How Do Coffee Machines Change Espresso Extraction?

Espresso extraction parameters cover six variables: dose, brew ratio, extraction time, flow rate, pressure, and water temperature. A fixed recipe will not transfer between setups, because coffee machines differ in pressure and temperature stability. The practical approach is to start from the filter basket capacity, typically 7-9 grams for a single and 18-20 grams for a double, then adjust the other variables around it.

Brew ratio compares the weight of dry grounds to the weight of the extracted shot, so a 1:2 ratio means 18 grams in and roughly 36 grams out. If the flow runs too fast the puck is likely loose or the grind too coarse; too slow points to an overfilled or over-compacted puck, the kind of issue seen on even a most expensive coffee machine. Concentration testing then shows whether the shot lands in the golden cup range.

To make a balanced espresso at home, relying on a fixed recipe alone is far from enough. Different coffee machines, different bean conditions, and even daily climate changes can all cause variations in the extraction result. This article systematically explains how to customize suitable espresso parameters for the blend beans you have, from six dimensions: dose, brew ratio, extraction time, flow rate, pressure, and water temperature. At the same time, for the common problems of flow rate being too fast or too slow, it provides troubleshooting and adjustment ideas one by one, and introduces how to calculate the extraction yield through concentration testing to determine whether it falls within the golden cup range. The article recommends two espresso beans suitable for beginners to practice with: Front Street Classic Blend and Front Street Strawberry Candy Espresso, helping you find your ideal flavor faster through practice.

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Friends who have read Front Street's popular science articles may have noticed that we rarely give a fixed espresso extraction time the way we do for pour-over. The reason is that the extraction result of espresso depends not only on the freshness of the beans and the coarseness of the grind, but is also affected by the coffee machine brand, model, extraction pressure, and water temperature stability. Even with the same blend beans, if operated by a different person, the taste may be completely different. So how can you find the extraction parameters suitable for the blend beans you have on hand?

How do you customize an espresso extraction plan for the blend coffee beans in your hands?

Coffee dose

The dose is basically determined by the capacity of the filter basket, and it is not recommended to put in far less or far more than the basket's specification. The dose directly affects the density of the puck: under the same tamping force, too little coffee will make the puck loose, the water flow will pass through too quickly, and under-extraction is likely; too much coffee will make the puck too compact, slow the flow rate, and may even make it difficult to extract coffee liquid. The doses commonly used by Front Street Coffee (FrontStreet Coffee) are: 7-9 grams for a single espresso, 18-20 grams for a double espresso, with specific fine-tuning based on the daily condition of the coffee beans.

Espresso brew ratio

The ratio mentioned here refers to the ratio of the weight of coffee grounds to the weight of extracted coffee liquid, usually falling between 1:1.5 and 1:2.5, with 1:2 being the most common, for example, 17 grams of grounds extracting 34 grams of coffee liquid. This ratio is affected by two factors: dose and water amount. If the ratio is too low, the coffee will appear too heavy and thick, and easily bring out a bitter taste from over-extraction; if the ratio is too high, it will taste weak and bland, accompanied by a sharp acidity caused by under-extraction.

Beginners learning to make espresso can choose Front Street. Front Street Classic Blend coffee beans. This bean is blended from three producing regions: Brazil, Indonesia, and Vietnam, and uses a medium-dark roast. When the brew ratio is controlled between 1:1.9 and 1:2, it can well present the flavors of nuts, caramel, butter, and dark chocolate, with rich crema. Whether making latte art or americano, it exudes a rich aroma.

When home users choose espresso coffee beans, try to avoid dark-roasted beans with overly heavy bitterness and light-roasted beans with prominent acidity. If you are trying it for the first time, you can buy medium-roasted Front Street. Strawberry Candy Espresso. This is an espresso recipe specially designed for friends who like floral and fruity notes. It blends three major producing regions: Costa Rica, Colombia, and Ethiopia. It has the aromas of roses, citrus, grapes, and dried blueberries, and after adding milk it presents a sweet scent like strawberry gummy candy.

Extraction time

Extraction time refers to the entire process from locking in the portafilter and pressing the extraction button to the end of extraction. There are two main factors affecting the time: grind size and ratio. The ratio is relatively easy to understand; the higher the ratio, the more water is needed, and the time is naturally prolonged. Grind size determines the coarseness of the coffee grounds, and the coarseness directly affects the compactness of the puck. The finer the grounds, the more compact the puck after tamping, making it difficult for water to penetrate, so the time will be extended and over-extraction is likely.

