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Defining a new vocabulary for craft brews
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OSU pilot brewery manager Jeff Clawson discusses OSU fermentation research and education influencing the Oregon brewing industry.

Give these guys a beer and they can describe the subtlest overtones from lemon-lime to burnt rubber. They are part of the fermentation science program at Oregon State University headed by Tom Shellhammer, and they’re building a new vocabulary of beer.

With a palate as refined as any wine connoisseur’s, Shellhammer’s goal is to tease out the taste of bitterness 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 tonic or grapefruit rind.

Jeff Clawson
Jeff Clawson manages the pilot brew house at Oregon State University, one of only two university-based teaching breweries in the nation. Photo by Lynn Ketchum.

Like many languages, the vocabulary of beer began as an oral tradition, people talking about what was tasty, or not, about particular brews. In the 1970s, sensory scientist Morten Meilgaard set out to standardize those conversations, to create a dictionary of words that would precisely describe the taste and aroma of beer. Meilgaard built his dictionary in the form of a wheel with three concentric circles. The Beer Flavor Wheel was the first sensory diagram ever developed for a particular food. Since then, food scientists have created sensory wheels for defining the flavors of wine, coffee, chocolate, even maple syrup.

The Beer Flavor Wheel categorizes more than 100 distinct tastes and aromas, with spokes that describe slightly nuanced differences. For example, the spoke labeled “roasted” branches to either caramel or burnt. Caramel branches to molasses or licorice; burnt branches to smoky or bread crust. Each category is unambiguous; there are no subjective choices such as thirst-quenching or rot-gut. The brewing industry adopted the Beer Flavor Wheel in 1979, and it continues to be the industry standard for brewers in the United States and Europe. But the dictionary was lopsided from the beginning. Sweet, for example, is broken down into oversweet, syrupy, jam-like, vanilla, honey, and more. But bitter is, simply, bitter.

hop flowers
Oregon is the nation’s second largest producer of hops, an industry valued at more than $29 million in Oregon in 2008.
hop conveyor
Flavorful hop flowers tumble down a conveyor into a drying facility at Goschie Farms near Silverton.
hop bales
Workers wrap bales of dried hops for shipment to breweries throughout the United States. Photos by Lynn Ketchum.

“Bitterness balances the sweetness of the malted grain,” Shellhammer says. “It comes from adding hops at different stages during the brewing process. This has produced an array of craft brew styles that have made Oregon beers famous. But there are no standard words to describe its variations.”

It’s the female flower of the hop plant that adds bitter-tasting compounds and contributes characteristic aromas to beer. Bitterness is most pronounced in IPAs, India pale ales, that were first crafted in the 18th century to serve British tastes on long voyages throughout the empire (among its many attributes, hops are a natural preservative, which is why they were first used in beer.). Today, IPAs are a signature brew of the Pacific Northwest.

“But most mass-produced American beers barely register any bitterness,” Shellhammer says. In fact, Coors Light has such a mild taste of its own that Shellhammer uses it as the base for mixing his flavor extracts, like painting color on a white wall.

There may have been little use for a complete beer vocabulary when the choice was either “great taste” or “less filling.” But with the proliferation of microbrews across the U.S., there’s more than ever to say about the flavor and aroma of beer. Portland now has more microbreweries per capita than any other city in the world. Shellhammer’s bitterness vocabulary will help the booming microbrew industry describe the full range of sensations now on tap.

Because almost all beer is made of barley, hops, yeast, and water, it’s the brewing process that makes most of the differences in flavor. In the first step, called malting, kernels of barley are steeped and sprouted, then roasted until dry. The higher the temperature, the more roasted, toffee-like flavors bubble up in the beer. Brewers mix the malted, milled barley with water and later boil this sweet extract. This is the point where hops are added. The amount of hops and the length of the boil determine a beer’s bitterness; the different hop varieties create aromas that are citrus, piney, or herbal.

After the mixture cools, brewers add yeast to start the fermentation, which adds flavor as well. Some fermentation by-products lend fruity tones, such as banana, pear, apple, even bubble-gum.

beer flavorwheel
Unlike the fine distinctions that describe sweet, acidic, or cooked vegetable, there are as yet no other words to distinguish the many bitter flavors of beer.

In Shellhammer’s world of sensory science, flavor is much more than the sensation of sweet, sour, salt, and bitter registered in strict voting precincts across the tongue. Flavor is the total impression of taste, odor, tactile, kinesthetic, temperature, and pain perceived by tasting. The perception of taste is prompted by stimulation of receptor cells throughout the mouth and transmitted to the brain where it is decoded in the cerebral cortex. Although laboratory tests exist that can identify chemical elements in beer, no instrument has been able to replace the nuance of human testers.

“We’re developing better quality beer for people, not machines,” Shellhammer says. “We’ve got to work with real tastes sensed by real people.”

At the OSU Sensory Laboratory, Shellhammer works with a panel of 15 testers to help him identify the notes and lingering phrases of bitterness in beer. These are trained testers, people who have developed a refined palate and the ability to precisely describe what they taste. For the test, Shellhammer has prepared three new reference flavors by spiking bland beer with three chemical extracts: caffeine, quinine, and sucrose octaacetate, an extract so bitter it is used to discourage thumb-sucking, nail-biting, even insects chewing on plants. He hopes he can get the testers to use the flavors he’s prepared to help them describe the flavors they sense in each of six different experimental beers, like matching color samples to a painted wall.

Shellhammer’s procedure for testing the bitterness of beer is precise and exacting. “In addition to the actual peak intensity of bitterness that one senses when drinking beer, our panel distinguishes bitterness based on the speed with which the bitterness presents itself and the length of time it takes for the bitterness to disappear,” he explains. He is searching for a precise language that describes whether bitterness is smooth or mild as opposed to harsh, metallic, or medicinal.

When training his testers to evaluate the full symphony of aroma, flavor, and texture, he guides them in the established ceremony of beer taste testing. He lifts the first glass and swirls the liquid, bringing the edge of the glass up to his nostrils, inhales, and pauses to write a few words on a piece of paper. He sips, swirls, and swallows, then writes more notes. With each sample, Shellhammer is recording the history of a sip of beer, from lips to tongue to palate, and finally down the throat. This one starts cool, lingers at the edges of his tongue, then assaults the back of the throat with a kick of astringency that makes him wince. He describes the transition from green vegetable to bad Brussels sprouts, from sharp to piercing. When the history is complete, he cleanses his palate with a sip of water and moves to the next glass of beer.

beer by Lynn Ketchum

When the last taste is recorded and rinsed away, Shellhammer asks the testers, “Well, what did you think?” The room fills with enthusiastic descriptions, from tin-can-liner to orange-juice-after-ice-cream.

“The last one tasted minty, almost shuddery, and lingered at the back of my throat.”

“This one was like sucking on a coin, harsh and metallic, like week-old coffee.”

Descriptions spiral in all directions, mapping intricate geographies of mouth, tongue, and palate. The group agrees on the taste of aspirin in one sample.

“We’re getting closer,” he says of his search for a bitterness vocabulary. He will work with the sensory lab scientists and a flavor chemist, perhaps to find an extract that describes orange-juice-after-ice-cream to test in the coming months, as he builds a new lexicon to describe the world’s oldest brewed beverage.


Web resources

OSU Pilot Plant Brewhouse
A Heady Success