D. M. VOLLMER (1), Y. P. Qian (1), G. Shellhammer (2), T. H. Shellhammer (1); (1) Oregon State University, Corvallis, OR, U.S.A.; (2) Shellhammer Consulting LLC, Corvallis, OR, U.S.A.
Technical Session 3 - Hop Aroma
Monday, June 15
Dry-hopping is a method whereby hops are added post-fermentation to deliver hop aroma to beer without subjecting the hop material to the volatilization that occurs in hot-side hopping techniques. The oil fraction of hop material is a reservoir of compounds with aromatic properties and we hypothesized that dry-hopping with hops having greater oil content would lead to beer with more aroma. Whole-cone Cascade hops with three different levels of total oil (0.6 mL/100 g; 1.2 mL/100 g; 2.0 mL/100 g) were used to separately dry-hop 12 L of pale ale at a fixed dry-hopping rate of 3.8 g/L for 12 and 24 hours. Dry-hopped beers were evaluated using descriptive analysis techniques and analyzed instrumentally by SBSE GC-MS. Sensory differences among the beers prepared with different levels of oil were shown to not be influenced by exposure time (P = 0.718) and were suggestively influenced by the level of total oil content (P = 0.055). Instrumentally, the effect of time was also deemed not significant for all of the target analytes with the exception of linalool and geraniol, and to some extent nerol and β-eudesmol. For the effect of oil, significant differences were measured among the treatments in terms of the concentrations of linalool, geraniol, geranyl acetate, and caryophyllene oxide among others. The conclusions of this work suggest that longer dry-hopping times do not necessarily result in increased aroma intensity in dry-hopped beers from a sensory perspective. There is a slight trend in hop aroma intensity with increasing hop oil content but this needs further testing to verify. Instrumentally, dry-hopping for extended periods of time, or with hops that have higher levels of total oil, resulted in increased levels of certain analytes, particularly terpene alcohols. This work provides insight into the role of hop oil content and quality and could elucidate which raw material properties serve as indicators of beer performance for hops primarily used for aroma purposes.
Daniel Vollmer is a doctoral candidate in the Food and Fermentation Science program at Oregon State University working in Thomas Shellhammer’s lab. His research examines the origins of hop aroma in beer, specifically studying the aroma of oxidized hops, water-soluble flavor precursors in hops, and the influence of hop oil content on dry-hop aroma in beer. Additionally he has developed course work in support of OSU’s annual Beer Analyses workshop series, focusing on quality assurance and control, and contributes to the execution and delivery of these courses. Daniel is a member of the American Society of Brewing Chemists and the Institute of Food Technologists. He completed the UC Davis Master Brewers Program in 2012 and received his M.S. and B.S. degrees in food science from the University of Massachusetts, Amherst, in 2011 and 2010, respectively.