How does grind size change coffee extraction?
Grind size controls how fast water moves through the coffee bed and how much flavor is pulled out. In a pour-over test using Ethiopian Sidamo Zhumang, a light-roast natural bean, three settings were compared: fine, medium-fine, and coarse. Too fine a grind let bitterness suppress the tropical fruit notes, while the coarser setting under-extracted and left the cup thin.
The medium-fine setting released citrus, mango, nectarine, and creamy aromas with a full body and a sweet aftertaste, finishing its brew in 1 minute 56 seconds versus 2 minutes 7 seconds for the finer grind. All three used 15 grams of coffee at 90 degrees Celsius with a 1:15 ratio and staged pours, starting with a 30-second bloom before the main coffee stages.
Grind size plays a pivotal role in pour-over coffee, directly influencing flavor expression and extraction efficiency. This article uses Ethiopian Sidamo Zhumang (natural process, light roast) as a sample, adopts the brewing framework recommended by Front Street Coffee, and conducts a segmented extraction comparison across three grind settings—BG-5I (75% pass rate through China standard No. 20 sieve), BG-5T (58% pass rate), and BG-7D (43% pass rate). The results show that too fine a grind lets bitterness suppress the tropical fruit notes; the medium-fine BG-5T more fully releases citrus, mango, nectarine, and creamy aromas, with a full body and pronounced sweet aftertaste; while the coarser BG-7D under-extracts, yielding a thin flavor. The article ends with some tips on pour-over extraction stages and water temperature control for coffee enthusiasts' reference.
Sidamo Zhumang
Region: Sidamo, Ethiopia
Altitude: 1750-2000 meters
Processing method: Natural process
Variety: Local heirloom varieties
Roast level: Light roast
Flavor: Citrus, mango, nectarine, tropical fruits
Grind size BG-5I ( ( 75% pass rate through China standard No. 20 sieve)
Parameters: 15g coffee; water temperature 90°C; coffee-to-water ratio 1:15; brewing method: segmented extraction. Bloom with 35g water for 30 seconds, pour to 132g for the first stage, then continue pouring when the water level is about to expose the coffee bed until reaching 226g to finish, and remove the dripper when the water level is about to expose the coffee bed (timing starts from the beginning of the bloom). Extraction time: 2’07”.
Flavor: Fermented aroma, citrus, mango, nectarine, overall rather bitter, intense, muddled, with a pronounced bitter aftertaste in the finish.
Grind size BG-5T( ( 58% pass rate through China standard No. 20 sieve)
Parameters: 15g coffee; water temperature 90°C; coffee-to-water ratio 1:15; brewing method: segmented extraction. Bloom with 32g water for 30 seconds, pour to 125g for the first stage, then continue pouring when the water level is about to expose the coffee bed until reaching 227g to finish, and remove the dripper when the water level is about to expose the coffee bed (timing starts from the beginning of the bloom). Extraction time: 1’56”.
Flavor: Citrus, mango, nectarine, cream, with a creamy aroma in the finish, a hint of light nuts, overall quite full-bodied, with a pronounced sweet aftertaste.
Grind size BG-7D( ( 43% pass rate through China standard No. 20 sieve)
Parameters: 15g coffee; water temperature 90°C; coffee-to-water ratio 1:15; brewing method: segmented extraction. Bloom with 34g water for 30 seconds, pour to 132g for the first stage, then continue pouring when the water level is about to expose the coffee bed until reaching 225g to finish, and remove the dripper when the water level is about to expose the coffee bed (timing starts from the beginning of the bloom). Extraction time: 1’53”.
Flavor: Tropical fruits, honey, cream, with a light fermented aroma in the finish, overall a relatively thin body, lacking the full-bodied richness of a natural process.
Looking at the results of the three brewing trials above, grind size BG-5I (75% pass rate through China standard No. 20 sieve) is a setting one step finer than medium-fine; the extracted coffee is on the bitter side, masking the tropical fruit flavors that Sidamo Zhumang should have. Grind size BG-5T (58% pass rate through China standard No. 20 sieve) brings out the flavors of this bean more fully, and is also the grind setting the author uses daily, mainly because this grind has good uniformity, which reduces the problem of uneven extraction and keeps the coffee flavor's dissolution rate in a relatively saturated state. Of course, this grind setting is also a pour-over reference value obtained by Front Street Coffee through repeated sieve calibration and continuous brewing refinement. Grind size BG-7D (43% pass rate through China standard No. 20 sieve) is slightly coarser than medium-fine; the extraction result clearly tends toward under-extraction, with a thin overall body and a lacking finish.
Finally, let's share some pour-over tips~
① Regarding coffee extraction, in general the aroma and flavor are intense and the concentration is high during the early stage of extraction; the further along it goes, the more the flavor and aroma fade. In other words, the early stage of extraction dissolves the coffee components to the greatest extent, and thus plays a decisive role in the coffee's flavor and aroma. What dissolves out in the later stage of extraction is the woody material that forms the structure of the coffee bean; this part contains more of the components that determine body and bitterness, which is also why we sometimes increase the water flow evenly and gently during the later stage to extract.
② Regarding water temperature, for extracting light-to-medium roasted beans, 90–92°C is more suitable. If the temperature is higher than this, some of the components contained in the coffee will change due to the higher water temperature, typically manifesting as heavier bitterness with a slight burnt taste; while for medium-dark beans the temperature should be 88–85°C. Because deep-roasted beans suffer more severe cell wall damage during roasting, the bean texture is relatively loose and absorbs water well, and the coffee bed expands easily when hit by water. If extracted above this temperature, the coffee will be relatively intense and over-extracted, producing astringency.
The above content is compiled by CoffeeHunters, a coffee news website.
