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. (c) 2007 Elsevier Ltd. All rights reserved.