Indigenous yeast population from Georgian aged wines produced by traditional "Kakhetian" method

The yeast microbiota present in wines produced by the ancient "Kakhetian" method in Georgia (EU) was studied. This technique involves the use of terracotta vessels (amphoras), during spontaneous fermentation, maceration phase and wine ageing. The analysed yeasts were collected from wines after maturation for one year in ten amphoras from a Georgian winery. The 260 isolates were all identified as Saccharomyces cerevisiae, and the majority were classified as for yeasts by restriction analysis of ITS region. A first technological and molecular screening was used to select 70 strains for further characterization. Both genetic and metabolic characterization discriminated for from non-for strains. The combined results obtained by analysis of interdelta region and mtDNA-RFLP yielded 23 different bio-types; no biotype was common to for and non-for strains. The wines produced by for yeasts showed a high content in acetaldehyde, acetic acid, acetoin, whereas the level of other compounds was similar to wines obtained by non-flat strains. This study represents the first report on the composition of yeast microbiota involved in the maturation of this traditional wine. These for strains represent an interesting yeast population, in possession of peculiar characteristics allowing them to survive during wine ageing, becoming the dominant flora in the final wine. (C) 2013 Elsevier Ltd. All rights reserved.