In our study, spontaneous alcoholic fermentations were carried out to isolate non-
and
yeasts from grape must from different vine-growing regions in Slovenia. Additionally, the diversity of native
...strains was evaluated during the process.
During spontaneous alcoholic fermentations the yeast population of non-
and
yeasts was sampled. We used eleven microsatellite markers to determine the genetic diversity of
strains. In addition, different ratios of the indigenous strains of
,
and
were tested for their possible use in alcoholic fermentation with inoculated yeasts by monitoring its course and measuring the concentration of aroma compounds in wine.
Sequencing of the internal transcribed spacer (ITS) regions of ribosomal DNA showed that of 64 isolates, 46 strains represent
and 18 strains belong to non-
yeasts. The identified non-
yeast species were
,
,
and
. The dendrogram grouped
strains into 14 groups. The number of
strains isolated from the musts was 10 (Posavje), 11 (Podravje) and 25 (Primorska vine-growing region). On the other hand, the alcoholic fermentation with inoculated yeasts, in which the native
strain predominated over
and
, gave the most promising result due to the highest alcoholvolume fraction, the lowest acetic acid concentration and significantly higher concentrations of volatile thiols 3-mercaptohexyl acetate (3MHA) and 3-mercaptohexan-1-ol (3MH), 2-methylpropanol, 2-methylbutanol, 3-methylbutanol and 2-phenylethanol) in the produced wine.
We confirmed the potential use of indigenous
and non-
yeasts in alcoholic fermentation with inoculated yeasts, which allows the positive properties of the yeast strains to be expressed and good quality wines to be produced. Thus, the results are encouraging for winemakers to create different wine styles associated with a particular terroir using indigenous yeasts.
In the present study, viticultural and oenological parameters of six clones of Muscat a Petits Grains Blancs (MPG) and five clones of Muscat giallo were investigated. Differences were found between ...varieties and clones in the occurrence of the phenological phases: bud break, véraison, and maturity. In the MPG clones (B41-5, FR 94, MPG 154, MPG 454, and MPG 455), all three phenological phases started earlier, resulting in earlier grape maturity and higher total soluble solids content (TSS) in grapes at harvest compared to the M. giallo clones (R1, VCR100, VCR 102, and VCR 5, BEMK 33). The MPG clones also resulted in higher cluster weight, higher yield per vine, and lower must pH compared to the M. giallo clones. The only exception was the MPG clone R2, which showed more similarities with the M. giallo clones. The wines of the MPG clones showed a tendency toward higher values for alcohol, citronellol, total acids, and total dry matter. In contrast, the wines of the M. giallo clones and the R2 clone of MPG showed higher pH and higher levels of linalool, α-terpineol, geraniol, and nerol. Although R2 is classified as a clone of MPG, our results indicate a strong similarity with the M. giallo clones studied. This study has highlighted the differences in phenological development and grape and wine quality characteristics between MPG and M. giallo clones. Therefore, clone selection can be an important tool for winemakers to develop the desired wine style and adapt to climatic changes.
The aim of this study is to evaluate the influence of yeast strains on the composition and sensory quality of Gewurztraminer wine. Three different commercial yeast strains were examined on the ...microvinification scale. In the wines, the chemical parameters and the concentration of free volatile monoterpene alcohols were measured and a descriptive sensory analysis was performed. Significantly more geraniol and nerol were detected in the fermentation conducted with reference Saccharomyces cerevisiae strain and more citronellol was found in the fermentation conducted with a hybrid of S. cerevisiae hybrid and S. paradoxus. However, more a-terpineol and linalool were found in the wine fermented with a combination of Saccharomyces and Torulaspora delbrueckii strains. The best wine flavour of tropical fruits was obtained using a hybrid of S. cerevisiae hybrid and S. paradoxus, and the best wine quality was achieved with a combination of Saccharomyces and T. delbrueckii strains. The selection of yeast strains for the fermentation of Gewurztraminer must significantly influenced the concentration of free volatile monoterpene alcohols and the sensory quality of the wine. With the selected hybrid of S. cerevisiae hybrid and S. paradoxus or the combination of Saccharomyces and T. delbrueckii strains either a better flavour or overall wine quality than with the reference strain can be achieved. Key words: Gewurztraminer, monoterpene alcohols, Saccharomyces sp., Torulaspora sp., wine, yeast strains
In this study, we compare the stable isotope composition of oxygen and carbon of wines from four Central and Southeastern European countries and from Argentina to study the similarities and ...differences in the isotope signatures and, thus, the potential of differentiation of the various wine-growing countries. We observe similar trends for wines from Austria, Slovenia, and Romania with respect to the vintages 2008 and 2009, which are absent in the Montenegrin and Argentinean samples. It is speculated that the weather develops similarly for Austria, Slovenia, and Romania, as these countries are positioned at a similar latitude and not too far away from each other (general central and eastern European weather situation), whereas Montenegro is not influenced by the latter being situated farther south and dominantly influenced by the Adriatic Sea. Investigations on further vintages are needed to test this assumption.
