The Epic of Gilgamesh, written around 2500 BC, is the oldest surviving epic tale and one of the earliest examples of literary fiction. In one of its sections, the hero, Gilgamesh, dives into the depths of the Persian Gulf to search for the "flower of immortality." This flower of immortality is the pearls found inside oysters.
Something similar happens with coffee. Each seed is like a pearl hidden within the berry; and within each seed lies a horizon of gustatory and physiological experiences when caffeine stimulates our nervous system. To extract the treasure hidden within each coffee bean, we must cultivate the berries, obtain and process the seeds, and then perform the extraction. And for proper extraction, we must grind the coffee. For this, we will need a coffee grinder.
Coffee grinders are an indispensable tool if we want to obtain the flower of immortality hidden within each coffee bean, even if that immortality is fleeting.
Why do we need a coffee grinder?
This question may seem obvious, but it's actually not. We could rephrase it this way: Why do we need a coffee grinder when we can just buy pre-ground coffee?
The answer is simple. We need a coffee grinder if we want to maintain the coffee's organoleptic qualities intact until extraction.
Coffee is an organic substance, and like all organic substances, it undergoes oxidation due to contact with oxygen (in this post, we explain the oxidation process in coffee in detail and how to slow it down). The greater the area of contact with oxygen, the greater the degree of oxidation. Therefore, by keeping it in the bean, we reduce the area of contact and delay oxidation.
The oxidation process of coffee
Coffee begins to oxidize from the moment the berries are removed from the coffee trees. But while the coffee is green, its natural chemical compounds have not been altered, and oxidation is minimal. Once the coffee has been roasted, the heat causes these natural chemicals to change and release gases. This gives us the beverage we love, but it also accelerates the process.
For this reason, it's important to store coffee beans until just before brewing. Since they're whole beans, coffee has less surface area in contact with oxygen than if it were ground. The smaller surface area also reduces oxidation, and therefore, there's less loss of flavor.
In addition to preserving the coffee beans, another important way to slow down coffee oxidation is proper bagging. As we've mentioned, when coffee is roasted, it releases CO2 as a result of a natural chemical reaction. These gases continue to emerge even after the roasting process is complete. Proper bagging involves a tightly sealed bag with a one-way valve. This way, the gases the coffee continues to release can expel the remaining oxygen from the bag through the valve and slow oxidation.
What is a manual coffee grinder?
Another question that may seem obvious, but isn't. A manual coffee grinder is a tool that allows us to reduce the size of coffee beans to a smaller size so that the water can extract all their properties.
So far, so good, but by this definition, any utensil that gives us the same results could be considered a grinder. And in a way, it is. Some of us have even ground coffee with two river stones for lack of one. But not all grinders are the same.
Manual or electric coffee grinder?
When we refer to a manual coffee grinder, we're talking about a tool designed to grind coffee manually. These two things are important: grinding and manual grinding. Because we might ask, what about an electric grinder? It could be an option, but only if you have the budget.
Everyday electric grinders won't grind coffee, but rather crush it. Furthermore, since they're motor-powered, they can heat the coffee. We should avoid both of these situations. When grinding, the resulting particles will vary greatly in size (we'll see later why this isn't good, but it has to do with the theory of extraction), and the heat can cause it to lose its qualities.
Manual grinders—especially those designed for grinding coffee—usually have conical burrs that help achieve a more even grind. And, since they're manual, you're the motor, so they don't heat up (although this sometimes creates a curious paradox: you need caffeine to grind, but you need to grind to get caffeine. We've solved this problem and offer a solution below).
Extraction theory
Now let's briefly focus on extraction theory. Extraction theory refers to how we extract solubles from coffee when they come into contact with water. It also refers to the quantity of solubles that this extraction should contain. Obviously, for this to happen, the coffee must be ground.
The coffee beverage is the result of extracting the soluble particles contained in each coffee bean with water. Coffee contains approximately 28% organic and inorganic matter, which, once roasted and ground, dissolves in water. The remaining 72% is cellulose from the seed fiber, which will not dissolve under normal conditions (and which we don't want to dissolve).
This 28% is made up of approximately 800-1,000 natural flavorings and aromas. These different compounds, which vary from coffee to coffee, are what gives each cup so much complexity and what differentiates one coffee from another.
Of this 28% solubles, for proper extraction, we must ensure that between 18% and 22% dissolve properly in the water. If it's more than this, we can end up with an over-extracted cup with bitter notes. If it's less than 18%, we can end up with an under-extracted cup that won't capture all the possible organoleptic notes.
The vanguard of specialty coffee is experimenting with extraction rates of up to 27%, but to achieve acceptable results with this percentage, we need to have a very clear idea of what we are doing and what we want to achieve.
Theory of extraction and distribution of grinding
It's obvious that to achieve these percentages, the coffee must be ground. If it were ground whole, this wouldn't be possible, since the water wouldn't penetrate deep enough into the coffee to achieve a proper extraction.
When grinding coffee, we aim for all the ground particles to be as uniform in size as possible. If this were not the case, if some ground particles were too large and others too small, some would be over-extracted and others under-extracted. This would result in a cup with bitter notes and a poor taste at the same time.
The way to check if our grind is correct is by measuring the coffee grounds. These will vary from one micron to 1,500 microns. But these are the extremes; most will be between 100 and 800 microns. Our goal when grinding is to ensure that all the particles fall within these limits and are as uniform as possible. This is the function of a good manual coffee grinder. You can also achieve this with an electric grinder, but your outlay will likely be much higher.
How does grind size affect coffee extraction?
This video (which is in English) clearly explains how different particle sizes affect extraction.
https://www.youtube.com/watch?v=kI3zOwFG9mg
The video shows an experiment to see how water penetrates coffee particles depending on their size.
