Wine is a complex chemical beverage. Besides the primary acids of tartaric, malic, lactic, and citric, Australian wine scientist Bryce Rankine has identified 23 additional organic acids found in wine in varying amounts, including acetic acid (responsible for the sour taste of vinegar), ascorbic acid (also known as vitamin C), butyric acid (causes a smell like rancid butter), sorbic acid (produces a geranium smell), and succinic acid (created by nitrogen metabolization). Rankine has also identified 23 varieties of alcohol in wine besides ethanol, as well as more than 80 esters and aldehydes, 16 sugars, and a long list of assorted vitamins and minerals. Wine can also contain harmless traces of lead and arsenic that come from the soil in which the specific grapevines are planted. Complex indeed.
Three of wine’s most basic components – sweetness, sourness and bitterness – are picked up by the tongue’s taste buds. A good wine has the perfect balance of sweetness from the sugar in the grapes, sourness from the acids—particularly tartaric and malic acid—and bitterness from alcohol and polyphenols, including tannins. Also, the flavor of wine, which is its aroma or bouquet, is detected not by the taste buds, but by millions of receptors in the olfactory bulb connected to the nose and located where the nasal passage connects with the brain. Evaluating a wine most involves smell rather than taste, but more on that later.
One very important fact about evaluating wine is that it is a subjective experience because no two person’s sensory systems are exactly the same. Due to our sensory uniqueness, each of us has different sensitivities and tolerances for the different wine components. One person may be sensitive to tannin, another person may be highly responsive to acidity, and a third person may readily notice sulfur dioxide. To a great degree, your sensitivities and tolerances determine your personal likes, dislikes, and preferences in wine. This is why some people like dry wines and others prefer sweet wines. It is also why some of us adore wines with strong tannins and others would just as soon suck on a wet washcloth. When it comes to evaluating wine it is very important to become aware of your own sensitivities and tolerances, because it is a virtual certainty that you will come across a wine that you detest, despite the fact that it is perfectly well made and typical for the grape varietal/style of wine.
Steps in Evaluating Wine
The process of wine evaluation involves the following four steps: (1) examine the appearance of the wine using your sense of sight; (2) examine the aroma and bouquet of the wine using your sense of smell; (3) examine the flavor and texture of the wine using your senses of taste, smell, and touch; and finally, (4) arrive at an overall assessment of the wine based on all your sensory information.
Examining the appearance of a wine can reveal quite a bit of information concerning its age, cellaring conditions, methods of vinification, and even a strong clue regarding its identity. Appearance primarily includes clarity/brightness, color, and, if a sparkling wine, the size, quantity, and duration of the bubbles.
Clarity/Brightness. Tilt your glass of wine forward against the white-paper background you brought along to this tasting and observe how much light is reflected in the glass and on the white surface below the glass. A little? More than a little? An eye-riveting cascade of crystalline reflections? Usually a wine that is “brilliant” in appearance is a very pale white wine that’s been in the bottle for less than a year, such as a young Riesling or Sauvignon Blanc. Red wines are rarely brilliant due to the intensity and pigmentation of their color not reflecting much light. Older red wines may contain some sediment at the bottom of the bottle; these are tannic acids, or tannins, that have precipitated out as the wine ages. This is not a wine fault. Some wines will contain small, dense crystals that resemble bits of broken glass at the bottom of the bottle and/or on the cork. These strange-looking crystals are tartaric acid, or tartrates, present in each and every wine. They’re tasteless and completely harmless, and should not be considered a wine fault.
Color. This quality will tell you a great deal about the age and condition of a wine. A white wine deepens in color as it ages, while a red wine loses color and becomes lighter. There is also a secondary color to notice. When tilting the glass of wine against the white-paper background, look at the outer edges of the glass where the wine is at its shallowest depth. For example, a white wine that has hints of green and possibly silver or unpolished brass on the outer edges are signs of a young wine that was produced from cooler climate grapes. The greenish color is chlorophyll, which comes from the unripe portions of the grape. For a red wine with considerable age, the color at the center of the glass is much deeper than the color at the rim, while a younger red has more uniform color in these same areas. For both white and red wines, oxidation may be detected by a brownish tint at the rim.
Effervescence. Do you observe the presence or absence of bubbles? Sparkling wines should have effervescence, with tiny, plentiful bubbles being more desirable than a few large ones, and the longer the bubbles last the better. Of course, in a supposedly still wine, effervescence is a negative. The exception is in a young white wine, where very slight effervescence is generally not considered a problem.
