D. M. VOLLMER (1), V. Algazzali (1), T. H. Shellhammer (1); (1) Oregon State University, Corvallis, OR, U.S.A.
Poster
Previous work by Peacock et al. (1980) acknowledges the impact of
oxidized hop compounds as they contribute to noble hop aroma. Our recent
work (Algazzali and Vollmer, 2012) showed that the instrumental aroma
profile of Hallertauer Mittelfrüh (HHA) hops changed upon storage under
pro-oxidative conditions. This exposure to pro-oxidative conditions led
to an increase in the oxygenated fraction of hop aroma compounds and a
generalized decrease in the hydrocarbon fraction. This project
investigated whether oxidized HHA hops used for dry-hopping a lager beer
would impact the total hop aroma in the finished beer using sensory
analysis techniques. A lager beer was prepared in the OSU pilot brewery
using a grist of 98% pale 2-row malt and 2% acidulated malt. Bitterness
was standardized at 15 ppm iso-alpha-acids using isomerized kettle
extracts. The wort was fermented and lagered prior to dry-hopping.
Dry-hopping was carried out in the presence of yeast (Wyeast 2124) in 22
L bale-top kegs for 3 days at 20°C at a rate of 5.8 g/L (1.5 lb/bbl).
HHA hop pellets used for the study were prepared similarly to previous
studies, with oxygen exposure at 37.8°C for 2 weeks. The beers were
filtered, carbonated, and bottled prior to sensory analysis. Ten trained
panelists were asked to discriminate the flavor of lager beers
dry-hopped with non-oxidized HHA pellets and oxidized HHA pellets.
Panelists were able to detect the flavor difference between the two
samples using triangle tests. Within the trained group, the beer
produced with the oxidized hops was described as more fruity, floral,
and herbal. These results demonstrate that oxidation during hop storage
may have an impact on qualitative changes in hop aroma when the hops are
used for dry-hopping.
Daniel Vollmer is a doctoral student at Oregon State University and a
member of Thomas Shellhammer’s laboratory. His research examines the
origins of hop aroma in beer, specifically studying the aroma of
oxidized hops, water-soluble flavor precursors in hops, and influence of
hop oil content on dry-hop aroma in beer. Additionally he has developed
coursework 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 ASBC Program Committee. He
completed the UC Davis Master Brewers Program in June 2012 and received
his M.S. and B.S. degrees in food science from the University of
Massachusetts Amherst.
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