First, the coffee is ground and the ground particles are separated by microns using several sieves:
Those from 0 to 250 microns
Those from 250 to 500 microns
Those larger than 500 microns
An immersion extraction is then performed, the coffee is allowed to rest, and measurements are taken in fractions of time to determine the percentage dissolved.
The result is that in particles ranging from 0 to 500 microns, complete extraction of all solubles can be achieved with adequate time. However, in particles larger than 500 microns, the water does not fully penetrate, so complete extraction is not achieved. The following image illustrates this easily. 
In the image, the dark brown color represents coffee particles, and the light brown color represents how far the water penetrates. As we can see, in the case of larger particles (>500 microns), the coffee doesn't penetrate to the center, and therefore, complete extraction isn't achieved.
How to use a coffee grinder?
Any coffee grinder worth its salt will have a way to adjust the grind size, whether it's a manual or electric grinder.
This is the most important thing when grinding coffee: adjust the grind to the extraction method you're going to use and ensure the grind is as even as possible.
And this is what separates a good coffee grinder from a bad one: adjustability and grinding consistency.
To achieve this, grinders designed for specialty coffee typically feature conical ceramic or steel burrs. They'll also have a mechanism for adjusting the grind size. All of the grinders we suggest below have at least these features, along with others that will also be very useful.
And, as a first reference for proper grinding according to the extraction method, you can follow this guide:
Espresso: very fine grind (almost like flour)
Mokka: fine grinding (like fine salt)
AeroPress: medium grind (slightly coarser than fine salt)
V60: medium grind (slightly coarser than fine salt)
Chemex: medium grind (slightly coarser than fine salt)
Plunger: coarse grinding (like coarse salt)
The best coffee grinders of 2024
We offer four coffee grinders that meet all the characteristics described above. Three of them are manual and one is electric. These grinders come in a variety of price ranges, so you can choose the one that best fits your budget, but all will give you a satisfactory result (we've tested them all!)
- Commander Manual Coffee Grinder: This grinder is the star of the manual range.
- Timemore C2 Manual Coffee Grinder: Excellent Value
- Hario Mini Mill Manual Coffee Grinder: For when you're on a budget, but without sacrificing the essentials
- Wilfa Svart Aroma Precision Electric Coffee Grinder: Best if you want to solve the 'I need caffeine to grind, but I need to grind to get caffeine' paradox.
Commander C40 Manual Coffee Grinder: The Star of Manual Grinders
This grinder has been designed to meet the highest expectations of all specialty coffee lovers.
It features an advanced design and material for its conical burr wheels, the result of this brand's research. This prevents the wheels from wearing down over time and maintains a consistent grind, use after use.
In addition, the rest of the components, including the body, shaft, and crank, are made of stainless steel.
The bearings are microball bearings and are made of the same material as the grinding wheels: martensitic stainless steel. This steel has a high nitrogen content, making it very durable.
The body has wooden details, both on the lid and the handle, from Black Forest oaks.
The container for the ground coffee is made of high-resistance glass.
It features an easy-to-adjust system for any type of extraction, from espresso to French press.
This grinder is elegant, useful, and very durable. It's a hefty but safe investment. If you don't lose it, you probably won't need another one.
Timemore C2 Coffee Grinder: Best Value
This grinder is a recent addition from a brand that is doing very well in the coffee world.
Its base is made of 5-blade stainless steel conical burrs. This ensures a consistent grind for longer.
The exterior is made of rugged aluminum, making it very durable and giving it a contemporary style.
Unlike the previous one, some interior elements, such as the shaft, are made of highly resistant plastic. However, these elements are protected from impacts and are not at risk of breaking.
It has a large crank to make it easier to activate the grinding wheels and reduce your effort.
It's a nice grinder that you can easily disassemble and take anywhere, ensuring a consistent grind. It's also easy to adjust.
It meets all the requirements we would expect from a specialty coffee grinder. It's a safe bet at a more affordable price and won't disappoint you either in terms of use or durability.
Hario Mini Mill Coffee Grinder: A Grinder for Everyone
This is the grinder we recommend to anyone new to specialty coffee. It's good, it's pretty, and it's affordable.
It's built around conical ceramic burrs that ensure a consistent grind for longer. And this is the most important thing in a grinder.
Everything else, except the crank and shaft, which are made of aluminum, is plastic. But that doesn't mean it's low-quality. It's well designed and built. It's attractive and easily disassembles for transport and cleaning. And, of course, the grind is adjustable.
So why is its price so much lower than the previous ones? Well, because apart from the grinding wheels, the cost of the rest of the materials has been reduced.
And this is noticeable. We've heard that both the part that holds the coffee beans and the part where they fall when ground have a tendency to break if they are subjected to a strong impact.
But for the price, we don't see this as a drawback; it's something to be expected. You just have to be more careful, because we've also had some that lasted for years.
Wilfa Svart electric coffee grinder
The answer to our paradox. The one that said, "I need caffeine to grind coffee, but I have to grind coffee to get caffeine."
If you're looking for a home coffee grinder, this is a great option. It features stainless steel conical burrs, and the grind size is easily adjustable. The motor is tuned to maximize efficiency and generates virtually no heat.
It also has a timer you can set and a large capacity (up to 250 grams). However, we don't recommend adding more coffee than you'll use each time, so that it doesn't oxidize and lose its sensory qualities.
It's made of black polycarbonate and is elegant. The only drawback is that you won't be able to take it anywhere, as it's relatively large compared to manual grinders.
As for price, it's a considerable but not excessive investment that's worth it if you want an electric grinder for home.
Choose your weapon
Now that you know the importance of proper grinding and the difference between an electric and a manual grinder—and when to choose one over the other—the question is quite simple...
Which one do you prefer?
