Evaluation of the Enological Suitability of Some Strains of Saccharomyces cerevisiae for Sauvignon Blanc
Emilio Celotti, Franco Battistutta, Alessandra Vnerich, Michela Maifreni, Roberto Zironi
Department of Food Science, University of Udine, Via Marangoni 97, 33100 Udine, Italy
Received July 29, 1997
Accepted January 15, 1998
Sauvignon Blanc, yeast, flavour, etiological characteristics, Sacch. cerevisiae
Recent research has demonstrated the significant effect of the yeast strain in the aromatic expression of Sauvignon Blanc. In order to evaluate some commercially available strains of Saccharomyces cerevisiae and some recently selected strains with particular enological characteristics, including different hydrogen sulphide production levels, fermentation trials were performed with Sauvignon Blanc must which had been clarified by flotation to a turbidity value of 100 NTU. The fermentative ability was evaluated by the determination of the concentration of reducing sugars during fermentation, and the aromatic characteristics of the resulting wines were analysed chemically and by sensory tests. In addition, the karyotypes of the Saccharomyces cerevisiae strains used were determined. All the yeasts tested completed the alcoholic fermentation but did so at different fermentation speeds; in particular, the D13 selection finished the fermentation very rapidly, while the strains Uvaferm CM, 71B and BF18 had slower kinetics. Through discriminant analysis applied to the 3 groups deriving from cluster analysis of aromatic compounds, the relative weight of the aromatic compounds has been determined in differentiating the groups, the most important compounds are 3-(2-hydroxyethyl)-indole, isoamyl alcohols (2-methyl-l-butanol and 3-methyI-l-butanol), bulanoic acid ethyl ester, n-caproic acid and other minor compounds. These compounds are also amongst the most important in discriminating other types of wine under the aromatic profile and it is therefore desirable that this topic be examined more closely. At the end of the fermentation, the products were subjected to a first round of sensorial analysis involving preference tests to identify the possibility of differences between the yeasts in terms of presence of aromatic compounds. These tests allowed the identification of two yeasts, namely P4 and R2, which had the typically intense, and persistent aroma of Sauvignon Blanc, while all the others, although not being organoleplically defective, yielded a product which was fairly neutral and anonymous. No difference was observed when comparing karyotype of the Saccharomyces cerevisiae strains tested.
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