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"We talk about colors in food, and how some are water soluble and some are fat soluble," she continues. A good example is saffron, says Jemiolo—they often finish each other's thoughts, and clearly enjoy their collaboration—"it gets its bright yellow color from a long hydrocarbon with a sugar molecule on either end, which allows it to be water soluble. This allows it to stain rice yellow when you make risotto." Both teachers are Italian-American, and their love of the traditional foods of that country is evident. Because Vassar has such a diverse student body, however, they go out of their way to use examples from cuisines around the world and tie them to culture and history as well as science. Potatoes originated in South America, for example, but when they became a monoculture in Ireland that dependency on a sole crop led to the Great Famine of the 19th century.
Food as Culture
Corn, another New World food that became a staple in Europe, offers another fascinating example of the perils of monoculture. Native people in the Americas treated their corn with lime, a process called nixtamalization, that softens the grains (as in the green bean example) and produces a lovely flour for tortillas. It also happens to free up niacin (vitamin B3), making it available to our bodies. At different times and places, like Northern Italy in the 18th century and the American South in the early 20th century, people subsisting largely on corn developed pellagra, a nasty disease resulting from a niacin deficiency; the body uses its own tryptophan (an amino acid) to synthesize niacin, but at the cost of other essential protein synthesis. "What came over was the corn, but not the culture," explains Jemiolo. Rossi offers some other examples: "We also talk about the effect of starch on foods; different kinds of rice have different starches, like sticky versus long grain," and that affects the types and textures of dishes that cultures develop, as does the need for combining foods—rice and beans being the simplest example—to create a complete protein.
By now most people are familiar with umami, the savory fifth basic taste. L-glutamate, the amino acid responsible for the flavor, is present in meat, mushrooms, hard cheese, tomatoes, and many other foods. The umami in glutamate is potentiated by several nucleotides, among them guanosine monophosphate and inosine monophosphate, which happen to be present in dried fish. What makes all this technical and polysyllabic information fascinating are the diverse ways in which different cultures have figured this out: tomato sauce with mushrooms or anchovies and parmesan on top in Italy, Chinese cabbage and chicken soup, fish sauce in Southeast Asia, and probably the purest expression of umami on the planet: dashi, the mother stock in Japanese cuisine, where glutamate comes from kombu (kelp) and dried bonito fillets provide inosinate. Humble, unassuming ketchup (derived from the Indonesian kecap) is a powerful umami-amplifier, based as it is on tomatoes and (originally, anyway) fermented anchovies, and everyone knows about soy sauce. If this still sounds arcane, try making your beef stew with a few anchovies and dried mushrooms and a bit of soy sauce and tomato paste and see if it isn't a lot more interesting.
The class works in the other direction, too; a deeper understanding of cooking chemistry makes scientific work more familiar. "All the processes are things we use in the lab all the time," says Rossi. "When you make espresso using a moka, the water comes up at a higher temperature than boiling [because it's under pressure] so the grinds are finer than you use for a drip, which is exactly what we do in high-pressure liquid chromatography," a technique for analyzing the chemical makeup of different compounds. The fine grind means more surface area, and thus better extraction, "but that also creates more resistance so you need more pressure."
The class compiles a cookbook at the end of each semester, and each student contributes a recipe. This is clearly an elective that people are happy to take; the students are attentive and cheerful. Henry Liang is an STS (Science, Technology, and Society) major who is writing his thesis on food labeling and GMOs. "It has increased my interest in both [science and cooking] and offered me more exposure because otherwise I wouldn't have the time." Sarah Haven is a psychology major who hopes to become a farmer. "I think it's important to make as much food as possible from scratch and thought this class would enhance my knowledge of cooking. Many of the food projects I am interested in—fermenting, canning, sourdough, and general preservation—have processes that could be strengthened by learning the basic chemistry behind them." Biology major Kevin Lee says that though his family loves to eat out, he wants to cook at home: "While the course has allowed me to appreciate chemistry even more, I feel so much pleasure and enjoyment while cooking, to the point where I am excited for the moment where I have a counter full of ingredients and cooking tools and I can make virtually anything I want." Haven, obviously angling for an A, concludes with a sentiment that should make her teachers proud: "I definitely will continue to cook and experiment with foods. I am grateful to have learned about the processes that occur in many different food projects and will keep this knowledge with me."