Program Book - Master Brewers Association of the Americas

P-82
Examination of the relationships between alcohol, original,
real and apparent extracts in pilot plant and commercially
produced beers
R. ALEX SPEERS (1), Anthony Cutaia (2), Anna-Jean Reid (1)
(1) Dalhousie University, Halifax, NS, Canada; (2) Science Source
Consulting, Ballwin, MO
Since the time of Balling (1865), brewers have been interested
in and reported on the density relationships between wort and
fermented beer. Most of these researchers were concerned with the
relationships between wort, beer extract and alcohol content and
published their work in German over a century ago. Approximations
based on relationships of the four brewing parameters, alcohol
content, original, apparent and real extracts (i.e., Aw/w OE, AE and
RE) were first reported by Balling (1865) and Holzner (1877). These
approximations (which were reported to be somewhat influenced
by OE) were developed long before linear regression methods were
developed in 1896. Aside from these approximations found in the
brewing literature (e.g., Handbook of Brewing, 1st Edition, 1995),
numerous websites report on and provide online calculators to
estimate Aw/w, OE, AE or RE knowing two of the four brewing
parameters. However, somewhat astoundingly, almost all the
reports of these ‘approximate’ relationships lack any report of the
error associated with their calculations. Given the development in
brewing sciences and advances in chemical and statistical analyses,
one might argue it is long overdue to re-examine the values of
the brewing values reported in the 1800s. In this paper we will
report various statistical analyses of relationships between Aw/w
OE, AE, and RE, as well as ratios between the corrected real and
apparent degrees of fermentation (RDF/ADF) using a dataset of
brewing parameters for 821 pilot plant and commercial beers. The
derivations and dependencies of these relationships on the original
extract relation as reported by Balling will also be reported. We will
also report on the error of these various fundamental and empirical
relationships. New predictions of AE calculated as a function of
Aw/w and RE analogous to the improved Tabarie’s formula will also
be reported. Finally, the suitability of the formula used in Great
Britain to calculate alcohol levels using original and final gravity
values for excise purposes will be commented upon. We expect this
paper will be of use to brewers in order to more accurately estimate
Aw/w and real extract values.
R. Alex Speers received his graduate education in food science at the
University of British Columbia, Vancouver, BC. He is a professor in
the Food Science and Technology program at Dalhousie University,
Halifax, NS, where he instructs students in brewing science, quality
assurance, and food product development. In the past, Alex has
been employed in the Quality Assurance departments of both Labatt
and Molson Breweries. Dr. Speers’ current research interests include
various aspects of the brewing process, including fermentability,
yeast flocculation, premature yeast flocculation, and the properties
of (and problems created by) β-glucan and arabinoxylan polymers.
He has organized and/or presented brewing workshops in China
(Changzhou, Qingdao, and Yangzhou) (1997–2005) and recently in
Toronto, San Francisco, and Nashville. In 2001 and 2002 Alex spent
a short sabbatical at CUB/Fosters in Melbourne Australia. In the
past he has instructed at the Siebel Institute of Technology, Chicago,
IL. Dr. Speers belongs to several professional societies, including the
ASBC, MBAA, and IGB. Alex is a member of the editorial boards of
Food Research International, the ASBC Journal, and the Journal of
the Institute of Brewing and chair the MBAA Technical Quarterly
Editorial Board. He has published or presented over 100 papers.
P-83
Analysis of trans-2-nonenal in beer using solid-phase
micro extraction with on-fiber derivatization and gas
chromatography/mass spectrometry
SAORI YAMAUCHI (1), Ayako Uehara (1), Osamu Ogane (1), Takeo
Imai (1), Yutaka Ogawa (1)
(1) Kirin Brewery Company, Limited, Yokohama, Japan
Flavor stability of beer is still a challenging issue for all brewers.
trans-2-Nonenal (T2N) especially is considered to play an important
role in the deterioration of beer flavor and aroma during storage.
Usually analysis data of T2N has used as an index for freshness
of beer. For analysis of T2N in beer, the HPLC method using
precolumn derivatization and column switching techniques was
reported; however, this method had some problems, which were
time-consuming; much use of materials and low reproducibility
originated from many isolation steps in this method. In this work,
we adopted solid-phase micro extraction (SPME) with on-fiber
derivatization and gas chromatography/mass spectrometry (GC/
MS) with a new internal standard as a solution for these problems.
On-fiber derivatization was conducted using O-(2,3,4,5,6pentafluorobenzyl)-hydroxylamine
(PFBOA), which was absorbed
onto a stable flex divinylbenzene/carboxen/polydimethylsiloxane
50/30 µm fiber and exposed to the headspace of a vial with a beer
sample. T2N selectively reacted with PFBOA, and the oximes formed
were desorbed into a gas chromatograph injection port, detected
and quantified by mass spectrometry with (2,3-D2)-trans-2-nonenal
as an internal standard, which was detected separately from the
target T2N. Because this newly adopted internal standard had the
same retention time as the target T2N, it enabled a very stable
method for analysis of T2N with high reproducibility. As a result,
this method detected T2N to a 0.005 µg/L level, which accordingly
showed higher sensitivity compared with the existing method.
SPME with on-fiber method and the following GC/MS don’t require
complex derivatization steps and much solvent, thus adopting this
method also enables simple and fast analysis of T2N, which would
lead to effective solutions for improving the flavor stability of beer.
Saori Yamauchi received a B.S. degree in brewing from Tokyo
University of Agriculture, Japan. She began employment with Kirin
Brewery Company, Ltd. in April 2005 as a staff member in the
research laboratories for brewing.
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