Program Book - Master Brewers Association of the Americas

O-12
Investigations on the behavior of organic radicals in barley
and malt during the malting and mashing process by electronspin-resonance
spectroscopy
FRANK-JUERGEN METHNER (1), Thomas Kunz (1), Naoyuki
Kobayashi (2)
(1) TU Berlin/VLB Berlin, Berlin, Germany; (2) Sapporo Brewery,
Ltd., Shizuoka, Japan
Barley, malt and spent grain as well as the malting and mashing
process were investigated by using Electron-Spin-Resonance (ESR)
spectroscopy. For solids a method using a new reference signal was
applied. The ESR spectroscopy is a rapid method for detecting ions
and organic radicals containing unpaired electrons. It can be used for
liquid and solid samples. Besides liquid measurements, ESR-spectroscopy,
using Mn 2+ as an internal standard, has been used in the
past to control the concentration of organic radicals in malt or green
malt and their development during the malting process. The new
reference signal is detectable directly besides that of organic radicals
in the ESR spectrum and allows a better quantitative detection of
organic radical concentration. Influences on the sample also have an
impact on the reference signal, because the substance responsible for
signal generation is positioned next to the sample in the spectrometer.
Based on this background, it is possible to analyze the radical
concentration in barley, malt and spent grain quantitatively. Besides
low temperature ESR-measurements (77 K) for the detection of typical
metal ions in malt, the new reference signal has been used for the
investigation of organic radical concentration in different fractions
of malt samples as well as the development of organic radicals during
the mashing and malting process under different technological conditions,
such as steeping degree, germination time, withering and
curing under different atmospheres like oxygen, nitrogen and CO 2 .
The results show different concentrations dependant on certain malt
fractions. The highest concentrations were located in husks, whereas
the lowest were found in the endosperm. Therefore a correlation
between extract yield and radical concentration in spent grain with
respect to mass was achieved. It could be shown that mashing conditions
also have an impact on the concentration of stable organic radicals,
because they are able to react partially with organic reactants
during the process. Based on this background it is possible to use this
method to investigate spent grain analysis via ESR to observe influences
on mashing, e.g. the applied mashing process (temperature,
time, rests) or the use of sonic waves. Withering and kilning have a
major influence on radical generation in malt depending on malting
conditions. A strong increase in radical concentration during withering
and kilning shows high stress conditions and intensive oxidation
reactions. Investigations on barley have shown that the concentration
of organic radicals can vary strongly depending on environmental
and storage conditions (humidity, temperature, drying).
From 1975 to 1981, Frank-Juergen Methner studied brewing science
at the Technical University of Berlin (TU). After these studies, he
began working as an operating supervisor at the Schlosser Brewery.
From 1982 to 1986 he worked as a scientific assistant with teaching
duties at the Research Institute for Brewing and Malting Technology
of VLB in Berlin. His research projects and Ph.D. thesis, “Aroma
Formation of Berliner Weissbier with Special Focus on Acids and Esters,”
were additional tasks. For 18 years, starting in 1987, Methner
held a leading position as a director at the Bitburg Brewery, Bitburg,
Germany, with responsibilities in fields such as technology and quality
management. Beginning with the winter semester 2004/2005, he
took over the chair of brewing science at TU and is currently the head
of the Research Institute of Technology for Brewing and Malting of
the Research and Teaching Institute for Brewing (VLB). Since 2005
he has been vice-chair of the EBC Brewing Science Group.
70
Technical Session IV: Nutrition and Health
Moderator: Charles Bamforth, University of California, Davis, CA
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.
O-13
Hops and health
MARTIN BIENDL (1)
(1) Hopsteiner, Mainburg, Germany
Hops has been declared the “German Medicinal Plant of the
Year 2007”. This award makes it obvious that hops is not just a
raw material for beer production but is also a recognized natural
medicinal product. Mankind presumably used hops as a healing
plant for a long time before discovering during the Middle Ages that
it has preservation properties as a beer ingredient. Since the early
Middle Ages, use of hops in folk medicine has been documented.
It served as a remedy for treating a variety of diseases, e.g. stomach
complaints, ear infections or toothache. It is noteworthy that
such uses of hops were known both in European and in Indian-
Ayurvedic medicine and were also common in a large number
of Native American tribes in North America at a time when no
transfer of knowledge could have taken place between continents.
Hops continued to be used for healing purposes for centuries.
Today, it is mainly recommended for calming and to aid sleep. The
effectiveness of hops is attributed to its many positive constituents,
above all bitter substances and polyphenols. Especially in the last
decade, pharmacological research into the positive health aspects
of hops and hop constituents has been considerably stepped up.
Accordingly, scientific investigations are ongoing worldwide. They
are providing new information continuously that contributes to
an understanding of medicinal properties that have been used for
centuries. In the case of α-acids and β-acids, the best known hop
bitter substances, manifold antibacterial, but also anti-inflammatory
and even carcinostatic, properties have been discovered. Mixtures of
certain hop polyphenols have proved to be effective against bacteria
that cause caries or allergies. The prenylflavonoids in hops seem
to be particularly interesting. They are also classed as polyphenols
but occur relatively rarely in the plant world. The best known is
the prenylflavonoid xanthohumol, mainly because of its cancer
preventive potential, which is of exceptional interest. Some of
these hop constituents with proven positive effects are carried over
unchanged into beer during brewing (e.g. rutin, the glycoside of the
potent anti-oxidant quercetin); others are converted chemically (e.g.
isomerizations of xanthohumol to isoxanthohumol or α-acids to isoα-acids).
A multitude of positive effects has also been shown to be
associated with these isomerized compounds, e.g. isoxanthohumol
is effective against osteoporosis and iso-α-acids against diabetes. All
these nutritionally valuable beer ingredients originating from hops
as a brewing raw material promote the image of beer and provide
some convincing arguments in the discussion about beer and health.