Chemist says creating the perfect cup of coffee is all about the water

Eric Pfeiffer
Coffee beans at a Nairobi Java House outlet in Nairobi. (Noor Khamis/Reuters)
Coffee beans at a Nairobi Java House outlet in Nairobi. (Noor Khamis/Reuters)

Chris Hendon has set out to help a British barista, Maxwell Colonna-Dashwood, win the title of world’s best barista, and he says the secret to success lies in using the perfect water.

Writing for the Royal Society of Chemistry, the University of Bath computational chemist says the challenge was a natural one for him considering that “brewing coffee might be the most practiced chemical extraction in the world.”

Now, there is no shortage of expert opinions on making the perfect cup of coffee, including a few that attempt to break down the process scientifically.

And Hendon doesn’t discount the more obvious factors in making an outstanding cup of coffee: bean origin, roast, the size of grindings and so forth. But when it comes to the variable of water, he writes:

“This variable is less obvious, but it is clear that the chemical composition of water plays a very important role.” Specifically, different types of water bring out different flavors from the coffee bean — sometimes good and sometimes bad. And being both a chemist and coffee lover, Hendon wanted to experiment with how different variations could be used to extract specific flavors from coffee.

“This was particularly intriguing for the signature drink which featured an espresso shot mixed with two grape extracts brewed in different water — one with high cation content, one with high base content — to extract different flavours from the grapes,” he writes.

For its part, the National Coffee Association says, "The water you use is very important to the quality of your coffee. Use filtered or bottled water if your tap water is not good or imparts a strong odor or taste, such as chlorine. If you are using tap water let it run a few seconds before filling your coffee pot. Be sure to use cold water. Do not use distilled or softened water."

Hendon’s explanation can sound a bit complicated if you don’t have a strong base of knowledge in chemistry. But put simply, he says, many of the assumptions about the ionic composition in water types are too broad, since the actual composition of water varies in different regions across the world and in places, like England, where it rains a lot.

He and his team used an atomic absorption spectrometer to experiment with different ionic levels, leading to Colonna-Dashwood winning a national coffee competition and and maybe even a “victory for science.”

So the next time you encounter a coffee snob who wants to tell you about the perfect type of coffee, you can respond with, “Sure, but what’s in your water?”

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