How Fine Should Espresso Coffee Grind Be? How to Adjust Grind for Espresso?

Regardless of the extraction method used, finding the right grind size is a crucial step. The coarseness of the grind directly affects extraction stability and flavor expression. Espresso extraction involves high temperature and pressure, demanding even finer precision in coffee grinding.

What is Espresso Coffee?

Before espresso emerged, coffee was brewed through immersion methods, requiring slow extraction that meant waiting several minutes for a single cup. Espresso was invented in the early 19th century when Italians conceived of using steam pressure to force high-temperature, high-pressure water through a coffee puck, accelerating the traditional drip extraction rate to produce a rich cup quickly. Through continuous improvements and updates, this evolved into the semi-automatic and fully automatic espresso machines we commonly see today.

When using an espresso machine for extraction, soluble flavor compounds must be released into hot water within mere tens of seconds. This requires more thorough contact between coffee and water, necessitating an extremely fine and uniform grind. Because espresso extraction is pressurized and short-duration, it also means that all characteristics are amplified—positive flavors are enhanced, but so are defects. This makes the requirements for grinding even more demanding.

How Fine Should Espresso Grind Be?

If a coffee shop's menu includes both espresso and pour-over coffee, they typically equip at least two different grinders. The grinder used for espresso produces coffee powder as fine as powdered sugar, with particle sizes between approximately 150-300 microns. The coarseness and uniformity cannot be visually discerned, but we can determine the correct grind size by observing the coffee's extraction state with water.

If the grind is slightly too fine, water passes through the coffee bed more slowly, leading to over-extraction. If the grind is slightly too coarse, water passes through too easily, causing under-extraction. Such deviation might result from merely a 0.1 difference in grind setting. Therefore, we typically observe the flow rate and taste the espresso during brewing to determine if it's within the appropriate range, then make adjustments accordingly.

How to Adjust Espresso Grind?

When we encounter unfamiliar coffee beans and want to brew a delicious cup, the first step is determining the appropriate grind size. If we haven't used our grinding equipment before and don't know how to identify the suitable setting range, we can test with small amounts of coffee beans at different setting intervals. When the coffee powder feels as fine as flour to the touch, you can feel it with your hand—soft and without roughness.

At this point, we can apply the standard espresso extraction formula. FrontStreet Coffee suggests using a brew ratio of 1:2, meaning extracting approximately 2 grams of coffee liquid from 1 gram of coffee grounds, with extraction time between 20-30 seconds. For example, FrontStreet Coffee uses a 20-gram capacity portafilter basket, filling it with 20 grams of coffee grounds to extract 40 grams of coffee liquid. If the time is less than 20 seconds, it indicates the flow rate is too fast; when extraction exceeds 30 seconds, it shows the flow rate is too slow. Fast flow rate means water spends insufficient time passing through the coffee grounds, often resulting in weak or overly acidic flavors, requiring a finer grind adjustment. Similarly, too-slow flow indicates the coffee is ground too fine, making it difficult for water to pass through the coffee bed, easily producing bitter flavors, thus requiring a coarser adjustment.

Adjusting grind settings typically relies on accumulated daily experience. If the time differs from the target by less than 5 seconds, adjustments can be made in 0.2 increments. If the time difference is significant, bolder adjustments of 0.5-1 increments can be made. Even if this changes the extraction from too long to too short, you can lock in this grind setting range and gradually fine-tune to the target value.

The formula mentioned above by FrontStreet Coffee is only meant to help us quickly find a suitable grinding range and doesn't necessarily represent a delicious espresso extraction. Ultimately, we still need to evaluate whether the extraction is qualified based on the coffee beans' characteristics and flavors.

For example, when espresso shows明显的焦苦味 but has moderate concentration, it might be due to excessive extraction time releasing too many bitter compounds. The grind can be adjusted slightly coarser. If the crema color on the coffee liquid surface appears light and thin, it might indicate excessive tail-end extraction. You can reduce the coffee liquid weight—that is, extract less—recommending an increase in the brew ratio to 1:1.5-1:1.7. When the espresso flavor is rich but the aftertaste is short, you can appropriately extract more coffee liquid, trying to adjust the ratio to 1:2.5.

Important Notice :

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473