Malt, wort and beer samples representing a single
pilot brew were extracted from Celite columns with Freon
114. Total extracts were analyzed by gas
chromatography/mass spectrometry. Compounds were
identified that were unique or common to beer, wort or
malt and quantities present were determined for those
common to the three sample types.
Concentrated extracts were separated by liquid
chromatography on partially deactivated silica gel packed
in Teflon tubes, using Freon 11 as the solvent.
Fractions from liquid chromatography were analyzed by
descriptive sensory evaluation. Those fractions selected
as bearing cereal-like, grassy, nutty or malty aroma
characteristics were analyzed by gas chromatography.
Freon extracts and fractions were found suitable for
descriptive sensory evaluation and this was used to advantage in locating fractions with the desired aroma
characteristics. Cereal-like, grassy, nutty or malty
aroma characters were associated with liquid
chromatographic fractions containing primarily alcohols,
aldehydes and ketones.
The Ascending Method of Limits for determination of
the threshold of added substances in beer was critically
reviewed and a new threshold test was developed. The new
test design reduces the sample requirement from eighteen
to twelve for each session. In contrast to the Ascending
Method of Limits, the new test design was amenable to
statistical evaluation and statement of a level of
confidence for the threshold intervals determined.
Both a nine-point intensity scale of difference from
the labeled reference and a category scale were applied
to the new test design. Intensity scale data were
normalized and subjected to analysis of variance and a
series of one-sided t-tests to determine individual and
combined panel threshold intervals. Category scale data
were analyzed by a rank sums test to determine individual
thresholds and the R-index values thus obtained were
subjected to analysis of variance and orthogonal
contrasts of means to establish the combined panel
threshold.
The intensity scale method applied to the new test
design provided the lowest and narrowest estimates of the
threshold interval in comparative testing with the category scale method and the Ascending Method of Limits
and, in addition, required fewer replications than the
category scale method to establish the threshold
interval. / Graduation date: 1989
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27231 |
| Date | 17 May 1988 |
| Creators | Lukes, Bryce K. |
| Contributors | McDaniel, Mina R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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