As the dog days of summer pass, and wile many start moving their regular order from iced to pumpkin spice, I thought it was time to investigate the chemistry of America’s original favorite beverage, coffee.
Locally, there is no better person to talk to about the ways of caffeine than Wendy Cahill, owner of Bethel’s community coffee house, Molten Java.
Coffea is a shrub or small tree, native to tropical parts of Africa and Asia, but now widely grown in tropical parts of Central and South America. The plant produces caffeine to deter insects and browsers from eating it, but, as with many plant toxins, humans like what it does to their body, so they have cultivated it to make more of the toxin! There are two main species; Robusta, which has a lot of caffeine, and Arabica, which has less caffeine but is sweeter. The coffee fruit is not really a ‘bean’ or a ‘cherry’, though we call them that.
The soil the plant is grown in, how much rain and sun, and how the ‘cherries’ are processed all produce very distinct flavour profiles in the final coffee beans. Cahill’s favorite raw beans are from Honduras, where the high-mountain farms still tend to be small-scale and often use the ‘wet process’ to finish the raw bean. This is where the cherry is pulped, which can then be used for caffeinated soft drinks. The beans are then fermented to remove any clinging pulp, and finally washed – by actual monsoon rains in Papua New Guinea – then usually sun-dried, all of which results in a ‘brighter’ tone in the final roasted bean.
The raw bean contains a heady mix of different chemicals, predominantly caffeine, but also flavonoids, the starter chemicals for many of the flavors humans crave. Important in coffee are those that provide its characteristic bitterness, chlorogenic acids. Milder chocolate flavors are the result of chlorogenic acid lactones, like 3-caffeoylquinic-1,5-lactone, and darker, more bitter flavors come from a further breakdown of the chlorogenic acids to phenylidanes. Most other flavors come from the Maillard reaction. This is seen when proteins and sugars in food combine into flavor compounds that are controlled by the heat and temperature the food is cooked at, which is where the roasting process comes in.
Large-scale roasting happens in drum roasters, which look like massive washing machines. Cahill’s roastery is small-scale and uses a hot air roaster, not dissimilar to a popcorn air popper. She controls the temperature and the longevity of the roast to get different complexities from her beans. Being small scale allows Molten Java’s coffee to be very distinct from other offerings, and also allows her to make beans to her customers’ preferences. “From the plant to how they pick it, and how they dry it, all of that can be really different from plantation to plantation”, so she works with specific smaller operations to maintain her coffee’s consistency. I asked Wendy the best way to drink coffee and she says, “For me, there is no better way than traditional Italian Espresso, where you get all the darker notes and it pulls all the oils out to make that beautiful crema.”
Excuse me, while I order my coffee, hold the pumpkin spice! •
