Reglitz, K., Deutsche Forschungsanstalt für Lebensmittelchemie, Freising, GERMANY
Technical Session 2: Hops I
Sunday, June 04, 2017
2:45–4:00 p.m.
Gardens Ballroom
To increase the shelf life of beer and enhance its bitterness, hops are traditionally added at the beginning of the wort-boiling process during beer production. To impart a hoppy aroma, a second portion of hops must be added later in the process, typically after wort boiling (late-hopping) or during conditioning (dry-hopping). One of the key compounds for the hoppy aroma in beer is citrusy smelling linalool. Depending on the variety, further hop compounds can be transferred into the beer in aroma-active amounts. One of these is black currant-like smelling 4-mercapto-4-methyl-2-pentanone (4MMP), which exhibits an odor threshold as low as 0.00055 µg per liter of beer. The aim of this study is to get a deeper insight into the concentration of 4MMP in different hop varieties, its variability and its behavior during hop processing. As a first step, a sensitive analytical approach based in a stable isotope dilution assay (SIDA) in combination with the selective enrichment of thiols on mercurated agarose gel and GC×GC-TOFMS was developed. Application to more than 80 samples of hops covering 45 different varieties from the U.S. and Europe revealed 4MMP concentrations between 0 and 114 µg/kg and allowed, therefore, an estimation of the impact of variety and provenance on the 4MMP contents in hops. Further experiments were focused on changes in 4MMP concentrations during hop processing. Results indicated that the temperature and the pelletizing process did not have a significant influence on the 4MMP concentration.
Klaas Reglitz is a research scientist in the group of Martin Steinhaus at the Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut (German Research Center for Food Chemistry, Leibniz Institute) in Freising-Weihenstephan, Germany. He studied brewing and beverage technology at the Technische Unversität, München (Technical University of Munich) and received a Ph.D. degree in food chemistry for a thesis on the “Influence of Composition and Structure on the Release of Aroma Compounds from Foamed Milk Model Systems.” Klaas is currently working on the identification of odor-active compounds in different materials, including hops, orange juice, and consumer products.
