Fermentation of the grape must into wine is one of the most important steps
in winemaking. Selected yeast strains of Saccharomyces cerevisiae have
been used for many years to ensure complete and even fermentations. The
formation of volatile compounds also occurs during fermentation and will
influence the sensory perception of the wine. The main objective of the
research was to study the sensory and chemical composition of 1992 Oregon
Riesling, Chardonnay and Pinot Noir wines fermented with different
commercial S.cerevisiae strains.
In the first study, Free-Choice Profiling was used to study the sensory
profiles of all three varieties after 7 and 20 months of aging. This method was
used in order to utilize a panel of expert winemakers for the tastings. The
sensory data analyzed through Generalized Procrustes Analysis showed that
some strains were similar while others were different in terms of aroma and
flavor at 7 months of age. After 20 months of aging, differences and
similarities were still present although the sensory profiles were different from the young wines. This last finding showed that differences are still present
after a period of aging.
In the second study, the chemical composition of all three varieties and the
volatile composition of selected wines of Riesling and Chardonnay were
studied. In both white varieties, statistical differences in titratable acidity,
residual sugar, volatile acidity and malate content resulted from fermentation
with different yeast strains. The volatile composition was qualitatively similar,
but some quantitative differences, as relative concentration, were found.
Whether or not those differences had a sensory impact was not investigated.
Results of the present study showed the need for further studies in order to
understand the role of yeast in flavor development. Relationships between
sensory profiles and volatile composition could help winemakers to
understand the influence of a selected strain on a particular variety and to
select yeast strains to optimize wine quality. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27431 |
| Date | 23 November 1994 |
| Creators | Dumont, Ann |
| Contributors | Watson, Barney T. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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