TY - JOUR
T1 - Selection from industrial lager yeast strains of variants with improved fermentation performance in very-high-gravity worts
AU - Huuskonen, Anne
AU - Markkula, Tuomas
AU - Vidgren, Virve
AU - Lima, Luis
AU - Mulder, Linda
AU - Geurts, Wim
AU - Walsh, Michael
AU - Londesborough, John
PY - 2010
Y1 - 2010
N2 - There are economic and other advantages if the fermentable sugar
concentration in industrial brewery fermentations can be increased from
that of currently used high-gravity (ca. 14 to 17°P [degrees Plato])
worts into the very-high-gravity (VHG; 18 to 25°P) range. Many
industrial strains of brewer's yeast perform poorly in VHG worts,
exhibiting decreased growth, slow and incomplete fermentations, and low
viability of the yeast cropped for recycling into subsequent
fermentations. A new and efficient method for selecting variant cells
with improved performance in VHG worts is described. In this new method,
mutagenized industrial yeast was put through a VHG wort fermentation
and then incubated anaerobically in the resulting beer while maintaining
the α-glucoside concentration at about 10 to 20 g·liter−1 by
slowly feeding the yeast maltose or maltotriose until most of the cells
had died. When survival rates fell to 1 to 10 cells per 106
original cells, a high proportion (up to 30%) of survivors fermented VHG
worts 10 to 30% faster and more completely (residual sugars lower by 2
to 8 g·liter−1) than the parent strains, but the
sedimentation behavior and profiles of yeast-derived flavor compounds of
the survivors were similar to those of the parent strains.
AB - There are economic and other advantages if the fermentable sugar
concentration in industrial brewery fermentations can be increased from
that of currently used high-gravity (ca. 14 to 17°P [degrees Plato])
worts into the very-high-gravity (VHG; 18 to 25°P) range. Many
industrial strains of brewer's yeast perform poorly in VHG worts,
exhibiting decreased growth, slow and incomplete fermentations, and low
viability of the yeast cropped for recycling into subsequent
fermentations. A new and efficient method for selecting variant cells
with improved performance in VHG worts is described. In this new method,
mutagenized industrial yeast was put through a VHG wort fermentation
and then incubated anaerobically in the resulting beer while maintaining
the α-glucoside concentration at about 10 to 20 g·liter−1 by
slowly feeding the yeast maltose or maltotriose until most of the cells
had died. When survival rates fell to 1 to 10 cells per 106
original cells, a high proportion (up to 30%) of survivors fermented VHG
worts 10 to 30% faster and more completely (residual sugars lower by 2
to 8 g·liter−1) than the parent strains, but the
sedimentation behavior and profiles of yeast-derived flavor compounds of
the survivors were similar to those of the parent strains.
U2 - 10.1128/AEM.03153-09
DO - 10.1128/AEM.03153-09
M3 - Article
SN - 0099-2240
VL - 76
SP - 1563
EP - 1573
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
IS - 5
ER -