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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 affect the taste of the coffee. But at the same time, coffee grind size is also the most headache-inducing thing 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 must 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 whose packaging has a one-way exhaust valve and a roasting date for the coffee beans. The "one-way exhaust valve" (the small button-like 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 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, a large amount of carbon dioxide will continue to be released during the brewing process, making the entire extraction process very unstable. So how long should they rest? Front Street suggests that light-to-medium roasted coffee beans should rest for 3-4 days, and medium-to-dark roasted coffee beans should rest for 4-5 days.
As just mentioned, 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's flavor and aroma. These small-molecule aromatic substances volatilize faster than the large-molecule substances that reflect coffee's 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 matter how you grind them, it will not help~
How does coffee grind size affect the flavor of coffee?
1. At the same weight, the finer the grind, the more times it needs to be cut, the greater the surface area, and the greater 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 ground particles to their center the shorter the time for water to reach the inner part of the coffee ground particles 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 happens when 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 filtration time during brewing is longer. A finer grind results in smaller coffee ground particles and a larger surface area of coffee particles, increasing the places where water can extract coffee substances, so concentration and extraction yield increase, and the coffee tastes rich, with obvious bitterness and astringency, while the other flavors are masked.
What happens when 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 ground particles and a reduced surface area of coffee particles, reducing the places where water can extract coffee substances, so concentration and extraction yield also decrease, and the coffee tastes weak and bland, with a light mouthfeel and almost no flavor.
How do we determine coffee grind size?
Front Street here recommends that everyone measure grind size using a No. 20 sieve (mesh size 0.85mm) forcalibration. Then use 10g of coffee beans, grind them roughly, pour them into the sieve and sift. After completely sifting, see how much coffee powder finally falls into the tray under the sieve, and calibrate the grind size through the pass rate. Front Street Coffee (FrontStreet Coffee) grind size standard sieve pass 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 of different roasting levels, the corresponding grind size used is also different. For example, for brewing light-roasted coffee, Front Street uses a grind size with a pass rate of 80-85%% through a 0.85mm aperture sieve. For medium-roasted coffee, a grind size with a pass rate of 70%-75% through a 0.85mm aperture sieve is used. And for dark-roasted coffee, a grind size with a pass 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.
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 put together a small summary of coffee grind sizes, so you can see roughly what grind sizes your own coffee brewing tools use. 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 can truly extract the essence of the coffee. The more uniform and delicate the grind, the tighter the coffee grounds after tamping, and the more balanced the resistance to water. Only then will the "pressed out" espresso have rich crema.
Fine: suitable for making drip bag coffee
This grind coarseness is Front Street's "soul mate" for making drip bag coffee. This is mainly because the entire drip bag is filter paper, so the water flow is very large. 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 even more to increase the extraction area and extract more substances.
Medium-fine: suitable for brewing light-to-medium roasted coffee (various pour-over coffee drippers), recommended: Front Street Fruit Ding Ding, Front Street Huakui, Front Street Geisha, Front Street Strawberry Candy
When brewing light-to-medium roasted coffee beans, Front Street uses a medium-fine grind, about the size of fine granulated sugar, with a grind size between 75%-80% pass rate. Because light-to-medium roasted coffee beans generally have rich acidity, a medium-fine grind can enhance the overall sweet-and-sour performance of the coffee~
Medium: suitable for brewing medium-to-dark roasted coffee (various pour-over coffee drippers), recommended: Front Street Jamaica Blue Mountain, Front Street Golden Mandheling, Front Street Huila
When brewing medium-to-dark roasted coffee beans, Front Street uses a medium grind, about the size of coarse granulated sugar, with a grind size between 70%-75% pass rate. Medium grind is not prone to producing extra-fine powder, and it is also not easy for a large amount of water to accumulate in the dripper and soak the coffee grounds because of unstable water flow control at the beginning, which would cause over-extraction of the coffee.
Coarse: suitable for making coffee with a French press
The French press extracts the most original taste of coffee by steeping for 4 minutes. Compared with pour-over coffee, its coffee liquid is relatively cloudy because the metal filter has a larger aperture during filtration, so in terms of grind size we need to use coarse grounds. First, the flavor of the coffee is slowly extracted, and second, when the French press presses down the filter, the coffee grounds will not "escape" through the gaps in the filter and mix into the coffee, affecting the mouthfeel when tasting.
The above content is compiled by CoffeeHunters, a coffee news website.
