account the characteristics of the Warm Sun Blend espresso and the cup size of the store’s output. Front Street’s iced Americano has a ratio of water to coffee liquid of about 1:9. Because it uses the store’s own blended espresso beans, unlike other coffee shops that pursue nutty flavors, FrontStreet Coffee’s Americano has a rich wine aroma, abundant crema, an overall mellow body, a creamy texture, and a long chocolate finish. Compared with hot Americano, iced Americano is more refreshing. Using different espresso beans also produces coffee drinks with different flavors. To meet needs in various aspects, Front Street has designed four espresso beans in total: Specialty Blend, Commercial Blend, the espresso bean recommended by many baristas—Front Street Black Cocoa Blend, and Warm Sun Blend.

The espresso bean recommended by many baristas—Front Street Black Cocoa Blend—uses commonly used bean varieties suitable for espresso, such as Brazilian, Colombian, and Yunnan coffee beans, with the goal of obtaining a better coffee flavor and mouthfeel at a lower cost. For coffee shops pursuing rich crema, Front Street’s Commercial Blend adds 10% robusta beans. While enhancing the overall body, the coffee’s flavor is also more fragrant and mellow. The nutty flavor stands out, and the chocolate flavor paired with the sweetness of milk is very perfect. The Specialty Blend uses arabica coffee beans from Brazil and Colombia. All-American arabica can present a cleaner coffee taste, and the flavor performance of these two producing regions is nutty and chocolatey, very suitable for espresso output.

Sunflower Warm Sun Blend coffee beans were a new attempt by Front Street in 2019. At that time, the concept of specialty (single-origin) coffee was prevailing, and many SOEs sold on the highlight of flavor had also appeared, but Front Street planned to use high-quality single-origin beans for blending to make a blended coffee bean whose main purpose was flavor. In the end, Front Street decided to use 30% Yirgacheffe Red Cherry and 70% Honduras Sherry as the recipe for Sunflower Warm Sun Blend coffee beans. The rich vanilla cream and fermented wine aroma attracted a large audience.

Generally speaking, espresso extraction has certain standards. Depending on the portafilter basket, the weight of coffee grounds is usually between 18 and 22 grams. Make sure the weight of the coffee grounds is the amount you want, because a tiny difference can lead to a huge difference. The most common brewing ratio is twice the coffee grounds, meaning that if you have 18 grams of coffee grounds, then it is best to extract 36 grams of espresso liquid, because once this value is exceeded, the coffee is prone to an over-extracted taste.

Of course, this standard can also be adjusted according to individual needs. For example, the espresso served at Front Street’s store uses 20 grams of grounds to extract 36 grams of coffee liquid, in order to make the Americano and latte richer and fuller in flavor. What needs to be reminded here is that the weight of the liquid coffee is best 1 to 3 times that of the dry coffee grounds, with 2 times being commonly used.

Brewing time is the time used from pressing the button to the end of extraction, usually between 25 and 35 seconds. If the extraction time is longer or shorter than you expected, the biggest reason lies in the coffee grind, so you should adjust according to your own needs and optimize the extraction parameters.

Generally speaking, fast extraction makes the coffee’s acidity stand out and reduces its sweetness. Slower extraction causes the coffee to have a bitter and dull flavor.

The most direct way to judge whether espresso is ready to serve is to taste it. Taste is a very good method for judging the quality of espresso. However, because judging whether espresso is normal by taste is too subjective, some far-sighted baristas and roasters use refractometers to measure the total dissolved solids (TDS) in espresso. TDS measurement enables them to determine accurate brewing strength and extraction percentage, and to correlate their preferred brewing parameters with numerical data. Measuring TDS also means that we can calculate the extraction percentage using the following formula:

(%TDS x brewed coffee weight) / coffee grounds weight = extraction percentage

Many coffee enthusiasts who come to Front Street will show admiration for the baristas operating the coffee machine at the bar, curious about how they operate the seemingly very complicated coffee machine. In fact, what baristas master is nothing more than the detailed steps of making espresso. As for how the coffee machine operates, most baristas do not know. So today, Front Street will introduce the detailed production process of espresso for everyone! Taking the normal operating process of FrontStreet Coffee as an example:

Step 1: Wipe the portafilter basket to ensure the coffee basket is dry and free of water

Step 2: Weigh the coffee grounds, use an electronic scale to weigh an appropriate amount of coffee grounds, and keep the error within plus or minus 0.1 grams

Step 3: Distribute the grounds

Step 4: Tamp the grounds

Step 5: Lock in the portafilter

Step 6: Press the button to extract

Step 7: Remove the portafilter and clean the group head.

Front Street espresso extraction recommendation: dose 20g, extracted coffee liquid 40g, time 30 seconds

Just like that, a shot of espresso is finished extracting. If you want to make other coffee drinks, it is nothing more than adding sugar and milk to it. Iced coffee is relatively simpler to make, as it is simply adding hot espresso to cold milk. As for hot milk coffee, you will need to use the steam wand on the coffee machine. As for how to steam milk foam, FrontStreet Coffee also has a dedicated article for teaching. If needed, everyone can look it up themselves. It is worth mentioning that many coffee chain brands now use fully automatic coffee machines, whose operation is even simpler—just press a button.

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