With American universities growing increasingly concerned about the challenges of attracting qualified students into engineering majors, professor William Ristenpart believes he may have an answer:
Ristenpart, who holds the Joe and Essie Smith Endowed Chair of Chemical Engineering at UC Davis, leads a research team that investigates the physical, chemical and biological phenomena of fluids, including fluid motion caused by electrical fields, how different food metabolites affect red blood cells, and the behavior of fluids at the microminiaturized scale.
“In a way, I zap salad dressing,” he explains. “Electric fields are used widely to separate oil and water emulsions. I have other projects that involve taking blood samples and squeezing them through micro-channels, to mimic the hydrodynamic conditions during, say, arteriosclerosis. There are a lot of physiological implications to how blood cells respond under such conditions, and this research helps us understand how they regulate vasodilation.”
But where does coffee come in?
Like many engineering professors across the country, Ristenpart believes that universities must become more aggressive with outreach, in order to attract students who otherwise might not even contemplate careers in various engineering fields. Part of the solution, he believes, involves crafting lower-division courses that will engage undergraduates in inspiring, hands-on lab activities.
And he believes the situation is particularly critical when it comes to chemical engineering.
“Until very recently, no chemical engineering professor even saw students until their junior year,” he admits. “There were zero lower-division chemical engineering courses. The thinking was that younger students weren’t strong enough or mathematically talented enough, so the idea was to weed them out with freshman-level chemistry and physics.
“Now, though, we’re acknowledging the value of outreach to attract STEM majors. A lot of talented students out there never would think, in a million years, that chemical engineering could involve anything interesting,” says Ristenpart, who has joint appointments with the department of chemical engineering and materials science, and the department of food science and technology.
“Ask random people on the street what chemical engineers do, and they’ll have no idea; they might envision a smokestack wafting chemical pollutants into the air. But that’s not what any of us do around here, in terms of our research, and our graduates find work in a huge diversity of places.
“But we’ve never gotten to talk to all those other students because, until now, they essentially had to enter college already having bought into the idea of becoming a chemical engineer, or we never saw them. So we’re trying to change that.”
The result: ECM 1, “The Design of Coffee,” a course that Ristenpart is co-teaching this quarter with Tonya Kuhl, a professor in the department of biomedical engineering.
“The idea is to get a very small group of freshmen,” explains Ristenpart, of this spring’s 18 participants. “These are students normally accustomed to huge classrooms, with professors who are no more than a faraway dot — into a smaller lab/classroom situation, where they’ll be granted close contact with faculty. The students get a better experience that way.
But why coffee?
“I’m by no means a coffee expert,” Ristenpart acknowledges, with a chuckle, “although I’ve learned as much as I could, during the past several months. We wanted to offer some meaningful laboratory design experience for students who haven’t had much training in anything scientific or quantitative. We also wanted something that isn’t intimidating. Coffee fits the bill perfectly, because it’s familiar to most people. And, unlike beer or wine, everybody on campus can drink it.”
Ristenpart warms to his subject, much like a perfect cup of joe gently percolating.
“The most important point to make is that coffee brewing may seem like a simple process. People think of coffee as something they get from Starbucks. But if you design it from scratch, you’re dealing with lots of chemical reactions, issues of mass transfer — how chemicals get from here to there — issues of heat transfer and energy, and colloid science. Students can be introduced, in a very friendly fashion, to all these complicated topics that they’d study much more rigorously in upper-division classes.
“Then, moving forward, the quantitative and analytical tools that we’ll use to analyze coffee, can be applied to more complicated — and more important — subjects such as blood cells, influenza transmission or electrostatic dehydrators.”
Ristenpart and Kuhl have designed their 10-week course to match successive laboratory goals with the various steps involved in brewing. The segment on chemical reactions, for example, will focus on roasting coffee beans to perfection; mass transfer will demonstrate how extraction is the heart of coffee; thermodynamics will be introduced by talking about espresso, decaf and “the beauty of phase diagrams.”
Even so, Ristenpart acknowledges the obvious challenges.
“It’s not easy to discuss complicated concepts — mass transfer and flux, Flick’s Laws — with freshmen who haven’t studied differential equations or calculus. So we’ll teach via simple concepts. For the flux experiment, we’ll change the grind size. Brewing with whole beans produces one result, and then I’ll have the students use a mortar and pestle, to achieve a coarse grind, and then we’ll move up to making a really fine grind. We’ll use TDS (total dissolved solids) meters to track the results, just like coffee aficionados who know that the optimal yield, in your drink, is supposed to be 20 percent of the solubles from the grind. Not 19 percent, not 21 percent.
“And of course the students also will taste these distinctions. Whole beans will taste weak, like nothing; a fine grind, to a powder, will taste very bitter. The students will be able to compare these qualitative sensory evaluations with the quantitative differences recorded from the TDS meters. That’ll quantify a visceral response.”
The class will conclude, during its final lab session, with a competition. Each student will be challenged to make as perfect a cup of coffee as possible, and the results will be evaluated during a blind tasting. But because this is an engineering course, Ristenpart and Kuhl have added a quantitative twist.
“Each student will be tasked with making the best-tasting cup of coffee while using the least amount of energy,” Ristenpart emphasizes. “Each person’s process will be tracked with kilowatt meters, so final scores will be the blind-tasting score divided by the number of kilowatt-hours used. That’s a realistic design constraint; when you become an engineer, you always think in terms of minimizing cost and energy.
“How, then, does one make a truly excellent cup of coffee economically? If you make a darker and darker roast, to give more body to the final cup, the beans are in the roaster for a longer period of time, and you’re drawing more energy.
“Alternatively, you could throw green beans into a cup of cold water, using zero energy … but it wouldn’t taste very good!”
“Our plan, moving forward, is to make this a high-enrollment, general-ed class with a couple hundred students,” Ristenpart explains. “But it’ll be unlike all other general-ed classes on campus, because the whole point will be to have a lab section, to be hands-on. And then we’ll have students who’ve never even thought about graphing data, designing Excel bar charts about TDS.”
With those words, Ristenpart returns to the primary reason behind this new course.
“Yes, I have ulterior motives,” he smiles. “Our students are spending 10 weeks learning how to design the perfect cup of coffee.
“And I’ll be trying to design some perfect chemical engineers.”