Water: Effect of Temperature on Coffee

Water: Effect of Temperature on Coffee

As the title suggests, this post will be the first in a short series on water and how it effects our favorite brewed beverage. Given the average cup of coffee is roughly 95% water, a few short blog posts are the least we can do. The real work comes from you, the home barista, the discerning consumer of coffee, as you experiment with endless array of water preparation options in the never-ending search to dial-in your preferred method(s). Before we get too far along, a quick disclaimer: I don’t portend to have the “answer” here and frankly, I’m not sure there is a “right” way. Rather, my goal is to get the average coffee consumer thinking critically about the role of water in their coffee and the effects it might be having on the final product. Have you ever bought a cup of coffee at your local coffee shop, fell in love, decided to snag a bag of the same roast, brewed it at home, and been sorely disappointed? Before you jump to conclusions about the beans/roaster, take a moment to consider other factors that might be effecting the flavor. Coffee shops spend thousands on high quality water filtration systems – how do you think your tap water stacks up?

Water – as a topic in the specialty coffee industry – is quite broad, so we’re going to try to work through it as methodically as possible. This post will focus on water temperature, as I find it to be the most easily digestible and readily manipulated by the average home barista. As we’ve discussed in previous posts, water is used as a solvent to extract flavors/acids from coffee grounds. These extracted flavors are what give our cup of joe unique characteristics that vary from varietal to varietal (plant-to-plant).

Some of the more unique flavors in coffee are only extracted at higher temperatures, which is why coffee shops have traditionally prepared their coffee using near-boiling water. Hot water allows for a more full extraction of the solubles (grounds), a fact we can confirm with our own senses. When compared with cold-brewed coffee, hot coffee is noticeably more aromatic and flavorful. In fact, drinkers of cold brew oftentimes do so specifically because cold brew lacks the polarizing acidity and bitterness of hot coffee. This is because using cold water as a solvent to extract from the solubles is not nearly as efficient as hot water, and fails to extract the same flavor profile (thus the lengthy brew time for your average cold brew).

On this flipside, however, brewing at higher temperatures is a much more volatile process fraught with a much wider margin for error. Hot water is so ideal as a solvent for extraction that it can very easily result in the extraction of undesirable flavors. Industry professionals call this “burning” the coffee. Acids are also known to degrade at very high temperatures, transforming acids that once provided unique flavor attributes into those that add overwhelming bitterness.

So what is the ideal brewing temperature?

At this point, you’re almost certainly asking yourself the above. And like I said in the beginning, I don’t have a hard-and-fast answer for you. In the land of consumer beverages, you’re only ruled by your own preferences. BUT, in starting the journey to figure out your ideal water temperature for your tastes using your coffee on your equipment in your home, my recommendation is to start in the 196F – 205F range, trying each step in between as you dial down the taste differences to find your perfect set-up. Personally, I’ve had a lot of luck at the upper-end of that spectrum. After quite a bit of temperature exploration, I’ve found that 205F gives me the best extraction – too low and I find the body under-developed. Too high and the coffee is riddled with undesirable flavors.

Another key piece to keep in mind is that you may be limited by your equipment. A standard coffee maker may not be capable of raising water to that temperature, or it may routinely over-heat the water. In either case, it may be time to look for something that is either designed with the 196F – 205F specialty coffee standard in mind (like this from Moccamaster), or allows to greater adjustability (like this from Behmor, a leader in the home coffee roasting game). If you’ve got a pour-over setup at home – what kind of kettle are you using? Stovetop? Electric? What about your thermometer? Are you able to keep your water at a consistent temperature throughout the brewing process? Remember, hitting the right mark for water temperature doesn’t cease to matter after the first pour – you need to maintain temperature. This may not be possible with a stovetop/thermometer set up. I would recommend a variable temperature electric kettle. Something like this from Bonavita or this from Fellow works perfectly for home baristas and coffee shops alike.

Okay, that’s about it for this post. We’ll be back at it again before too long, talking about Water Composition. In the meantime, please feel free to reach out in the comments or at whinkscoffee@gmail.com if you have any questions!

Cheers,

Michael

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