The quality of wine is highly influenced by the weather.
Temperature, solar radiation and humidity influence the
formation and concentration of aroma-active compounds and
aroma-active precursors in the grapes. Pinot noir grapes require
a slow ripening, under cool temperatures, in order to achieve
their fullest flavor. The main objective of this study was to
provide an overall aroma picture that could help, along with the
chemical indices, to decide the optimum harvesting time to
obtain certain distinctive aroma attributes in the wine.
This particular work represents the first stage in a broad
plan aimed to understand the dependence of the wine flavor
chemistry on the ripening of the grapes. This maturity trial
was planned to last several years; it was expected that the
outcome and techniques developed in the present study would be
essential in delineating the steps to follow. The results of the
aroma analyses for the 1987 and 1988 vintages are reported
here. In each vintage, Pinot noir grapes were harvested at three
different times, covering a range from early to late maturity.
A sniffing technique based on gas chromatographic aroma
detection by a trained panel was implemented. This technique
has proved to be a useful tool to measure qualities and
intensities of aromas. The method was effective in detecting
many of the aroma-active compounds and in identifying aroma
differences between the wines studied.
The aroma profiles for the wines were found to be very
different from each other within and across vintages. There
were only 10 aroma peaks common to all three 1987 wines, 16
aroma peaks common to the 1988 wines, and 4 aroma peaks
common to both vintages. Late maturity wines had more aroma-active
peaks than the other 2 wines for both vintages. The 1988
wines had a higher number of aroma-active peaks than the 1987
wines. The percentages of aroma-active peaks not detected by
the Flame lonization Detector (FID) were 45% in the 1987
wines, and 66% in the 1988 wines. The overall climatic
conditions in those years were very different. The 1987 season
was characterized as hot and dry, producing an early harvest.
The weather in 1988 was more of a typical season for Oregon,
producing a normal to late harvest. Further study is needed to
fully understand the flavor chemistry occurring during grape
ripening. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27366 |
| Date | 07 December 1990 |
| Creators | Miranda-Lopez, Rita |
| Contributors | McDaniel, Mina R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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