Introduction:Grind size is the soul switch of pour over coffee flavoring！ This article takes Ethiopia’s Natural Sidamo Candleberry as an example, using three different grind sizes — BG-5I, BG-5T, and BG-7D (with 20-mesh sieve passing rates in China of 75%, 58%, and 43% respectively) — under identical conditions of a 1:15 coffee-to-water ratio and 90°C water temperature. From bitterness and off-flavors to layers of fruity aroma, it takes you through the key technique of how “grind coarseness affects extraction efficiency,” complete with segmented pouring parameters and flavor notes. Ideal for coffee enthusiasts looking to improve the consistency of their pour overs.
Over 60% of a pour over coffee’s flavor profile depends on precise control of grind size. This Ethiopian Sidamo single-origin light roast bean, grown at altitudes of 1750–2000 meters and processed using the natural method, features bright notes of citrus, mango, and tropical fruits—but presents completely different extraction results depending on grind coarseness.
We selected three commonly used grind settings for comparison: BG-5I (20-mesh sieve passing rate of 75%, close to medium-fine grind), BG-5T (passing rate of 58%, standard medium-fine), and BG-7D (passing rate of 43%, slightly medium-coarse). With a fixed coffee dose of 15 grams, a 1:15 coffee-to-water ratio, and 90°C water temperature, we used a segmented extraction method throughout, adjusting only the grind size to observe flavor variations.
First, we tested the finer BG-5I (75% passing rate).Parameters: 35g water for a 30-second bloom, then pouring up to 132g for the first segment, followed by pouring to 226g just before the coffee bed becomes exposed.Total extraction time was 2 minutes and 7 seconds. The cup clearly delivered fermented aromas mixed with citrus notes, but the mango and nectarine fruitiness was overshadowed by heavy bitterness, with a prominent dry astringency in the aftertaste—resulting in an overall intense and gritty mouthfeel. This is a classic case of over-extraction, where the overly fine grind increased the contact surface area with hot water, causing excessive release of bitter compounds and woody fibers.
After adjusting to BG-5T (58% passing rate), the flavor balance improved significantly.The parameters were slightly adjusted to 32g water for a 30-second bloom, pouring to 125g for the first segment, then continuing to 227g.Extraction time was shortened to 1 minute and 56 seconds. The citrus and mango acidity and sweetness became clear and bright, with nectarine aroma accompanied by a creamy, full-bodied texture. The finish revealed subtle nutty notes, and the aftertaste had a long-lasting sweetness. This grind size, achieved through evenly distributed particles (calibrated with a sieve), ensured sufficient extraction efficiency to bring out the fruity flavors while avoiding the bitterness caused by fine particles—it's the pour over setting I use most often.
Finally, we tried the coarser BG-7D (43% passing rate).Parameters: 34g water for a 30-second bloom, pouring to 132g for the first segment, then continuing to 225g.Extraction time was 1 minute and 53 seconds. Although the tropical fruit and honey-like sweetness were still present, the overall body felt thin, lacking the rich layers expected from the natural process. The fermented aroma in the finish was weak—a sign of under-extraction due to the coarse grind allowing water to pass too quickly, leaving some flavor compounds inadequately dissolved.
From this test, we can summarize three key takeaways:First, the early stage extraction determines aroma intensity.The initial 30-second bloom and early pouring dissolve the acidic and aromatic compounds in the coffee, directly affecting the vividness of the flavors.Second, the mid-to-late stage water flow should be gentler.Slowing down the pouring speed in the later stages helps avoid bitterness caused by over-extracting woody fibers.Third, match water temperature to roast level.Light to medium roasts (like this Sidamo Candleberry) suit 90–92°C; higher temperatures can produce scorched off-notes. Medium-dark roasts are better at 88–85°C, while dark roasts should be kept below 85°C to prevent over-extraction and astringency.
Bonus practical tip: After grinding, it’s advisable to check the passing rate with a sieve (such as a 20-mesh sieve) and adjust the grinder settings to maintain consistency. During segmented pouring, make sure the water level doesn’t fully expose the coffee bed to avoid channeling and uneven extraction. Mastering these details allows you to use grind size as the “key” to unlocking the optimal flavor potential of your coffee beans.
The above content is compiled by CoffeeHunters, a coffee news website.