Legs or Tears. Ok, now I’m going to mention one final thing about a wine’s appearance that does not figure into its quality, but it is something talked about so often by wine drinkers that I figured I’d better write a few words about it. After swirling the glass, hold it up and observe the tears or legs of the wine as they make their way back down the glass. Note the size and width of the tears, and how quickly or slowly they move down the glass. Legs or tears can tell you something about the relative level of alcohol in the wine and/or the presence of residual sugar. Thin, quickly moving legs indicate a light-to-medium-bodied wine that has relatively low alcohol or no residual sugar. Thick legs that move slowly down the glass indicate a more full-bodied red wine with considerable concentration and high alcohol content, or a wine—red or white—that has considerable residual sugar. Despite their visual appeal, cascading legs or tears indicate absolutely nothing at all about the quality of a wine. There is no such thing as “good legs,” or “bad legs” in wine.
Aroma and Bouquet
Although you have been using your nose since the minute of your birth, perhaps you are not now using it properly when it comes to smelling wine. Most people smell wine by simply sticking their nose in the glass and sniffing away in what is called passive inhalation. In contrast, active inhalation occurs when you smell wine using both your nose and your mouth. To do so, tilt the wine glass forward and lean your head forward, situating your nose just above and over the glass opening. Now slowly open your mouth about a quarter of an inch and begin breathing in and out gently through both mouth and nose just as you once did as a newborn, sans the alcohol. This active inhalation makes it much easier to notice aromas and secondary flavors. The UC-Davis Wine Aroma Wheel depicted above is a very useful tool to use in assessing a wine’s aroma.
Most aroma compounds are volatiles, meaning they have a relatively low boiling point and their molecules easily drift away from your wine glass and tongue towards your brain’s olfactory bulb where they are processed. Once processed, you will be able to detect whether the odors are in harmony with one another. Some of these aromas will be noticeable at your first sniff, while others are detected later as an aftertaste, so patience and re-sniffing is vitally important here in fully evaluating a wine. And speaking of patience and re-sniffing, periodically give your nose a 30-second rest before sniffing the wine again; this allows your olfactory sense to recover a bit.
Primary Fruit Aromas. After noting any flaws in the wine, it is time to analyze its fruit qualities, meaning the natural flavors of the grape or other fruit from which the wine was made. Some wine experts refer to these flavors that come directly from the fruit as the “aroma” of the wine, whereas they refer to the odors that come from the winemaking technique as the “bouquet” of the wine. There are different fruit qualities associated with specific grape varietals, so when you smell a white wine, for example, you might notice apple-like and pear-like odors. In contrast, when smelling a red wine you may detect cherry-like or plum-like odors. These are all primary fruit aromas from the grapes. Listed below are some of the primary “fruit groups” for white and red wines:
Tree fruit: apple, peach, apricot, pear
Citrus fruit: lemon, lime, grapefruit, orange
Tropical fruit: pineapple, mango, guava, kiwi
Red fruit: sour cherry, raspberry, cranberry, strawberry
Black fruit: blackberry, black currant, blueberry, plum
Dried fruit: raisin, date, prune, fig, fruitcake
Primary Non-Fruit Aromas. Besides, fruit aromas, there are also non-fruit primary aromas associated with flowers (e.g., rose, lilac, lavender), vegetables (e.g., bell pepper, tomato, grass), spices (e.g., black pepper, thyme, anise), and earth (e.g., potting soil, slate, volcanic rock). A white wine may have apple and citrus aromas accompanied by non-fruit aromas such as flowers, green herbs, vegetables, and spices. As a general rule, European red wines tend to have an earthy quality, while wines from the United States and other New World countries tend to have little earthiness and are more fruit-driven.
Secondary and Tertiary Aromas. Besides primary aromas, there are also secondary and tertiary aromas that are often referred to as a wine’s bouquet. These aromas arise from the chemical reactions of fermentation and aging of the wine, such as the type of yeast selected, the type of fermentation (e.g., cool fermentation, carbonic maceration, extended maceration, malolactic fermentation), the duration and level of oak exposure, and even the aging process in the bottle. Having stated this definition of bouquet, I should note that some wine experts reserve this term for only tertiary aromas, meaning aromas developed solely during the post-fermentation and aging process. Common aromas under my more liberal use of the term are the secondary aromas of butter, mushroom, and cream, as well as the tertiary aromas of vanilla, smoke, leather, tobacco, and coffee. A good, mature wine will have a complex bouquet.
Off-Odor Faults. There are odors that indicate a problem with a wine. You probably have heard about “corked” wine, which is the presence of Trichloroanisole (TCA) from a tainted cork and this is a musty cardboard odor. Sulfides and Mercaptans in a wine give of disagreeable odors that smell like cat pee, garlic, and burnt rubber. Brettanomyces in wine smell like horse manure or a sweaty leather saddle. The presence of volatile acidity gives off vinegar and balsamic odors. A burning match smell indicates that the winemaker used an excessive amount of sulfur dioxide, which detracts from the wine’s quality. One thing to keep in mind, however, is that newly bottled wines can sometimes have a very slight sulfur smell, but it “blows off” shortly after being uncorked. So, if this sulfite smell disappears after you swirl the glass a bit, this is not a wine fault.
