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Why Coffee Grind Size is Important
Here is why it's important to use the right grind setting when brewing coffee
Published August 17, 2021
Vasileia Fanarioti
Coffee experts@The Coffee Lab
A key factor for the successful preparation of coffee is the degree of grinding. An incorrect grind setting can lead to a watery, bitter or sour flavour, which in turn has a significant influence on the taste of the coffee. But don’t worry, I am going to help you set the right grind for your coffee brewer!
Whether you are using a portafilter, pour over, French Press, V60 or fully automatic coffee machine, it is the preparation method that ultimately decides how coarse or fine the grind setting has to be. Today, I’ll give you a quick breakdown as to why that is, and a few tips to get your started!
At a glance:
- Brewing factors and extraction
- What is coffee extraction
- Why the brewing method is important
- Coarse or fine?
- What if I want my coffee to taste strong?
- Over-extraction vs. under-extraction
- Over-extraction
- Under-extraction
- Why does my coffee taste bitter?
- Why does my coffee look so thin and flat?
- Why is my coffee sour?
- Tips for grinding coffee beans
- The French Press example
- What about espresso?
- Other reasons why your coffee doesn't taste good
Brewing factors and extraction
Naturally, the flavour of the coffee does not only depend on the grind setting. In addition, the most important factors are:
- Dosage (amount of coffee used)
- Quality of the coffee beans
- Type of preparation
- Brewing temperature
- Brew time
What is coffee extraction?
Coffee as a drink is created through what is known as extraction. Extraction? Don't be put off by this technical term. During the brewing process, hot water dissolves the ingredients or flavours from the coffee: a maximum of 30% of the components can be extracted from a coffee bean.
But 30% is not the goal, because then the coffee will already taste bitter and too strong. Nerd-Fact: The extraction range recommended as ideal by the SCAE (Specialty Coffee Association of Europe) is between 18-22%.
This range is based on studies by American researchers, who determined these values through surveys and tests in the 1960s. In this spectrum, the optimal amount of ingredients is extracted and the coffee achieves a great balance of aromas and intensity.
The extraction strength can be technically checked with special refractometers. However, these tools are quite expensive and not necessary for home use. As a passionate coffee drinker, you should decide on the basis of taste whether you like the coffee or not. The grind is one of many factors that affects the extraction strength of coffee.
Why the brewing method is important
There are very many brewing methods out there to make a cup of coffee. The most well known ones are:
- Pour over
- French Press
- Espresso machine
- Espresso pot
- Clever Dripper
- Siphon
- Cezve
- AeroPress
- Moka Pot
- Fully automatic
Each of these options differs in addition to the accessories used, in the dosage, the degree (particle size) of grinding, the brewing temperature of the water and the brewing duration. With fully automatic coffee machines, technical criteria, such as the pump pressure in an espresso machine, are also important.
Setting your grinder right is only one variable that will influence the result in your cup. However, it’s a very important one, and even if you do everything else right while brewing, then your coffee might taste bad if you get it wrong.
Coarse or fine grind?
With a coarse grind, the water takes longer to extract the aromas and flavor carriers. When grinding coffee, remember: Espresso has very fine sand-like consistency, while filter coffee only needs medium to coarse grind setting.
If you are not grinding your coffee at home, you can ask the baristas at your favourite coffee shop to grind it up for you. Just let them know which brewing method you are using.
What if I want my coffee to taste strong?
It’s important here to understand that by saying strong, we are not talking about caffeine content but flavour. The finer you grind the coffee beans, the greater the resistance that the water has to overcome.
Conversely, there is a faster flow when the coffee is coarsely ground. Therefore, choose a very fine grind for a strong coffee. The long brewing time releases a particularly large number of aromas from the coffee.
Over-extraction vs. Under-extraction
What if the coffee you just brewed doesn’t taste good? It can be due to the poor quality of the coffee, the handling during preparation, water that is too hot or too cold, the brewing time or simply the wrong grind. All of this influences the degree of extraction of aromas and flavours, lead to over- or under-extracting the coffee.
