Most People Don’t Know Wine Moves Like This | EVERYDAY MYSTERY

Thats really interesting. When testing wine and talking about qualities of the wine, one usually doesn't just wait for the "legs" to form by Marangoni effect. Usually, one swirls the wine, causing the residual wine to drip down the sides, in "legs". We've always thought that the longer those legs run down the glass, the higher the residual sugar content in the wine, since dissolved sugars increase the viscosity of the wine. One can see this in the difference between ports (high sugar) and zinfandel (lower sugar). While the alcohol contents are slightly different (port is ~19%, zinfandels ~16-17%), the residual sugar contents are WAY different: an old vine zin has 3-5g of sugar per liter, most ports run around 100-150 g per liter. Consequently, the legs last way longer in a port than a dry wine. The difference between different wines can often show up as well in legs that are more or less persistent.


Incidentally, this formation of legs doesn't say anything about THE quality of the wine, rather about A quality, namely, the residual sugars. This can tell enthusiasts whether the grapes were likely harvested late or early, what type of grapes might be in a blend, etc. But given this interesting work here, I guess it also tells us about the potential alcohol content. One might guess that the sugar content will also have an effect on the surface tension gradients formed to make the Marangoni effect.