The conversion of grape must to wine is a complex biochemical process and the primary role of wine yeast is to catalyse the rapid, complete and efficient conversion of grape sugar into ethanol, carbon dioxide and other minor, but important secondary. Indigenous yeasts with oenological potential are considered autochthonous and are present on the surfaces of undamaged grapes and their success depends on the sum of physical, chemical and biotic factors. In the spontaneous fermentation of grape must, there is a progressive growth pattern of indigenous yeast, with the final stage invariably being dominated by alcohol-tolerant strains of Saccharomyces cerevisiae. An investigation was carried out in order to characterize the yeast population present in the spontaneous fermentation of "Primitivo" must, an important grape cultivar for the industrialized production of Apulia wine. The objective of this study was the identification and characterization of natural yeast flora with peculiar technological and oenological properties from "Primitivo" grapes collected from different vineyards of the Apulia Region. Identification and characterisation of yeast species and strains have been carried out by morphological, physiological, biochemical and molecular methods by sampling the micro flora present on grape skin and in the must during spontaneous fermentation, i.e. beginning (d=1.125 g/l), middle (d=1.070 g/l) and end (d=1.000 g/l) fermentation The colonies from each sample have been selected on the bases of morphological and physiological characteristics and the isolated population identified at genus level by PCR-RFLP analysis of the internal transcribed ITSI- 5,8S - ITS2 region. Further identification of S. cerevisiae isolates has been carried out by PCR analysis of the amplified d interspersed elements. The technological properties (ability of the strains to utilise different carbon sources, production of ethanol, glycerol and hydrogen sulphite, surviving in dry conditions, etc.) of the selected S. cerevisiae strains have been studied. The significance of the above findings and their implications for selection of autochthonous industrial starters will be discussed.
Population dynamics of yeasts in "Primitivo" must derived from natural fermentations
Tristezza M;Cappello MS;Bleve G;GRIECO F
2005
Abstract
The conversion of grape must to wine is a complex biochemical process and the primary role of wine yeast is to catalyse the rapid, complete and efficient conversion of grape sugar into ethanol, carbon dioxide and other minor, but important secondary. Indigenous yeasts with oenological potential are considered autochthonous and are present on the surfaces of undamaged grapes and their success depends on the sum of physical, chemical and biotic factors. In the spontaneous fermentation of grape must, there is a progressive growth pattern of indigenous yeast, with the final stage invariably being dominated by alcohol-tolerant strains of Saccharomyces cerevisiae. An investigation was carried out in order to characterize the yeast population present in the spontaneous fermentation of "Primitivo" must, an important grape cultivar for the industrialized production of Apulia wine. The objective of this study was the identification and characterization of natural yeast flora with peculiar technological and oenological properties from "Primitivo" grapes collected from different vineyards of the Apulia Region. Identification and characterisation of yeast species and strains have been carried out by morphological, physiological, biochemical and molecular methods by sampling the micro flora present on grape skin and in the must during spontaneous fermentation, i.e. beginning (d=1.125 g/l), middle (d=1.070 g/l) and end (d=1.000 g/l) fermentation The colonies from each sample have been selected on the bases of morphological and physiological characteristics and the isolated population identified at genus level by PCR-RFLP analysis of the internal transcribed ITSI- 5,8S - ITS2 region. Further identification of S. cerevisiae isolates has been carried out by PCR analysis of the amplified d interspersed elements. The technological properties (ability of the strains to utilise different carbon sources, production of ethanol, glycerol and hydrogen sulphite, surviving in dry conditions, etc.) of the selected S. cerevisiae strains have been studied. The significance of the above findings and their implications for selection of autochthonous industrial starters will be discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
