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Legs : Dr. Lipton, please report to the information desk

Hi

a discussion on IHV, the italian wine group, has prompted me to seek your expert chemical advice on the origin of legs or tears.

My understanding is as follows: a) what most wine experts refer to as glycerin is in fact glycerol, mainly because wine contains NO glycerin but SOME glycerol. And glycerol is just one of the types of alcohol present in wine, though present in minute proportions. b) neither glycerin or glycerol are volatile at room temperature, in fact glycerol at room temperature is barely above fusion temperature, never mind the boiling point that is way above water's. So what is evaporating is mainly ethanol. c) a water and alcohol solution like wine crawls up the side of the glass, due to complex effect at the interface between glass and solution and surface tension effects. This is where I am at a loss, Mark please help us. What is happening here? Whence the strange geometry? Does the type of glass influence legs? d) given that the solutions climbs up the glass, the legs are due entirely to alcohol evaporating out of solution, leaving the remaining water to fall back into the wine. e) glycerol, present in small quantities, does add roundness to a wine and contributes somehow to its mellowness.

there, anyone want to have a go at this one?

Mike

Mike Tommasi, Six Fours, France email link

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Reply to
Mike Tommasi
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Hi, Mike - I can clear this part up. Glycerine and glycerol are the _identical_ compound: 1,2,3 propanetriol. Of the two names, glycerol is the more correct chemical name because the ending indicates that the compound is an alcohol. It is produced as a side product in alcoholic fermentations by the action of yeast. IIRC, the side reaction is favored by the presence of sulfur dioxide in the must/juice. Glycerol adds both viscosity and apparent sweetness to wines. Supposedly, an old trick in Burgundy was to add a glassful of glycerol to a barrel of wine to improve its organoleptic properties.

I'll leave the part about legs to Mark or someone else who understands the physics to answer. :^)

Tom S

Reply to
Tom S

OH!

(sorry, 'in' joke)

Reply to
Bill Spohn

Obviously a taster can insulate himself from the aroma by holding his nose - but how could one separate mouthfeel from taste? Sounds like urbane legend to me...

Tom S

Reply to
Tom S

In the case of Mr. Waugh, it was the result of a car accident in which he lost his sense of smell (so, not entirely without a sense of taste, just mostly)

Mark Lipton

Reply to
Mark Lipton

Legs are evidential of the alcoholic strength of wines. The fatter the legs, the higher the alcohol.

Legs generally appear after two or three swirls of the glass.

A german auslese, while fat in the mouth and full of glycerin, will not show legs due to the lower alcohol content. It will sheet, not drip into legs.

I particulary enjoy reds whose legs drip the deep color of the wine, exhibiting much extract, sure to indicate deeper flavors and skillful winemaking.

I am of the opinion that legs are created due to the different evaporative qualities of water and alcohol, not due to the content of glycerin.

Reply to
D T

Salut/Hi D T,

Isd this the first time you've posted here? I don't recognise your name I'm afraid. If it is, "welcome to the madhouse".

le/on Sun, 25 Apr 2004 01:30:44 -0700, tu disais/you said:-

Yes, I know this is often said.

I'd like to be able to agree with you but then how to explain the immense legs that I observed in a Tokaji Eszencia - still fermenting - with only around 3-4% alcohol. Also, I'm afraid that I DO find that Auslesen and higher (with low sugars therefore) can have very fat legs, if they are from areas where the vines have worked hard.

I feel (without any experimental data, but nevertheless some 30 years observation of the behaviour of good wine) that it's a lot more complex than that.

Reply to
Ian Hoare

Sorry, no.

Having tasted some 160 Austrian Beeren- and Trockenbeerenauslesen in the last two weeks, of which roughly one half had an alcoholic content of 11.0 percent or less, I definitely can assist Ian here: They *all* showed significant legs on the glass.

M.

Reply to
Michael Pronay

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