(259g) Beer Brewing As a Practical Application of Chemical Engineering Fundamentals in Lab and Design

The craft beer industry is growing exponentially due to increased consumer interest in homebrewing and new styles of beers; craft beer sales volume grew 8% in 2021 and retail sales of craft beer account for almost 27% of the $100 billion U.S. beer market. [1] Learning about the brewing process as an undergraduate chemical engineering student provides opportunities to better understand bioreactor design, process control, and reaction engineering in a more relatable and interactive way.

Brewing involves several key steps (including malting, milling, mashing, and hop leaching) with the main process step being fermentation, where chemical conversion of sugars into carbon dioxide and ethanol occurs through the growth of yeast in a bioreactor. All of these steps require close monitoring and control of key parameters including temperature, pressure, and pH in order to produce a high-quality product. By learning about these processes as undergraduate student and having a hands-on lab experience, students gain valuable knowledge on the effects that key parameters can have on the final products and how they relate to industrial brewing. This knowledge translates to other bioreactions in the chemical engineering field including the production of pharmaceuticals, biopolymers, perfumes, and other bioproducts. [2]

We created a beer brewing experiment in the senior chemical engineering laboratory course which focuses on the fermentation aspect of brewing; students use dry malt extract (DME) to create a wort that is boiled, cooled, and fermented. The experiment is aimed at investigating the effect of different parameter changes and process controls in several small-scale bioreactors of various sizes and capabilities on the final alcohol by volume (ABV) of a beer. The experiment is inquiry-based: students are encouraged to experiment with different ingredients, concentrations, or brewing techniques to allow for creativity in the number of factors that affect the quality of the final product. Important QC/QA criteria like specific gravity and temperature are measured in real time using a tilt hydrometer and students also learn to characterize their product in other ways including final pH and/or yeast cell count/turbidity. Students learn to model the kinetics of the fermentation reaction via the Monod kinetic model and aim to model and validate with data things like biomass accumulation, ethanol production rate, and substrate uptake. They also use a refractometer to do live cell counts and can use their results to compare to their kinetic model.

Additionally, the senior capstone project for the same cohort of students asked groups to do a conceptual design of a manufacturing facility for production of either 1,000 or 15,000 barrels of beer per year and some other co-product (either biochar or PHA bioplastic). Students were asked to produce both the beer and the co-product with the overall sustainability of the process in mind, considering the cultural, social equity, technical, economic, and environmental impacts of the new process over its entire lifecycle. We aim to present the results of student work from the most recent instantiation of the lab and design courses and to demonstrate the broad appeal of brewing as an application which is relevant to students.

[1] Craft Begins Recovery Amid Supply Chain Challenges. The New Brewer 44–48 (2022).

[2] Benz, G. T. Bioreactor Design for Chemical Engineers. Chemical Engineering Progress (2011).