By Molly Spencer
The coffee industry had been established long before it was introduced to the academic world. The industry had mostly operated on empirical observations based on what worked and what didn’t work. However, in this day and age, the industry faces complex issues such as sustainability and environmental production challenges, the need for consistency in the final cup despite multiple complex processes (growing, roasting, grinding, and brewing), and a growing consumer demand for specialty coffee. This is in addition to the need to build consumer knowledge of coffee flavor notes and awareness of personal sensory preferences in coffee. There is an increasing need to introduce coffee to the world of academic research and incorporate scientific studies into the coffee industry. I am thrilled to be involved during this exciting time in the coffee industry, and I am honored to have the opportunity to share the experience of my initial steeping in the coffee industry.
I was a fresh-faced, mildly caffeinated first- year PhD student when I decided to apply to be a teaching assistant for the relatively new University of California, Davis (UCD) “Design of Coffee” general science/engineering education course, taught by William Ristenpart, PhD, and Tonya Kuhl, PhD. At that point, I drank coffee most days, but I regret to admit that I would add obscene amounts of sugar and milk. Dr. Ristenpart’s class was a great learning experience for not only all of the students, but for me as well. The class demonstrated that each of the various complex processes, from the green bean to roasting to grinding to brewing, can have a tremendous effect on the final outcome, the cup of coffee. The class also taught the students that with appropriate methods of farming, roasting, grinding, and brewing, the flavor of a cup of coffee can be extremely enjoyable in and of itself—with no milk or sweetener added. This class completely changed my mindset about coffee, and I expect that it will have a similar effect on its students for years to come.
Later that year, in the summer of 2015, the Specialty Coffee Association of America (SCAA) came to UC Davis with an extensive coffee lexicon that had been developed in collaboration with World Coffee Research, Kansas State University, and Texas A&M University. There were over 100 words describing coffee flavor (that is, taste and aroma), texture and mouthfeel, and balance. The goal was to arrange the unorganized vocabulary list into a flavor wheel in a statistically and scientifically valid way that also made sense intuitively. I had enjoyed teaching in Dr. Ristenpart’s coffee class, so I eagerly took on this project, under the guidance of my professor, Jean-Xavier Guinard, PhD.
For this project, we recruited 29 highly trained panelists who were regular coffee drinkers and familiar with most of the flavor descriptors in the coffee lexicon. These panelists had experience with Descriptive Analysis, a sensory science technique, in chocolate and/or wine at UC Davis. Additionally, we recruited 43 industry participants, with a wide range of experience in the coffee industry. The lexicon was reduced to 99 coffee flavor attributes, and these attributes, along with their definitions, were imported into a web user interface. The 72 participants were asked to remotely complete a free sorting exercise, sans tasting, arranging the attributes into a hierarchy of as many clusters and levels and as they deemed necessary. The definitions were conveniently provided on the website to assist the participants when they were less familiar with a flavor descriptor.
Once all 72 subjects had completed the sorting exercise, the data was compiled and summarized. The datasets from the two groups, industry experts and trained panelists, were compared using a statistical technique called Multiple Factor Analysis (MFA). The groups were not significantly different, which was fascinating and exciting because it demonstrated agreement between the coffee industry experts and the trained panelists we have here at UC Davis—regular consumers of coffee. This is important because it indicates that the Coffee Taster’s Flavor Wheel can be used as an effective communication and training tool in the coffee industry, a research and education tool in the academic world, and a resource with which everyday consumers can expand their knowledge.
Since the coffee industry and sensory expert groups were not significantly different, the flavor wheel was built by combining the data from both groups, then using two multivariate statistical techniques to develop the structure of the wheel. Agglomerative Hierarchical Clustering (AHC) was used to determine the structure of the main categories and levels for the wheel. Multidimensional Scaling (MDS) was used to establish the positioning of the main categories and sub-categories around the wheel, placing those most similar near each other, and those most dissimilar further from one another. Once the flavor wheel structure was established, marketing took over and designed it to be aesthetically pleasing.
Since its release, the flavor wheel has had numerous articles written about it, countless “selfies” taken with it, and has appeared at multiple conferences. My first professional coffee event was the Sensory Summit hosted by the SCAA in January 2016 at UC Davis. At the Summit, I assisted Emma Sage, SCAA’s coffee science manager, in unveiling the new flavor wheel. The project and final product were met with enthusiasm, and it was such a pleasure to meet so many friendly faces in the coffee industry, including some of those that I had worked with on this project. The flavor wheel was met with the same enthusiasm, on a larger scale, at the Re:co Symposium and SCAA Expo in April 2016.
The most exciting aspect of the Coffee Taster’s Flavor Wheel is its universality. As we discovered during its creation, the wheel is intuitive and useful to anyone involved in specialty coffee, from the coffee industry experts, to scientists and educators, to consumers. As more people become involved in the specialty coffee industry, the academic and general population will gain exposure to specialty coffee and gain knowledge from tools like the flavor wheel. The Coffee Taster’s Flavor Wheel project is a pioneering example of how mutually rewarding collaborations can successfully merge the coffee industry with university research to advance coffee science. There is a wealth of untapped potential for coffee research in sensory science, as well as many scientific disciplines, to study the intricate complexities of the numerous processes involved in coffee production, from the agricultural production to the final brewed cup of coffee. Future collaborations between the coffee industry and academia will assist in advancing the coffee industry and solving the industry’s complex current issues in ways that may not have been feasible in the past.
Molly Spencer is a second-year PhD student in the UC Davis Food Science graduate group. She currently works in Dr. Jean-Xavier Guinard’s sensory science laboratory on projects related to sensory determinants of food intake, nutrition, and consumer research. Molly attended North Carolina State University (NC State) to obtain a B.S. in Food Science in May 2013. She took a year off from school, working in the pharmaceutical industry in an analytical chromatography lab, before beginning her studies at UC Davis in fall of 2014.