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.
BACKGROUND AND AIMS: Some wineries, in order to promote the growth of yeasts able to ferment grape musts, traditionally produce wines using the ‘pied de cuve’ method. The aim of the present work was ...to study the performance of fortified pied de cuve (FPdC) prepared by addition of wine. METHOD AND RESULTS: Two FPdCs were prepared with the addition of wine at 1.5 and 3% (v/v) of ethanol to the musts and allowed to spontaneously ferment. The FPdCs were then added to fresh bulk musts in order to accelerate the spontaneous alcoholic fermentation (AF). Interestingly, several Saccharomyces cerevisiae strains isolated during the pied de cuve preparation were detected at the highest concentration throughout AF. The chemical composition of the wines conformed to commercial regulations. The volatile organic compounds (VOCs) were mainly represented by diethyl succinate and ethyl lactate, as well as by hexanol and isoamyl alcohol. Principal component analysis of the chemical parameters, VOCs and sensory data showed that the use of experimental pied de cuve influenced positively the composition of the final wines. CONCLUSION: The FPdC had no negative impact on the microbiological and chemical composition of wines, but it affected the diversity of the species S. cerevisiae present during AF and the sensory profile of the final wine. SIGNIFICANCE OF THE STUDY: This study provided evidence that FPdC accelerates spontaneous AF and influences the sensory profile of red wines.
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