Genetic and Chromosomal Stability of Wine Yeasts

The conversion of grape juice into wine is a complex fermentation process in which yeasts play a central role. The composition of the yeast flora in the fermenting must vary according to geographic location, climatic conditions, and grape variety (e.g.,
ref.1
). During the early phase of fermentation, apiculate yeasts belonging to the species
Kloeckera apiculata (Hanseniaspora uvarum)
are dominant, but
Candida, Pichia, Rhodotorula, Kluyveromyces, Hansenula, Metschnikowia
, and
Saccharomyces
strains can also be detected (
1
). Most of them die off when the ethanol concentration rises to around 4% (
2
) and leave
Saccharomyces
to complete the fermentation. The major
Saccharomyces
species found among wine yeasts is
S. cerevisiae
, but
S. bayanus
can also be detected. The
S. cerevisiae
flora itself is also variable, it can change in the course of fermentation and various strains can grow simultaneously as subpopulations (e.g.,
ref.3
–
6
).