Over-extraction
An over-extracted coffee or espresso is unpleasantly bitter and very intense, often almost burnt. The unwanted bitter substances and tannic acids completely cover the fine aromas. It's very dark. With an espresso, the edge of the crema is almost black.
Under-extraction
If insufficient aromas and ingredients are extracted during the extraction process, this is known as under-extraction. The coffee or espresso then tastes watery, thin and is a flat, underdeveloped mixture. Sometimes it might even taste very sour.
If you think the reason behind this might be the grind setting and you’re doing everything else right then follow this simple rule: if it tastes sour go finer, if it tastes bitter go coarser.
Why does my coffee taste bitter?
The beans were ground too finely and the brewing (extraction) time was too long. Too many bitter substances have dissolved. The effect increases when the coffee, especially delicate varieties, are brewed with boiling water, so make a habit of not letting the water reach boiling temperature.
Why does my coffee look so thin and flat?
If it is ground too coarsely and the brewing time is too short, not enough aromas and flavors can be extracted. If the water is not hot enough when brewing, the coffee will also taste watery and without body.
Why is my coffee sour?
Coffee is naturally acidic. If it tastes too sour, it might mean that the water you used was not hot enough. However, depending on the degree of grinding, the coffee can also be under-extracted, which means it was ground too coarsely and only the natural acids were extracted.
Another reason: stale coffee also has a sour taste. It goes without saying that the grind is not the sole cause of any of the bad flavours. There are usually many factors that work together.
Tips for grinding coffee beans
The following tips will help you choose the right grind for preparing filter coffee.
1. Grind the coffee fresh just before brewing.
2. Select a medium - coarse grind setting.
3. Do not add boiling water, 90-95 °C is ideal.
In addition to the factors already mentioned, the quality of the water, the correct ratio of coffee to water, the degree of roasting, the type of grinder and the bean fragility (cell structure of the wet or dry processed coffee beans) play a role.
The French Press example
- Grind the beans coarse and put them in the French Press carafe
- Pour hot water on top, approx. 90-95 °C (194 - 203°F)
- Let it steep for 3 ½ - 4 minutes
- Plunge down and pour the coffee into your cup
What about espresso?
Sour taste, no body and too thin - the classic characteristics of an espresso if the grind setting is not right. At least that is the cause in most cases. Basically, the settings on a fully automatic machine or an espresso machine are left to personal taste.
Many fully automatic coffee machines have a multi-stage mechanical regulator in the bean compartment for setting the degree of grinding, which ranges from very fine to coarse. In the delivery state, the basic setting is usually set to a medium grinding degree. With a little background knowledge and a little tweaking, choosing the right grind setting is easier.
Other reasons why your coffee doesn't taste good
In addition, there are other reasons why your coffee doesn’t taste great even if you are using the right grind setting:
- The coffee has a lot of acidity: choose low-acid varieties instead.
- You bought a very dark roast: try light to medium roast instead.
- The brewing temperature is too high: try somewhere between 90-95 °C.
- Dirty portafilter or clogged powder compartment: clean your equipment well!
- The coffee beans are stale: always try to brew fresh coffee.
Final Thoughts
As you can tell, brewing a delicious cup of coffee depends on many variables. Choosing the right grind size is one of them. But don’t forget that coffee flavour is also a matter of personal preference. For example, what’s delicious to me might be too weak or too intense for you.
The secret lies somewhere between practice, controlling the variables, and discovering your own personal taste in coffee. First, learn about all the different variables that might affect your brew and then practice so you can control them.
From the first sip you’ll know immediately if this is something for you or not. So go out there, experiment, and have fun while trying to figure out what best suits your own personal coffee taste!
About the author
Vasileia Fanarioti
My name is Vasileia and I’m here because i decided to combine my two favourite things: writing and coffee. I love travelling around the world and visiting coffee shops but my biggest goal is to visit a coffee farm, to see where it all starts! You can follow my coffee adventures via my blog: thewanderingbean.net
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