here - the 34th European Brewery Convention

P34
Yeast biodiversity as a tool for flavor improvement in beer
Catrienus de Jong 1 , Amparo Gamero 1 , Michael Katz 2 , Zoran Gojkovic 2
1 NIZO food research, Ede, Netherlands, 2 Carlsberg Group, Copenhagen, Denmark
During the brewing process, Saccharomyces species contribute to beer aroma development, but
hundreds of other poorly studied yeast species exist, being an underutilized resource with potential for
product innovation. MicroBeer is a miniaturized brewing process (5 ml) highly useful for screening
purposes. In this study, twelve strains presenting high potential for aroma formation were tested in
pure and mixed culture at 12°C. The results of the MicroBeer pointed out problems in maltose
utilization and masked aromas in mixed cultures. These problems were solved in the lab-scale
fermentations employing enzyme-treated wort and lower proportions of Saccharomyces yeast. This
was a clear example of the usefulness of the microsystems to screen different conditions as a tool for
improvement. In addition, some yeasts were able to produce high amount of esters, which could mean
a potential increase in beer fruitiness and some yeast combinations result to be useful for flavor
improvement.
P35
Characterisation of fresh and aged single-hop beers via hop oil constituents fingerprinting and
sensory assessment
Filip Van Opstaele 1 , Ann Van Holle 2 , Jan Van Nieuwenhove 2 , Dirk Naudts 2 , Denis De Keukeleire 3 ,
Guido Aerts 1 , Luc De Cooman 1
1 KAHO Sint-Lieven University College, KU Leuven Association, Ghent, Belgium, 2 De 'proef'brouwerij,
R&D department, Lochristi, Belgium, 3 Em. Prof., Ghent University, Ghent, Belgium
The focus of this study is on scrupulous investigation of hop oil constituent fingerprints of fresh and
aged single-hop beers aromatised with particular hop varieties using late and dry hopping techniques.
The results clearly reflect analytical and sensorial differences between fresh late and dry-hopped
beers produced with the same hop variety on the one hand and between single-hop beers aromatised
with different varieties on the other hand. Upon ageing a significant decrease of the level of hop oil
esters and terpene hydrocarbons was observed for all beers. Our results point to adsorption of
volatiles at the haze formed upon ageing and adsorption of particular volatiles at the crown liners. Hop
oil volatiles belonging to the ester and monoterpene hydrocarbons group always decrease to a higher
extent in dry-hopped beers. Sensorial data show that the fresh flavour of dry hopped beers is less
stable compared with the corresponding late hopped beers investigated in this study.
P36
From wort to beer: The evolution of hoppy aroma of single hopped beers produced by early
kettle hopping, late kettle hopping and dry hopping
Michael Dresel 1 , Tatiana Praet 1 , Filip Van Opstaele 1 , Ann Van Holle 2 , Jan Van Nieuwenhove 2 , Dirk
Naudts 2 , Denis De Keukeleire 3 , Guido Aerts 1 , Luc De Cooman 1
1 KAHO Sint-Lieven University College, KU Leuven Association, Laboratory of Enzyme, Fermentation
and Brewing Technology, Ghent, Belgium, 2 De 'proef'brouwerij, R&D Department, Lochristi, Belgium,
3 Em. Prof., Ghent University, Ghent, Belgium
Knowledge of the impact of early kettle, late kettle and dry hopping on the final flavour sensation of
beers is rather fragmentary. To gain insights into the way hoppy aroma develops, samples were taken