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

Abstract

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.