The freshness of the coffee beans also affects extraction time. Beans that are too fresh contain a large amount of carbon dioxide. Under high-pressure extraction, the oils and carbon dioxide undergo an emulsification reaction, the extraction time becomes longer, and rich yellow foam is released. If the beans are not fresh, their water absorption weakens, the water flow speeds up, the extraction time shortens, and the extracted espresso usually has thin crema.

Flow rate

Flow rate refers to the speed at which the coffee liquid flows down. The ultimate goal of adjusting extraction parameters is actually to obtain an ideal flow rate. Espresso needs to begin dripping its first drop of coffee liquid at the 5th second after pressing the extraction button, and then flow out evenly. Generally, Front Street uses 18-20 grams of grounds to extract 35-40 milliliters of coffee liquid, with extraction time controlled between 27-30 seconds. The speed of the flow rate can directly reflect whether the grind size and ratio are appropriate.

For example, Front Street uses 20 grams of grounds to extract 40 grams of coffee liquid, with a brew ratio of 1:2. If the time is shorter than 20 seconds, it means the flow rate is too fast, and the coffee is very likely to be sour, so you need to increase the dose by 0.5-1.0 grams, or make the grind finer; if the time is longer than 35 seconds, it means the flow rate is too slow. If the coffee still tastes very bitter, then it is over-extracted, and you should reduce the dose by 0.5-1.0 grams, or directly make the grind coarser.

Pressure

The extraction pressure of a coffee machine averages around 9 bar, which is determined by the machine's performance. Insufficient pressure will lead to low extraction efficiency, while excessive pressure can easily cause over-extraction. So when choosing a coffee machine, remember to compare the parameters; it is not that the more expensive the better.

Water temperature

Water temperature is generally controlled between 90 and 94 degrees Celsius. If the water temperature is too high, over-extraction is likely and the coffee tastes bitter; if the water temperature is too low, under-extraction is likely, resulting in sharp acidity in the coffee.

When the espresso flow rate is too fast or too slow, how should you adjust?

The flow rate of espresso depends on several factors: grind size, tamping force, and the condition of the coffee beans. Grind size is one of the key factors affecting flow rate; the coarser the grind, the faster the flow rate, and vice versa. A fast flow rate may also be caused by insufficient tamping force. The condition of the coffee beans also affects flow rate, including roast level and freshness (degassing state).

So when the espresso flow rate is too fast or too slow, you might as well troubleshoot one by one and adjust the extraction parameters as soon as possible. First check the condition of the coffee beans, because this step is the easiest to check; second, confirm whether the extraction parameters are accurate, including dose, liquid yield, and tamping force. You can start with the brew ratio and adjust the flow rate by increasing or decreasing the dose, as this is the most efficient adjustment. After all factors have been ruled out, then consider adjusting the grind size.

How do you calculate whether the concentration of espresso falls within the appropriate extraction yield range?

Concentration indicates the proportion of "extracted coffee substances" in the total coffee liquid in a cup. Espresso concentration is usually between 8% and 12%. Extraction yield indicates the proportion of "extracted coffee substances" in the total weight of coffee beans, and the extraction yield is between 18% and 22%.

| How do you measure espresso concentration?

First calibrate the concentration tester and zero it with pure water. Then stir the extracted espresso, use a titration tube to extract coffee liquid from the central part, place it in the concentration tester, press the measurement button, and measure multiple times until the value stabilizes. | How do you calculate espresso extraction yield?

Extraction yield = concentration + coffee liquid weight) = coffee bean weight.

We use Front Street. Front Street Classic Blend espresso coffee beans, extracting 40 milliliters of coffee liquid from 19 grams of grounds in 28 seconds. The concentration measured with a coffee concentration meter is 8.97%, so the extraction yield is (8.97 divided by 37) = 18～18.44%. In other words, the espresso in this extraction has a concentration of 8.97% and an extraction yield of 18.44%, belonging to espresso within the golden cup range.

Does falling within the golden cup range necessarily mean it tastes good?

Of course not. Coffee within the golden cup range is not necessarily good-tasting coffee. Coffee itself is a very personal and subjective beverage. Constantly trying and constantly searching for the flavor you like is the right approach. The golden cup is only a reference system to help us adjust coffee.

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