By Rebecca Wooden, Nicole Ferris & Darryl Peter
This week we’re bringing the heat and talking about all things temperature. Temperature, alongside recipe ratio and duration of brew, is one adaptable variable that plays a key role in extracting the perfect coffee. These multiple factors can make or break your coffee extraction. With a little bit of research and some taste testing along the way, you can find a sweet spot that allows your coffee to sing. In the interests of perfecting a recipe, a great tip is to change just one of these variables at a time, allowing you to pinpoint just what’s going on with your brew. Our suggestion is to nail that recipe ratio first and brew time first, and then begin to experiment with temperature.
For this article, we’re looking specifically about the art of espresso extraction (... maybe we will take a deep dive into the wormhole of hand brewing next time?) Here’s why the all-important temperature of your water plays such a crucial role in the final extraction.
Coffee contains a number of compounds, with only a few of these relating to flavour and smell. Some of these compounds are more sensitive to changes in temperature than others. In particular, phenolic compounds that are responsible for those more smoky or spiced notes we might find in some coffees can be highly affected by temperature. This means with even a very moderate change in temperature, we are not just altering the amount of coffee extracted, but also the overall profile of the brew at a compositional level. With this in mind, a one or two degree change to brew temperature can make a huge difference to the final cup.
In comparison to filter coffees, when making espresso, coffee is brewed in a far more concentrated period of time. This means any fluctuation of temperature can have a dramatic effect on the overall taste. Regularly checking your brewing temperature and making sure that your machine is well serviced can help improve not just the longevity of your machine, but the flavour in your espresso too.
In true Climpsons style, we decided to prove the science with a taste test. Adjusting the settings on our La Marzocco KB90 and putting our professional palettes to good use, here’s what our expert team thought of espresso’s running from a cool 88°C to a steaming 96°C. We ran this experiment using tried and trusted, The Baron, with an 18g dose of coffee at a 42g yield at a time of 30 seconds. The proof really is in the flavour.
88°C: This brew felt pretty flat and one dimensional and it was obvious in the profile that not enough coffee had been extracted during the process. One of our experts compared this to using lukewarm water to brew a cup of black tea. Unpleasant, to put it lightly.
91°C: Again, this coffee was still feeling very flat. Lacking in sweetness here and no real punch to the flavour. A slight improvement on the previous shot, but it still felt as if the coffee had more potential that we hadn’t quite brought out.
93°C: Perfection. An enjoyable balance of sweetness in flavour and fullness in body. This really is the sweet spot for us.
96°C: This espresso felt a little over extracted and the more bitter profiles of the coffee became far more prevalent.
So it seems like 93 really is a sweet spot and we can certainly recommend this as a brilliant starting point to set your machine. From here, you might explore making subtle changes of 1 degree each way, particularly if you’re changing your coffees often. We love this simple advice from the La Marzocco team.
“For the most part, setting your espresso machine at a brew temperature of 200 °F / 93 °C will give you good results. You can think of Brew Temperature as a way to adjust to different roasts and brew ratios. Normally, light roasts and larger brew ratios will require higher brew temperatures, whereas darker roasts and smaller brew ratios will require lower brew temperatures.”
It’s also worth noting the effect a busy service can have an effect on your set brewing temperature (do keep an eye out for control lights that will highlight when your machine is running off temperature!) When consistently pouring shots, portafilters can sustain a higher temperature, exacerbated by heat produced from a busy grinder, causing fluctuations in the brewing temperature. You could consider a second grinder with an alternate coffee to share the load, and heat. Using the same group head again and again during a busy service could also lead to a consistent drop in brewing temperature. We suggest alternating between groups with each shot.
Home baristas? Find out more at our next Home Espresso Workshop on Saturday 8th July from Climpsons HQ in London Fields.