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How to Brew Good Espresso At Home - Part 2, the grinder.

Grinding your beans fresh is a must when making espresso. Once ground, coffee will quickly oxidize, stale, and cease to produce the desired flavor profile. Combine top quality beans with a good burr grinder and you’ll never have to drink a bad cup of coffee again!

In this post, lets go into detail about why selecting the right grinder is the first and possibly most important step towards consistently brewing great espresso.

What’s wrong with pre-ground coffee?

Good grinders are expensive. They are also an additional piece of equipment to care for. New espresso machine buyers may get tempted to skip the investment in a grinder and opt to buy pre-ground coffee. For espresso, which is all about consistent but tiny particulates, pre-ground is not an option.

Coffee begins to stale as soon as it’s ground. The surface area of the coffee increases upon grinding and reacts with air and moisture in the air. Even if you buy whole beans there is a freshness window; with ground coffee, this window is much smaller - minutes, if not seconds.

If that makes you think about the blade grinder you already own, Sorry! it just won’t do. Not only will the teeth of the blade grind down the coffee beans unnecessarily severely, but the resulting grounds will also not be of consistent in size and shape. A blade grinder will also heat the coffee up as it grinds, and thus ‘cook’ it, changing it’s flavour profile.

What you want is a brand new burr grinder

So how does a burr grinder work? by ‘crushing’ the coffee beans between two grooved surfaces as one surface remains stationary and the other one spins.

This offers a very uniform grind and allows you the ability to customize your grinds very precisely.

So now that we have established that burr grinders offer much better consistency than blade grinders, produce less heat and are able to produce more uniform grounds, lets talk about the two main types of burrs (or grinding discs, if you will), that burr grinders use. A burr grinder will be equipped with either a conical or a flat burr set. Whether or not one is better at grinding than the other is subject of much debate. It is however, certainly true that the same coffee will taste different depending on the type of burrs used to grind it; everything else being the same.

Conical burrs

Many entry-level grinders, almost all manual grinders and some very high end grinders use a conical burr set.

Conical Burrs

Conical burrs consist of two parts, a cone shaped burr is surrounded by a ring and the coffee is ground or ‘crushed’ in the space in between these two parts. The sharpness and overall geometry of the ridges on these burrs can make their host grinders either great for brewing espresso or specialize in grinding for manual brew methods.

Flat burrs

Flat burrs

Flat burrs

Most espresso focused grinders come with a flat burr set. Unlike conical burrs, they are two metallic discs of the same size, one on top of the other. The space between the upper and lower disc determines the fineness of your ground coffee. Like conical burrs, the sharpness and geometry of flat burrs can either favour espresso fineness or make them more suitable for grinding coffee meant to be brewed manually.

Depending on who you talk to, some people say conical burrs need to be dialed in much more than flat burrs (well, I say that, but I also ready someone else write the exact opposite of it!). Flat burrs might have a tendency of retaining more coffee, this is probably why some single dosing grinders use conical burrs; there are also several higher-end single dose grinders that use flat burrs however, and they are known to retain very little ground coffee if any at all.

The jury is still out on the advantages of conical vs flat burrs for espresso, if you can, try both, and see which one you like best, if you are buying and have to choose one, I’d go with a flat burr grinder, they are more ubiquitous with mid to higher-end espresso grinders and in my experience they are more forgiving than conical burr grinders which require dialing in your grind much more often.

Dialing in your grind size

Per conventional wisdom, a ‘correct’ espresso shot is when 18 grams of ground coffee goes into an espresso machine’s portafilter and 36 grams of liquid coffee out of it in 20 - 30 seconds. Modern espresso brewing has evolved beyond this way of thinking; especially with the advent of pressure profiling and flow control in espresso machines. You create a brew according to your taste and preferences, when happy with what you made, that is the perfect shot of espresso. The basic principle however, is still the same. A certain amount of grounds go in, water from the espresso machine flows through them at a certain pressure for a determined period and a certain amount of brewed coffee is outputted - all of these variables are to be dialed in, and grind uniformity and size are essential for all.

The perfect grinder for espresso will offer precise control grind size and thereby offer the most consistent and repeatable output.

There are several other factors that go into selecting the perfect espresso grinder for your home espresso set-up. The above was only an overview. Over several future posts, I hope to into more nuance about various aspects of fine tuning your espresso grind. To conclude, I will say this: