Coffee’s Secret Soul
[ Coffee scientist Christopher Hendon recently made national news for his claim that we may have been brewing espresso “all wrong.” We’re no stranger to his ideas. In the Fall of 2018, we profiled Hendon in The Bean Magazine and have reprinted it here. Enjoy! ]
Christopher Hendon, Coffee Scientist, On Why Water Matters More Than You Think
Coffee has never been more valued than it is now, and its quality never more scrutinized. A little over a decade ago, a coffee selling for $50 a pound could make headlines. Compare that to this past July when a geisha varietal sold for $801 a pound at the Best of Panama auction, shattering the previous year’s auction record of $601. It’s easy, now, to imagine high-end coffees soon vying with wines in terms of availability and prestige. “I’d like something dark, chocolatey, in the $40 range,” you might say to your local coffee shop clerk in the not-too-distant future.
For casual coffee drinkers, the question of a quality cup is simple: It’s the brand of coffee you buy. For those with more knowledge, it’s the type of bean and how it’s roasted, and then brewed, that determines the taste.
But that leaves out one huge component of any cup, the one that we — to our peril — have a habit of taking for granted, assuming we don’t live in, say, the Sahara or Flint, Michigan.
That ingredient? Water.
Ask Christopher Hendon, assistant professor of computational materials chemistry at the University of Oregon. He literally wrote the book on the subject (“Water for Coffee,” aptly enough), and the coffee industry has eagerly imbibed its lessons.
“I’ve seen in the past three years a transformation — the entire industry has transformed now to be aware of water,” Hendon says.
As one might guess from his job title, the lessons Hendon has been teaching through his talks, book and research articles concern chemistry — the chemistry of water and coffee. If pressed, he’ll describe one of the major takeaways of his research in terms of the ratio of calcium and magnesium to bicarbonate.
“If you have too little magnesium and calcium, you’re going to struggle getting body out of your coffee,” Hendon says. “If you have too little bicarbonate, you’re going to have a sour cup; too much and you’re going to have a chalky, bitter cup.”
Water with lots of magnesium and calcium (among other minerals) is known, in less scientific parlance, as hard. But that doesn’t mean it makes the best cup. Many big coffee cities — New York, Portland (Oregon), San Francisco and Hendon’s hometown, Melbourne, Australia — benefit from their soft water, according to Hendon. Because there’s less stuff in it, so to speak, there’s less variability, making it easier to brew a standard cup at multiple shops.
And then there’s Bath, England, where Hendon’s journey with coffee began. One day in 2012, while still a Ph.D. student of chemistry at the University of Bath, he happened to enter a local cafe co-owned by roaster, champion barista and author Maxwell Colonna-Dashwood. Before this, Hendon hadn’t been much of a coffee drinker, but the information displayed about each brew — the processing method, its country of origin — sparked his interest, as did conversations with the shop’s proprietor. Later, they’d write “Water for Coffee” together.
Bath’s water, as Hendon describes it, is an unusual example of “remarkably hard water” offering distinct benefits for coffee brewers. “It is extremely high in sulfates, which means that the water in Bath can be filtered readily to render coffee-brewing water that is not corrosive [a typical side effect of hard water on brewing equipment], but that also doesn’t destroy the acids in your brewed cup.”
Even without my asking, Hendon is ready to counter the presumption that he’s uncovered some kind of ideal water or water source, or that there’s some magic number or formula for brewing the perfect cup. That’s the real message of his work, and of “Water for Coffee.” “There’s no single solution,” he says. “The purpose is to demonstrate an understanding of why there is disparity in flavor profiles and what we can do to compensate for it.”
Indeed, variety is a recurring theme in our conversation — the variety of possible tastes, the variables that go into producing each cup. Hendon still doesn’t drink a lot of coffee, and he doesn’t seem interested in any particular bean, or brew, or taste. I can’t imagine him ever effusing “That’s a damn fine cup of coffee” like Agent Cooper from “Twin Peaks.” For Hendon, coffee represents a puzzle, a field for subtle experimental play and observation. And the puzzle reduces, essentially, to figuring out what happens when one tiny part is tinkered with, and how you might compensate for that change, or increase it, or suppress it, by tinkering with other parts.
And not searching for a single taste, but relishing the spectrum of results.
“I enjoy it more now,” he says of the beverage since his fateful visit to Colonna-Dashwood’s cafe. “But I like the variability it has. I like tasting the differences between coffees more than I do drinking any particular cup.”
Talking with Hendon is like talking to any scientist: No matter how simple the subject may at first seem, it’s always more complex the more you dig. Water is not a given, not a simple element as the ancients would have it. Terms like hard and soft break down on scrutiny, or at least become “unhelpful.” Water isn’t even necessarily natural, but something that can be “designed” or “constructed” in a lab — or a kitchen.
That’s probably what makes the topic of coffee and water, a topic of surface simplicity hiding complex depths, so effective for teaching chemistry.
Hendon has given talks to industry and academic audiences, and often draws on coffee-based examples for his introductory chemistry lectures. Professors from other institutions have contacted him about developing their own coffee-focused chemistry courses, and to borrow the visualizations of water chemistry he uses during his presentations. Coffee, Hendon has found, allows him to illustrate, and illuminate, basic chemistry concepts — like polarity and kinetics — that nonchemist audiences often struggle to understand.
The second edition of “Water for Coffee” is scheduled for publication in 2019 and will rely more strictly on concepts and terms from chemistry, rather than industry jargon, in an effort to make the subject clearer and more informative to a broader audience. The book will reflect how much more Hendon and Colonna-Dashwood have learned since the first edition. Readers will be able to better predict how a particular water will affect a coffee’s taste, and better understand some of the principles of chemistry.
As Hendon says, “As a teaching tool, it’s one of the more powerful ones, because there are very few things in chemistry you can drink.”
For more from Dr. Coffee, visit: https://around.uoregon.edu/drcoffee