P. S. Jensen (1), C. ERMEY (1), S. W. Garden (1);
(1) John I. Haas, Inc., Yakima, WA, U.S.A.
Hops are typically analyzed for their bitter acids composition through the use of ultraviolet (UV) spectrophotometric or high performance liquid chromatography (HPLC) analysis. American Society of Brewing Chemists (ASBC) methods have been developed for UV spectrophotometric and HPLC analysis of CO2 hop extracts (Hops-8 and Hops-14, respectively). Hops-14 can also be used for HPLC analysis of hop cones and pellets, but a separate method has been approved for UV spectrophotometric analysis (Hops-6a). Each of the three ASBC methods (Hops-6a, 8, and 14) utilizes a different solvent protocol for extracting hop components for instrumental analysis. If the same solvent could be used to prepare samples for both UV spectrophotometric and HPLC analysis, it would reduce sample preparation time and laboratory solvent use significantly. Methanol is a solvent commonly employed in the extraction of hop components for analysis. In this study we explored the use of a common methanol solvent protocol for the preparation of cone hops, hop pellets, and CO2 hop extract samples for UV spectrophotometric and HPLC analysis of their bitter hop acid components. A single solvent system utilizing methanol was found to produce statistically comparable results for UV spectrophotometric and HPLC analyses of CO2 hop extracts. However, a methanol solvent system was not appropriate for extracting hop cones and pellets for UV spectrophotometric and HPLC analysis as the results were significantly different from analysis performed using the standard ASBC solvent protocols.
Cheryl Ermey earned her bachelor’s degree in biology, with a minor in chemistry, in 2005 from Central Washington University in Ellensburg, WA. Since graduation she has worked in chemistry laboratories and has lots of experience in instrumental analysis. She has been working for John I. Haas in their Hop Quality Assurance Lab since her employment in 2008. Prior to working at Haas, Cheryl worked as a microbiology technician for Ag Health Labs in Sunnyside, WA, and as a chemistry technician for Batelle Toxicology Northwest in Richland, WA. Cheryl also spent 5 years as a volunteer firefighter with the West Valley Fire Department in Yakima County.