2 research outputs found

    Biodiversity and Enological Potential of Non-Saccharomyces Yeasts from Nemean Vineyards

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    Vineyards in Nemea, the most important viticultural zone in Greece, were surveyed for indigenous non-Saccharomyces (NS) yeasts of enological potential. NS populations were isolated from the final stage of alcoholic fermentation and identified by a range of molecular methods. The enological profiles of Hanseniaspora guilliermondii, H. osmophila, Lachancea thermotolerans, Starmerella bacillaris and Torulaspora delbrueckii strains were evaluated. Significant interspecies variation was observed in fermentation kinetics. H. osmophila and T. delbrueckii showed the highest capacity for prompt initiation of fermentation, while S. bacillaris achieved a higher fermentation rate in the second half of the process. Significant differences were also observed in the chemical parameters of NS strains. S. bacillaris SbS42 and T. delbrueckii TdS45 were further evaluated in mixed-culture fermentations with Saccharomyces cerevisiae. NS strains achieved lower population densities than S. cerevisiae. SbS42 exhibited a higher death rate than TdS45. The chemical profiles of different ferments were separated by principal component analysis (PCA). Both NS strains were associated with lower levels of ethanol, when compared to single S. cerevisiae inoculation. TdS45 increased the ethyl acetate levels, while SbS42 caused a different production pattern of higher alcohols. This is the first report to explore the enological potential of NS wine yeast populations from Nemea. Based on prominent enological traits identified, the selected S. bacillaris and T. delbrueckii strains may be further exploited as co-culture starters for improving the quality and enhancing the regional character of local wines

    <i>Torulaspora delbrueckii</i> May Help Manage Total and Volatile Acidity of Santorini-Assyrtiko Wine in View of Global Warming

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    Non-Saccharomyces (NS) yeasts are gaining popularity in modern winemaking for improving wine quality. Climate change is one of the biggest challenges winegrowing now faces in warm regions. Here, Lachancea thermotolerans LtS1 and Torulaspora delbrueckii TdS6 combined with Saccharomyces cerevisiae ScS13 isolated from Assyrtiko grapes from Santorini island were evaluated in grape must fermentation with the aim to mitigate major consequences of temperature rise. Different inoculation protocols were evaluated, including simultaneous and sequential mixed-strain inoculations, displaying significant variation in the chemical and kinetic characteristics. Both LtS1 and TdS6 could raise the titratable acidity (TA). TdS6 also reduced the volatile acidity (VA) and was thus chosen for further evaluation in microvinifications and pilot-scale fermentations. Consistent with lab-scale trials, sequential inoculation exhibited the longest persistence of TdS6 resulting in minimum VA levels. Diethyl succinate, ethyl propanoate, and ethyl isobutyrate were significantly increased in sequential inoculations, although a decline in the net total ester content was observed. On the other hand, significantly higher levels of TA, succinic acid, and 2-methylpropanoic were associated with sequential inoculation. The overall performance of TdS6 coupled with a high compatibility with S. cerevisiae suggests its use in the fermentation of Santorini-Assyrtiko or other high sugar musts for the production of structured dry or sweet wines