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P 092
Reactivation of exhausted yeast
physiological activity
P 093
Evaluation of Near-Infrared Spectroscopy
(NIRS) for on-line determination
of critical process parameters
for fermentation process
control
P 094
A systematic search for novel yeast
strains with superior fermentation
characteristics
Mario Novak 1 , Filip Cingesar 1 , Zvonko
Petrović 2 , Philippe Cario 3 , Božidar Šantek 1
1University of Zagreb, Faculty of Food Technology and
Biotechnology, Department of Biochemical Engineering,
Zagreb, Croatia, 2 Ireks Aroma d.o.o, Zagreb, Croatia, 3 AEB
SPA, Brescia, Italy
Lucas Vann 1 , Johnathon B Layfield 1 , John D
Sheppard 1
1North Carolina State University, Food, Bioprocessing & Nutrition
Sciences, Raleigh, United States
Jan Steensels 1 , Gino J.E. Baart 1 , Tim Snoek 1 ,
Esther Meersman 1 , Veerle Saels 1 , Martina
Picca Nicolino 1 , Kevin J Verstrepen 1
1KU Leuven, CMPG/VIB, Leuven, Belgium
DESCRIPTION OF TOPIC:
Aims: The aim of this research was to prolong
the yeast re-pitching process without loosing
beer quality.
Methods: In this research lager yeast (5th
generation stored at + 4 oC for 5 days) was
used for wort fermentation where yeast properties
and metabolites concentrations were
monitored. In order to reactivate yeast activity
different nutrients mixtures (amino-acids,
peptides, proteins, vitamins and minerals)
were prepared.
Results: The use of inorganic or organic nutrients
mixtures insures that fermentation will
be successfully completed compared to the
fermentation without nutrients mixture. The
use of organic nutrients mixture resulted in
the increase of yeast concentration and in the
reactivation of fermentation process. Reactivated
yeast was also capable to perform a
few more fermentations.
Conclusions: The use of organic nutrients
mixture can significantly improve exhausted
yeast activity and to reactivate declined fermentation
without considerable impact on the
beer quality.
DESCRIPTION OF TOPIC:
The search for improved methods for process
control has led to the development and application
of Near-Infrared Spectroscopy (NIRS).
NIRS can be implemented in real-time with
several determinations being made simultaneously
from a single spectral scan thereby
maximizing process monitoring and control
capabilities. The present research explores its
potential for on-line fermentation monitoring
of specific gravity (SG), free amino nitrogen
(FAN) and percent alcohol by volume (% EtOH
v/v) for the purpose of control of fermentation
rate and maturation time. Pilot-scale batch
model predictions correlated well with offline
analysis yielding the following average
error of predictions: SG (0.09%), EtOH (3.39%),
FAN (4.85%). The findings support the possibility
of incorporating NIRS into commercial
brewing operations for continuous “real time”
assurance of quality by permiting early fault
detection and the real-time control of yeast
metabolism, for example, through temperature
adjustment.
DESCRIPTION OF TOPIC:
Fermented foods and beverages have been
consumed by humans for over 8000 years.
Originally, these fermentations were spontaneous
processes, without any control or
knowledge of the microbial driving force behind
them. To increase reproducability, welldefined
starter cultures were introduced.
Until recently, the tools and knowledge were
lacking to make a scientifically found choice
about which strain to use in these starters. In
this study, we screened a wide variety of industrially
relevant yeast strains. This resulted
in a large collection of yeast strains (>600),
with each strain characterized to an unprecedented
level of detail. Our data allows us to
rapidly select strains for specific industrial
purposes. Additionally, this dataset provides
an excellent platform to select strains for
breeding of novel yeasts with beneficial traits
from both parents. Using several different
breeding approaches (all non-GMO), hybrids
with superior beneficial characteristics were
constructed.
Mario Novak
Lucas Vann
Jan Steensels
Research Assistant / PhD student at University
of Zagreb, Faculty of Food Technology and
Biotechnology, Department of Biochemical
Engineering. Research area is mathematical
modelling and mass transfer research in production
of biofuels and mathematical modelling
of fermentation and yeast metabolism.
Currently employed as a Senior Scientist in
the Biomanufacturing Training and Education
Center at North Carolina State University and
is pursuing a PhD on the use of NIRS for the
control of a variety of cell-culture processes,
as applied to brewing and biopharmaceuticals.
He has a masters degree in Biosytems
Engineering from McGill University in Canada,
where he helped in the development of a biosensor
for measuring diacetyl concentration
in beer.
Jan Steensels received a BSc in Bioscience
Engineering from the University of Leuven,
Belgium in 2008 and a MSc in Bioscience
Engineering, major “Cell and Gene technology“,
minor “Industrial Microbiology“ from the
same university in 2010. He did his master
thesis in the Centre for Malting and Brewing
Science in 2009-2010. In 2010, Jan joined
the VIB laboratory for Systems Biology led by
prof. Kevin Verstrepen as a PhD student.
75 34 TH EBC CONGRESS · LUXEMBOURG 26 – 30 MAY 2013