So, what is espresso?
How does it differ from other forms of coffee?
How did it originate, develop and become the world’s most widely brewed coffee style?
How is it made and what makes a good one? In this quick-fire tour, we cover it all.
What is espresso?
Espresso is a type of coffee that is made by passing hot water through finely ground coffee under considerable pressure. It’s a thick, concentrated, strong coffee, much as spirits are concentrated alcohol.
This very strength makes it perfect for combining with milk to form the many coffee drinks we know and love: from piccolos to cortados, lattes to cappuccinos and pumpkin spice creations.
Many of these helped fuel espresso’s first ‘bloom’ in the 1950s, often in coffee shops run by Italian immigrants, the rise of chain coffee in the 90s and 2000s and later the specialty coffee flat white explosion.
Why is espresso so popular?
Although nowadays, the espresso shot is the base for all manner of milk based drinks, its popularity was originally driven by speed and efficiency - its quick extraction time allowed it to be served to many people in a short period of time.
When a new product is a success, it’s usually because it solves an existing problem. In the case of espresso coffee, the problem was, ‘How can we prepare and serve coffee to the public quickly, on demand, in the commercial setting?’
Given the time it takes to brew filter coffee, before espresso, the only answers were to either reheat filter coffee or keep it warm on a hotplate – neither of which produced tasty coffee.
Shots of espresso can be prepared in twenty to thirty seconds, solving the problem neatly.
A brief history lesson
Now, let’s dip into the rich European, more specifically, Italian history of espresso.
Fast brewed coffee meant pressure, and that pressure relied on precision engineering of parts and (initially) steam power, both of which were becoming available as the 20th century beckoned – although it was a while initially before the combination of metal and steam pressure could be entirely safe.
In the 19th Century there were several machines created in France and Italy that used steam pressure to quickly brew filter strength coffee.
Around the turn of the century these became commercially available thanks to the work of pioneers like Angelo Moriondo, Luigi Bezzera and Desiderio Pavoni. Although these machines were fast, and made popular by Victoria Arduino’s clever marketing, they didn’t produce enough pressure to make anything we’d recognise as espresso today.
Although an early stroke of fortune was the addition of a steam release valve, ideal for steaming milk.
It took until after the second world war for what we now recognise as espresso to emerge, and the key figure in its birth was Giovanni Achille Gaggia, the father of modern espresso.
In 1947, Gaggia finally realised his idea of using spring pistons rather than steam to generate pressure.
The lever espresso machine was born, and with it, the pressure to finally produce what we recognise as espresso - a thick, viscous liquid with the trademark ‘crema’ on top.
Gaggia espresso machines revolutionised coffee and espresso spread around the world.
Some people still prefer lever machines to this day, but there was a remaining key innovation.
Ernesto Valente’s Faema E61 introduced electric pumps to replace spring pistons, and water temperature that was better regulated by continuous circulation from the boiler.
The E61 espresso machine remains in use and is capable of producing great espresso, although more recent machine innovations have given us useful features like separate boilers for brewing coffee and steaming milk (La Marzocco), temperature fine tuning using feedback from PIDs (proportional-integral-derivatives) and volumetric and gravimetric control of water, as well as pre-infusion timers.
Characteristics of espresso coffee
Crema is the term used to describe the foam that appears on the top of the shot of espresso. Its name came from Gaggia, who had the genius to refer to it using the Italian term for cream, thus making what might have seemed like scum immediately desirable to early drinkers.
Crema can be a sign of fresh espresso coffee - that it contains sufficient CO2. And while it’s part of the multisensory appeal of espresso, it’s best mixed with the coffee to drink, and we’d recommend stirring it with a spoon.
Blends vs Single Origin
Robusta coffee is known to produce greater, if less stable, crema and that less delicate, more caffeinated coffee species has historically been a key ingredient of Italian and European traditional espresso blends, adding body and bitterness and reducing cost, blended with Arabica which has more delicate, fruity flavours.
Specialty espresso coffee has generally steered clear of Robusta though, in favour of multi-origin Arabica blends that balance body, sweetness, acidity and bitterness.
And more recently, single origin espresso has become popular in the UK, as roasters and coffee drinkers alike become more interested in the origin and story of their coffee.
Coffee is often roasted slightly darker for espresso. Why is that? Because traditionally, roasters and coffee shops have favoured producing coffee with a lower acidity and heavier body, allowing it to work as a black shot, or blended with milk.
Also, as espresso is like coffee under a magnifying glass, small differences in extraction and flavour get amplified.
As with all brew methods, espresso aims for that perfect extraction, avoiding the sourness of under extraction and the bitterness of over extraction.
Darker roast espresso tends to be more forgiving when dialling in the extraction, with a wider margin for error.
Tastes are evolving though, and some people (including us) love a juicy, acidic single origin espresso as much as a balanced and full bodied blend.
Our guiding light is to aim for bringing out the coffee’s best characteristics regardless of brewing method.
More often than not, that will result in a coffee that we can recommend across filter and espresso, but if we think it’s best for one or the other, we’ll tell you so.
Until recently, espresso brewing has been less common at home due to the cost of equipment and the time and knowledge required to ‘dial in’.
However, with more cost-effective machines being developed, and more time spent at home triggered by the Covid pandemic, it’s becoming more accessible.
Many make the mistake of skimping on grinder cost, but it has a crucial role in providing a consistent grind for the even extraction of tasty coffee. So a quality grinder that grinds fine enough for espresso is a must, alongside the obvious espresso machine.
Home baristas also need a tamper which is pressed gently down on the coffee in the portafilter before brewing, to ensure even water flow and avoid ‘channelling’ of water.
Considering the number of variables that can be tweaked when brewing espresso, we recommend keeping most under control while you experiment with one to ‘dial in’ as some will affect others - most often this is grind size.
Other variables include your coffee dose (amount of ground coffee in), brew time, and yield (amount of liquid coffee produced).
On more advanced machines you’ll also be able to control water temperature and pre-infusion. You can read our step-by-step starter guide for brewing espresso here.
Dialling in and extraction
Dialling in means setting up the coffee machine to extract the best shot of espresso from your beans, and the exact set-up can vary from coffee to coffee.
Over extracted coffee can be bitter and under extracted weak and sour, so it's a question of getting the correct ratio of coffee to water (brew ratio), avoiding channelling, and hitting the appropriate brew time.
Measuring your brew ratio is easiest done by weighing the coffee in and out (e.g. a good starting point is 18g in, 36g out - a 1:2 brew ratio). Target brew times are generally between 25 and 30 seconds.
Tasting and Experiencing Espresso
There are no rules for tasting a shot of espresso but here’s what we recommend to get the most out of the experience.
First, stir your espresso with a spoon. Take a sip of water if you need it. Smell the coffee, then let it cool slightly so it’s easier to pick up the full spectrum of aromas.
Drink, and swirl the espresso in your mouth to examine the body. Espresso is around ten times as viscous as filter coffee, but would you describe it as juicy, syrupy, creamy or smooth?
Then try to notice the amount of bitterness (some, but not too much, is a good thing) sweetness and acidity.
Check the aftertaste, then on your second sip, see which flavour notes emerge.
Or alternatively, ignore all this and just enjoy it.
That enjoyment is the key, because espresso can be a wonderful sensory experience as treacle-like coffee coats the tongue and reveals beautiful flavours that reflect the skills and knowledge of farmer, picker, importer, roaster and brewer.
Take your time, discover your preferences, and experiment.