Technical Session 13: Hops III Session
Douglas B Walsh, Washington State University, Prosser, WA, USA
ABSTRACT: Today’s beer consumer knows that hops are a key
ingredient in beer. An increasing population of connoisseurs has gained
an appreciation for hops’ essential role in creating the distinctive
flavors that characterize specialty brews. Yet, few consumers are aware
that producing hops is stressful. Hop growers face the stress of
uncertain market demand, shifting price structure, consolidation of key
customers, cancellation of contracts, increasing input costs for labor
and fuel, and environmental regulation, along with the often stressful
challenge of growing this unique specialty crop. Hop plants are subject
to stress, as well, from a variety of biotic and abiotic factors. Biotic
stress comes from pests and diseases, while abiotic stress comes from
bright sunshine, high temperatures, wind, and dust that are typical of
summer conditions in the inland Pacific Northwestern United States, in
addition to water availability. To assist growers in understanding and
overcoming stress factors, a transdisciplinary team sought and received
USDA Specialty Crop Research Initiative (SCRI) Coordinated Agricultural
Project (CAP) funding to study the plant stresses resulting from spider
mites, aphids, downy mildew, powdery mildew, and varying levels of
deficit irrigation with respect to impacts on hop quality and quantity
and also on the subsequent quality of the beer brewed with hops
subjected to controlled amounts of various stresses. The team includes
entomologists, plant pathologists, weed scientists, irrigation
specialists, economists, a sociologist, a sensory scientist, and an
outreach specialist, with researchers from Washington State University,
Oregon State University, the University of Idaho, and the USDA
Agricultural Research Service. The impacts of the various stresses have
been measured quantitatively on yield (kg/ha) and on the levels of
alpha- and beta-acids (determined by high-performance liquid
chromatography) and qualitatively in controlled laboratory sensory
(taste) analysis. In general, results thus far indicate that aphid
feeding had no impact on alpha- and beta-acids. Spider mite feeding
reduced alpha- and beta-acids, and powdery and downy mildews increased
alpha- and beta-acid levels. Deficit irrigation (water stress) decreased
yield and tended to decrease alpha- and beta-acids. The interaction of
mite spider mite feeding and deficit irrigation did not have a
significant effect on alpha- and beta-acids. Single-hop ales were brewed
within each hop stress type, with the amount of hops adjusted to
compensate for the variability in alpha-acids content. These brews were
evaluated by sensory panels at the School of Food Science at Washington
State University. Flavor panels rated brews that sustained mite and
aphid feeding or infection with downy mildew as inferior to brews made
with undamaged hops. Flavor panels preferred brews made with powdery
mildew damaged hops. At the submission of this abstract the brews made
from deficit irrigated hops had yet to be evaluated by the sensory
panel. The results of these beer studies will be described in greater
detail in the presentation.
Douglas B. Walsh is the integrated
pest management coordinator for Washington State, a professor in WSU’s
Department of Entomology, and the research director of the Environmental
and Agricultural Entomology Laboratory at the Irrigated Agriculture
Research and Extension Center in Prosser, WA. He functions as the
overall coordinator and director of the SCRI-CAP project and directs the
activities relating to arthropod management. Douglas works closely with
and has research supported by the Washington Hop Commission and the Hop
Research Council.
VIEW PRESENTATION 45
