The degradation and proliferation of alpha and beta Acids in hops
Bachelor of Science
Hop pellets and plants contain alpha and beta acids that are essential to the brewing of beer. The levels of these acids increase as the hop plant matures and decrease due to oxidation as hop pellets age. Preliminarily, moisture tests were performed on both Galena and Hallertau fresh hops as well as Northern Brewer and Mt. Hood hop pellets. Fresh hop samples, Galena and Hallertau, both contained a moisture level of approximately 80%, while Nothern Brewer and Mt. Hood hop pellets had moisture levels less than 10%. The proliferation rate of alpha and beta acids in Hallertau and Galena was monitored over a course of 64 days, testing the acid content semi-weekly using UV-visible spectrophotometry. The alpha acid content of Galena hops showed an increase of 0.08% per day while the beta acid content showed an increase of 0.01% per day. Hallertau also showed an alpha acid content increase of 0.08% per day and a beta acid content increase of 0.01% per day. Over 123 days, the degradation of alpha and beta acids in Nothern Brewer and Mt. Hood was also monitored. Samples were stored at three different storage temperatures: room (23°C), fridge (4°C), and freezer (-17°C). The acid content of each storage condition sample was tested weekly using UV-visible spectrophotometry. Both hop pellet samples stored at room temperature showed a decrease in alpha acid content throughout the experiment, while samples stored in both a fridge and a freezer maintained a relatively constant alpha acid content. The beta acid content of both samples showed a decrease at the room temperature, a slight decrease at the fridge temperature, and remained relatively constant under freezer conditions.
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