And He Shall Laugh Them to Scorn!

Peter Harper, Smoke Signals #28, December 1997

If drinking wine is one of the greater pleasures of life, listening to someone else talking about wine has to be one of its greater annoyances. To my mind, wine is like sex, it is best enjoyed, not talked about. All hate those who kiss and tell. Still there are unrepentant talkers on both topics. And did you notice that curiously they often use the same vocabulary for both activities: full body, great nose, foxy, sweaty, perfumed, sun-cooked, peachy, young, ripe, ,... but also musty, flabby, flat... are they talking about wine or the body of a lover? An expression which amuses me when used by a woman: "il est long en bouche" - wine or lover, or both?

But we live in non-romantic age, in which you can count on someone debunking all the great things in life. And so it is with wine, and scientists are hard at work to find what is behind the bouquet-aroma of wine. Armed with gas-chromatographers, mass-spectrometers, and other paraphernalia, they are probing the chemical composition of wine to discover the secret mix which distinguishes a great wine from a rot-gut.

Professeur Dubourdieu of the Université de Bordeaux reminds us that if wine is 80-85% water and 9-15% alcohol, it also contains some 4 000-odd chemicals of which about 500 enter into the composition of the aroma. It is this 0.1-0.15% of the bottle that makes the real difference. Among the common ingredients are sugars (0.2-15%), glycerine (0.8-1.5%), 30 or so organic acids (1-1.5%), vinegar (0.02-0.05%), 20 or more
minerals (0.3-0.4%), and about 40 phenolic compounds (0.2-0.6%). A study of the Sauvignon grape used for Sancerre and Pouilly wines indicates that its "tropical note" is due to mercatohexanol as in passion fruit and the greenery taste comes from mercatomethylpentanone as in box-tree.

Similar studies are being conducted by flavour chemists on the same topic at the Universities of Erlangen (Germany), California at Davis, and Cornell and they were recently reported on by the New Scientist (26 July 97) in an irreverent article entitled "Château La Feet". There is no bad aroma, but only a combination of pleasant and unpleasant smells, which occur in good or bad proportions. "The delicate fragrance of cat
pee is one of the key components in the bouquet of a Sauvignon blanc - just as cow urine and horse manure are crucial to the noses of an old Riesling and a complex Bordeaux. And bubbling under the brew are the odours of mouldy socks, rotten eggs and burning rubber. Such are the
delights revealed by scientists trying to deconstruct the chemistry of the perfect summer wine."

And so dimethyl disulphide gives off a smell of onion, dimethyl sulphide one of asparagus. Methoxypyrazine at low levels provides a smell of chalk dust or old books and at higher concentrations of bell peppers, and is one of the main aromas of Cabernet Sauvignon. The glycoside associated aromatics are released by the action of acids and provide flavours such as honey, tobacco, chocolate, and dried fig.

Other chemicals are ambivalent: methyl mercaptan smells like burnt rubber, but a low concentration gives wine character, complexity and interest. 2-acetyl-1-pyrroline is responsible for the long-lasting taste of some wines (the "long en bouche" referred to above), but it actually smells like rodent urine and leaves on the tongue the feeling of having licked "a mouse nest". Some of the chemicals come from the yeast: they add a floral or spicy taste to Rieslings, but others smell more like wet horse blankets, cow manure, or plastic bandages. The wine cask provides octalactone (coconut), eugenol (clove) and vanilin (vanilla) all adding interest to the wine. Even the cork adds to the aromas, but sometimes can ruin a wine by rendering it corky: the musty smell it can generate comes from 2,4,6-trichloroanisole, one of the most potent smells to affect the human nose.

And so next time you drink a fine wine, remember that like so many other great gifts of the Creator, it is a perfect blend of the best and the worse that nature has to offer. And who says God doesn't have a sense of humour... and I am sure that he gets a
great laugh listening to wine connoisseurs, discussing the merits of... cat pee.