The development of varietal aroma from non-floral grapes by yeasts of different genera

A fraction of glycosidic precursors extracted from different non-floral grapes has been reconstituted with a synthetic must and the must has been fermented in duplicate by yeasts belonging to different genera previously selected by their high glycosidase activity (Saccharomyces cerivisiae, Saccharomyces bayanus; S. cerevisiae x S. bayanus, Brettanomyces bruxellensis, Hanseniaspora uvarum, Kloeckera apiculata, Torulaspora delbrueckii and Debaryomyces carsonii). Fermentation was allowed to take place for 3 weeks, but only was complete for Saccharomyces yeasts. The wines obtained were analyzed by sensory analysis and by gas chromatography and gas chromatography–mass spectrometry to determine the sensory descriptors and the aroma composition. The results have shown that the yeast genus exerts a critical influence on the levels of most varietal aroma compounds, affecting to all families coming from precursors, including nor-isoprenoids, terpenols, benzenoids, volatile phenols, vanillins and lactones. Leaving aside ethylphenols and vinylphenols, most aroma compounds are produced at relatively low concentrations, but in numbers enough to likely cause a sensory effect.