The coarseness of the grind in coffee directly affects the contact area between coffee and water as well as the extraction time, and it will directly impact the taste of the coffee. But at the same time, the coffee grind size is also the biggest headache for many people! In this article, Front Street will explain how to determine what the grind size should be for different coffee beans.
First, we need to make sure that the single-origin coffee beans or espresso blend coffee beans we buy are freshly roasted!
When buying single-origin coffee beans or espresso beans, we must buy coffee beans with a one-way exhaust valve on the packaging and with the coffee bean roasting date. The "one-way exhaust valve" (the button-shaped small hole at the top of the coffee bag) is designed to allow coffee beans to release naturally produced carbon dioxide while blocking other outside gases from entering the packaging. Every bag of coffee beans from Front Street Coffee (FrontStreet Coffee) is freshly roasted and uses packaging with a one-way exhaust valve.
After buying the coffee beans, we can look at the roasting date, because during the roasting process coffee beans produce a large amount of carbon dioxide inside the beans, so we need to give the beans 3-7 days to release carbon dioxide on their own, commonly known as resting the beans. If we directly brew coffee beans that have just been roasted, the large amount of carbon dioxide continuously released during the brewing process will make the entire extraction process very unstable. So how long should they rest? Front Street recommends resting light-to-medium roasted coffee beans for 3-4 days, and medium-dark roasted coffee beans for 4-5 days.
We just mentioned that the most direct manifestation of coffee bean freshness is the release of carbon dioxide from the coffee beans. In addition to carbon dioxide, the freshness of coffee beans also determines the aromatic substances responsible for coffee flavor and aroma. These small-molecule aromatic substances volatilize faster than the large-molecule substances that reflect coffee bitterness, so the less fresh the coffee beans are, the less carbon dioxide and aromatic substances they have, and therefore the fewer extractable substances there are. If the coffee beans are already stale, no amount of grinding will help~
How does coffee grind size affect coffee flavor?
1. At the same weight, a finer grind requires more cuts, increases the surface area, and increases the area where water can contact the coffee grounds.
2. The finer the grind, the finer the particles the coffee grounds are cut into the shorter the distance from the surface of the coffee particle to its center the shorter the time for water to reach the inner part of the coffee particle for extraction / the easier it is to extract coffee flavor substances.
Simply put, under otherwise identical parameters, the finer the particles, the higher the extraction yield; the finer the coffee is ground, the larger the contact area with water, and the higher the concentration of dissolved coffee; conversely, the coarser the coffee is ground, the smaller the contact surface area with water, and the lower the extracted concentration of coffee.
What are the signs that coffee is ground too fine?
From the appearance of the particles, the particle size is smaller, and because the particles are smaller, the spacing between particles is shorter, making it harder for water to pass through, so the drip time during brewing is longer. A finer grind results in smaller coffee particles, an increased surface area of the coffee particles, and more places where water can extract coffee substances, so the concentration and extraction yield increase; the coffee tastes rich, with obvious bitterness and astringency, while the other flavors are masked.
What are the signs that coffee is ground too coarse?
From the appearance of the particles, the particle size is larger, and because the particles are larger, the spacing between particles is greater, making it easier for water to pass through the coffee grounds, so during brewing, the filtration time is shorter. A coarser grind results in larger coffee particles, a reduced surface area of the coffee particles, and fewer places where water can extract coffee substances, so the concentration and extraction yield decrease accordingly; the coffee tastes weak and bland, with a light body and almost no flavor.
How do we determine the coffee grind size?
Front Street here recommends using coffee grind size calibration sieve No. 20 (mesh size 0.85mm). Then use 10g of coffee beans for a rough grind, pour them into the sieve and sift, and after completely sifting, see how much coffee powder finally falls into the tray below the sieve, and calibrate the grind size through the passing rate. Front Street Coffee (FrontStreet Coffee) grind size standards by sieve passing rate: cold brew > pour-over siphon 80% > moka pot American drip 75-80% > cupping 70-75% > French press 65-70%.
Of course, for coffee beans with different roast levels, the corresponding grind size used is also different. For example, when Front Street brews light-roasted coffee, the grind size is one with a passing rate of 80-85%% through a 0.85mm aperture sieve. For medium-roasted coffee, a grind with a passing rate of 70%-75% through a 0.85mm aperture sieve is used. For dark-roasted coffee, a grind with a passing rate of 65%-70% through a 0.85mm aperture sieve is used. However, everyone's requirements for coffee strength are different. These data are for reference only, and everyone can still adjust to different degrees according to their own taste preferences for strength.
What if you don't want to buy a coffee grind size calibration sieve?!
Front Street knows that this whole process is quite troublesome, so here Front Street has made a small summary of coffee grind sizes, so you can see roughly which grind sizes to use for your coffee brewing tools. Front Street divides coffee grind coarseness into 5 types: extra fine, fine, medium-fine, medium, and coarse.
(From left to right: coarse, fine, extra fine)
Extra fine: suitable for making espresso (moka pot, espresso machine)
When making espresso, you must tamp the coffee grounds firmly so that they create resistance to the high-pressure hot water, and only then can the essence of the coffee truly be extracted. The more even and delicate the grind, the tighter the tamped coffee grounds will be, and the more balanced the resistance to water. The espresso "squeezed" out this way will have rich crema.
Fine: suitable for making drip bag coffee
This grind size is Front Street's "soul mate" for making drip bag coffee. The main reason is that the entire drip bag is filter paper, so the flow rate is very high. Unlike pour-over, which has a narrowed opening, such as the commonly used three-hole dripper, which actually slows down the speed of water flowing out, drip bags need fine grounds to increase the extraction area and extract more substances.
Medium-fine: suitable for brewing light-to-medium roasted coffee (various pour-over coffee drippers)
When brewing light-to-medium roasted coffee beans, Front Street uses medium-fine grounds, about the size of fine granulated sugar, with a grind size between 75%-80% passing rate. Because light-to-medium roasted coffee beans generally have rich acidity, a medium-fine grind size can enhance the overall sweet-and-sour performance of the coffee~
Medium: suitable for brewing medium-dark roasted coffee (various pour-over coffee drippers)
When brewing medium-dark roasted coffee beans, Front Street uses medium grounds, about the size of coarse granulated sugar, with a grind size between 70%-75% passing rate. Medium grounds are less likely to produce extra fine powder, and are also less likely to cause over-extraction due to unstable water flow control at the beginning, which can lead to a large amount of water accumulating in the dripper and soaking the coffee grounds.
Coarse: suitable for making coffee with a French press
The French press extracts the most original flavor of coffee by steeping for 4 minutes. Compared with pour-over coffee, its coffee liquid is relatively cloudy. The reason is that when filtering with a metal mesh, the aperture is relatively large, so in terms of grind size we need to use coarse grounds. First, the coffee flavor is slowly extracted, and second, when the French press presses down the filter mesh, the coffee grounds will not "escape" through the gaps in the mesh and mix with the coffee, affecting the taste when drinking.
The above content is compiled by CoffeeHunters, a coffee news website.
