Coffee beans need to be freshly ground before you can experience its full aroma, which shows the importance of grinding coffee beans. When grinding, many people have a misunderstanding about which scale to choose. Normally, the larger the number, the thicker the powder, and the smaller the number, the finer the powder. However, the assembly, transportation, use and maintenance of each coffee machine are different. Even though they are grinders of the same brand and model, the same grinding scale produces two different sizes of powder.
Coffee grinding is a hurdle that everyone cannot overcome. According to Front Street’s answers to so many friends’ questions, basically more than half of the reasons for poor flushing are problems with the grinding degree.
Why does coffee need to be ground?
For those who don’t know much about coffee, their concept of coffee may be limited to instant coffee, but the coffee you can buy in cafes now is basically made from freshly roasted coffee beans, which contain dregs. Coffee needs to be ground into powder and then brewed because the coffee substances released in this way are much faster than brewing whole beans.
The finer the grind, the greater the surface area of the coffee particles and the faster the release of coffee substances.
How coarse should the grind be? How fine should it be ground?
As mentioned before, Pour over(V60) coffee is a filtered extraction method. If the ground is too fine, the coffee powder blocks the passage of water. On the one hand, fine grinding makes it easier to release substances. On the other hand, the water is slower and the steeping time will be longer. Then the coffee is prone to over-extraction, resulting in heavier flavors, stronger bitterness, stronger acidity, and astringency.
If the coffee is ground too coarsely, the gaps between the coffee powder will become larger. On the one hand, coarser ground coffee releases substances more slowly, and on the other hand, the water drops faster, so the coffee is prone to have a lighter taste, weaker bitterness, weaker acidity, less impurities, and clarity.
Therefore, a suitable grinding degree for hand brewing should take into account the powder diameter and the speed of water discharge. Generally, the extraction time for Pour over(V60) coffee for 1-2 people will be controlled at about 2 minutes. According to the SCA cupping grinding calibration standard (cupping grinding requires a No. 20 sieve pass rate of 70-75%), and the hand grinding requirement is finer than cupping grinding, so the hand grinding grinding degree is a No. 20 sieve passing rate of 75-80%. This grinding scale can be roughly understood as what major stores call fine hand grinding.
One disadvantage of the calibration of the No. 20 sieve is that it can only separate coffee particles larger than 0.85mm and smaller than 0.85mm. As for the distribution of various powder diameter intervals below 0.85mm, it cannot distinguish. Generally, we believe that the ideal hand grinding powder diameter is between 0.6-0.8mm. In other words, the larger the proportion of coffee powder in this range, the better. Therefore, if economic conditions support it, you can purchase several more screens with different apertures.
Take our two coffee beans as an example. Medium roasted Front Street Strawberry Sugar coffee beans need to be ground to a fine sugar level for hot hand brewing, which corresponds to a No. 20 sieve screening rate of 80%; dark roasted Front Street Gold Mandheling coffee beans need to be ground for hot hand brewing to coarse sugar, which corresponds to a No. 20 mesh screening rate of 70%.
Powder smaller than 0.3mm is called ultra-fine powder. Appropriate amounts of fine powder can enrich the flavor of coffee. Too much ultra-fine powder will seriously affect the flavor of coffee. As for how to define this value, Front Street believes that the standard is 7% as the limit (there is no absolute value).
Maybe we can still rely on experience to judge
Of course, in addition to the preparation of data to judge the fineness of coffee grinding, we can also judge whether the degree of grinding of coffee is appropriate based on the coffee brewing process. First of all, the brewing time can be a reference for the grinding thickness. According to the standard brewing parameters in the past, the normal extraction time of coffee for 1-2 people is about 1 minute and 50 seconds to 2 minutes and 10 seconds. If the grinding is too fine, the extraction time will be extended; if the grinding is too coarse, the extraction time will be shortened. This can be used to first judge whether the coffee grinding degree is suitable based on the extraction time.
You can also observe the water flow speed of the coffee powder layer during brewing. Under normal circumstances, the sedimentation speed of the coffee powder layer decreases at a constant speed. If you find that the drop speed is fast, it may be that the grinding is too coarse. If the settling speed is getting slower and slower, or even blocked, then the grinding may be too fine or there is too much fine powder, and the bottom of the powder layer will appear muddy.
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
