VIEW ARTICLE DOI: 10.1094/ASBCJ-54-0050
Effect of Starvation on the Flocculation of Ale and Lager Brewing Yeasts. Maureen R. Rhymes and Katherine A. Smart (1), School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, U.K. (1) Corresponding author. J. Am. Soc. Brew. Chem. 54(1):50-56, 1996. Accepted September 11, 1995.
Starvation has
been shown to
influence the
technological
behavior of
brewing yeast.
Starved yeast
were observed
to be less flocculant
in beer, therefore,
the effect of
starvation on
the flocculation
of lager and
ale brewing
strains was
examined. The
characterization
of the yeast
cell surface
involved the
use of techniques
such as dye
retention, solvent
partitioning,
latex microsphere
attachment,
biochemical
analysis, and
electron microscopy.
Starved lager
yeast cells
exhibited significantly
less negative
surface charge
than did those
that were non-starved,
although surface
hydrophobicity
was largely
unaffected.
Starved ale
yeast exhibited
an increased
surface charge
and a reduced
surface hydrophobicity
compared with
those that were
non-starved.
The effect of
starvation on
the subsequent
fermentation
performance
of the lager
yeast was examined
in wort. Starvation-induced
modifications
in flocculation
were retained
by subsequent
generations.
It was observed
that starvation
resulted in
a reduction
in surface phosphate
concentration,
and, although
the thickness
of the cell
wall decreased
after starvation,
the relative
proportions
of other cell
wall components
were not observed.
Keywords: Cell
wall, Flocculation,
Hydrophobicity,
Starvation,
Surface charge,
Yeast.
Al término
de una fermentación
cervecera, la
cosecha de levadura
es removida
de la cerveza
verde, almacenada
y reinoculada.
El efecto de
la reinoculación
en serie sobre
la condición
del inóculo
y su subsecuente
actividad fermentativa
es importante,
pero no bien
caracterizado.
Las propiedades
físicas
de la superficie
celular de la
levadura cervecera
influyen en
la floculación
y pueden ser
usadas para
determinar el
estado fisiológico
de la célula.
Levadura cosechada
de fermentaciones
a escala de
laboratorio
e industrial
han sido examinadas.
El efecto de
reinoculación
en serie sobre
las propiedades
físicas
de una cepa
de producción
ale fue monitoreado
usando retención
de colorante,
unión
microesfera
latex, microscopio
electrónico
y técnicas
con colorantes
fluorescentes.
La floculación
de cada generación
fue determinada.
Se observó
que existe una
correlación
entre la condición
de la superficie
celular y la
actividad fermentativa.
Se propone que
la condición
de la superficie
celular puede
ser usada para
predecir la
actividad fermentativa
del subsiguiente
inóculo.