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P 053
Sake fermentations:
what can brewers learn
P 054
Unraveling the yeast flocculation
mechanism at the molecular level
P 055
Worldwide breeding strategy for
LOX-less barley and characteristics
of new Australian malting barley
variety ‚SouthernStar‘
Daniel Kerruish 1 , Trevor Phister 1 ,
Katherine Smart 2
1University of Nottingham, Nottingham, United Kingdom,
2SABMiller plc, Woking, United Kingdom
Francesco Ielasi 1 , Katty Goossens 1 ,
Ronnie Willaert 1
1Vrije Universiteit Brussel, Brussels, Belgium
Makoto Kihara 1 , Wataru Saito 1 , Takehiro
Hoki 1 , Takashi Iimure 1 , Naohiko Hirota 1 ,
Masayuki Shimase 2 , Kiyoshi Takoi 2 , Jason
Eglinton 3 , Shinji Yamada 1
1SAPPORO BREWERIES LTD., Bioresources Research and
Development Department, Gunma, Japan, 2 SAPPORO BRE-
WERIES LTD., Product & Technology Innovation Department,
Shizuoka, Japan, 3 The University of Adelaide, School of
Agriculture, Food and Wine, Waite Campus, Australia
DESCRIPTION OF TOPIC:
Sake fermentations use rice, water and a
co-culture of Aspergillus oryzae (Koji) and
Saccharomyces cerevisiae (Kyokai) to achieve
ethanol yields of up to 22%. Sake fermentations
derive fermentable sugars from the
breakdown of polished rice by the exogenous
enzymes produced by Aspergillus oryzae.
These fermentable sugars are then utilised by
S. cerevisiae. Sake fermentations are therefore
complex in nature and poorly understood.
The purpose of this work is to understand the
reasons why Sake yeast are apparently so
ethanol yielding and ethanol tolerant.
There are several possible reasons for this:
fermentations are conducted with Aspergillus
oryzae this mixed fermentation may be beneficial
to the yeast; Sake yeast strains may
also have a more effective ethanol defence. In
this presentation these two hypotheses will
be discussed.
DESCRIPTION OF TOPIC:
Yeast cell flocculation is exploited in the brewery
industry as an easy and cost-effective
way to separate the aggregated yeast cells
from the beer at the end of the primary fermentation.
The flocculation mechanism is
based on a lectin-carbohydrate interaction,
but was until recently not yet fully clear. The
Flo adhesin family, in particular FLO1 and Lg-
FLO1 gene products are lectins responsible
for the Ca2+-dependent yeast flocculation
phenotype. A biophysical study of the flocculation
mechanism on the molecular level was
carried out. The N-terminal carbohydratebinding
domains of Flo1p from the ale yeast
Saccharomyces cerevisiae and Lg-Flo1p
from the lager yeast S. pastorianus were produced
from suitable recombinant expression
systems. Later on, a combination of protein
crystallography, kinetic binding experiments
and Single-Molecule Force Spectroscopy allowed
us to refine the model for the binding of
these proteins to yeast cell-wall glycans.
DESCRIPTION OF TOPIC:
For years, people talk about the quality of
draught beer and their potential for improvement.
Developments in dispensing systems
are, however, in most cases, just to improve
the appearance of the equipment. The most
important aspect for a brewer - hygiene - is
often neglected. As a consequence, the quality
of beer is destroyed in the last few meters,
just before the consumer enjoys it.
We carried out extensive studies on construction,
cleaning and maintenance of dispensing
equipment. It was found here that the microbial
load in draught beer could be reduced by
good hygiene practices in 6 weeks by more
than 90%. The investigation of design aspects
also brought strong improvements. Here also
immense hygienic improvements were observed.
The presentation shows these findings and
gives advice, such as fast recontaminations
can be avoided and the draught beer quality
can be improved. The presentation also will
show the growth and sensorial influence of
microbial infections in draught beer.
Daniel Kerruish
Francesco Ielasi
Makoto Kihara
Having gained a degree in microbiology from
Liverpool University in 2001 and a PhD from
Kings College London in 2007; Daniel spent 4
years working as a technical brewer before
furthering his research interests at the University
of Nottingham. His current research
interests are focussed upon sake fermentations
and ethanol tolerance of yeast.
PhD student at the Vrije Universiteit Brussel
- VUB
Since 1990: Research Scientist in the Plant
Bioengineering Research Laboratories, Sapporo
Breweries Ltd., Since 2009: Chief of Barley
R&D center in the Bioresources Research
and Development Department, Sapporo Breweries
Ltd.. Since 1999: Doctor (Title of doctor
thesis: Establishment of technique for the
production of transgenic plants using protoplast
culture system in barley).
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