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The Origin of Flavors in Wine

Erica Landin-Löfving Erica Landin-Löfving
At a dinner many years ago I sat next to a woman who, when I said I worked as a wine writer, told me that her favorite wines were the ones with blackberries and plums. For a second I was perplexed, pondering how many wines actually had added fruit flavors to them, but then realized she was referring to a ripe cabernet.
How easy it could be to misinterpret us wine writers when we say a wine is “bursting with black fruit” or “notes of grapefruit and wild strawberries”! And even though most of us, once we’ve developed an interest in wine, understand that the flavors are not actually added to the wine, it still isn’t inherently obvious what brings the flavor of “toasted brioche,” “grass” or “underwood” to your glass. Parts of the most wild descriptive language is more entertainment than precision (who wants to read a boring wine writer?) but there are definitely parts of this language that are quite useful and connected to specific chemical compounds. 

Primary, secondary, tertiary

In wine, we speak of primary, secondary and tertiary flavors. Simply put, the primary flavors come from the grape itself and are affected by things such as variety, clone, terroir and ripeness. These flavors include fresh apple, blueberry, raspberry, blackberry and other fruit, berry and herbal flavors. Secondary flavors and aromas come from the winemaking process.
Though most fine wines use neutral yeasts, many rosé wines and fruity, less expensive wines get some extra fruit flavors from aromatic yeasts used in the fermentation process. With that exception, the fermentation gives notes like toast, bread, hard cheese, spice or bacon (caused by low levels of the wild yeast brettanomyces) and vanilla (from newer oak barrels), while the malolactic conversion will mainly add aromas of cream or butter.
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Primary Flavors: Grape derived aromas include fruit (such as fresh apple, blueberry, rasperry, blackberry etc.), flower, and herb aromas, which are affected by variety, clone, terroir and ripeness. (Photo by Roman Synkevych on Unsplash)
The tertiary flavors develop during the wine’s maturation and are more complex. Now we go from talking aromas to talking wine “bouquet” with words like earth, coffee, forest floor, leather, tobacco, spices and mushrooms. The process of oxygenation, from a generally small exposure to air through the cork or the barrel, creates most of these though some are provided directly from the wood a barrel. With the development of tertiary flavors, some of the primary flavors will disappear. 
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(Photo by Jesse Dodds on Unsplash)

Primary Flavors:  Aromas include fruit, flower and herb aromas.

Secondary Flavors: Fermentation aromas smell like cream, bread, mushroom, or butter.

Tertiary Flavors: Aromas that develop with aging and oxidation include nuttiness, vanilla, coffee, and tobacco.

More interesting articles:
>> Aging With Grace

A thousand chemical compounds

For us to be able to smell the chemicals, they need to be volatile. That’s why we swirl our glass too, or aerate the wine, so they can be released and available for our nose. Some aromas are transient, evaporating with exposure to air or coming and going in the glass. 
There are around a thousand flavor compounds that have been identified in wine - many times more than we would get in straight, unfermented grape juice. The complexity is what makes wine so stimulating! The point of learning a few key flavors, apart from possibly impressing your friends, is mainly that it can help you better pinpoint what wines you enjoy as well as expressing the characteristics you prefer when speaking to a sommelier in a restaurant or a sales person in a bottle shop.
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Swirling (and aerate the wine) helps release the hundreds of different aroma compounds found in wine. These compounds are the reason why wine has such an array of aromas. Some aromas are transient, evaporating with exposure to air or coming and going in the glass. (Photo by Mae Mu on Unsplash)
Saying you like Chardonnay is a big step up from saying you feel like a white wine, but saying you like a creamy, buttery Chardonnay with mature aromas like mushrooms and wet leaves, rather than one that is dominated by fresh, green apple is much more useful for singling out a bottle that will rock your world (or your dinner, where the former might go well with a meaty white fish with a buttery mushroom sauce and the second is a better match for a fresh salad). 

