Tracking IBU Through the Brewing Process: The Quest for Consistency

Aaron Justus. Director of R&D and Specialty Brewing, Ballast Point Brewing.
International Bitterness Units (IBUs) were measured with a spectrophotometer throughout the brewing process for a wide variety of beer styles. Most of the data were collected at our 50 BBL Scripps Ranch facility, although some data were also gathered from our 5 BBL R&D brewery and 150 BBL production facility. It was determined that mash hops add a small amount of IBUs to wort with an average utilization of 9.1%. As expected, 60 min hop additions added substantially more IBUs; the average hop utilization was 44.0%. Whirlpool hops also contributed high IBUs with an average utilization of 29.9%. In addition, hot-side wet hopping had 8.0% utilization. A large amount of IBUs are lost during the first 2 days of fermentation. Losses were also observed during filtration. It was discovered that high amounts of dry hopping resulted in an increase of IBUs. However, the average overall IBU loss in the cellar was 33.7%.

Keywords: Utilization, Hop rate, IBU, Iso-α-acid, Spectrophotometer, Isomerization

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