The Science Behind the Main Aromas in Wine

A bold splash of grapefruit, tasteful speckling of white pepper, delicious hints of kumquat.

Suffice it to say, sometimes wine descriptions can read a little floral. Can you really smell kumquat?

Yes, you really can. Every scent in wine can be boiled down into a fine science. 

Our favorite wine aromas emerge from the interactions between hundreds of different chemical compounds within each varietal, mixing and clashing and playing together in a pressure chamber of flavor.

While a perfect glass of wine might taste like a unique work of art, the truth is that a great deal of tried-and-tested science is used to craft a delicious vino. 

Modern winemakers exercise tight control over their vineyards and the fermentation process, using many components of food science to amplify desirable aromas while muting the less desirable ones. 

Let’s dive into the chemistry and compounds that bring out those coveted wine vapors in our favorite varietals of wine.

Basic Wine Chemistry

Just like the elements on the periodic table, many foods are made up of the same basic compounds. It’s in the distribution and combinations of those compounds that we find the vast spectrum of food and drink we love.

In unfermented grapes, many of the aroma molecules that come to life in a delicious, full-bodied wine are still bound up with sugar molecules, rendering them relatively odorless. 

Once the fermentation process begins and those sugars are converted into alcohol, those aromatic flavor compounds are partially unleashed into vapors that excite our sense of smell.

Most of the compounds we find in wine can be traced back to the original grape, the fermentation process, or the specific wooden barrel the wine is aged in. This creates the primary aromas, secondary aromas, and tertiary aromas that give each wine its one-of-a-kind character.

To heighten any wine tasting experience, be sure to properly chill, oxidize, and sniff your wine before tasting. This ensures that you get the most out of your wine aromas, meaning the most out of every glass.

You might think you need a sharp nose to detect these compounds, but all it takes is a little practice and a little science.

Let’s dip a toe into the world of food chemistry and explore those delicious compounds that make up your favorite varietal of vino.

Esters

Perhaps the most sought-after of all the wine compounds, esters lead to scents of exotic fruit flavors like banana and pineapple. Over 160 different esters have been found across the wine world, and many esters influence one another to form entirely new scents.

If you’re sipping on a young rosé bursting with fresh fruit flavor, you’ve only got esters to thank.

Terpenes

These compounds are found in many of the most beautiful parts of nature — in blossoms, fruits, and leaves of various plants. Pine and desert sage are two classic scents that only exist due to terpenes.

In wine, terpenes are primarily found in grape skins and might lead to a smell of rose petals, citrus, or lavender. If your nose detects a eucalyptus aroma in an Australian Shiraz or a hint of rose in a Muscat Blanc, you can thank the terpenes found in each.

Rotundone

This compound is known for the peppery aroma it gives off, found in the oils of rosemary, thyme, oregano, and basil. 

If you’re smelling a sharp, spicy bouquet off of a Syrah or Shiraz or a basil scent teeming off a Riesling, you’re likely inhaling this compound.

Lactones

These esters are found in coconut, roasted hazelnut, butter, and sweet pork, giving each of them their uniquely sweet, creamy flavors.

If you’re wondering where those hazelnut flavors in a vintage sparkling red or hints of coconut in your white wine come from, look no further than lactones. 

Pyrazines

Pyrazines are a fundamental compound in chocolate and coffee, and these compounds give off vegetable-like Bell Pepper scents in a Cabernet Franc and wheatgrass in a Sauvignon Blanc. 

Making up many of the “greener” flavors we love in our favorite vinos, pyrazines bring a bit of the vineyard into every sip.

Thiols

In small amounts, thiols give off a desirable earthy, fruity aroma. Although winemakers have to be careful to keep this compound under control — if it takes up too large a presence in a wine, it can start to smell like garlic and damage the flavor profile of a wine.

When it’s properly handled, thiols imbue a bittersweet, grapefruit flavor in popular vinos like Vermentino or Sauvignon Blanc, or even a Black Currant aroma in a Red Bourdeaux.

Sulfur Compounds

Providing textured minerality to your favorite varietal of dry Champagne, sulfur compounds are also the reason for a chalk-like aroma that’s characteristic of a top Chablis.

Again, moderation is key, as some sulfur compounds can dominate the flavor profile of a wine, filling it with scents like wet newspaper. This usually points to UV damage in the storage of wines.

Bacteria

Wine is a living, breathing liquid. Hungry yeast particles transform the sugar of grape juice into dry, bitter alcohol, giving wine its characteristic bittersweet flavor. Meanwhile, bacteria in each varietal can lead to the formation of acetic acid. 

A tiny amount of acetic acid can add a stunning, extra dimension to a fine wine like a top Chianti. Too much acetic acid and the wine begins to take on a slight taste of acetone — not desirable.

Become a Wine Chemist with Wine Connoisseur

Furthering your wine education isn’t just about seeking the finest varietals and the best vineyards, it’s also about bringing some chemistry into the equation. 

Proper winemaking resembles a perfect balance between art and science, allowing both fields to play together in harmony and build off each other to make each sip tastier than the last. 

If you’re interested in stepping up your game, look for a wine aroma kit to slowly learn to identify those compounds and pick out your favorite flavors. After all, smelling wine is an integral part of fully tasting each sip.

If you’re not properly chilling and oxidizing each glass, you’re not making the most of a top varietal, especially a fruity wine. The creamy lactones won’t taste quite as creamy and the earthy thiols might turn overly pungent.

To get the most from each of those delicious compounds, look to an expert wine aeration machine like the Wine Connoisseur. The Wine Connoisseur ensures every glass is served to perfection, bringing out the best in a wine’s bouquet and maximizing the taste of every sip.