UBC Theses and Dissertations
Effect of mixed Saccharomyces cerevisiae strains on Chardonnay wine composition Saberi, Sara
Chardonnay is the global standard for white wine. Traditional Chardonnay wine is fermented using natural microbial flora, while current Chardonnay wines are fermented using an individual Saccharomyces cerevisiae strain. Wine makers are looking for possibility of producing wines with enhanced complexity that has disappeared from current wines due to the use of commercially available yeast starter cultures across the world (Howell et al., 2006). Conducting controlled fermentation using multiple species or strains of yeasts can be one of the available capacities to provide superior Chardonnay wines. Selected yeasts should have certain technological characteristic as requirements for industrial wine production. In this study, two novel individual Burgundian S. cerevisiae strains (C2 and C6) and mixtures of these strains (M1, M2, M3 and M4) were used to produce wine. First, the genetic fingerprinting and killer phenotype of the Burgundian yeasts were discovered. Secondly, the enological characteristics of the Burgundian yeasts were examined. Finally, Chardonnay must was fermented at 16 °C and 20 °C with the S. cerevisiae strains. The volatile compounds of the resulting wines were identified and quantified using gas chromatography-mass spectrometry (GC-MS) and compared. The odour active values (OAVs) were calculated for each volatile compound to estimate their sensory contribution of volatile compounds to the overall aroma of the wine samples. The Burgundian strains C2 and C6 had unique genetic fingerprints and showed a positive killer phenotype. The enological characterization of the Burgundian strains showed that they are enologically equivalent to the available commercial strains. No significant (p ≥ 0.05) difference existed in the production of 18 volatile compounds by wine yeast strains across the two fermentation temperatures. Principal Component Analysis (PCA) of the volatile compounds and estimated sensory profiles of Chardonnay wines indicated that the individual and mixed Burgundian strains were more similar to one another than the industrial strains. The Burgundian strains collectively produced pleasant aromas with OAVs above the sensory threshold. In conclusion, the potential exists to support the hypothesis that Chardonnay wines, when fermented with mixed Burgundian strains, produce a unique complex aromatic profile which is different from those obtained from commercially available yeast strains.
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