What makes a great tasting beer? That question drives the research of Tom Shellhammer, OSU’s Nor’Wester Professor of Brewing Science, and an international expert in the flavor chemistry of hops.
Yes, Shellhammer agrees, beer is made with only four ingredients, but hops alone have hundreds of compounds that add flavor and aroma in a dizzying array of choices. Shellhammer’s looking for particular compounds that will give brewers the flavor palette they need to create new, distinctive beers.
“We’re looking for the five or six key compounds that provide 80 percent of beer’s aroma and bitterness,” Shellhammer says. He’s exploring the chemical signatures that create what we sense as spicy, piney, floral, citrus, and fruity. Brewers across the country are closely following Shellhammer’s findings.
Part of his research is to tease out the taste of beer into a full spectrum of vivid and precise descriptions. It’s not enough to say beer is bitter; he wants to know if it’s bitter like aspirin or grapefruit rind. He wants to unravel the chemistry behind a particular nuanced bitterness. And he wants to know how consumers respond to each attribute of flavor, aroma, foam, and mouthfeel. He wants to know, do they like it?
Sign me up! comes a chorus of undergraduates cheering from the sidelines. But, no. Sensory testing is not a party game. It’s an integral part of the Fermentation Sciences Program at OSU and an essential skill within food and beverage industries.
“People think being on a tasting panel is like hanging out drinking beer with your friends. It’s not like that at all,” Shellhammer says.
As a brewing chemist, Shellhammer works with trained tasters tapped from the ranks of OSU faculty researchers, graduate students, and professional brewers and maltsters. Each are trained in the lexicon of beer flavor and aroma so they can agree on the difference between, say, tarry and smoky, or metallic and can-liner. They can debate the nature of bitterness: Is it fine and fleeting or coarse and lingering? Each descriptor is unambiguous; there are no subjective choices, nothing that says “thirst-quenching” or “rot-gut.”
“It’s important to have a vocabulary with standard meanings,” Shellhammer says. “It’s the first thing we do when we train a sensory panel.” It takes weeks to standardize the palates of the tasters; and many more weeks to go through the samples and record impressions, sensations, and perceptions at every angle. This is the most thorough and precise type of sensory testing, necessary to analyze the various treatments Shellhammer is testing at the molecular level.
Eventually, Shellhammer collects the data he needs to document the sensory perception of flavor profiles. In that way, he’s found that hop-related aromas such as grapefruit and pine are positively correlated with consumer liking. In contrast, he found that consumers reject the cooked-cabbage scent of dimethyl sulfide. No argument there.
This work is helping to redefine American beer beyond fizzy, pale yellow lager. “Don’t discount the difficulty in making standard American lager,” laughs Jeff Clawson, OSU’s brewmaster. “To make Budweiser that tastes the same in Hong Kong, Anchorage, or Buenos Aires takes a lot of standardization.” Any variable in water, temperature, humidity, or even ambient wild yeasts can throw a monkey wrench into a recipe that’s meant to produce a consistent product, any place, any time.
If there’s a wild card in brewing science, it’s the yeast, those hard-working microbes that turn sugar into alcohol. Yeasts have been domesticated to do the heavy lifting in fermentation [see sidebar “Beauty in the Yeast"] “As brewers, we’re basically yeast farmers,” Clawson laughs again. “And like many domesticated animals, they never do exactly what you expect them to do.
”Brewing consistency is part of Clawson’s job as he combines yeast, malt, and hops into a variety of treatments for Shellhammer’s testing. “It’s critical to each experiment to replicate the process and vary the treatment,” he says. “That way our results are measurable, not magic.”
Among his many responsibilities as teacher, mentor, and pilot brewery manager, Clawson is currently fitting a new, fully automatic brewery into the pilot plant. “We’ll keep the manual brewery for first-year students; they’ll learn the process by running it each step of the way,” he says. “Once they know the how and why of the whole brewing process, we’ll advance them to the new automated brewery, like what they’ll encounter in their careers with commercial breweries.”
And those students who graduate from OSU’s Fermentation Sciences Progam are advancing into careers where they, themselves, are redefining American beer. “Students use this pilot brewery seven days a week,” Clawson says. “They get a lot of hands-on experience. It’s what makes this program distinctive in the world.”
Distinction. That’s what defines American beer in the 21st century, beyond the predictable “refreshing” and “less filling” toward complex flavors, aromas, styles, and textures derived from an almost endless arrangement of four basic ingredients.