Contribution to the aroma of white wines by controlled Torulaspora delbrueckii cultures in association with Saccharomyces cerevisiae

Abstract

Although the positive role of non-Saccharomyces yeasts on the overall quality of wine is encouraging research into their oenological potential, current knowledge on the topic is still far from satisfactory. This work analyzes the contribution of starter cultures of Torulaspora delbrueckii, inoculated sequentially with Saccharomyces cerevisiae (multi-starter fermentation), on the fermentation and aromas of two different white style wines, i.e., dry and sweet wines. Chemical analysis of Soave and Chardonnay wines (dry wines) showed that multi-starter fermentation greatly affected the content of several important volatile compounds, including 2-phenylethanol, isoamyl acetate, fatty acid esters, C4-C10 fatty acids and vinylphenols. Moreover, strain-specific contributions have been shown by testing two different T. delbrueckii strains. Evidence of the positive impact of T. delbrueckii activity on wine quality was also demonstrated in Vino Santo, a sweet wine. Due to its low production of acetic acid, this non-Saccharomyces yeast is recommended for the fermentation of high sugar grapes. T. delbrueckii also influenced the content of different variety of chemical groups, including lactones. From a sensory perspective, all wines produced by multi-starter fermentation have greater aromatic intensity and complexity than wines resulting from a monoculture fermentation. These results emphasize the potential of employing T. delbrueckii, in association with S. cerevisiae, for the production of white wines of different styles with improved and enhanced flavour.

Torulaspora delbrueckii Yeast Strains for Small-scale Chenin blanc and Pinotage Vinifications

“…1). The duration of these co-inoculated fermentations is similar to that in other studies, which took between 12 and 24 days, but the single-inoculant group took much longer (24 vs. 32 days) (Azzolini et al, 2015;Belda et al, 2015). The zero-hour co-inoculations fermented at the same rate (slope of logarithmic growth phase) as the S. cerevisiae reference yeast.…”

“…The alcohol levels were only lower where less sugar was consumed, showing that these T. delbrueckii isolates are not suitable as a means for lowering the alcohol content of the wine. This is in contrast to other published works where, T. delbrueckii vinifications produced between 0.14% and 0.47% lower alcohol levels than reference S. cerevisiae fermentations (Azzolini et al, 2015;Belda et al, 2015;Renault et al, 2015). Glycerol produced by the single-inoculant fermentations was found to be slightly higher than in the co-inoculated wines and the S. cerevisiae reference fermentation, which is similar to what has been observed in other trials (Jolly et al, 2003a;Belda et al, 2015).…”

“…However, all the values fell within the legal limit for South African wines (≤ 1.2 g/L) (Anonymous, 1989). The higher values were not expected, as it has been mostly reported that T. delbrueckii strains generally produce lower levels of volatile acidity (Lafon-Lafourcade, 1983;Bely et al, 2008;Renault et al 2009;Azzolini et at., 2015). However, some reports show higher levels of acetic acid (major component of volatile acidity) for single-inoculant T. delbrueckii wines compared to reference S. cerevisiae wines .…”

“…In recent years, selected non-Saccharomyces wine yeasts have been commercially dried, or have been included as part of mixed active dried starter cultures with S. cerevisiae Jolly et al, 2014;Azzolini et al, 2015). This gives the winemaker the beneficial effects of spontaneous fermentation without the accompanying risks (Romano et al, 2003;Ciani et al, 2006).…”

Influence of vintage and selected starter on Torulaspora delbrueckii/Saccharomyces cerevisiae sequential fermentation

“…Several studies have reported on positive influences of non-Saccharomyces yeast species on wine quality, with evaluation of the specific involvement of selected strains [1][2][3]. In this context, there is an increasing interest in the practice of co-inoculation of grape juice with a Saccharomyces cerevisiae starter strain coupled with a selected culture of a non-Saccharomyces yeast.…”