This is a fundamental for anyone getting started making espresso. Espresso coffee is a highly concentrated beverage made under high pressure and temperature. Espresso can be extracted quickly because of these intense conditions. The drawback is that small changes can have large results. In this photo I am using an 18g VST basket. I will dose 20g of coffee into this basket, so I can have a little coarser grind. More mass of coffee will result in longer extractions, and less will result in faster extractions. We neither want extraction to take too long, or be finished too quickly. We want to balance the extraction to take around 25 – 30 seconds. When dialling in a grind, always dose the same mass of coffee. You may find you need a scale accurate to within 0.1g. In the photo I am using, the brewista smart scale.
The most important thing for good espresso is a good grind. What is meant by a good grind? I use the definition that the particles of coffee are the same size. The more similar in size the particles are, the better. In order to get this to happen, good grinders are very precisely machined. This adds to their cost. Espresso requires a fine particle size. The machining tolerances are very low because of this small size. We’re talking in the order of 0.01 of a millimetre. I know everyone gets excited when buying a new machine, but consider this. A great machine without a decent grind, will not be able to make good espresso. When buying new equipment budget at least half the cost of the machine on a grinder, perhaps more. Consider used grinders and buy a new burr set to help with cost. When setting up a new coffee, grind coarsely at first and keep grinding finer (dosing the same mass) until you are hitting the extraction times you want. If all the particles are the same size, and you’re doing the same mass, the only variable that should be changing is your grind size. If no coffee comes out the machine at all, increase the grind size. The grind should be light and fluffy with no clumping.
Tamping is the process of compressing the grind into the portafilter. People tend to agonise over this detail of coffee making, but it needn’t require so much attention. In the photo I am using a 58mm basket. The machine, during extraction is going to apply 9 bar of pressure to the coffee. That is equivalent to approximately 240kg! So the amount of force a person will be able to apply to the coffee is nowhere close to what a machine will be able to put out. So in terms of the amount of force required, the coffee needs a firm push to pack the grinds tight enough to prevent channelling. Channelling is when the puck of coffee fractures and the water takes the easy way out and runs through the crack. Espresso should be extracted evenly, meaning none of the coffee should be exposed to more of the water than any other part. The most important thing is that the coffee be tamped flat and evenly distributed.
In this photo we see that the coffee has been pushed into the porta filter nice and evenly. If the puck is not level the water will take the easiest path out. You can think of the water as being fundamentally very lazy. It will always seek the easy way out. If that happens to be a crack in the coffee, or slightly less distance to travel, it will do it. Everything we’ve done up to this point, picking good green, making sure the roast is even and grinding all the particles to the same size is about ensuring that all the particles are the same. Even extraction is no exception to this rule. Flat, evenly distributed coffee will produce great espresso.
The brew ratio is the ratio of water to coffee that ends up in the cup. I have a lot of people say “I like a strong coffee”, but that can mean many different things. A strong cup could be a darker roast, for example. If you enjoy a smokier more roasted profile, a darker roast will suit you better. You may just be saying you enjoy a more concentrated flavour. Espresso brewed at 1:2 ratio will mean that for 20g of coffee, you’ll end up with 40g of espresso. It should taste intense, thick and sweet. Now this is where you can feel free to try some different ratios. Try pouring a 1:1, 1:2 and 1:3 and trying them side by side. Another interesting experiment is to line up 3 cups and catch the first 8 seconds of pour in one, the next 8 seconds in the second cup and the remainder in the third. You will notice different flavour profiles throughout the extraction.
This is a great tool for beginners. Part of the problem with portafilters is you don’t get to see how the extraction is progressing clearly. It’s great if you’re looking to divide the coffee into 2 cups, but not so awesome if you’re just starting out. A “naked” or bottomless portafilter is exactly what it sounds like. The ideal extraction forms a golden cone that drops into the cup. Flecks and streaks of dark orange proceed from the outside of the filter and into the cup. As the shot progresses you will note a colour change from a dark orange to a straw colour. This is called “blonding” and is typically associated with bitterness in the cup. If there’s spraying or long blond streaks happening, then your espresso is channelling and not extracting evenly.
At the end of extraction this what you are left with. This was taught to me, affectionately called the “godshot”. It is a beautiful thick drink of concentrated coffee. It is rich and gold in colour with flecks of dark orange, or mottling, in its surface. The flavours are complex and interesting, with almost overpowering aroma. So drink up, you earned it!
For the cappuccino and latte lovers out there, this is the next step. Firing up the steam wand is its own challenge that I will detail in another post.
Espresso can be difficult to master. The process of perfecting a shot can be tedious and will on occasion frustrating. The equipment is also inordinately expensive. The main commercial advantage of the drink is that is can be made in about 30 seconds. Multiply that by enough sales and eventually the sales will be worth the outlay. For a home user, enjoying excellent coffee at home can be as simple as grabbing a Chemex or Aeropress, a decent grinder and a freshly roasted bag of beans. But for those who enjoy hissing sound of steam, the whir of pumps and watching all the variables line up, espresso is hard to beat.