V. A. ALGAZZALI (1), T. Shellhammer (1); (1) Oregon State University, Corvallis, OR, U.S.A.
Hops
Friday, June 6 - 8:00 a.m.-9:45 a.m.
Level 4, Red Lacquer Ballroom
The oxidation of hop alpha- and beta-acids leads to formation of many
compounds similar in chemical structure to the well-known bitter
iso-alpha-acid. Two of these oxidation products, humulinones (from
alpha-acids) and hulupones (from beta-acids), have received attention in
the literature for allegedly having a prominent bitter taste. Numerous
studies have focused on the identification, synthesis, and isolation of
humulinones and hulupones, but fewer studies have focused on the sensory
qualities of said compounds. This study focused on quantifying the
bitterness intensity of humulinones and hulupones compared to
iso-alpha-acid. Humulinones and hulupones were synthesized from alpha-
and beta-enriched hop extracts, using previously established oxidation
reactions, and then further purified. Identification and quantification
were carried out via HPLC-MS, and the chromatographic purity of the
standards was measured as greater than 95%. The standards were dosed
into unhopped lager made from 2-row pilsner malt with final
specifications of 5.1% ABV and 2.4% real extract. A trained sensory
panel assessed the bitterness intensity of humulinone, hulupone, and
iso-alpha-acid in the lager beer base. Sensory testing results revealed
the hop acids to be significantly different in bitterness intensity,
with iso-alpha-acid being more bitter than hulupone and hulupone being
more bitter than humulinone. At a concentration level of 20 ppm in the
lager beer base, the bitterness intensity of iso-alpha-acid was
approximately 1.4 times that of hulupone and 1.9 times that of
humulinone. The bitterness intensity of humulinone and hulupone is not
trivial when compared to iso-alpha-acid. These findings may help brewers
better understand the change in overall bitterness of hops as they
oxidize during processing and storage.
Victo
r Algazzali is a master’s degree student in Thomas Shellhammer’s
lab in the Department of Food Science and Technology at Oregon State
University (OSU). His research encompasses sensory science, chemistry,
hops, and beer. At OSU he has researched the bitterness quality of hop
acids, sensory changes in sour beer maturation, and oxidized hop aroma.
Prior to joining the food science program at OSU, Victor earned a B.S.
degree in food science at the University of California, Davis. During
his time at UC Davis Victor worked in a sensory science lab assisting
with consumer studies, descriptive panels, and sensory statistics.
Victor spends his free time playing soccer, camping, and brewing beer.
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