Specialty Coffee’s Resident Scientist

A computational chemist is changing the way coffee makers think about water.

STR New / Reuters

Wherever he goes, Christopher H. Hendon brings a homemade supply of powdery white chemicals. Made from coral-reef care sets, the little bottles and plastic bags may raise some TSA eyebrows, but they serve a perfectly innocent purpose. The substances comprise his personal water filtration titration kit.

“Who travels with this much white powder?” Hendon says with a laugh. His duffel currently contains several compounds including calcium chloride, magnesium sulfate, and potassium bicarbonate. These mixtures help detect the invisible chemicals present in a glass of water, he explains. Using them, Hendon can determine how hard the water is in any geographical area, based on the minerals it contains.

This information is especially important, it turns out, for those who are particular about how their coffee tastes. In 2014, Hendon published a paper in the Journal of Agricultural and Food Chemistry on how water hardness affects coffee flavor. What he found was that hard water contains compounds that can be “sticky” and attach to flavorful elements in roasted coffee beans during the brewing process. Hard water with high levels of magnesium, for example, might pull more flavor out of a coffee bean.

Soft or distilled water, conversely, has a chemical composition that does the opposite—and is actually bad at attaching to and “extracting” those aromatic coffee compounds.  This is one of the reasons why beans brewed in one part of the country might taste differently when brewed the same way in another state.

Hendon is currently completing his post-doctoral work at MIT as a computational chemist and plans on continuing his foray into coffee research. In addition to his analysis on water, he’s recently published a paper on how temperature affects the coffee grinding process. According to Maxwell Colonna-Dashwood, an award-winning barista that Hendon has collaborated with, he’s well on his way to becoming the resident scientist for the specialty coffee community—a field which until recently, has largely lacked the scientific grounding that’s been present in other food industries.

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Hendon’s interest in coffee began in 2012, while he was working on his chemistry Ph.D. in Bath, England. Fed up with his roommate’s “dreadful” homebrew, a quick Google search for “good coffee” led Hendon to an independent specialty shop in London named Colonna & Smalls. There, he met Colonna-Dashwood, the co-owner of the store, whom he’d later learn was a U.K. Barista Champion and a World Barista Championship finalist.

Despite being a “know-it-all customer,” who initially seemed more confident in his own coffee judgment than Dashwood’s professional advice, Hendon and the barista eventually bonded over conversations about science and coffee. One day Colonna-Dashwood approached Hendon for help with a few questions, including understanding some water chemistry readings that came up during the roasting process.

“It became clear that in order to help him answer his questions, he needed to teach me coffee,” Hendon says. “And for him to understand the answer to the question, he needed to understand chemistry.”

The duo ultimately teamed up, publishing “Water for Coffee,” a book that expands on Hendon’s water study. Colonna-Dashwood also invited Hendon along to compete in the 2014 World Barista Championship in Italy, which he says was a turning point for spreading their research within the coffee community.

“It's got a huge audience, and a lot of ideas are explored there,” Colonna-Dashwood says. “They become the zeitgeist for next year maybe.” In addition to being a competition, the championships function like coffee-themed TED talks, proffering new techniques and research to the specialty world.

“It got people thinking about water in a different way,” says Benjamin Brewer, the director of quality control at Blue Bottle Coffee, a specialty coffee roaster and retailer based in California, known for its obsessively high-quality products. “In the industry, [water has] always been oversimplified.”

Brewer notes that Hendon’s work is especially relevant as Blue Bottle expands throughout the U.S. and Tokyo—to help them figure out how to maintain high quality standards in every place they go. “Our company is located in four very different regions,” he says. “For our product to be the same in those four different regions, we need to make adjustments.”

While Hendon notes that much of his work may seem like common sense to those outside the industry, what makes his research innovative is that it applies scientific principles to coffee-related questions in ways that, until recently, no one had bothered to try.

“Over time, we’ve struggled to achieve the same scientific rigor behind our industry that others, like wine and beer, have,” says Emma Sage, the science manager at the Specialty Coffee Association of America (SCAA). “Now we’re changing that.”

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While science and coffee may not have always been so closely intertwined, java-obsessed scientists have long played their part in refining the beverage. In the 1950s and 60s, a food-technology Ph.D. from MIT named Ernest Earl Lockhart developed a set of guidelines for preparing coffee that are still considered “brewing fundamentals” today. Peter Schlumbohm, the inventor of the Chemex—an hourglass-shaped drip coffeemaker that’s heralded for the crisp taste of the coffee it produces—was also a chemist.

Producing cut-and-dry scientific results for something like “good coffee,” which is often based on subjective perceptions can also be tough. “Specialty coffee has a strong element of artisanal craft and romanticism,” Colonna-Dashwood says. “For a while there was this barrier that science was cold and robotic.” But injecting science into the coffee world, Colonna-Dashwood argues, actually creates more room for creativity.

Sage, a botanist by trade, agrees. She was hired by the SCAA five years ago in order to help bring the coffee industry and scientific community closer together. Part of her job entails working with scientists to promote coffee research. One of the efforts the SCAA supports is the UC Davis Coffee Initiative—which aims to “investigate the biophysical and health properties of coffee”—by helping to suggest areas of study the program should focus on.

The broad chain of coffee production—from harvest to roast—opens up the industry to scientists interested in a range of fields, from botany to environmental sustainability to physics. In Brazil, for example, Flavio Borém has conducted a wide range of research into the biology and agriculture of coffee, with a focus on evaluating seed quality. In the U.S., Charles Spence has used coffee in some of his sensory science studies and demonstrated how the taste of the drink can vary depending on the color of the mug containing it. Sage notes that each element of the coffee production and consumption process could use more scientific investigation.

In his most recent paper on the subject, Hendon looks at how temperature and bean origin (where the coffee was grown) affects how coffee grinds up. The team’s findings suggest that not only should coffee be frozen before grinding, but also that all types of coffee beans grind the same way, regardless of origin, roast, and processing methods. Both of these conclusions are contrary to what coffee fanatics might otherwise consider common knowledge, Hendon says. He and his team predict these findings could impact the industrial production of coffee as well as how people store and use it daily.

Several companies—including those involved with water filtration—have shown an interest in Hendon’s work, but he aims to continue sharing the research as democratically as possible with everyone from baristas to armchair coffee enthusiasts. “I’m trying to build a picture to show people that every aspect of coffee can be explored if you want,” he says. All it takes is a little curiosity—and a lot of coffee.