| Abstract
| - The ability of three Saccharomyces wine yeasts (S. cerevisiae AWRI 838, S. cerevisiae AWRI 1537,and S. bayanus AWRI 1375) to liberate volatile compounds from sugar-bound aroma precursorswas investigated using synthetic and grape glycosides under different experimental conditions. Inmodel systems involving the incubation of yeast cells with either synthetic or grape-derived glycosidesunder conditions more favorable for glycosidase activities and less favorable for acid-catalyzedhydrolysis (pH 5.0 and 30 °C), all yeast strains studied proved to be capable of hydrolyzing glycosides,with S. bayanus AWRI 1375 displaying greater hydrolytic activity than S. cerevisiae AWRI 838 andAWRI 1537. During the fermentation of a chemically defined grape juice-like medium containingglycosidic precursors extracted from Vitis vinifera cv. White Frontignac (synonym Muscat à Petit GrainsBlanc), all yeasts promoted a significant hydrolysis of different precursors, which varied according tothe chemical structures of both the sugar and the aglycon moieties, as determined by GC-MS analysisof trifluoroacetylated derivatives. Hydrolysis of the White Frontignac derived glycosidic precursorsduring fermentation resulted in the release of monoterepene alcohols, terpene oxides, terpene diols,and 3-oxo-α-ionol, demonstrating the significant potential of these yeast strains to contribute to winevarietal volatile composition during alcoholic fermentation. Keywords: Glycosides; yeasts; fermentation; Saccharomyces cerevisiae; Saccharomyces bayanus;wine aroma
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