The aromas of wine are more diverse than its flavors. The human tongue is limited to the primary tastes perceived by taste receptors on the tongue – sourness, bitterness, saltiness, sweetness and savoriness.
The wide array of fruit, earthy, leathery, floral, herbal, mineral, and woodsy flavor present in wine are derived from aroma notes sensed by the olfactory bulb.
In wine tasting, wine is sometimes smelled before taking a sip in order to identify some components of the wine that may be present. Different terms are used to describe what is being smelled.
The most basic term is aroma which generally refers to a “pleasant” smell as opposed to odor which refers to an unpleasant smell or possible wine fault.
The term aroma may be further distinguished from bouquet which generally refers to the smells that arise from the chemical reactions of fermentation and aging of the wine.
Identified aroma compounds
Some of the identified aroma compounds include the following:
Methoxypyrazine – grassy, herbaceous aroma compound associated with Cabernet Sauvignon and Sauvignon blanc.
Monoterpenes – responsible for the floral aromatics of varieties like Gewürztraminer, Muscat and Riesling. Includes geraniol, linalool and nerol.
Norisoprenoids – Carotenoid derived aromatic compounds that includes megastigmatrienone which produces some of the spice notes associated with Chardonnay and zingerone responsible for the different spice notes associated with Syrah.
Other norisoprenoids include raspberry ketone which produces some of the raspberry aromas associated with red wine, damascenone which produces some of the rose oil aromas associated with Pinot noir, and vanillin.
Thiols/Mercaptans – sulfur-containing compounds that can produce an aroma of garlic and onion that is considered a wine fault.
They have also been found to contribute to some of the varietal aromas associated with Cabernet Sauvignon, Gewürztraminer, Merlot, Muscat, Petit Manseng, Pinot blanc, Pinot gris, Riesling, Scheurebe, Semillon and Sylvaner.