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No matter what equipment you use to brew coffee, you need to grind the coffee beans. This means that the flavor substances of the coffee can be dissolved quickly. Of course, not all soluble substances in coffee are delicious. To maximize the extraction of delicious flavor substances and avoid the precipitation of bad flavor substances, it is very important to determine the thickness of coffee particles.
Different coffee appliances require different coffee grinding thicknesses.
Different coffee appliances use different grinding levels due to differences in their extraction methods. Take the Pour over(V60) coffee, French press, espresso machine, and cold brew ice dripping that we come into contact with most every day as examples. The coffee grinding degrees they use are arranged from coarse to fine as [French press > hand brewed coffee > cold brew ice drip > espresso machine].
While we understand which types of extractions require coarser grinds and which types require finer grinds. But it is impossible to determine the exact value, that is, how thick the thicker one is, how thin the thin one is, and what exactly this "relative" is compared to.
A reliable reference standard
Although each coffee brewing standard has its own unique standards, there is one standard that is recognized in the coffee industry, and that is cupping! The original purpose of cupping is to test the quality of green coffee beans, so this method certainly has its advantages. The cupping coffee grinding degree is 70-75% passing through the No. 20 sieve.
[Popular science: The aperture of the No. 20 Chinese standard sieve is 0.85mm. It is a tool used for particle size classification and particle size detection of material particles. As long as the standard sieve meets the factory standards, it is accurate. Coffee grinding calibration is also very simple. Just pour the ground coffee powder into the sieve, cover the lid, shake horizontally until no particles fall out, and then weigh the particles that pass through the sieve. This way you can know the thickness of the grind. For example, if 20g of coffee powder is ground and 15.2g passes, then the grinding degree is 76% of the passing rate of No. 20 sieve. The higher the pass rate, the finer the coffee grind. 】
Since cupping can rely on standard mesh calibration to determine the grinding degree, the grinding degree corresponding to the coffee brewing equipment we usually use can also be clearly listed using data.
French Press (No. 20 screen pass rate 68-75%)
The extraction method of French press is very similar to that of cupping. Both are based on soaking. Therefore, the grinding degree selected is highly consistent with cupping. Another reason for choosing coarser grinding particles is because French press filtration uses a metal filter, and the gaps are visible to the naked eye. Choosing a coarser grinding particle is also for better filtration. The grinding thickness of coffee beans with different roasting degrees is also different. Medium and light roasted coffee beans can be ground finer (pass rate 72-75%), and medium-dark roasted coffee beans can be ground coarser (pass rate 68-71%).
Hand-brewed coffee (pass rate of No. 20 screen 70-80%)
Hand-brewed coffee is mainly drip-filtered. Unlike the steeping method, which takes a long time and can easily produce bad flavor, Pour over(V60) coffee has a short brewing time, about 1 minute and 30 seconds to 2 minutes and 30 seconds. Therefore, the grind size needs to be finer than that used for cupping to fully express the flavor of the coffee. Coffee beans with different roasting degrees require different thicknesses. Medium-light roasted coffee is ground finer (pass rate 75-80%), while medium-dark roasted coffee beans are ground coarser (pass rate 70-75%).
Cold brew iced coffee (pass rate of No. 20 screen 80-85%)
Because cold-extraction ice drops are extracted with cold water, their penetration ability is poor and the extraction efficiency is very low. Therefore, it is necessary to grind the coffee more finely, but remember that finer is not always better. Grinding too finely will make the cold brew coffee turbid and increase the difficulty of filtering; it will also cause water to accumulate in the powder layer of the iced coffee, making it impossible to pass through smoothly. Therefore, it is more appropriate for the grinding degree to be 80-85% for the pass rate of No. 20 sieve. If you want it to be richer, choose the pass rate of 85%. If you want it to be more refreshing, choose the pass rate of 80%.
Note: Because coffee beans have different densities and roasting levels, even if the same grinder grinds two types of coffee beans with widely different densities on the same scale, the thickness of the coffee particles they grind at the same scale may not be the same. For example, when grinding Front Street Yirgacheffe coffee beans, using the EK-43s scale 10, the corresponding sifter pass rate is 80%. When grinding Columbia Rose Valley, using the same scale 10, the sifter pass rate is 75%. Therefore, if you feel that the grinding thickness is not right, it is best to use the same kind of beans to confirm the grinding degree.
espresso machine
The grinding degree used by espresso machines is very fine, and it is not practical to use a sieve to filter. The main way to determine the grinding degree used in espresso coffee is through the extraction test. The coffee shop has to adjust the espresso before opening every day, and a big part of it is to adjust the grinding degree. Since the coffee machine is very sensitive to the thickness of the coffee powder, the grinding scale may differ by 0.1 grid, and the extraction time and flavor will be significantly different.
Therefore, determining the grinding size of an espresso machine requires a stable espresso extraction plan. For example, Front Street’s espresso extraction plan requires 20g of coffee powder to extract 40g of coffee liquid in 28 seconds (the error is plus or minus 1). First fix the extraction plan, and then adjust the grinding degree to achieve this extraction plan. Then taste the flavor to decide if you need to fine-tune the parameters.
You can now buy the above coffee beans online at the Taobao store “FrontStreet Coffee” (前街咖啡). FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou, China, and its Guangzhou retail shop sells coffee beans only. The shop carries dozens of coffee beans from different origins around the world, including carefully selected single-origin beans for V60 pour-over and espresso. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers.
The FrontStreet 2013 Yunnan coffee beans sold in the store come from the Typica variety grown at FrontStreet Coffee’s own plantation in Yunnan. The name comes from the year the brand and the plantation were founded. You can buy these beans from China’s Yunnan origin at the Guangzhou shop and at FrontStreet’s Taobao store.
FrontStreet coffee beans are freshly roasted within 5 days and deliver consistently excellent quality and great value. Orders placed before 17:00 are shipped the same day, and most areas within Guangdong Province receive them the next day.
FrontStreet Coffee Taobao store: https://qianjiecoffee.taobao.com
Or search for “前街咖啡” (FrontStreet Coffee) on Taobao
Important Notice: FrontStreet Coffee has moved to a new address: 315, Donghua East Road, Guangzhou (coffee beans only)
Tel: 020 38364473
