Viscosity of Wine

I have never seen a measure of the viscosity or stickiness of a wine.

I suppose it is a function of the alcohol and residual sugar but it would be nice to see a measure of it particularly for sweet wines to differentiate between sweet and thin an sweet and gloopy wines.

Hi Warren,
Besides alcohol and residual sugar another component, which could contribute to viscosity, is glycerol (it is produced during fermentation).

Salute

Hi Warren,
I think you will also find some sorbitol in the wine .

Hi Warren,
I think you will also find some sorbitol in the wine .

Hi Philip,
Your assertion regarding sorbitol in wine surprises me. I am not a chemist or other type of scientist, but from what I read, sorbitol does not occur in grapes. Or it might be that it occurs very rarely. So, if this is true can you please explain how it might be found in wine. Also, from reading I find that sorbitol can wreck havoc on the human stomach causing an irritable bowel syndrome. Would you tell us what you know on the subject? Thanks.

I was curious about some of these issues and consulted my copy of Margalit's Concepts In Wine Chemistry. Water/ethanol mixtures are more viscous than either liquid by itself, with the most viscous mixture occuring at 40% alcohol. At the 12% alcohol typical of wine the viscosity would be about 1.4 centipoise vs. 0.89 for pure water (at 25C). Sugar also contributes to the perceived viscosity and body. Glycerol is present at about 1/10 the concentration of alcohol in most wines, with this being higher for botrytis affected grapes. While glycerol is very viscous by itself, it does not contribute significantly to the actual viscosity at the concentrations found in most wines. The effect of glycerol on the body is complicated by the fact that it is also sweet, and sweet wines are perceived as having more body.

Margalit presents a "suppleness index" due to Peynaud and Ribereau-Gayon which goes as follows:
SI = alcohol% (v/v) - {acidity (g/L) + tannins (g/L)} . Wines in with SI around 4 will presumably be perceived as thin while those up around 6 will be perceived as soft and full bodied.

Oh, sorbitol is one of the several poly-alcohols found in wine at small concentrations, typically 50-200 mg/L, with higher levels in late harvest (botrytis) wines.

Oh, sorbitol is one of the several poly-alcohols found in wine at small concentrations, typically 50-200 mg/L, with higher levels in late harvest (botrytis) wines.

It is also apparently used to adulterate wine:
http://grande.nal.usda.gov/ibids/index. ... row=400293

Margalit presents a "suppleness index" due to Peynaud and Ribereau-Gayon which goes as follows:
SI = alcohol% (v/v) - {acidity (g/L) + tannins (g/L)} . Wines in with SI around 4 will presumably be perceived as thin while those up around 6 will be perceived as soft and full bodied.

Interesting. I can understand tannin contributing to the body of a wine, but not to its being soft or viscous in the mouth.

And thinking about astringency emphasises the difference between a wine's viscosity as measured "scientifically" by a rheometer, and the perception of viscosity in the mouth in the presence of protein-bearing saliva .

Suppleness I believe includes both viscosity (“thickness”) and body (texture). So the dry extract content of the wine (both sugar and non sugar dry extract) will contribute to a wine’s texture and body.

Salute