Yeast and Fermentation Session
Blanca Gómez G., Laboratorio Tecnológico del Uruguay (LATU)
Co-author(s): Aaron MacLeod, Grain Research Laboratory, Canadian
Grain Commission, Canada; Tania De León, Laboratorio Tecnológico del
Uruguay (LATU), Uruguay; Michael J. Edney, Grain Research Laboratory,
Canadian Grain Commission, Canada
ABSTRACT: Fermentability is an important malt quality
parameter as it predicts potential beer production. The most important
process in brewing fermentation is the assimilation of carbohydrates and
nitrogenous compounds by yeast. An adequate level of free amino acids
in wort ensures efficient yeast growth and, hence, appropriate
fermentation performance. Wort is a very complex medium containing a
range of nutrients, and this complicates research on relationships of
fermentability with micronutrients. To study the relationship between
individual amino acid profiles and fermentability, a controlled medium
(broth) was created with high maltose syrup and pure amino acids. The
broth simulates a standard wort (12°P), and pure amino acids were added
to the solution at concentrations similar to what is expected in a
standard 12°P malt wort. Four amino acids (glutamine, asparagine,
arginine, and lysine) were studied in depth by varying their
concentration in the broth while maintaining the same total amino acid
content. Each amino acid was studied separately by preparing three model
solutions. The first contained the standard concentrations for all
amino acids; the second increased the proportion of the one amino acid
being studied; and the third contained a decrease in the proportion of
the one amino acid being studied. Each solution was fermented using
three different yeast strains (lager, ale, and Fleischman). Results
showed a significant effect of yeast strains on fermentability level.
Furthermore, changes in lysine and glutamine concentrations showed a
significant effect on fermentability for some of the yeast strains, but
asparagine and arginine presented no significant effect on
fermentability for any of the yeasts. Similar significant reductions in
pH during fermentations were also found. It was concluded that
individual yeast strains have varying requirements for amino acids, and
these requirements are not the same for each essential amino acid.
Blanca
Gómez received a B.S. degree in biochemistry from Universidad de la
República in Montevideo, Uruguay. She began employment with Laboratorio
Tecnológico del Uruguay (LATU) in 1998 as a chemist in the analytical
laboratory of the Malting Barley Unit. She worked in quality assurance
and became a quality manager for ÖVQ. In 2009 Blanca received an M.S.
degree in food science from the University of Manitoba and is working on
her research project at the Grain Research Laboratory, Canadian Grain
Commission, in Winnipeg, MB. Since 2009 she has functioned as a
scientist in the Cereals Department of LATU and is in charge of research
projects. She belongs to the Uruguayan Barley Board, serving as
executive secretary from 2010 to 2011.
VIEW PRESENTATION 245
