Adjusting Espresso Grind Size - The Correct Espresso Bean Grind Setting

When brewing coffee, we all know that the grind size is crucial. A slight misstep in finding the right grind size or uneven grinding can easily lead to under-extraction or over-extraction. Compared to pour-over, cold brew, and other methods, espresso requires a much finer grind and more precise adjustments to achieve the perfect espresso flavor.

How Fine Is Espresso Grind Size?

For pour-over coffee grind size, FrontStreet Coffee uses a Chinese No. 20 standard sieve to calibrate by measuring how many coffee particles pass through fixed-size mesh holes. However, espresso is a pressurized, short-time extraction method, which means it amplifies all characteristics—both positive flavors and defects are magnified. Therefore, the requirements for grinding are much more stringent. The coffee grounds are finer than fine salt, making it impossible to observe the fineness and uniformity with the naked eye, and using sieves becomes even more impractical.

If the grind is slightly too fine, water passes through the coffee bed more slowly, easily causing over-extraction. If the grind is slightly too coarse, water passes through the coffee bed too easily, leading to under-extraction. Such deviation might be caused by a mere 0.1 difference in grind setting. Therefore, we usually observe the flow rate and taste of the espresso during brewing to determine the appropriate fineness range.

How to First Determine the Appropriate Grind Size Range?

When we get a bag of unfamiliar coffee beans and want to brew delicious coffee, the first thing we need to do is determine the grind size. If our grinding equipment hasn't been used yet and we don't know how to determine the appropriate setting range, we can first test with small amounts of coffee beans at different setting intervals. When the coffee grounds feel as fine as flour to the touch, you can feel the coffee powder with your hand—it should be soft without any roughness.

At this point, we can apply the common espresso formula for extraction. FrontStreet Coffee suggests using a liquid ratio of 1:2, meaning extracting 2 grams of coffee liquid from 1 gram of coffee grounds, within 20-30 seconds. For example, FrontStreet Coffee uses a 20-gram capacity portafilter, which holds 20 grams of coffee grounds to extract 40 grams of coffee liquid. If the time is less than 20 seconds, it means the flow rate is too fast; when the espresso flow exceeds 30 seconds, it indicates the flow rate is too slow.

Fast flow rate means water passes through the coffee grounds in too little time, and the coffee often tastes bland or sour. At this point, you need to adjust finer. Adjusting grind settings usually relies on accumulated daily experience. If the time difference from the target is less than 5 seconds, you can adjust by 0.2 increments each time. If the time difference is too large, you can be bolder, adjusting by 0.5-1 increments. Even if it changes from too long to too short, you can lock this grind setting range and gradually narrow it down. Similarly, if the flow rate is too slow, it means the coffee grounds are too fine, and water has difficulty passing through the coffee bed, making the coffee taste bitter. Therefore, you need to adjust coarser.

How to Find the Correct Grind Setting?

The formula mentioned by FrontStreet Coffee above is just to help us quickly find the suitable grind range and doesn't necessarily mean the espresso extracted this way will taste good. Ultimately, we still need to judge whether the extraction is qualified based on the characteristics and taste of the coffee beans.

If the espresso has a distinct burnt bitter taste but moderate concentration, it might be due to excessive time causing over-release of bitter substances. You can slightly adjust the grind coarser. If the crema on top of the coffee liquid is pale and thin, it might be due to excessive tail-end extraction. You can reduce the coffee liquid weight, meaning extract less, and suggest increasing the coffee-to-liquid ratio to between 1:1.5-1:1.7. When the espresso flavor is quite rich but the aftertaste is short, you can appropriately extract more coffee liquid, trying to adjust the ratio to 1:2.5.

Finally, extraction formulas are just references. If you're constrained by them, it becomes difficult to adjust for good flavors, and you can only keep adjusting the grind setting, wasting coffee beans. The 1:2 ratio is not necessarily the golden ratio that completely suits this coffee bean—sometimes 1:1.7 might taste better, and sometimes 1:2.5 might taste better. Time doesn't necessarily have to be limited to 25-30 seconds either; sometimes 36 seconds or 24 seconds is the state where this coffee bean tastes best. FrontStreet Coffee is for daily store production, so parameter adjustments are based on accumulated daily experience. If we have lower cup production at home and find it difficult to grasp, FrontStreet Coffee suggests recording and summarizing the relationship between extraction parameters and flavor performance, which will help us adjust faster and save unnecessary waste.

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Important Notice :

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