Impact compounds

There are a group of aroma compounds that scientists call “key food odorants” and sommeliers may refer to as “impact compounds”. They are chemical compounds that produce very characteristic aromas in wines and that anyone working on recognizing a wine in a blind tasting must master. They don’t generally tell you exactly what wine you are smelling but it definitely points in a very strong direction. 
Methoxypyrazine - gives the aroma of fresh cut grass to a Sauvignon Blanc or the bell pepper scent in some young, red bordeaux varietals can also taste like raw cocoa. Not pleasant to all people in a young red wine but mellows with aging, giving way to smoother flavors of cherry and chocolate. 
Monoterpenes - flowery compounds that can remind us of roses, sweet fruits, sweet spices or even coriander. For some people they come off as soapy or remind us too much of perfume. Mainly in white wines like Gewürztraminer, Viognier, Riesling, Muscat Blanc… Monoterpenes include Geraniol, Nerol and Linalool, Wines with these compounds are described as floral or aromatic. Monoterpenes can actually be tasted in the grape itself.
Soloton - pleasant oxidized compounds in purposely oxidized wines like Vin Jaune and Sherry or in older Chardonnay or old Sauternes. Sweet aromas of walnuts, toffee apples, molasses, cumin and maple syrup. 
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All aromas have different scents. For example, Rotundone has a more concentrated smell like black pepper and cocoa powder, while Soloton has sweet aromas of walnuts, toffee apples, molasses, cumin and maple syrup. Photo by American Heritage Chocolate on Unsplash


TDN (more correctly 1,1,6,-trimethyl-1,2-dihydronapthalene, but who can remember that after two glasses of wine?)  Have you heard someone describe a riesling as having a scent of bike tires? TDN gives aromas like kerosene, petroleum, plastic or diesel and is prevalent in aging Riesling, though it can show up also in Sauvignon Blanc and Chardonnay. If the grapes were grown in a warmer climate or warmer year, the diesel aromas will appear earlier in the aging process. 
Rotundone - this is the compound that we find, much more concentrated, in white and black peppercorns. It can smell like black pepper, cocoa powder or deep, rich spice. It has a strong impact on the perceived flavor of Syrah, Grenache, Zinfandel, Petite Sirah and Grüner Veltliner. 
Diacetyl - butter, cream aromas and a creamy texture. Diacetyl is created during the malolactic conversion process where malic acid is broken down by bacteria into lactic acid. Common practice in red wines but only done on some white wines, like rich, buttery Chardonnay and Viognier. 

From clear to complex

In general, in the beginning of our wine discovery journey we enjoy clear cut primary flavors and we like recognizing them easily. The gooseberry in a €15 New Zealand Sauvignon Blanc is fun until we crave more complexity. That’s usually where the interest in more aged wines can appear, or wines where the supporting scents are so subtle that we need to give the wine time.
Some of the aromas will be present in larger amounts and others can be very minute. This doesn’t necessarily determine how prominent the scent will be. They affect each other too, so the presence of one might change the perception of another. A wine bouquet is more complex than the sum of its parts! Finally , the aroma of a wine is determined in one part by the wine, but in one part also the drinker herself.
Different people can have a genetic predisposition to pick up on some aromas but exposure also matters. Two people can smell the same chemical but still describe it differently. A gooseberry won’t evoke the same flavor profile to someone from Oregon, where it is tart, and someone from Marlborough where it can show tropical flavors.
Do you have a cat? Cat’s pee might be a very specific description to you (and a surprisingly commonly used one) but someone who has never changed a litter box but who lives in California might prefer boxwood. We should, however, use descriptions that can be more or less universally understood unless describing a wine is only for our own, personal recollection. You might be strongly reminded of personal references, like “grandma’s pantry,” but they aren’t as much use in describing the wine to your work colleague who has never been hanging out with nonna’s spice rack. 
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It is common that two people who smell the same chemical will experience different smell and flavor. Same chemical can be described differently, depending on personal references or genetic predisposition. Photo by Lasseter Winery on Unsplash


Spoilage from yeasts or bacteria gone off the rails can come during winemaking or aging and can give aromas that are acceptable or even add complexity at low levels but ruins the wine at higher levels. These are generally unpleasant to everyone at high amounts but our tolerance and appreciation can differ in low amounts.

