The Flavor of Wine

By Matthew Citriglia, MS on July 9, 2006

Between helping candidates who are studying for Sommelier exams become better tasters and simply helping newbies better understand their own personal tastes, I put wine into a lot of people’s mouths. Whether novice or experienced the most difficult thing to comprehend when tasting is, where do all the flavors and tactile sensations come from? Are they added? Why don’t the grapes taste like the wine? How can a wine taste like raspberries if it is made from grapes? And so on.

To understand where the aroma and flavors in wine develop you need to begin with fermentation. When grapes ferment, yeast eats the natural sugars found in the grapes and multiplies. The byproduct of this is carbon dioxide, alcohol and over 200 aromatic esters. Think of an ester as specific aromatic aroma. If you wake up and smell eggs and bacon cooking, do you need to see the eggs and bacon? If you were blindfolded and someone walked you through a barn, into an open field, through the woods and over a dry riverbed, would you be able to identify these areas without seeing them? Sure you could. The aromatic esters of each of these items would conjure an image in your minds eye.

Each grape variety has a unique physiological make up with aromatic compounds found in trace amounts within the grape skin cells. The concentration of each of these aromatic sensations is dependent on the grape type and is mostly undetectable until the juice is fermented. Fermentation magnifies and makes these aromas more easily perceived by the nose, so think of wine as a caricature of the grape.

When we taste wine we smell the aromas that were created during fermentation combined with the taste and tactile elements of the grape. This is why many times people smell a wine and think they will like it, but when they put the wine in their mouth they say yuk! It is not because they don’t like the wine, rather it is because the brain was expecting different stimuli in the mouth based on the aromatics and when the brain didn’t get what it was expecting, it tells the body to reject it.

Over the years your brain has associated specific aromatic esters with either visual or taste / tactile sensations. The problem with wine is that fermentation creates over 200 aromatic esters that the brain has associated with both visual and taste / tactile sensations. This causes confusion at first as the brain tries and adjusts to the new stimuli. This is also why people new to wine sometimes think that all wine tastes the same, or they can’t smell certain aromas as the brain is being overloaded with too much information that needs to be processed differently than before.

To better understand the taste and flavor of wine you will need to retrain your senses. This starts by redefining the terms aroma, taste and flavor, and concludes with reviewing components of grapes and wine making that impact flavor in the finished wine.

Aroma vs. Taste vs. Flavor
Although these three words tend to be used interchangeably, they mean very different things to our senses. To better understand the reactive components in food and wine, it is necessary to better define what aroma, taste and flavor represent.

Aroma - An aroma refers to an actual aromatic compound with a specific scent that can be identified by smelling. Strawberries, coffee and bacon all have a specific aromatic compound that allows us to identify them solely by their smell.

Taste / Tactile - The tongue only can sense taste and feel texture. It senses sweetness (the presence of sugar), sourness (the presence of acidity), bitterness and saltiness. In addition, it can feel heat from alcohol, astringency from tannin and creaminess from milk. (I will leave the controversial and complicated subject of Umami out of this article.)

Flavor - Flavor is the brain’s association between what it smells through the nose, tastes with the tongue and feels in the mouth. For example, the flavor of strawberry is the brains association between a specific aromatic compound; a sweet and sour taste; and a specific tactile sensation of the strawberry being chewed.

Remember in wine there are roughly 200 different aromatic compounds in varying concentrations that were created during fermentation. So not only is the brain struggling to pull apart all these different smells, but it has the added burden of applying different visual, taste and tactile sensations to aromas it recognizes as something else. Combine this with each taster’s individual sensitivity to specific aroma, taste and tactile stimuli and it is easy to see why tasting wine causes so much difficulty.

Components of Wine Flavor
Now that we have defined some terminology for tasting, let’s look at some of the components that contribute to the aroma, taste and tactile sensations of wine.

