Continuous Fermentation

Petell, Taylor; Poll, Alex; Olexa, Brendan; Sailer, Meghan

Student Work

Continuous Fermentation

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Mead is a honey-based alcohol, similar in taste profile to wine, that originated in Africa thousands of years ago. Since then, mead has been produced the same way using honey, water, and a proprietary yeast strain in a batch vessel to produce distinctive meads. That was until Dr. Garth A. Cambray created a new system that combines fluidize and packed reactor technologies for much quicker and effective mead production. This unique system was adapted by our project sponsor, Maine Mead Works, who have been producing mead with this technology for 10 years. Our research analyzed Maine Mead’s continuous fermentation system and evaluated the different fermentation media within it. The media in question was the strain of yeast and the substrate used to grow the yeast and induce flocculation, which in this case was ginger. The goal of our analysis of these two media was to understand if the type of yeast and ginger affects the growth rate of yeast in the system as well as the alcohol content. To accomplish this, a pilot scale version of Maine Mead’s packed and fluidized bed column was created in our lab. After troubleshooting the scaled down column, a matrix of mini batch reactors was assembled. These mini reactors allowed for the analysis of three different substrates (Maine Mead ginger, store bought ginger, and silica beads) and two different yeasts (Maine Mead yeast and Champagne yeast). By pairing one substrate type and one yeast type it allowed us to see how specific media types affect growth and alcohol content. After two weeks the yeast growth was quantified using a UV Spectrophotometer. At the same time the alcohol content was quantified using Gas Chromatography – Mass Spectrometry. From this it was determined that the type of yeast and substrate does not affect yeast growth as the data were very comparable. However, alcohol content was variable, with silica beads and Maine Mead ginger being the most effective substrates and Maine Mead yeast being the most effective yeast. Upon determining silica beads were effective a second column was set up containing silica beads and Maine Mead yeast. As the column ran, the yeast growth continued grow on the silica beads and the alcohol content followed a positive trend. These results proved that the column media is not unique to the process and production can be supported with other materials.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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