Coffee Grinding 101

Coffee Grinding 101

Coffee needs to be ground before it can be brewed. Discover why we grind coffee and learn about how tweaking the grind can be so important to your brew.

Grinding is an important step in the coffee journey, in fact, it’s kind of crucial. You can’t skip the grinding step, unless you want to try drinking a cup of hot water that’s lightly browned and with the odd few beans bobbing around the top of it! With that in mind, let’s take a closer look at the grind, how and why we do it. Hopefully, by the end of this article you’ll have developed an obsession shared by all baristas for the grind.

Why We Grind Coffee

To better understand how the grind can affect our brewing experience, we must understand why we grind in the first place. It’s pretty simple to answer but can be equally tricky to explain, it’s all down to extraction. When we brew coffee, we’re trying to draw out flavour from the beans and transfer it to the hot water - extraction. Trying to extract flavour from a wholebean isn’t impossible but it would take a really long time, and the result would most likely not be pleasant. Even cold brews that can take up to 16 hours require ground coffee. Why? Because we need the water to penetrate the bean to draw out all of its pleasant flavours.

Like most tasks, extracting flavour from a roasted coffee bean is made easier when we first break the bean down into tiny pieces. When we make it easier for the water to penetrate the beans, we make it easier to extract those pleasant flavours. This also explains why we adopt different grind sizes, depending on the brew-method and the roast profile of the beans that we intend to use.

Smaller Grinds Can Make A Big Difference

Understanding why we grind coffee beans down into small granules is relatively easy to get your head around. Knowing which sizes work best depending on the brew method and the coffee you are using is where professional baristas really get their kicks. It requires an understanding of the roasted coffee you are using, the flavour characteristics you want to achieve and the brew method you plan to use.

The brew-time, temperature and ratio of coffee:water will all determine the grind size you need. Below is a list of common grind-sizes:

  • Extra Fine - for Turkish style coffee, a quick brewing process designed to be very intense in flavour.
  • Fine - for espresso or moka pot, both intense in flavour although the espresso is a much quicker brew of 25-30secs.
  • Medium - for pour-over filters, varying degrees of intensity but generally always roasted lighter to showcase more delicate flavours and aromas of specialty coffees. Around 3-5 minutes brew-time.
  • Medium Coarse - for Chemex, as above.
  • Coarse - for French Press (cafetiere), usually best brewed using light filter roasts, but can also work with medium roasts too. Around 5 minutes brew-time.
  • Extra Coarse - for cold brew, very long brew-time (16+ hours) using cold water. Should be light and refreshing in flavour.

As you can see, for a method such as cold brew for which the process is very slow, the coarseness of the grind is also very high. Why? Because the cold water requires longer to extract the flavour from the beans. If we tried a cold brew method using a very fine grind, it would end up tasting over-extracted and unpleasant.

At the opposite end of the scale, you can see that espresso requires a fine grind because the brew process is very quick, with the added elements of both heat and pressure. You could say that espresso-brewing is the most volatile due to these added elements. That’s why specialty coffee baristas will continuously ‘dial-in’ their coffee throughout the day. Dialling-in is the term given that refers to adjusting the recipe to ensure that the espresso is extracting correctly - ie, showcasing the best flavours and characteristics of the coffee. This most commonly involves adjusting the grind, even by the finest margins, it will make a difference.

Let’s say your ideal espresso ‘recipe’ is 19g of ground coffee for a 40g shot of espresso and you’re looking for an extraction of 25-28seconds. If your extraction is too slow, you can determine that as it is probably over-extracted, which means the shot is likely end up tasting unpleasantly bitter. You can usually fix this by adjusting the grind to be slightly coarser which will speed up the extraction. If it brews too quickly, the coffee will likely be under-extracted and taste sour. This can be fixed by adjusting the grind to be a little finer, thus slowing down the brew and allowing more coffee to be extracted.

Of course there are all the other variables like your tamping technique, the espresso machine calibration, consistency of water temperature, days since the coffee was roasted, ambient conditions, and etc, but for the sake of today’s article, we won’t get into that level of detail!

The same principles can be applied to filter brewing methods also, with any recipe. For example, a Chemex for 2-3 people (about 30g of medium ground coffee for 500ml of hot water) should take around 5 minutes to brew, delivering a balanced but refreshing taste. If the brew tastes sour or like licking a battery, you can assume it has under-extracted, it probably would’ve flushed through the filter in well-under 5 minutes also. Next time you brew a Chemex, you can try using a finer grind to slow down the brew.

As you can see, and will hopefully soon learn from experience, even minor adjustments to the grind can greatly alter the flavour of your beverage. With that said, any adjustments you make to the grind should be gradual.

Does This Mean I Need A Grinder?

In short, yes it does. But don’t see it as a chore or an unnecessary expense. Owning your own grinder can take your brewing-standards on leaps and bounds, and will also open up a huge array of new specialty coffees that maybe otherwise wouldn’t have been available to you. When you own a coffee grinder you own your brewing experience all the more.

What Grinder Do I Need?

Always look for a burr grinder, and avoid anything that uses blades. We’ve determined that grind-size is important to the outcome of your brew, and grind-consistency is also crucial. Burr grinders feature (you’ve guessed it) two solid metal burrs that rotate to grind down the beans that are dropped in the gaps between them. When you adjust the grind, you are adjusting the gap between the burrs in which the coffee can pass through. This allows you to create anything from a gravel-like grind to a fine powder.

Unlike burrs, blades will just spin and hack at whatever passes through them. While they can certainly make light work of a roasted coffee bean, what you end up with is ‘chunks’ of coffee beans that come out in varying sizes. This means that in brewing, some bits will extract much quicker or slower than others, giving you a cup full of both under-extracted and over-extracted coffee. With no way of controlling the consistency of the grind, you stand little chance of controlling the consistency of your brew.

Admittedly, burr grinders can be expensive, but you’ll get a lot of value out of say a Baratza Encore or even a Hario Handmill if you want to heighten your coffee drinking at home.

Discover even more specialty coffee facts and single origins around our website today. You can read up on tips on our blog before purchasing a bag of freshly roasted coffee to try at home.

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