Staling in beer is inevitable. Oxidation and increased temperatures are the
main causes of stale flavors in bottled beers. Since 1934, research has been done
to identify compounds and pathways involved in creating stale flavors. Although
many research papers report stale flavors, there is not a lexicon per se of stale
aromas for North American lagers. This study has been divided into two parts, 1)
the process of developing a lexicon for stale aromas for North American lagers and
its application, and 2) the use of a consumer panel to determine whether the North
American lager consumer has a preference for aged versus fresh beer and whether
the consumer could perceive a difference between the two.
In the first study, three brands of North American lagers were aged in
27°C storage for three months and 38°C storage for two weeks. A lexicon for
staling aroma for North American lagers was created, using a trained descriptive
panel. The lexicon had two tiers; the first tier had five descriptors that were
category headings for the second tier of descriptors. Panelists were instructed to
rate the first tier descriptors, but using the descriptors in the second tier was
optional.
To validate the lexicon, descriptive analysis was performed on the stored
samples. The data were analyzed using principal components analysis (PCA) for
the first tier descriptors and generalized procrustes analysis (GPA) for the second
tier descriptors. The lexicon was used successfully, characterizing the control
beers as sulfury and fruity and the aged beers as sweet brown. Within the sulfury
category, panelists described control beers with the attributes perm solution and
skunky. Within the sweet brown category, panelists described the aged beers with
the descriptors baked pineapple and honey. The beers stored at different storage
temperatures behaved differently across time. The maps constructed with PCA
and GPA show a tendency for control samples to start out sulfury and, through
time, age with sweet brown characteristics.
In the second study, a consumer panel was implemented to 1) determine if
the average North American lager consumer had a preference for fresh versus
stored beer, and 2) to determine if perceivable differences existed between the
fresh versus stored samples.
A consumer test was designed using the three North American lagers that
were tested in the trained panel. The target number of consumers for each brand
was 100. The aged beer was stored at 38°C for 1 and 2 weeks, and the control was
stored at 1°C for that time period. A preference test, followed by a triangle test,
was performed on control versus 1 week at 38°C and control versus 2 week at
38°C for each brand (2 preference and 2 triangle tests for each brand; control
versus 1 week and control versus 2 weeks). The results showed no significant
preference for any brand/time point. Brand A had the only significant difference
(p <0.05) between samples stored at 38°C for 2 weeks and the control (The results
showed no preference). Additional research must be done for more conclusive
information, but this research shows that a small group of North American lager
consumers do not have a preference between aged beer and fresh beer and, for the
most part, cannot tell a difference between aged beer and fresh beer. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26569 |
| Date | 19 December 2001 |
| Creators | Edwards van Muijen, Christina Veronique |
| Contributors | McDaniel, Mina R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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