For anyone that’s ever paused to take in the complexity of a glass of wine, I’m sure the question has arisen, where does the aroma come from?
The aroma of wine comes from a wide array of volatile and non-volatile chemical compounds found in grapes, the fermentation process, and the barrel it may be aged in.
What Is A Volatile Compound?
The volatility of a substance is how readily it turns to vapor. Highly volatile compounds can easily exist as vapor at room temperature. Vapor is detected by the nose as various scents.
Wine is more so experienced by our nose than our palate or tongue. This is why drinking wine with a head cold can often lead to dull experience made up of just the acid’s sour taste, the tannin’s bitterness, and the alcohol’s burn.
According to the Court of Master Sommeliers:
“A wine’s flavor is approximately:
85% smell, 8% taste, and 7% tactile
The human olfactory bulb is very sensitive and is believed to be able to ascertain 300,000 different aromatic compounds.
These aromatic compounds, or scents, are released from wine when the glass is swirled.
Swirling coats the entire glass, which allows the alcohol to volatize more completely and carry aroma to your olfactory bulb.”
The 3 Types Of Aromas In Wine:
- Primary – aromas from the grape itself
- Secondary – aromas from the fermentation process
- Tertiary – aromas from oak or bottle ageing
What’s The Difference Between Aroma And Bouquet?
Aroma and bouquet are used interchangeably in casual drinking conversation. The difference is that aromas come from the specific grape itself, while the bouquet arises from the fermentation process and “opening up” of a wine with the ageing process.
Pinot Noir will exhibit the “aroma” of cherries, but over time its “bouquet” may exhibit “cola” from its time spent in oak barrels.
Examples Of Compounds Are:
- Methoxy”pyranzines” – (grassy, herbaceous aromas like bell pepper) found in Sauvignon Blanc and Cabernet Sauvignon.
- Mono”terpenes” – (floral, citrus aromas) found in Riesling, Muscat, Gewürztraminer.
- Thiols/ Mercaptans – (sulfur, garlic, onion) usually a “fault” in wine and beer but also found in Merlot and Cabernet Sauvignon
The inherent chemical compounds found in a grape are what nature uses to attract bees and birds to pollinate.
These compound names are becoming more and more widely known as essential oils gain popularity.
Terpenes are found in small and large compound form. There are many types with many different expressions.
Popular terpenes in wine are geraniol, linalool, and nerol. Nerol is found in the Neroli plant where it got its name.
Terpenes are used by plants as a deterrent for herbivores.
Hops (used in brewing beer) and cannabis are both known to have a wide variety of “terps” that contribute floral, citrus, and piney scents.
Aromatic white wines are sometimes referred to as “terpy.”
What Is Le Nez Du Vin?
Le Nez du Vin translates to “the nose of wine” and is a set of wine aromas created by Jean Lenoir to help students of wine learn how to identify classic scents.
Examples such as butter, hay, clove, cedar, violet, pepper, cinnamon, mushroom, and many more are included.
The sets are not cheap and can easily run over $500, but they are of high quality and invaluable as educational aides.
There’s even a “coffee kit” available now!
How Does Ageing Wine Affect Its Bouquet?
A wine’s bouquet changes as its alcohol, acid, and esters strive to find an equilibrium over time. Wines that are high in acid tend to evolve with more complexity than those with lower acidity.
Examples of wines with good acidity that age and evolve well are; Burgundy (Pinot Noir or Chardonnay), Barolo, and Riesling.
If a wine is aged in oak barrels, tannins in the wood interact with compounds in the wine creating notes of vanilla, baking spices, coconut, dill, and sometimes butterscotch.
There are countless ways that winemakers can assist or create aromas in their wines.
The choice of yeast or the temperature of fermentation can lead a grape like Chardonnay to smell very different from estate to estate.
Some Champagne and Chardonnay houses let their Chardonnay ferment “sur lie” or with “lees.” Lees are dead or residual yeast cells that can impart hazelnut or brioche aromas.
Beaujolais and Pinot Noir producers will sometimes include some stems in the fermentation process which will produce “green” or “stemmy” aromas.
The fervent study of aromatics is ongoing.
The wine, coffee, and fragrance industries are constantly learning more and more about what, and how we smell.
Scientists are chemically analyzing compounds in plant material and finished wines.
It’s astonishing to think that in only 150 years humans went from learning how to measure temperature precisely, to producing a spectral analysis of the chemical make up of things!
Enjoy taking in the aromas on your next glass of wine with a new perspective.
Cheers!
