A. D. GREGOIRE (1), S. A. Tomellini (2), K. A. Packard (2), E. A.
Brady (2), J. S. Henry (2); (1) Craft Brew Alliance, Portsmouth, NH,
U.S.A.; (2) University of New Hampshire, Department of Chemistry,
Durham, NH, U.S.A.
Poster
Several brewers report the perception that late (little to no boil time)
hop additions during the brewing process are used to increase the aroma
of the final product with minimal to no increase in bitterness.
Late-hopping has grown in popularity with the evolution of the craft
brewing industry over the past three decades, yet limited research
defines the degree of isomerization occurring in the process. We
investigated the increase of iso-alpha-acids and the analysis of
specific hop compounds in late-hopping additions in the brewing process,
specifically the addition of hops to a whirlpool. We collected samples
from an industrial brewhouse at specific times throughout the brewing
process and analyzed by HPLC and/or LC/MS for particular hop compounds. A
modified version of ASBC Method Beer-23 was used to analyze wort
samples for iso-alpha-acids and other hop compounds. Employing the
DCHA-Iso, ICS-I3 iso-alpha-acid standard obtained from ASBC and
utilizing integrals of areas of peaks in chromatographs of the ICS-I3
standard and wort samples, a determination was made for the
concentration of iso-alpha-acids in the wort throughout the brewing
process. Results show an increase in iso-alpha-acids throughout the
whirlpool process. Once the concentrations of iso-alpha-acids are
determined, calculations were preformed to determine the utilization of
the whirlpool hops at different time intervals throughout the whirlpool
process.
Austin Gregoire started working in the brewing industry in 1998, as a
summer seasonal employee in the quality assurance lab for Anheuser
Busch, while he was attending university. He graduated from St.
Michael’s College in 2000 with a degree in physics. He then obtained a
degree in brewing and distilling from Heriot-Watt University in 2004.
After graduation, he worked a short stint at Longtrail Brewing Company.
He then took a position at Redhook Ale Brewery, where he has been
working for the past eight years. He has held several positions,
including brewer and QA technician, in his time there. For the past
three years he has been working with the University of New Hampshire on
whirlpool hopping research. He is a member of IBD, from which he
obtained his diploma in brewing, and he is also a member of MBAA and
ASBC.
