What’s with smelling the wine?
Smelling is an important part of tasting because aromas and flavors are so closely linked. We’ve all experienced this, when we’ve had stuffy noses and can’t taste food very well. The food tastes bland because we are using only our sense of taste to perceive it, and we’re missing the aromatic component of the experience. For more details on the relationship between taste and smell, check out this article.
Another reason to smell or “nose” the wine is that our sense of smell is actually stronger and more sensitive than our sense of taste. We can only taste 4 different flavors – sweet, sour, salty, bitter (5 if you count umami) – but we have the potential to smell between 5,000 and 10,000 distinct aromas, if we develop that ability. For more on how our sense of smell works, read this.
What’s with all the swirling?
Aromas in wine come from chemical compounds that are present in the grapes and/or created during the fermentation process. When the wine is swirled, more of these compounds are exposed to oxygen and “volatilize,” which just means they evaporate into the air and directly up your nose, if you've positioned it at the top of the glass! The swirling makes the wine aromas stronger, so we can smell them better. For more detail on this subject, the Wikipedia page on wine aromas is a good resource. And here’s a list of some of the chemical compounds, called esters, and what they smell like.
How to Train Your Nose
While some of us will naturally have a more or less acute sense of smell, we can all train our noses to work better!