Of course swirling looks cool, but it’s also useful to understand characteristics of wine.
Legs & Tears
When wine is swirled, the “legs” (or "tears") stick to the glass. Wine that swirls more slowly is likely higher in alcohol.
When we stop swirling, the wine’s “tears” flow down the side of the glass. Slower moving tears are signs of higher alcohol, sugar, and tannins.
Aroma
Swirling also oxidizes the wine. It causes the alcohol to evaporate and releases aroma compounds from the wine. These aroma compounds, which allow wine to have a scent, stick to the evaporating alcohol and travel through our olfactory system. The result? More complex fragrances such as violet, lemon, and eucalyptus. Because the majority of our sense of taste is smell, releasing aromas also adds complexity and deliciousness to the wine's taste.
The Perfect Swirl
Doesn’t exist!
But swirling in a glass less than half full allows more oxidation and a better opportunity to see legs and tears.
Next time you drink, try smelling and tasting the wine before and after swirling. What differences do you notice?