Taste and Texture
Taste the wine by swishing and swirling it around in your mouth so that it saturates all areas, allowing the volatile components of the wine to be channeled to your sensory receptors.
Dryness/Sweetness. How dry or sweet is the wine? Is it bone dry, simply dry, off dry with just a touch of sweetness, or full-blown dessert wine that is very sweet or even syrupy. The level of sweetness and or dryness can be a very important clue as to the varietal, style, or origin of a wine.
Acidity. Without acidity a wine would be flabby and incapable of aging. However, too much acidity renders a wine undrinkably tart. Good balance is the key. Natural acids impart tartness or sourness in wine. Most wines that have sweetness, such as White Zinfandel and many Rieslings, also have a very high acidity to keep the wine from tasting flat or cloying. Dry wines tend to taste more acidic because they do not have the sweetness balancing and covering the sour taste. White wines tend to be higher in acidity than red wines.
Tannin. Tannins come from the skins, seeds, and stems of grapes, as well as any oak that has been introduced to the wine during fermentation and/or aging. Typically, red wines contain much more tannin than white wines because the former are fermented with their skins and seeds (and sometimes even with their stems), while the latter are fermented after the juice has been pressed off the grape pulp. You will sense tannins as a gritty or puckery feeling on your tongue, cheeks, and teeth, similar to sucking on a wet black tea bag. Tannin has two components, bitterness and astringency. Bitterness is one of the primary taste sensations, whereas astringency is a tactile feeling of roughness and dryness. Astringency is felt in the mouth because the wine’s tannins bind with the proteins in your saliva and this causes increased friction between your mouth surfaces, which you sense as dryness or roughness. The term “mouthfeel” is often used to describe this sensation, and it is an important property of a balanced wine, which is why tannin could easily be incorporated into the “body” category below. However, most wine experts place it in its own category because its presence or absence can make or break a wine, especially a red wine. Tannins add balance, complexity, structure and make wines age a longer period of time.
Body. Body is a tactile sensation rather than a taste sensation. It is a sensation of fullness or “roundness” in the mouth that texturally distinguishes wine from water. One way to think of body is in terms of the three different types of milk at the grocery store. A light-bodied wine has the texture and weight of non-fat milk, a medium-bodied wine feels like 2% milk, and a full-bodied wine has the texture and weight of whole milk. Alcohol and glycerin both add body to a wine. However, do not confuse body with sugar content. Sugar can give “fullness” to a wine, but this is a taste sensation, not a textural sensation.
Fruitiness. Novice wine drinkers often confuse fruitiness and sweetness when describing how a wine tastes. A dry wine that has a perception of sweetness is often a “fruit-forward” wine, meaning that fruit is its dominant flavor. The confusion occurs because our brains are accustomed to equating fruit flavors with sweetness. The easiest way to distinguish fruit from sugar is to plug your nose and taste the wine again. Because you mostly detect fruitiness with your olfactory sense, a truly sweet wine will still taste sweet when your nose is plugged, but a fruity dry wine will lose almost all of those sweet characteristics.
Alcohol. Detecting alcohol while the wine is in your mouth is a tactile sensation; for a high-alcohol wine you will feel a warm glow in your mouth, throat, and, if you swallow the wine, perhaps even in your chest. A low-alcohol wine will have a decided absence of such heat. The amount of heat you detect when tasting the wine will confirm what you’ve already seen in the quality of the legs and the presence of heat on the nose.
Balance. A wine is balanced if nothing is out of place and if all the components work together well. In other words, the concentration of fruit, level of tannins, acidity, and sweetness are in harmony. Balanced wines are elegant, pleasant to drink, and tend to age gracefully.
One final taste assessment if a wine’s aftertaste, which refers to the taste left in your mouth when you swallow or spit out the wine. Is the aftertaste short, medium or long? The longer the wine’s taste lingers in your mouth—we’re assuming it is a pleasant taste—the finer the quality of the wine. If the pleasant aftertaste lasts longer than two minutes, with no undesirable tastes coming into play, it’s a long finish, meaning this is a good wine.
What Is Your Overall Impression of the Wine?
Now it is time to pull all your assessments together to give your overall impression of the wine. If you assess it as an excellent, well-made wine, then you very much like all its components. But, of course, some of you reading this article may be thinking at this point, “What’s all this nit-picking all about? To me, a red wine tastes and smells like a red wine and a white wine tastes and smells like a white wine! I cannot identify specific aromas and tastes!” My response to such a statement is to simply recommend that you try practicing patience and also get in the habit of trying to evaluate as many wines as possible, which is especially important if you are a winemaker. The more you practice, the more your brain will rewire itself so that you can identify specific positive and negative qualities in wine, which will make your winemaking efforts all the more productive. Now that’s something to raise a glass to in celebration!