Issue Date: June 12, 2017 | Web Date: June 6, 2017
The secret to great wine? Organic chemistry.
For Andrew L. Waterhouse, being tasked with wine selection when having drinks with family, friends, or inquisitive journalists is something of an occupational hazard. “It’s just part of the job,” the professor of viticulture and enology at the University of California, Davis, says.
It’s a good bet that Waterhouse will pick a winning wine. He’s widely respected for his expansive knowledge of wine chemistry and has educated a generation of winemakers during his 26 years teaching in UC Davis’s world-renowned program.
But Waterhouse hasn’t always been a wine connoisseur. With training in natural product synthesis, he started his career at a different school teaching organic chemistry primarily to premed students and researching conformational analysis of polysaccharides. One day, while paging through C&EN on a flight, Waterhouse saw a job posting for an assistant professor of viticulture and enology at UC Davis. He wanted to return to the West Coast, where he went to school, so he applied.
“As soon as I heard I got the job, I started reading,” he remembers. “Professionally, I knew nothing. I was a wine lover, but I had no idea what was in wine, really, other than alcohol.” Now he studies wine’s complex natural products, such as flavonoids. “Winemakers call it chicken wire chemistry,” he says, because the hexagons in the flavonoid structures resemble chicken wire to those untrained in chemistry.
Waterhouse says when he first started at UC Davis he tried to teach organic chemistry to budding winemakers the same way he taught it to premeds. “It didn’t work,” he says. For example, when he taught his students about terpenes—important flavor compounds in certain wines such as Rieslings—he discussed how the compounds undergo acid-catalyzed rearrangement during aging.
“I was showing the students allylic cations forming, rearranging, and eliminating. And it was completely useless to them,” he says. “They have to understand something about terpene chemistry, but they don’t have to understand mechanistic transformations from one terpene to another.” This made Waterhouse completely rethink how he taught chemistry to these students. He needed to talk about chemistry that would be useful in wine making. “That’s why they take classes—they want to understand what’s happening so they can manage it better. It’s a very applied use of chemistry.”
And students of wine chemistry differ from premeds in another way, Waterhouse found. Whether the wine-making students are pursuing bachelor’s, master’s, or doctoral degrees, all approach the subject with passion, Waterhouse says. “When I was teaching organic chemistry to premeds, they had no interest in the subject. They just needed an A. It was a hurdle class for them and they didn’t like it.” That’s not the case with the students he teaches at UC Davis, he says. “They really want to know the information, and they want to know why it is useful.”
In 2016, after 25 years as a wine chemist, Waterhouse decided to create a resource for others who might be interested in teaching the subject or for chemists who are just interested in knowing more about the chemistry of wine. Along with Cornell University’s Gavin L. Sacks and the University of Adelaide’s David W. Jeffery, he coauthored “Understanding Wine Chemistry.”
The book, he says, is different from other wine chemistry resources because it focuses on the organic chemistry of wine. “Most of the chemists in the field are analytical chemists, and they’re very good at that, but when they write about it, they focus on analytical issues, such as comparing analytical results with taste and sensory results.” While that’s important, Waterhouse says, he and his coauthors wanted to create a book on the chemical reactions that take place in wine.
“Just by understanding the chemistry you can intervene in very simple ways,” Waterhouse notes. For example, sauvignon blanc wines from New Zealand are known for a guava- and passion-fruit-type aroma, but that fruity note would often be missing after storage. An organic chemist figured out that the aroma arises from an ester that can hydrolyze. Now, New Zealand winemakers keep the sauvignon blanc as cold as they can until it’s bottled and shipped, thus preserving that flavor. “So understanding chemistry is very powerful, even in wine making,” Waterhouse points out.
But, Waterhouse is quick to add, chemistry does not have all the answers. “When I came to Davis, I thought all we have to do is figure out what are the key molecules that are present in great wine. Many people have this idea, and I was not any different. It turns out that there have been a lot of smart people thinking about this for a really long time,” he says.
“What I’ve discovered is that it’s not really just the chemistry that makes wine interesting or valuable. There’s a lot more behind the story of wine than chemistry. I know that might be disappointing for some chemists, but the reality is that people love wine. And people love wine not just because of the way it tastes. They love wine for many reasons,” he says. “When you’re a winemaker one of the key things you have to be able to do is convey a message about your product—a story about yourself or the land or the history of the property. Those things are, in some way, more important to a wine drinker than wine that just tastes good.”
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