There’s so much to consider when brewing exceptional coffee: grind size, brew time, pulsing and water dispersal, brew temperature… and elevation?
While some of us don’t have to worry too much about elevation, head into mountainous regions and you may find yourself needing to tweak your recipe. Why? It’s all to do with brew temperature.
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Colombian coffee, ready to drink. Credit: Behmor
Why Is Brew Temperature Key For Great Coffee?
Brew temperature has a direct impact on the flavour of your coffee. Let’s take a quick look at why.
When brewing coffee, your aim is to extract the flavours and aromas from the coffee grinds into the liquid coffee. Certain things speed up extraction, certain things slow it down. For example, a finer grind will speed it up. And so too will hotter water. The hotter the water, the quicker the extraction. The cooler the water, the slower the extraction.
As Joe Behm, creator of the award-winning, SCA-certified Behmor Brazen and Connected Brewers, says, “Everything we do with regards to coffee, temperature is paramount. I mean, obviously there are many factors, such as the freshness of the roast, roasted bean quality, so on and so forth, but water temperature plays a significant role.”
So, what’s the problem? Well, even though your aim is to extract those flavors and aromas, you don’t want to extract too many of them. Over extraction is just as much of a problem as under extraction.
You see, not all flavours and aromas extract at the same time. First, you get fruity acids; second, sweetness; then, bitterness; and finally, astringency. In other words, you don’t just want to extract compounds. You want to extract the right ratio of those different compounds from the coffee grounds – and that means having as much control as possible over all the factors that affect extraction levels and rates.
Including brew temperature.
Freshly brewed batch-brew coffee. Credit: Behmor
The Ideal Brew Temperature
The Specialty Coffee Association (SCA), for example, only endorses batch brewers that meet certain temperature requirements:
“Minimum technical requirement is for the water temperature at the point the water contacts the coffee grounds to reach 92°C within the first minute, maintain at least that temperature (92°C) for the remainder of the brew cycle, and never exceed 96°C.”
Of course, you can experiment with temperature. After all, we would never have cold brew coffee if we always stuck to 92–96°C/198–205°F. But generally speaking, you want your water to sit within this range. And if your coffee is coming out a little bitter, try dropping the temperature by a degree or two. A little too sour for your liking? Bring the temperature up.
However, that’s only when water temperature is working as you would expect. When you start adding higher elevation to the mix, everything changes…
Setting variables on the Behmor Brazen brewer, including elevation. Credit: Behmor
The Impact of Elevation & Boiling Point
Water boils at 100°C/212°F. It’s one of those facts that everyone knows. Except it’s only half the story. In reality, water boils at 100°C/212°F when at sea level.
However, as the elevation increases, pressure decreases – and pressure is key for boiling. This is because a liquid evaporates when the pressure (which, in this case, is caused by heat) inside the liquid is equal to that of the pressure in the atmosphere. As pressure decreases, so too does boiling point. In other words, the higher the elevation, the lower the boiling point.
The problem is that this has an impact on your coffee recipe. As Joe tells me, “It really affects it. When you affect the boiling point, you affect the full temperature range.”
A cup of black coffee ready to be enjoyed. Credit: Ben Kolde
How Does This Affect Your Brew?
Joe has done significant research into how elevation affects coffee recipes. After all, not only do the Behmor brewers offer 1°F (0.55°C) temperature control and accuracy, but they also have automatic temperature calibration for elevation above sea level.
He tells me that brewing coffee at 5,000’ (1,524 m.a.s.l.) requires significant adjustments. “You’ve lost 10°F [5.5°C] on boil point.”
This makes it much harder to get the idea extraction rate. He tells me that “you’re going to have a thin cup and a weak cup” if you use a standard batch brewer. Your only options, he says, are pour overs or brewers that are designed to calibrate the temperature to take into account elevation.
Of course, as Juan Mario Carvajal, Technical Judge in the World Barista Championships and Founder of the Specialty Coffee Association of Latin America, reminds me, it’s important to always look at the bigger picture.
The green light on the Behmor Connected Brewer means the coffee is ready. Credit: Behmor
When Elevation Gets Complicated
Elevation affects the ideal brewing temperature, but so too do many other factors.
Sometimes water hardness, for example, can compensate for higher elevations; at other times, it makes it more challenging. Juan Mario explains that soft water can lead to a faster extraction, which means that you can use a lower temperature.
“When you are in a city like Bogota with an altitude of 8,600’ or 2,640 m.a.s.l.,” he says, “and the water is very soft, at high elevation this compensates for the temperature loss. Therefore, your extraction has to be at a lower temperature as the boiling point is lower which will make for a slower extraction.”
On the other hand, in a high-elevation city with harder water, he tells me that “there would be a problem”.
Yet even this is more complex than it sounds.
As Tamas Christman, CEO and Founder of Dragonfly Coffee Roasters in Boulder, Colorado, USA, reminds us, not all hard water is the same.“The hardness only tells us a limited amount, we don’t know what ionic compounds are in the water and in what percentage… I think it would really depend on the water,” he stresses.
Cup of freshly brewed black coffee. Credit: Nathan Dumlao
Can You Compensate For Elevation?
If you’ve got a batch brewer that automatically calibrates for elevation, then you’re in luck – it will do it all for you.
But if you don’t have this type of brewer, what you can do?
Tamas stresses the importance of adjusting for this, not just so you get the best coffee but so that your machine lasts. “If you are, let’s say, at 5,000’ [1,524 m.a.s.l.] and you get to 197–198ºF [92ºC], you’re going to be boiling [the water]. And you will be working that machine and you will be potentially causing issues with the boiler and your electronics. So be careful. Adjust according to where the boiling point matches the actual boiling point of that altitude.”
If you’re using a manual brew method, fortunately, this all becomes a little bit easier. Andre Di Bonaventura is the CEO and Founder at Bona Coffee, also in Boulder, Colorado, USA. He tells me that he is at 1,665 m.a.s.l./5,463’. He likes to use an AeroPress, since “you can compensate low pressure with high pressure”.
What’s more, when using a pour over, he adjusts the grind size and brew ratio as much as possible. The higher the elevation, the finer the grind and the more coffee he tends to use, in order to speed up the extraction and allow for an overall cooler water temperature.
“In some villages, even Bogotá or Cuzco, which is more than 3,000 m.a.s.l. [9,843’], probably water would boil at a lower temperature so I would try a fine grind and maybe use a method with more pressure,” he says.
Freshly brewed coffee for two. Credit: Behmor
It’s easy to overlook the importance of elevation when brewing coffee. But it can have a significant effect – both on your coffee quality and on your machinery. In order to get that perfectly extracted cup of coffee, as well as ensure our machines lasts, you need to be aware if you’re brewing at high elevations.
As Joe Behm says, “Temperature is so important. And altitude just plays a role in temperature.”
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