Yeast Population Dynamics during the Fermentation and Biological Aging of Sherry Wines

Abstract

Molecular and physiological analyses were used to study the evolution of the yeast population, from alcoholic fermentation to biological aging in the process of "fino" sherry wine making. The four races of "flor" Saccharomyces cerevisiae (beticus, cheresiensis, montuliensis, and rouxii) exhibited identical restriction patterns for the region spanning the internal transcribed spacers 1 and 2 (ITS-1 and ITS-2) and the 5.8S rRNA gene, but this pattern was different, from those exhibited by non-flor S. cerevisiae strains. This flor-specific pattern was detected only after wines were fortified, never during alcoholic fermentation, and all the strains isolated from the velum exhibited the typical flor yeast pattern. By restriction fragment length polymorphism of mitochondrial DNA and karyotyping, we showed that (i) the native strain is better adapted to fermentation conditions than commercial strains; (ii) two different populations of S. cerevisiae strains are involved in the process of elaboration, of fino sherry wine, one of which is responsible for must fermentation and the other, for wine aging; and (iii) one strain was dominant in the flor population integrating the velum from sherry wines produced in González Byass wineries, although other authors have described a succession of races of flor S. cerevisiae during wine aging. Analyzing all these results together, we conclude that yeast population dynamics during biological aging is a complex phenomenon and differences between yeast populations from different wineries can be observed.

Response to acetaldehyde stress in the yeast Saccharomyces cerevisiae involves a strain‐dependent regulation of several ALD genes and is mediatedby the general stress response pathway

“…The case of ALD6 is particularly interesting, where basal levels are higher under growth in 2% glucose in flor yeasts. Strain C is the most resistant to ethanol and acetaldehyde and the most abundant in the wineries from which these strains have been isolated (Esteve-Zarzoso et al, 2001). Moreover, it is the only one where there is no decrease in ALD6 mRNA levels after acetaldehyde addition under these conditions.…”

“…for S. cerevisiae 'flor' yeast strains involved in the biological ageing of sherry wines (Jackson, 1994;Martínez et al, 1997a,b). These strains are different from those involved in the fermentation stage (Esteve-Zarzoso et al, 2001) and form a thin velum (film) on the surface of the wine. During biological ageing, yeast cells are affected by ethanol stress because the final fermentation product is supplemented with ethanol up to a final concentration of 15-15.5 • .…”

Intraspecific Diversity of Yeast Associated to Vitis vinifera Albariño Must from Different Vineyard Ecosystems

“…The high level of polymorphism in the structure of the nuclear and mitochondrial genomes found in different studies on natural populations has allowed the differentiation of closely related isolates 22,29,37 . Different authors 4,6,12,25 have found a greater genetic variability of the mitochondrial genome.…”

A Microtiter Plate Assay as a Reliable Method to Assure the Identification and Classification of the Veil-Forming Yeasts during Sherry Wines Ageing

“…After the process is finished, wine is fortified to 15% (v/v) and it is put into oak barrels for storage. The process of biological ageing begins at this moment, using the "Solera" system [3].…”