here - the 34th European Brewery Convention

Production of the CO 2 hop extract and hop pellets (type 45) provide by-products rich in polyphenols
that may be used to initiate the formation of colloidal haze earlier in the brewing process. The haze
can be removed during filtration resulting in an improved colloidal stability and extended shelf life. We
brewed three beers: one, the control beer, was brewed in a standard way with hop extract, the others,
the test beers, were brewed with hop pellets and hop by-products. All three beers were brewed to
have identical bitterness and colour. The content of total polyphenols in the test beers was significantly
higher than in the control beer. In addition, the antioxidant capacity in the test beers was also
significantly higher. Thus, the addition of hop by-products can improve the colloidal and sensory
stability of beer without negatively influencing its sensory characteristics.
P72
Applicability of pectin as a stabilizing and fining agent for the brewing process
Thomas Kunz 1 , Kerstin Rudolph 1 , Gunnar Dingel 1 , Frank-Jürgen Methner 1
1 Technische Universität Berlin, Department of Biotechnology, Lab of Brewing Science, Berlin,
Germany
The interactions between polyphenols and proteins have been identified as one of the main reaction
systems for haze formation in beer.
Aim of the study was to evaluate the suitability of an aqueous pectin solution of citrate and potassium
metabisulfite as a stabilizing agent as described in the literature. In comparison to silica gel and PVPP
the treatment with pectin only showed no effect on the colloidal stability. The increased haze stability
seemed only based on the indirect addition of citrate and SO 2 .
Furthermore the application of pectin as a fining agent and the influence of the calcium content in beer
on the fining effect have been investigated. The fining activity of pectin could be verified and is caused
by the interaction between pectin and Ca 2+ ions which develop a network formation that traps and
sediments haze particles and yeast cells.
With the proper handling pectin is very suitable to shorten the filtration time up to 30%, and to
consequently reduce the costs.
P73
Different aliphatic structures are the cause and the remedy against primary gushing
Zahra Shokribousjein 1 , Ann Philippaerts 2 , Sylvie M. Deckers 1 , Kurt Gebruers 3 , Guy S. Derdelinckx 1 ,
Jean Titze 4 , Vladimir Illberg 5
1 KULeuven, FBIW-M²S-MbS-LIBR/site Arenberg 33, Leuven (Heverlee), Belgium, 2 KULeuven, FBIW-
M²S-COK, Leuven (Heverlee), Belgium, 3 KULeuven, FBIW-M²S-CLMT-LFoRCe, Leuven (Heverlee),
Belgium, 4 University College Cork, Cork, Ireland, 5 University of Applied Science Weihenstephan-
Triesdorf, Weihenstephan, Germany
Primary gushing of beer is due to the explosion of pressurized nanobubbles formed by the association
of Class 2 hydrophobins (HFB) around non dissolved CO 2 . It´s typical of hydrophilic containers. Once
this structure is formed, it´s impossible to destroy, except temporarily, by a physical treatment (thermic
or ultrasonic). Nevertheless, after a period, the nanobubbles rebuild as described in the model
proposed by Deckers et al (2012). In fact, the affinity between the hydrophobic patch of HFB and
gaseous CO 2 is so high that is impossible to dissociate the structure. It means that HFB need to be
associate with hydrophobic structures before they are in contact with CO 2 . Due to the low
concentrations of HFB involved (as low as 3 microg/L) peculiar aliphatic compounds and techniques of
food applications and surface chemistry (magnets) were used in order to improve the specificity and
place of the tratment and the dispersion rate of the molecule added. Industrial upscaling is now going
on.