1. Where It Started: Water Chemistry and Coffee Flavor

Professor Christopher Hendon began his research into the relationship between coffee and water when he met Maxwell Kana Dashwood during his graduate studies at the University of Bath, UK, in 2014. At the time, Maxwell's café was using coffee from a different roaster, and some batches tasted "phenolic and fishy" — simply bad. After much discussion, they realized it wasn't the coffee itself but the chemical composition of the water that was affecting the flavor.

"At the time I didn't realize this was an important problem. I thought, why not just pick a different coffee?"

Over time, however, he came to understand that every person uses different water, and that this has a massive impact on the coffee industry. Because coffee companies cannot control what water consumers use to brew, a scientific approach is essential.

"I came to see how much the industry cared about science, and that's what drew me into this field."

Hendon notes that while water chemistry is not yet a fully solved problem, his focus has been on explaining the cause of the problem. Products like "Third Wave Water," which add specific minerals to water, emerged as a result of this work.

"My intention wasn't to solve the problem — it was to let people know why it was a problem in the first place."

2. Optimal Water Composition for Coffee Extraction: What Matters Most?

Early on, magnesium and calcium were thought to be the key variables, but now Hendon emphasizes that the concentration of bicarbonate ions — the water's buffering capacity — is the single most important factor.

"With water high in bicarbonate, you simply cannot produce a coffee with vibrant acidity."

• Soft water can still produce delicious coffee, but high bicarbonate content strips away acidity.
• Most people, he adds, prefer acidity over complex aromatics.

3. Water Challenges in the Korean Market and Solutions

Korea presents a particularly difficult case because water hardness and chemical composition vary greatly by region, making it hard to standardize coffee flavor.

"Seoul, the south, inland, coastal areas — the water is all different. That makes Korea a tough market for solving this problem."

• The most practical approach is using reverse osmosis (RO) filtration to strip all minerals, then adding a small amount back to produce soft water.
• However, this only achieves an "average" result — it doesn't optimize for the best possible flavor.
• Adding minerals directly to deionized (DI) water yields the best outcome, but the cost and effort make it impractical for most consumers.

"In coffee competitions this approach makes sense, but most people just don't have the time for it."

4. Coffee Grinding and Extraction Efficiency: Real Benefits for the Industry

Hendon has researched the relationship between bean temperature, particle size distribution, and extraction efficiency. Coffee prices have risen recently, and there is growing social motivation to pay farmers more — yet café operators struggle to pass costs on to consumers.

"The problem is we want to pay more, but we don't want to charge more."

In this context, getting the best flavor from the least amount of coffee becomes critical.

• His research experimentally demonstrated that static electricity generated during grinding causes waste.
• He also emphasizes that longer espresso extraction times can actually produce worse flavor — short extractions of 7–15 seconds can be perfectly delicious.

"Just adding water during espresso extraction increases the dissolved solids in the cup by 10–20%. It's like getting one free shot for every five you make."

5. The Impact of a Scientific Approach on Specialty Coffee

Hendon argues that we must respect the diversity of specialty coffee.

"We enjoy the fact that an Ethiopian washed coffee tastes different every year. We don't want every Colombian coffee to taste exactly the same."

• The role of science is not to standardize flavor into uniformity, but to help baristas and roasters more easily produce great-tasting coffee.
• "Better" doesn't mean one cup is tastier than another — it means multiple cups come out equally delicious.

6. How Scientific Research Can Be Applied in Education

Hendon explains the difference between practical education and theoretical education.

"An SCA trainer teaches content you can use tomorrow. I teach why these phenomena happen."

• Experimental findings on static electricity during grinding, differences in particle size between dark and light roasts, and using a small amount of water on beans to eliminate static can all be incorporated into training curricula.
• The established definition of espresso extraction time is also changing — short extractions can be just as delicious, he stresses.

"If it tastes good at 7 seconds, that's fine. Why insist on 25?"

• Looking ahead, he believes that applying electricity to coffee could transform the future of the beverage.

"When you apply electricity to coffee, things that seemed impossible suddenly become possible. Teaching this properly will require a lot of new education."

7. Research Collaboration and the Potential for Scientific Advancement in Korea

Korea has an enormous and diverse coffee market — from budget options to ultra-premium specialty — and Hendon sees opportunity in that range.

"The Korean market is like the car market — you sell everything from cheap cars to luxury ones."

• The coexistence of consumers who prefer sweet drinks and those who seek out specialty coffee means there are limits to how widely specialty coffee can be mainstreamed.
• Scientific research requires funding, and he suggests that if many cafés contributed small amounts collectively, large-scale research becomes feasible.

"If every café in Korea invested $1,000 a year, you'd have millions of dollars for serious research."

• That said, he acknowledges that because each café has different goals, it's difficult to align them all in one direction.

8. The Most Memorable Moments in His Research

Hendon says the most rewarding moments are when a paper is published and the world finally learns what he's discovered, and when students bring him new ideas.

"That brief moment when we know something nobody else in the world knows yet — that's genuinely exciting."

• He emphasizes that science is a process of making consistently good decisions, and his role is to help students make those decisions well.

9. Future Research Goals and the Future of Coffee

Hendon is convinced that research into improving robusta coffee flavor could transform the industry.

"If we can make robusta taste good, we can relieve pressure on the arabica market. If an 80-point arabica can be replaced by a 78-point robusta, that's a massive change."

He is also deeply interested in developing technology that compensates scientifically for barista mistakes, so that anyone can consistently produce high-quality coffee.

"Imagine a famous person visits a café just once and that single cup comes out wrong — what a shame. If measurement and adjustment can prevent that kind of mistake, you're genuinely helping the barista."

10. The Single Most Important Factor When Brewing Water

Hendon singles out bicarbonate ion concentration as the most critical variable.

"Bicarbonate stabilizes the pH of water. If you want a coffee with vibrant acidity, you need to carefully control bicarbonate concentration."

11. The Biggest Variable in Extraction: Grinding and Static Electricity

• Grind settings have the greatest impact on extraction, and static electricity significantly affects particle size distribution and extraction efficiency.
• Conical burr grinders grind slowly, but because beans contact the burrs more frequently, they can generate more static.

"If static isn't properly controlled, particle size becomes inconsistent and a range of problems follow."

12. Democratizing Coffee Science: An Approach for Experts and Everyday Consumers Alike

Hendon stresses the importance of scientific communication.

"Scientists are often bad at communicating with the public. I try to engage with the media as much as I can. You all play the role of making science easy to understand."

• He believes ordinary people are fully capable of being scientific, and explicitly says "I don't assume everyone can't do anything."

"If you ask someone in Korea to measure 1 ml, most people can do it. You don't need a university degree to be scientific."

13. Closing

In closing, Hendon shares his enthusiasm for collaborating with students, the joy of new discoveries, and his hope for the future of coffee science.

"I barely do hands-on research myself anymore. Students bring me new ideas, and I help them make the right decisions. That's the greatest reward of this work."

Key Topics:

• Water chemical composition
• Bicarbonate ions
• Static electricity and grinding
• Extraction efficiency
• Diversity in specialty coffee
• Scientific communication and education
• The future of robusta coffee
• Characteristics of the Korean coffee market

☕️ The future of coffee — made more delicious and more diverse through science!