Sara Moore | Science Editor
On Nov. 4, the community gathered at the Lyric Theater in downtown Wooster, not to watch a film, but to attend this month’s Wooster Science Café. November’s lecture was titled “The Chemistry of Flavor,” and was presented by Joe Vaughan and Courtney Farnsworth from the J.M. Smucker Co., based in Orrville, Ohio. Vaughan and Farnsworth work as research and development scientists for Smucker’s coffee division, producing brands like Folgers, Café Bustelo and Dunkin’ at home.
Vaughan’s portion of the talk began with the science of flavor. Flavor is perceived through a combination of aroma and taste. Aroma is detected in the nose by olfactory receptor neurons (ORN), which can be found throughout the nasal cavity. ORN transfers the signals to the olfactory bulb, which processes the signals and relays that information to the brain. Genetics control sensitivity to smells and preferences on pleasant versus repulsive smells. Taste is detected by taste receptor cells, which are located within tastebuds and throughout the mouth. These cells are connected to neurons that carry the signals to the brain. Humans have five specialized taste receptors for sweet, salty, sour, bitter and umami flavors. Using the senses of taste and smell, humans are able to perceive the different compounds they consume as flavor.
Vaughan then introduced the coffee value chain, which describes how coffee flavor is developed from plant to cup. His work focuses on the breeding of trees and seed harvesting to ensure that the beans are of the best possible quality. There are over 125 species of coffee, but the most common commercial species are arabica and canephora (robusta). The species and breeding of the coffee plant determine its base flavor profile, including the concentration of key compounds like sucrose and amino acids. The environment that the coffee is grown in is also important as coffee requires immense levels of specificity when it comes to temperature, moisture and elevation. Due to these specific requirements, coffee can only be grown in certain parts of the world near the equator. Once the coffee is harvested, it is then processed to remove the seed (bean) from the fruit. Different forms of processing impact the flavor of coffee through fermentation and length of drying time. The beans are then graded to ensure they meet buyer and processor standards. A large portion of Vaughan’s job involves tasting cups of coffee to ensure that the product is acceptable for consumers and ready to be sent to roasters.
After Vaughan’s presentation, Farnsworth discussed how roasting and brewing style impact the flavor of coffee. Coffee is roasted in large batches to transform the green seeds into the rich beans we know and love. Compared to dark roast coffee, light roast coffee is more acidic, has more caffeine and maintains more of its original flavor. As the coffee is roasted, it loses its water content and undergoes the Maillard reaction, where the natural sugars within the beans begin to caramelize, giving coffee its unique flavor. The longer it is roasted, the more caramelized it becomes, impacting the final taste. The last element that determines coffee flavor is the brewing method used. The fineness of the grounds and the use of heat or pressure when brewing influences which flavor notes of the coffee are noticeable in the final cup. Since it all comes from the same plant, this process is what ultimately differentiates espresso from drip coffee.
The researchers ended the talk by discussing how everyone’s personal tastes are different, so they work to make the best quality coffee possible while still leaving room for the consumer’s preferences. As Farnsworth summarized, “At the end of the day, coffee flavor is subjective. And most coffee has cream and sugar added to it. You like what you like!”
The Wooster Science Café occurs on the first Tuesday of the month from September through May. For more information on future events, please visit https://www.woostersciencecafe.org/