Angels’ share challenge
Reinhard Meusinger
0
) NMR Abteilung, FB Chemie,
Technische Universitt Darmstadt
, Petersenstr. 22, 64287 Darmstadt,
Germany
We would like to invite you to participate in the Analytical Challenge, a series of puzzles to entertain and challenge our readers. This special feature of Analytical and Bioanalytical Chemistry (ABC) has established itself as a truly unique quiz series, with a new scientific puzzle published every other month. Readers can access the complete collection of published problems with their solutions on the ABC homepage at http://www.springer.com/abc. Test your knowledge and tease your wits in diverse areas of analytical and bioanalytical chemistry by viewing this collection. In this challenge, flavorants are the topic. And please note that there is a prize to be won (a Springer book of your choice up to a value of 100). Please read on
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Meet the angels share challenge
The small portion of wine or distilled spirit that is lost during
long aging in wood barrels is known as the Angels share (if
this nip is larger than two percent per year, the alertness of
the tax collectors will awaken). Many flavoring compounds
are extracted from the wood of the barrels during this time. In
fact, several hundred flavorants have been detected in these
complex beverages, including a gamut of alcohols, carbonyl
compounds, carboxylic acids and their esters, terpenes,
nitrogen-containing and sulfur-containing compounds,
tannins and other polyphenolic compounds, and
oxygencontaining heterocyclic compounds [1].
In this challenge we are looking for such a compound
which occurs in whiskies, cognac, rum, and also old wine.
The complexity of this subject is grand, which is why this
challenge will be limited to whisky.
The flavor and color of whisky arises due to three
reasons: the distillation, the cask maturing, and
additives. During distillation, the flavor develops in part
because of the presence of fermentation products, for
example acetals, ketones, esters or aldehydes, and higher
alcohols. Most of these compounds contribute to the hangover
(veisalgia) and will not be given closer attention here. The
additional flavor and color of whisky depends strongly on
local regulations. For instance, a Scotch whisky may contain
no additives other than the caramel coloring (E150a). Last, the
presence of our flavorant in whisky is because of the aging
process.
Laws in several jurisdictions require that whisk(e)y
must be aged in wood barrels. Similar regulations exist
for brandy, sherry, and cognac. In addition to the length
of aging, the volume of the barrels and their storage
location, the type of wood and its provenance also play
an important role in the quality of the end product. The
type of the wood used for barrels will be kept a secret
in this challenge. This tree is a symbol of strength and
endurance and a national tree of many countries. In
Greek mythology it was sacred to Zeus and in Norse
mythology it was sacred to Thor, and a legend goes that
the Christianization of Germany was marked by the
felling of this sacred tree by an Anglo-Saxon missionary
in 723. Today, both the common name and the botanical
(Latin) name of this tree features in the trivial names of
our compound.
The barrels for aging alcoholic beverages are made
from European and American trees. The choice between
these two kinds of tree is especially important for wine
producers. For maturing of whisk(e)y, different rules are
prescribed by law. As an example, the straight
whiskey must be stored in the United States for at least two
years in new, charred wood containers; Bottled in
Bond Bourbon whiskey liquor must age for four years
whereas all Scotch whisky must be aged in wood
barrels for at least three years and one day [2]. Therefore,
it seems that only the fanciers of fresh distilled
whisk(e)y, named new spirit, moonshine, or poitin
underestimate the value of our flavor compound. All
other consumers enjoy spirits matured in wood casks.
Misleadingly, the maturing of Scotch whisky in a new
cask does not mean the use of a fresh unused cask. In
Scotland, the first fill typically describes maturing in
an American cask formerly used to mature bourbon
whiskey. Recently, a new trend, the so-called finishing
has gained in popularity with the product known as
double matured or wood-finished. Here, the spirit
spends further time in a second cask, usually one that
has been used to mature fortified wine, sherry, port
wine, Madeira, or even standard wines. However, this
may still not be the end of the life of a wood cask. For
example, the pepper mash used to make Tabasco sauce
is aged for three years in used whiskey barrels (Fig. 1).
From the scientific literature, it appears that our
compound was first reported at the end of the 1960s. For
convenience, it was first christened after the peak
number in the gas chromatogram of red wine flavorants.
Shortly after the first description it was found that four
possible stereoisomers can exist, and in the aft (...truncated)