Vin Santo of Gambellara is a typical sweet white wine produced in the Veneto region (Italy) with the specificity of Controlled Designation of Origin. Its winemaking procedure includes a withering step, where Garganega grapes are partially dried in attics for five-six months, a slow fermentation phase, and finally an aging period of two or more years in oak barrels. The high sugar levels of the must (up to 350 g/L), the presence of inhibitory substances and the poor control of fermentation parameters, as the indigenous microbial population and the temperature, can cause frequent sluggish and stuck fermentations or high production of volatile acidity. To avoid all possible risks which can occur during vinification and preserve the typical sensory properties of Vin Santo of Gambellara, the aim of the present study was the development of a protocol to provide indigenous yeast starter cultures to better overcome the stressing conditions of the alcoholic fermentation. A large collection of Saccharomyces and non-Saccharomyces yeasts from spontaneous fermentation of musts and wines aged in barrels was constituted. The isolates showed a high interspecific biodiversity as depicted by molecular methods, and they were found to belong mainly to the species S. cerevisiae, Zygosaccharomyces rouxii, Z. bailii, and Z. gambellarensis. Strains were screened for several oenological properties and the most promising ones were employed in pilot-scale single and sequential fermentation trials. The combination of S. cerevisiae with Zygosaccharomyces spp. strains prevented the risk of stuck or sluggish fermentations. Furthermore, wines obtained were characterized by the presence of positive metabolites, as fruity esters and higher alcohols, and by low levels of acetic acid and ethyl acetate with respect to the spontaneous fermentations. In conclusion, the present study suggests that the use of the newly selected indigenous Saccharomyces and Zygosaccharomyces cultures represents a valuable strategy for the management and optimization of the fermentation process of Vin Santo of Gambellara, minimizing the production of spoilage metabolites and to preserve the complexity of the wine aroma composition.
Use of Saccharomyces and non-Saccharomyces yeasts for the management and optimization of the Vin Santo of Gambellara fermentation process
TORRIANI, Sandra;SALVETTI, Elisa;LORENZINI, Marilinda;FRACCHETTI, Fabio;FELIS, Giovanna
2014-01-01
Abstract
Vin Santo of Gambellara is a typical sweet white wine produced in the Veneto region (Italy) with the specificity of Controlled Designation of Origin. Its winemaking procedure includes a withering step, where Garganega grapes are partially dried in attics for five-six months, a slow fermentation phase, and finally an aging period of two or more years in oak barrels. The high sugar levels of the must (up to 350 g/L), the presence of inhibitory substances and the poor control of fermentation parameters, as the indigenous microbial population and the temperature, can cause frequent sluggish and stuck fermentations or high production of volatile acidity. To avoid all possible risks which can occur during vinification and preserve the typical sensory properties of Vin Santo of Gambellara, the aim of the present study was the development of a protocol to provide indigenous yeast starter cultures to better overcome the stressing conditions of the alcoholic fermentation. A large collection of Saccharomyces and non-Saccharomyces yeasts from spontaneous fermentation of musts and wines aged in barrels was constituted. The isolates showed a high interspecific biodiversity as depicted by molecular methods, and they were found to belong mainly to the species S. cerevisiae, Zygosaccharomyces rouxii, Z. bailii, and Z. gambellarensis. Strains were screened for several oenological properties and the most promising ones were employed in pilot-scale single and sequential fermentation trials. The combination of S. cerevisiae with Zygosaccharomyces spp. strains prevented the risk of stuck or sluggish fermentations. Furthermore, wines obtained were characterized by the presence of positive metabolites, as fruity esters and higher alcohols, and by low levels of acetic acid and ethyl acetate with respect to the spontaneous fermentations. In conclusion, the present study suggests that the use of the newly selected indigenous Saccharomyces and Zygosaccharomyces cultures represents a valuable strategy for the management and optimization of the fermentation process of Vin Santo of Gambellara, minimizing the production of spoilage metabolites and to preserve the complexity of the wine aroma composition.
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