Program Book - Master Brewers Association of the Americas

O-22
The development and practical use of lipoxygenase-1-less
malting barley with good brewing performance
MASANORI SHIRAI (1), Kiyoshi Takoi (2), Shigeki Furusho (2),
Hideki Chiba (1), Katsuaki Maeda (2), Junji Watari (2), Hiroshi
Akiyama (1)
(1) Product & Technology Development Department, Sapporo
Breweries, Ltd., Yaizu, Japan; (2) Frontier Laboratories of Value
Creation, Sapporo Breweries Ltd., Yaizu, Japan
Lipoxygenase-1(LOX-1) is of great interest, because lipid oxidation,
which is catalyzed by LOX-1, produces deteriorating substances
in the brewing processes. Especially, trans-2-nonenal (T2N) is
considered to be a major component of the off-flavor in aged beer,
and trihydroxyoctadecenoic acid (THOD) is known to have an
adverse effect on beer foam stability. Recently, we have discovered
LOX-1-less barley lines which do not show significant LOX activity.
The LOX-1-less malting barley was made by the introgression of
the LOX-1-less character into the LOX-1-normal barley using the
molecular marker assisted selection-mediated backcross breeding
program. The brewing trials of the LOX-1-less malt indicated that
the happoshu (Japanese low malt beer) brewed with this malt has
improved flavor and foam stability. The purpose of the present
study is to show the further advantage of the LOX-1-less malt when
using another style of beer. To verify the superiority of the LOX-
1-less malt, we performed brewing trials in a 50 or 400 liter scale
pilot brewing plant. These trials included two types of the beer and
two types of the happoshu. As a result, it was found that the T2N
contents of the aged LOX-1-less beer (stored for 7 days at 37°C) were
lower than that of the control beer. The sensory evaluations showed
a noticeable superiority of the LOX-1-less beer in flavor stability.
The amount of THOD in the LOX-1-less beer was lower than that
of the control beer, which may reflect the superior beer foam
stability (NIBEM value) of the LOX-1-less beer. We found no obvious
changes between the LOX-1-less beer and control beer regarding
the thiobarbituric acid index (TBI) value and the level of strecker
aldehydes, which are indicators of aging caused by factors other than
lipid oxidation. These results suggest the superiority of the LOX-1less
malt in brewing not only happoshu, but also other various types
of beers. At present, we are producing a commercial LOX-1-less
malting barley variety, and we expect that the LOX-1-less malt will
contribute to progress in future brewing industries.
Masanori Shirai graduated from the Tohoku University, Japan
(Department of Biological Chemistry, Division of Agricultural
Science) in 1996. In 1998, he received a M.S. degree in biological
chemistry. He then joined Sapporo Breweries Ltd. as a brewing
engineer in the Gunma brewery. In 1999, he moved to the Hokkaido
brewery. In 2004–2005, he studied brewing technology at TU-
München-Weihenstephan, Lehrstuhl für Technologie der BrauereiⅠ,
Germany. Since September 2005, he has served as a deputy manager
in the Product & Technology Development Department of Shizuoka.
His specialty is brewing technology, and he is now working in the
field of new products and brewing technology development.
O-23
Thiol oxidase and the reason why we store malt
CHARLES BAMFORTH (1), Makoto Kanauchi (2)
(1) University of California, Department of Food Science and
Technology, Davis, CA; (2) Department of Food Management,
Miyagi University, ku Sendai, Japan
A single thiol oxidase (molecular weight 35,700) has been purified
from malt. The enzyme has a high pH optimum around pH 8.0 but
only approx 20% of the activity at pH 5.5 and barely any if the pH
is lowered to 5.0. It is relatively thermo-tolerant, with significant
survival of activity even at 80°C. The enzyme is present in raw barley
and decreases in activity during germination. The enzyme declines
in activity during storage of malt, with complete decay in 2 weeks at
30°C and almost complete disappearance after 3–4 weeks at 20°C.
It was demonstrated that thiol oxidase reduced filtration rates in gel
protein systems. We propose that thiol oxidase-catalyzed oxidation
of gel proteins in mashes is a key factor in lessening rates of wort
separation. We further propose that the reason that malt storage
leads to increased rates of wort separation is because there is a
progressive decline in the amount of thiol oxidase in malt.
Dr. Charlie Bamforth is chair of the Department of Food Science &
Technology and Anheuser-Busch Endowed Professor of Malting &
Brewing Sciences at the University of California, Davis. He has been
part of the brewing industry for almost 30 years. He formerly was
the deputy director-general of Brewing Research International and
research manager and quality assurance manager of Bass Brewers.
He is a special professor in the School of Biosciences at the University
of Nottingham, England, and was previously visiting professor of
brewing at Heriot-Watt University in Scotland. Charlie is a Fellow of
the Institute of Brewing & Distilling and of the Institute of Biology.
Charlie is Editor-in-Chief of the Journal of the American Society of
Brewing Chemists and has published numerous papers, articles, and
books on beer and brewing.
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