Impact of mother sediment on yeast growth, biodiversity, and ethanol production during fermentation of Vinsanto wine

The aim of this study was to determine the impact of Vinsanto mother sediment both on the growth and
biodiversity of the yeast microflora and on the production of ethanol under natural and inoculated
fermentation of Vinsanto wines. To achieve this ten fermentation trials were carried out in 50-L barrels, five
without added mother sediment and five with. Moreover, eight of the ten barrels were inoculated with four
Saccharomyces cerevisiae wine strains, while the remaining two barrels were not inoculated and were used as
controls to study the behaviour of the natural yeast microflora in the absence and presence of mother
sediment. The counts of viable yeasts at three different sampling times indicated that the mother sediment
had a positive influence on yeast growth and persistence during fermentation. Molecular characterization of
the Saccharomyces type colonies isolated after three months of fermentation showed that the addition of
mother sediment had no effects on the dominance of the wine starters. In contrast, the mother sediment had
a positive influence on the biodiversity of the spontaneous S. cerevisiae yeasts. Moreover, possibly due to its
content of fatty acids and sterols and other nutrients, the addition of mother sediment also showed a positive
effect on the fermentative activities of wine yeasts as measured by their ethanol production.