The main objective of this study was to investigate the influence of different commercial wine yeast strain combinations on wine varietal aroma and glutathione concentration. Four combinations of ...yeast strains were selected to produce Sauvignon Blanc wine under controlled conditions. The concentration of volatile thiols and methoxypyrazines in produced wines was quantified using GC-MS and the concentration of glutathione during fermentation was monitored and quantified using HPLC-FLD. Sensory analysis of wines was performed by a group of experienced wine assessors. The results indicated that the yeast strain combinations differed significantly in terms of their ability to release volatile thiols and to preserve glutathione levels, but had no impact on methoxypyrazine concentrations. In accordance with the chemical composition of wines, significant differences were found in their sensory quality. It can be concluded that the selection of an appropriate yeast strain combination for alcoholic fermentation presents the potential to greatly modulate wine aroma.
The capacity for the removal of pyrimethanil and fenhexamid, two fungicides commonly used for the control of Botrytis cinerea in vineyards, has been evaluated during an alcoholic fermentation process ...in batch system. Commercial and wild strains of Saccharomyces cerevisiae were used. Batch fermentations were carried out in yeast extract-malt extract medium (YM) with 18.0 % (by mass) glucose, and the fungicides were added separately at three concentrations: 0.1, 1.0 and 10.0 mg/L. The removal capacity of yeast strains was also examined in stationary phase cultures of Saccharomyces cerevisiae. Stationary assays were performed with yeast biomass harvested from the stationary phase of an anaerobic fermentation process, with separate additions of 0.1, 1.0 and 10.0 mg/L of both fungicides. Removal studies with stationary phase cells were performed with viable and non- viable cells inactivated with sodium azide. This study clearly shows that both Saccharomyces cerevisiae strains were able to remove fenhexamid and pyrimethanil in stationary and fermentative assays. The removal potential is shown to be strain dependent in stationary but not in fermentative assays. However, the removal potential is dependent on the type of fungicide in both stationary and fermentative assays. In stationary phase cultures no significant difference in fungicide removal potential between viable and non-viable cells was observed, indicating that both pesticides were not degraded by metabolically active cells. However, the presence of both pesticides influenced fermentation kinetics and only pyrimethanil at 10.0 mg/L increased the production of volatile acidity of both strains. Key words: alcoholic fermentation, S. cerevisiae, pyrimethanil, fenhexamid, synthetic media
During the period 2004-2015, the upper soil layer (0-20 cm) was sampled in eight agricultural production areas in Slovenia. Overall, 53, 249, 169, 139, and 413 samples were respectively taken from ...vegetable fields, arable cropland, hop fields, orchards, and vineyards. Copper was measured in the aqua-regia extracts of these samples using flame atomic absorption spectrometry. The minimum, maximum, average, and median concentrations were calculated for five land uses and for all eight production areas in Slovenia. Sample portions below and/or above the limit, warning, and critical concentrations of 60, 100, and 300 mg/kg, respectively, were calculated as well. The results were compared for different land uses and production areas and showed that the copper concentrations in the vegetable, arable crop, and hop fields and orchards did not exceed the critical concentration. In addition, the copper concentrations in the vineyards exceeded the critical concentration but the maximum copper concentration (508 mg/kg) was still lower than the concentrations reported from other vine-growing Mediterranean countries. Also, the copper concentrations in hop fields exhibited an increasing trend in the Celje (and Maribor) area(s).
PDF
