Espresso is one of the great inventions of the last few hundred years. Concentrating coffee so it's easy to quickly consume, while still being very delicious? Yes, please! But what actually is espresso? And how can you make better espresso at home?
What Is Espresso?
To start, espresso is a brewing method. Just like French press, pour over, and automatic drip are different ways of making coffee, so is espresso. While different roasters have different ideas about what kind of coffee beans and roasts make for good espresso, there really isn’t anything that objectively makes certain beans “espresso beans” as opposed to “coffee beans.” Your results will vary, but you can make espresso with any beans, whether they’re single origins or blends, the lightest light or the darkest dark roast.
Now that we’ve established that espresso is a brewing method and not a particular kind of bean, let’s discuss what makes it different from other brew methods. First of all, espresso is a small drink. There’s no exact measurement for how small, but if your drink is larger than a few ounces on its own, it’s hard to call it espresso. You could run your espresso machine until it puts out a 12 oz cup of brown liquid, but you wouldn’t really call it espresso (this was briefly popular in a few specialty shops about half a decade ago; we called them “coffee shots”).
Another thing all espresso has in common: it’s quite concentrated compared to regular drip coffee. You can’t just pour 2 oz of drip coffee into a demitasse and call it espresso. A double espresso will usually use around the same amount of coffee beans as a 10 to 12 oz cup of coffee, just a lot less water.
Espresso is brewed pretty quickly , too. And, like its size, we don’t have an exact definition for how quickly. Espresso comes from the Italian Industrial Revolution after all, and the idea of a faster drink for a faster pace of life is very much part of its mythology. An espresso shot is not a drink that’s going to take more than a minute to make and usually it’s quite a bit faster than even that.
For espresso to be made that quickly, while still extracting all those tasty coffee solids, it is made with a fine grind. A finer grind means that more total surface area is exposed to water. That helps extraction go as fast as we need to get our highly concentrated, delicious shots.
Finally, and maybe most importantly, espresso requires pressure. That pressure — like the fine grind — allows for faster extraction and helps push water through that puck of very fine grounds, which put up a lot of resistance. The pressure is also what creates crema: the brown foam created by oils from the coffee and water emulsifying around bubbles of carbon dioxide escaping from the coffee. Most modern professional espresso machines use a pump to create that pressure, though physical levers and steam are still definitely options.
What Isn't Espresso?
There are a few brew methods that sometimes get called espresso, that don’t exactly fit our definition. And whether or not they qualify as “real espresso” only really matters in that any espresso brewing advice doesn't really apply to those brew methods.
The first of these is a moka pot, AKA a Bialetti or stovetop espresso maker. It definitely does use steam — making it not that dissimilar from a small version of an early 20th century espresso machine — but it doesn’t use quite enough pressure to create the same kind of thick, strong beverage as the espresso you get at your coffee shop.
An AeroPress is also sometimes called an espresso maker. In fact, it’s right on the box. An AeroPress does use some manual pressure, but even a very strong recipe, doesn’t quite make coffee as strong as an espresso machine. Also, it doesn’t use nearly as much pressure. In the end, we tend to prefer using the AeroPress to brew something closer in strength to filter coffee.
So, to summarize: espresso is not any particular kind of coffee bean, but rather a tiny cup of super-strong coffee made quickly from finely ground beans using very high pressure. And now that we have that definition down, we can start talking about how to make that tiny cup of coffee as delicious as possible.