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La Salle News

September 18, 2020

Where home brewing and microbiology intersect

A non-traditional project in professor Brian DeHaven’s course calls attention to the practical applications of laboratory microbiology.

Brian Dehaven demonstrating microbrewing in his kitchen

For two hours, Brian DeHaven’s kitchen became his classroom. His countertop acted as a makeshift lab table.

On this September day, DeHaven guided his students through a detailed step-by-step process that called for steeping, boiling, and ice-bathing various materials. His students monitored the color and consistency of their concoctions. They noted mixed results—One student had sediment firmly stuck to the bottom of her container. Another referred to the material as “slime-like.”

“Remember, we want to be drinking this stuff next week, not chewing on it,” said DeHaven, Ph.D., assistant professor of biology at La Salle University.

For 22 students in DeHaven’s upper-level microbiology course, this was not a standard laboratory experiment. It’s actually a semester-long, beer-brewing project that requires precision and attention to detail.

A broader move in the biology discipline is seeing instructors across the country convert traditional textbook learning and components of classroom instruction into hands-on laboratory experiments. Popularly, in recent years, professors like DeHaven rely on beer-brewing to call students’ attention to the practical applications of laboratory microbiology.

For DeHaven’s course, students scheduled times to visit La Salle’s campus and retrieve beer-brewing kits from Holroyd Hall. (Only one student needed DeHaven to ship the kit by mail.) Under DeHaven’s watch—through a synchronous Zoom session—the students boiled water before adding material from their kits, like a sugar source (dried malt extract) and hop pellets, which are actually antimicrobial. “Hops are in beer,” he said, “to keep out other elements that will get you sick.” The addition of yeast represented the final step. The concoction, DeHaven said, needed to cool before yeast is introduced to prevent—among other outcomes—killing the cells before they can make any alcohol.

Brian Dehaven instructing his students online through his laptop

Once they get the basics down, students capture wild yeast by placing a petri dish filled with agar outside of their homes.

“Wild yeast is pervasive. It’s literally everywhere. It’s in the air. You could swab bark or leaves, for example, as a way to capture it,” said DeHaven, who introduced this project and has overseen it for three years. (This year’s project is a bit different, as La Salle is delivering a majority of its fall courses through remote instruction.)

Upon adding yeast, DeHaven’s students used a hydrometer to measure the material’s specific gravity. This calculation helps brewmasters determine the alcohol by volume (ABV) and the calorie count of a beer. The project’s objective, DeHaven said, is for students to question their recipes, procedures, and scientific methods to improve the taste of their beer each time the process is repeated.

Two of DeHaven’s students are not of legal drinking age. “That doesn’t take away from the project’s value,” he said, “because their calculations will tell the story.”

In past years, DeHaven’s students have presented their brewed beverages as a competition at La Salle’s Holroyd Symposium—during which students across the STEM disciplines showcase their work from the fall semester. While that is unlikely to transpire this year, DeHaven said he is working behind the scenes to highlight his students’ accomplishments. He is in discussions with a local brewery to position his amateur brewers for internships. He’s also detailed the project in an article he has submitted for journal publication.

“I developed this lab to show students that what they learn in lecture has real-life, practical applications,” DeHaven said. “Being able to teach a lab virtually has been a wonderful bonus.”

—Christopher A. Vito