Choosing a good Coffee Grinder
Necessity of a Coffee Grinder
We all know that coffee comes in a bean form and need to be ground to brew it. There is one way to brew a whole beans cold brew that I'll share in future. But, for all other practical purposes, one needs to grind the coffee beans to brew them. Even in instant coffee, it's ground and brewed before being frozed and packaged.
The question remains on whether to grind it at home or to get it pre-ground? Pretty much all coffee sellers offer to grind coffee and ship, for no additional cost. As we discussed in the previous post, pre-ground coffee loses it's flavour much faster than freshly ground coffee due to oxidation. Thus, freshly ground coffee does provide a much superior taste over pre-ground, this has been especially noticable post 1 week after grinding. The drop off in the taste is steep post 1 week mark.
Thus, a grinder is a valuable investment in experiencing a tasteful cup of coffee. And not to forget, freshly grinding a coffee is a sensory experience that all coffee heads love.
Types of Grinders
There are broadly 3 categories of grinders that are available to grind coffee
Blade Grinders are quite similar to a mixer-grinder that we have at home. They offer convenience of grinding coffee at home with one touch. Using one over a mixer grinder has a slight advantage that they allow to adjust grind size. Though it is limited and not even enough. Blade grinder also heat up while grinding which leads to loss of flavour.
Easy to Use
Limited Control of Grind Size
Despite all it's drawbacks it is popular for price, convenience and simplicity. It can be a stepping stone for coffee lovers
Burr grinders use two set of burrs that are placed for evenly distributed grind size. The distance can be adjusted to change the desired grind size. Burr grinders grind more evenly than any other grinders. Though the evenness depends on the tolerance and burr design. More on this later in the article.
Control over Grind size
Initial learning curve
Burr grinder is a worthy investment for anybody who brews coffee regularly. It is an investment that pays itself off well over time.
Steel vs Ceramic Burrs
Steel burrs generate more heat and also require sharpening over a period of time but are the most popular in the home category due to cost of manufacturing and long lasting nature.
Ceramic burr grinders in low budget have not been a good experience as they lack good tolerance and thus lead to high unevenness in grind. I'll explain why this matters in the sections below.
A good burr grinder can have a significant advantage in taste retention as it heats up less.
Electric vs Hand Grinder
This section doesn't need much of an introduction. Electric grinders are powered by electric motors. Whereas hand grinder is manually operated by a hand crank.
Hand grinders tend to be much cheaper and thus you can get a much better bang for the buck at the cost of convenience. That said, manual grinders are portable and can be carried around anywhere. Operating a hand grinder is also an immersive experience in coffee brewing.
Electric grinders are quick, offer a better parallelized workflow and allows one to grind much bigger quantities of coffee. It is also more preferable for people who have wrist issues or injuries.
Espresso vs Filter(Manual Brewing)
With an exception of a handful of grinders, all grinders are optimized for either espresso or manual brewing. There's a very good reason as we'll see. Pick a grinder based on your usage. It's always better to use 2 grinders if you are deeply into espresso as well as manual brewing. Espresso based grinders will not do justice at manual brewing, espeically as you start going towards the coarser end. Conversely, manual brew optimized grinders will not offer enough adjustment at the espresso end of business.
Flat vs Conical Burrs
This is an advanced topic and both sides have people who will swear by it. If you don't have an opionion on it yet, you want a conical burr, that majoriy of the grinders come with. Flat burrs are known to help with a sweeter cup of coffee but are also known to be more finicky and require more maintenance.
Please ignore this section if it sounds overwhelming
Mortar and Pestle
The good old mortar and pestle is a very good option for grinding coffee. It has it's limitations but is indeed a viable option if your brewing method can do well with finely ground coffee.
No control of grind size
Mortar and Pestle can be an excellent way to grind coffee evenly and retain flavour as long as your brewing method can work with fine grind. No wonder South Indian Filter Coffee works brilliantly with a fine grind and provides an excellent cup of coffee.
What Makes a Grinder Good
What really makes a coffee grinder good? Firstly, for this part we'll focus on burr grinders only as they are the only serious contendors that offer the right set of parameters to work with - adjusting grind size, grinding evenly and applying low heat.
Before we start with it, an important part to know is that coffee grind size is measured in microns. This measure also sets a baseline and a common ground to communicate the desired grind size with others.
Range and Steps
The range defines the minimum and maximum particle size that a grinder can grind. Generally most grinders in the market can do 200 microns to 1200 microns.
Steps defines the ability to jump from one grind size to another. A espresso grinder can allow you to move in smaller steps of 2-10 microns whereas a filter/manual brew optimized one may make a bigger jumps of 15-50 microns.
Why don't all grinders do smaller steps?
This seems like an obvious question at this point. The answer lies in the burr design and variability. The burrs for espress grinder are shaped slightly differently than those for manual brews.
The espresso brewing burr design has narrower cuts to allow smaller steps but it has tradeoffs that the grind consistency at medium and coarse setting will be much more variable than desired. Such grinders perform very well at finer grind settings and allow much more room for adjustment. But it comes with performance tradeoffs at as we go towards medium.
On the other hand, manual brewing burr design has wider cuts that maintain consistency over a very wide range from very fine to very coarse and thus offer excellent taste throughout. Where it falls short is the steps are too fine to dial in for an espresso. Espresso uses high pressure for coffee extraction, using much lesser water, over a smaller time. Thus, smaller adjustment steps are crucial to get good espresso.
This section sets a tone for grind range and steps. As critical as they are, the grind distribution being in the desired range is critical for making both the above things deliver quality.
Grind Distribution Curve
Though we described grind sized calculated in microns in the above section, in reality you can never get 100% uniform grind size. It is more of a distribution from ultrafines to coarse irrespective of the grind size you set. What is important is how much of coffee is ground at what size. The higher the amount of grind size closer to desired range, the better it is. This is better expressed as an acceptable percentage in the acceptable range.
For example, we are aiming for 450 microns grind size.
In the picture below, you can see that a peak is formed between 400 too 500 microns, which is the acceptable range for a good grinder that is set to 450 microns. About 50% of the coffee grinds are within the desirable range. This is a good grinder.
An excellent grinder like Malkoehnig Peak would do something like below. Where an even greater percentage of particles are in the desired range
On the other hand, a badly designed grinder, or a one that needs cleanup/repair would look like below. Lots of ultrafines and boulders, much lower percentage of grinds are in the desirable range.
When the distribution of grind particles is better concentrated in the desirable range, the coffee is brewed evenly. Since uneven paricles tend to clog the coffee bed more than even paricles that will line up better.
A great example I had once read about was, stones, pebbles and sand at the beach. If there are only stones they will be big in size with sizable gaps expected all around. If it is only pebbles it'll have smaller gaps. In case of sand it'll uniformly line up with narrow gaps. But when there's a combination of all 3, pebbles and sand starts unevenly lining up between the stones.
Thus, better the concentration of distribution closer to desired range, the better evenness you get during your coffee brewing. This should explain why just the range and steps are not sufficient by themselves until the distribution curve is good.
Distribution curve can be measured by using a sifter like Kruve and weighing at each particle size, for those who are curious. But, for most people it is sufficient to read up from sufficiently trustworthy sources and buy notable brands.
Based on the above datapoints, determine what matters to you and what falls within your acceptable criteria.
Below are a few grinder options with ratings out of 10 for price, convenience and Versatility. 10 is best, 1 is worst.
Mortar and Pestle
Agaro Coffee Grinder
Filter(Red Clix attachment gets close to espresso)
Kinu M47 Simplicity
Turkish, Espresso, Filter