GIFTS: A Chemical Engineering Module About Coffee

We developed a two-week module for a general first-year engineering course to teach students fundamental chemical engineering tools and processes using coffee. This work was a collaboration among the first-year engineering faculty, chemical engineering faculty, and experts of a local coffee roaster. Working in teams of four, students complete four labs: 1) brewing coffee with different brew methods, 2) programming a coffee analysis program using MATLAB, 3) creating a mass balance and process flow diagrams, and 4) creating a new coffee brewing device in a design challenge. Through brewing coffee, students learn about extraction and filtration, which are common chemical engineering processes. They determine the effects of changing the temperature, extraction time, brew ratio, brew method, and grind size on the brew quality, which is measured using both quantitative and qualitative parameters. The total dissolved solids (TDS) of the brew is measured using a portable refractometer. The percent of the original coffee bean extracted can then be determined from the TDS and the brew ratio. The relative flavor of the coffee can then be calculated from a plot of TDS vs. percent extraction. Finally, students evaluate the flavor and aroma of the brew by tasting. In addition, students learn how to create a mass balance and track the mass of coffee through the brewing process, accounting for the final mass in the brew, residuals in the filter, and any spillage. They also make a process flow diagram of a coffee brewing process.