Sniffing Out the Secrets of
White Wine Aroma
A quick glance
through some of the popular wine articles in magazines and
newspapers would leave most people perplexed. Descriptions of
wines in terms of things such as grandmothers drawers, cobblers
tar, drenched dogs, cats wee and the like leave many people with
the distinct impression that either wine tasting is difficult, or
that the people using such terms are very imaginative.
Notwithstanding the fact that wine journos need to be entertainers
as well as being informative, there are good reasons that so many
terms have been used to describe wines. Wine in its least romantic
sense is a complex cocktail of naturally occurring chemical
substances or compounds. Early estimates put the number of
compounds in wine at around 800, but there is undoubtedly many
more numbering in the thousands or perhaps even the tens of
thousands. Many of these compounds contribute to the aroma and
flavour of wine.
When you sniff a wine and savior its aromas you are in fact
sampling from the 'invisible soup' of substances that float around
in the headspace of the wineglass. Some of the compounds in this
soup are very odour active and are known as wine character impact
compounds. When you smell these compounds in their pure form they
immediately conjure up distinct impressions of a particular flower
or other type of fruit. Examples are, the lemony linalool (in
Riesling), and the capsicum like 2-methoxy-3-isobutylpyrazine (in
Sauvignon Blanc). Other compounds are subtler in their
contribution. These are known in the other great aroma domain of
perfumery as congeners and diversifiers. Congeners enhance other
aromas and 'fuse' them into new complex and seamless scents.
Diversifiers add 'notes' and nuances to existing aromas making
them complex and interesting. In the wine world, candidates for
such compounds are damascanone and alpha ionone (both found in
Chardonnay). Damascanone has an almost narcotic scent of exotic
flowers with a heavy fruity undertone while alpha ionone has an
alluring violet like aroma. Whilst being single compounds they
often display multiple aromas that fade in and out with your
passing attention. For this reason these substances probably play
a large role in the fruit complexity of great Chardonnay wines.
All the compounds and associated wine aromas mentioned above come
from the grape, and as such are known as varietal characters.
There are too many others to mention here, but one is rather
fascinating. Cat’s urine does exist in wine! Well its smell
anyway. Caused by the Dr Jekyll and Mr Hyde compound
p-mentha-8-thiol-3-one, this sulfur containing compound smells
exactly like cat's urine when in a particular concentration range.
When weaker, it exudes the
herbal scent of lantana bush, whilst when strong, it has an aroma
that can be likened to blackcurrants. And where do you find it?
That's right, in the variety where wine tasters see it the most,
Sauvignon Blanc and Cabernet Sauvignon (and of course in cat's
urine).
Other wine aromas and flavours derive from the chemical by-products
of yeast fermentation. These aromas are often distinctly in the
fruity part of the aroma spectrum and include banana, pineapple,
passion fruit and apple. They derive from a class of compounds
called esters, which incidentally give most fruits their
characteristic aromas and flavours.
When a wine ages, typically both its varietal and fermentation
characters will fade and will be replaced by a raft of other
substances that develop in the wine over time. While less is known
about these compounds, a few have been identified. The most
important substance associated with aged Riesling is the
impressively named 1, 6 trimethyl-1, 2-dihydronaphalene (or TDN). If
you have tasted an aged keroseney Riesling lately then you would
have tasted TDN first hand. Another compound that scientists are
beginning to get a handle on is the mouth-watering compound called
sotolon. Sotolon reeks of toffee apples and maple syrup and
contributes to the aged character of some white wines and
surprisingly is always found in the great flor Sherries.
Lists of wine characters by variety and winemaking practice can be
found elsewhere on the web
Click here.
You can also experience many of the aromas mentioned in this article
first hand by smelling the aromas contained in the
Wine Aroma Dictionary.
But don't forget that wine is there to be enjoyed. Somehow though,
the more you learn about wine the more you tend to enjoy it. But why
not keep a list of wine descriptors handy at your next wine tasting.
You never know, you may get a whiff of your grandmothers drawers in
some obscure Jerezian amontillado. But sometimes it is better
keeping some things to yourself!
Richard Gawel
This article originally
appeared in The Wine Tutor: Winestate Magazine
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