Besting the pro’s

At tastings, it’s common for people to say they don’t have as advanced a sense of smell as wine writers or professional sommeliers. That is generally not true. Even though a few wine experts are born supersmellers, there are two key reasons we can describe what’s in the glass. First, we practice. A lot. Sometimes too much. Personally, early in my wine tasting days, I would go to the grocery store and buy every fruit and spice and herb I could find and sniff them over and over to memorize details of the flavor.
Second, we get really good at the vocabulary and at sounding confident. It IS possible to be wrong (a very oxidized fortified white wine should probably rather be described with words evoking caramel, dried fruit and nuts and not dark fruit or berries) but you generally won’t be. If the wine makes you think of red fruit, it will be personal if you find strawberries or raspberries or more tart lingonberries in there. And if you smell cloves and your dinner guest doesn’t, just say it with enough confidence. Of all the tricks of the trade I have learned, describing wine with confidence is one of the most useful ones. Especially when I smell mouse droppings.  


Practical tip:

To practice, pick up a wine aroma wheel, developed at the famed wine department of UC Davis in California. Once you can identify a wine as “fruity” (easy, right?) you can move to the next level of the wheel to see if it is rather reminiscent of tree fruits or citrus fruits or tropical fruit? When you feel confident at this level, try your hand at discerning between mango, pineapple or melon. After this, if you decide to go wild in your descriptions, we might smile but we won’t judge. After all, some of the best wine writers in the world have made themselves a name from embroidering their wine descriptions to a point beyond actual use. 
WineFolly flavor chart has upgraded the classic aroma wheel with information where the scents come from and chemical compounds.
To do this wine tasting, go to a wine shop with good staff or use the wine descriptions of your favorite online wine store to get wines in these different styles. 
Exercise 1
1. a crisp, young Chardonnay, unoaked (steel tank). Preferably from France (ie Petit Chablis) or a cool climate like New Zealand. 
2. an oaked, ripe Chardonnay from a warmer climate such as California (note that California also makes some stunning cool climate Chardonnay so look for descriptions like lush tropical fruit) 3. an aged, quality Chardonnay, like a Meursault. 

Try to find the primary aromas of fruit in the wines. Is it citrus, tropical fruits, ripe apples? Use a wine aroma wheel or find one online. Now try to look for secondary aromas of oak or yeast (vanilla, toast, bread. Are there notes of butter or cream in the warm climate Chardonnay?).
Next, compare the aged wine with the two younger wines. What has been added to the bouquet with age? What has disappeared (and what was probably never there to start)? What style do you prefer? How might these wines differ in what foods they match?


Exercise 2
  1. a young, ripe, full bodied Shiraz or Syrah (same grape) from a warm wine region like South Africa, California, Southern Rhone or Australia (note that these regions might also produce “cool climate style” syrah so look at the description)
  2. a young, fresh Syrah from northern Rhone of the same vintage as wine 1
  3. an aged, quality Syrah/Shiraz (extra fun if you find the same wine as one of the first ones but with at least two years extra age, preferably more)

Compare the first two wines and compare their primary aromas. How does the fruit style differ? Are there notes of spices in one or the other? Which spice? Can you tell anything about winemaking, such as oak (more fun if you don’t know in advance if barrels or wood was been used or not)?
Now try the third wine. What flavors have appeared with time? If there is a decidedly “meaty” quality to the wine it has aged with less oxygen. More time or oxygen might remove that. Any new spices?