How Does the Espresso Brewing Temperature Affect Extraction?
Making espresso is not just pressing a button and waiting for the magic to happen. YOU get to influence the magic and make or break your morning brew (and, consequently, your whole day). No pressure.
One of the factors that can affect “the magic” is the brewing temperature of coffee. But let’s start with the basics.
Related: If you’re on the lookout for an espresso machine that suits your needs, here are the ones we recommend.
What Makes a Good Espresso
An espresso is a strong, highly concentrated black coffee that is extracted by pressurising and forcing a very small amount of nearly boiling water through finely ground beans. There’s more to it on how they work, but that’s the basics of it.
In most countries, it’s the base to make other types of coffee by adding water or milk. In its country of origin, though, it’s the embodiment of coffee itself (1).
Most Italian coffee orders can be made by uttering a single word. A caffè is a strong shot of espresso (the term ‘espresso’ is rarely used in Italian coffee bar parlance).
Because it’s not tempered with extra water nor milk, it must be perfect in itself. The true recipe of espresso is a balanced combination of coffee grounds and water, optimal brew temperature and correct extraction time (between 20 and 30 seconds). A good espresso will also have crema, a thin top layer of brown foam that should last up to two minutes.
How many grams of coffee are there in an espresso?
Traditionally, a good single espresso is made with 7-9g of ground coffee, which should fill the single basket inside the portafilter of your machine, but not to the brim. For a double espresso, use 14-18g (2).
How much coffee do I need for an espresso (coffee to water ratio)?
The ratio is measured between the weight of the coffee that you put in the basket and the weight that it’ll reach once it’s in the cup, after the water has dripped through the grounds. Given that espressos are highly-concentrated shots of coffee, don’t expect to fill a Starbucks-sized cup once the water has filtered through.
The recommended ratios are 1:2 (e.g. 8g:16g) and 1:3 (e.g. 8g:24g). Anything less than 1:2 will give you a “ristretto” (shorter and stronger), whereas something between 1:3 and 1:4 is a “lungo” (‘long’) (3). Anything higher than that will result in something more similar to an Americano (and angry Italians). Measuring coffee is important for perfect espresso: here’s a detailed guide.
How to measure the espresso water temperature?
Now that you know the correct doses and ratios, let’s get to the other factor that impacts the taste of your espresso shot.
Water temperature influences extraction because it determines the yield percentage, which is the amount of elements that are extracted from the coffee.
The yield percentage is calculated by multiplying the weight of the brewed coffee by the TDS percentage (total dissolved solids) and dividing it by the grams of coffee grounds (e.g. 36g x 10% TDS / 18g = 20%).
Yeah, it sounds complicated, but don’t worry: nobody expects you to do the maths before brewing your first coffee of the day. Just remember that water temperature determines this yield percentage and, consequently, the final taste of coffee. Let’s see how.
The optimal temperature for espresso extraction is between 90 and 96°C (195/205°F). If you set a hotter temperature, it’ll result in higher extraction yields (and burnt coffee, if using boiling water), whereas colder brew temperatures mean that less coffee is extracted at a slower rate.
Taste wise, hotter temps result in increased body and sweetness (with a greater chance of astringency and bitterness), while cooler temps emphasize less bitterness, body and sweetness (resulting in a sour, bright shot).
Many low-end machines won’t let you adjust the brew temperature, but, if yours has this feature, you can certainly calibrate it. The process is slightly different depending on the brand and whether you have a single or dual boiler espresso machine, or a heat exchange machine, so make sure you follow their instruction leaflet.
Here’s an example:
Dialling in the shot
After you’ve familiarized yourself with the temperature settings of your espresso machine, you can start dialling in the shot, which is the process of tweaking the brewing parameters to obtain the very best espresso.
Taste your espresso to figure out whether it’s under-extracted (sour and thin), over-extracted (bitter and burnt) or perfectly extracted (nice one!). If it’s any of the first two, you have an excuse to drink a few more espresso shots.
Adjust the temperature slightly and try again. As for coffee grounds and doses, we recommend not straying away from the original recipe, but trying different combinations within those parameters until you find the flavour that works best for your taste buds. Then, you can even move on to doing the salami technique to evaluate the flavors of your espresso.
Now you know that espresso is not just ‘pressing a button and waiting for the magic to happen’: it’s the handcrafted product of the conscious combination of these factors. It’s no wonder those machines cost what they do! Although, given their skills and the powers of the substance they deal with, we are pretty sure that baristas can still be considered wizards.
Craving for an espresso but don’t have a machine? Here are some methods you can use to make a nice shot of espresso!
Espresso should be brewed at 90-96°C (195-205°F). Because the water temperature affects the extraction yields (the amount of elements that are extracted from the coffee), brewing espresso at a higher temperature would create a more bitter coffee, while cooler temperatures would result in a more sour taste. You also don’t want the water to reach its boiling point (100°C/205°F), as it would give you a very bitter and burnt coffee.
Yes, hotter water makes stronger coffee because it increases extraction yields, meaning that a higher percentage of elements is extracted from the coffee. However, brewing coffee at higher temperatures compromises the flavour of the final product, resulting in a bitter and, potentially, burnt taste. If you want a stronger coffee, you should add more grounds instead of increasing the water temperature.
Espresso drinks are much stronger than regular coffee because they don’t come with extra water or milk to dilute the taste and ratios of caffeine. An espresso is a shot of coffee created by forcing pressurized water to drip through ground beans for 20 to 30 seconds.
- Sainsbury, B. (2016, June). How to drink coffee like a true Italian. Lonely Planet. Retrieved July 1, 2019, from https://www.lonelyplanet.com/italy/travel-tips-and-articles/how-to-drink-coffee-like-a-true-italian/40625c8c-8a11-5710-a052-1479d276c4a9
- The Perfect Espresso Shot (n.d.). Retrieved July 9, 2019, from https://www.e-importz.com/perfect-espresso-shot.php
- Blake, B., & Callender, S. (2014, October 24). Brew Ratios Around the World. Retrieved July 9, 2019, from https://home.lamarzoccousa.com/brew-ratios-around-world/