Acids – When grapes begin their life as small berries they are all acid and no sugar. As the ripening process takes place the acid level falls as sugar rises and juice increases the size of the berry. During the growing season, acidity levels fall quickly in warmer regions and slowly in cool regions, which can be sensed in the finished wine. Acidity pricks the tongue and stimulates the production of saliva. Because the acidity falls out of wine faster in warmer climates, the wines will taste less tart and will feel rounder than those grown in cooler climates. A person’s sensitivity and perception to acid will give the taster clues as to wines grape variety and growing region.

Aroma Compounds – These compounds are found mostly in the skin cells of the grapes and are directly responsible for the “primary aroma” that gives each grape variety its fruity character or identity. Extracting these flavors from the skins without extracting astringency and keeping the wine from oxidizing can be difficult especially for a white wine. This is an easy task for ripe grapes, but this also means the wine will have higher alcohol. Finding the balance is an art.

Glycerol – This component directly impacts mouth-feel by giving a wine smoothness and weight without overt sweetness or excessive alcohol. The amount of glycerol in a wine is dependent on grape ripeness and type of yeast used in the fermentation process. I have tasted many wines at 12.5 percent alcohol that had great mouth feel.

Malo-lactic Fermentation – This secondary fermentation takes place after the alcoholic fermentation has been completed. This is basically a bacteria fermentation that converts Malic acid into the softer lactic acid. The byproduct creates another ester known as diacetyl, which many of us refer to as butter. The amount of diacetyl produced is dependent on the amount of Malic acid present, the type of lactic bacteria used and the speed at which the conversion happens. So not all wines that go through ML have obvious signs of butteryness, the winemaker needs to pay close attention to this fermentation so not to rob or overpower the fruit of the wine.

Oak – This deserves an article all its own. To keep it really simple, each oak forest has its own set of favor constituents that it can be impart into the wine. I highly recommend, if you get a chance, to attend an oak seminar. Usually you get to taste the same wine aged in a variety of oak barrels that were toasted in variety of ways. Most oak will impart the aromas of vanilla, clove, hazelnut and smoke to name just a few. Oak is also porous and allows the wine to slowly evaporate over time. Excess aging in oak will not only overpower the fruit but will also imbue reductive qualities in the wine.

Polyphenols – Polyphenols are an important group of compounds that are found in the skins of the grape and to a lesser extent the pulp of the berry. For tasting purposes they contribute to the wines tannin and color (anthocyanins) and it is important to note that they are not dependent on each other. Therefore, a wine can be high in tannin and light in color such as Nebbiolo.

Prefermented Sugar or Potential Alcohol – This is the sugar created during the growing season that is converted into alcohol. Residual sugar left in solution is addressed below. Sugar is created in the grape via photosynthesis and heat. Higher sugar levels at harvest will cause the grape to be riper, which in turn will increase the alcohol percentage and create a more powerful wine. Because of this correlation between heat sunlight and sugar at harvest, it is possible to taste and feel this in the finished wine. Powerful wines tend to be grown in warm sunny regions while wines with more finesse tend to be grown in cooler growing regions. This is easy to see if you go out and get a bottle of Mâcon-Village at 12.5% alcohol and most any Australian Chardonnay at 13.9% alcohol.

Residual Sugar – This is the amount of sugar left in solution after fermentation has finished. Most wines contain some amount of RS but most palates are not sensitive enough to taste it once the level falls below 10 grams of sugar per liter of wine. To complicate matters sugar and acidity tend to neutralize each other. So if you taste two wines with the same amount of RS, the wine with higher acid will taste drier. Do not confuse fruitiness with sweetness. All wines are fruity as they are made from fruit; residual sugar refers to the amount of perceptible sugar remaining in solution after fermentation is complete.

The senses of a Master Sommelier are no better than anyone else’s. We do not have genetically altered noses or extra tastes buds or some type of sixth sense that makes us more sensitive to what is in the glass. What makes a Master Sommelier a great taster is our fundamental understanding of how the flavors in wine are developed and the role Mother Nature and the winemaker play in the creation of those flavors via fermentation. In reality, there is only one way to fully understand where the flavors in wine come from, pull a few corks and taste, taste, taste.