Taste & Aroma
Tasting wine is not the same as drinking wine: Wine tasting is a craft practiced with skill and care by wine experts. The ability to analyze wine systematically is the fundamental competence of a wine professional. Rigorous and systematic examination allows the professional to experience the wine thoroughly, form cogent opinions, and funnel perceptions to arrive at a logical and reasoned result that can be understood by other experts. It is important to recognize that this ability is not innate; rather, it is honed over time.
The basic protocol used by wine professionals is known as the “Five Esses”. It forms the basis for evaluating every type of wine. Winemakers use this very same analysis to determine what chemical reactions are occurring (or have already occurred) during the fermentation and aging process. In this way, the wine glass is said to be the winemaker’s laboratory. Any molecule present during vinification will affect the final product and can be either seen, smelled, or tasted by a skilled wine professional.
The Craft of Tasting Fine Wine
With about one ounce of wine in your glass, tilt the glass to a 45° angle over a white piece of paper or similar opaque surface. Students new to the study of wine are often surprised at how much time a wine expert will spend evaluating the color of a wine. For red wine, color ranges from pink, to ruby and garnet, to bluish-black tones. For whites, color can range from clear or transparent to rich gold. All of these are clues to the type of wine in the glass, how it was made, and its provenance.
Specific factors to look for include:
Clarity. The wine should be clear. A hazy or speckled wine is the first indication that a wine may be spoiled. In fact, there are only two sorts of deposits that are typically acceptable in a finished wine: tartrate crystals (which look like large grains of salt and derive from tartaric acid) and sediment. Young white wines and older reds will release more tartrates. A winemaker will often remove these particles by fining and filtering the wine before bottling. Sediment forms when color particles adhere to tannins, becoming heavier than the liquid itself. Over time these particles fall to the bottom of the bottle. Accordingly, older wines are more likely to contain sediment.
Brilliance. The wine should exhibit a noticeable brightness when exposed to light. A wine’s ability to reflect light is a result of its level of acidity. Wines with too little acidity may appear dull and listless, and tend to taste flat. A wine with good acid structure will look and taste vibrant.
Depth. The intensity of color is a very important clue as to how the wine was made, as well as the grape varietal(s) involved. For white wines, depth of color is often contingent on the aging process. Wines on the clear end of the spectrum are usually aged in stainless steel, while oak barrels can lend a more saturated yellow. For red wines, the depth of color is typically due to the amount of pigment in the must. This changes depending on the varietal. Pinot Noir is known for its bright ruby tones, while Zinfandel exhibits an almost opaque bluish-black hue.
Viscosity. “Viscosity” refers to a wine’s liquid consistency. A wine’s viscosity will may make it appear thin and watery or thick and syrupy. Viscosity is affected by the levels of glycerols (sugars) and alcohol found in the wine. Generally speaking, the higher a wine’s level of glycerols and alcohol, the higher the wine’s viscosity. Wines with high viscosity tend to cling to the side of a wine glass longer, and may leave “tears” or “legs” that drip down into the glass. Note: A high viscosity wine is not necessarily a higher quality wine. Viscosity merely provides clues to the body, or mouthfeel, of the wine.
Age. A dry white wine exhibiting a deep gold color indicates either an aged wine, or one that has been exposed to oak. A white wine that has darkened all the way to a brown shade is oxidized, which often means it’s either spoiled, aged, or both. Unlike white wines, red wine loses color as it grows older, fading to an adobe red color from its original purple or garnet. This is not due to oxidation (a wine fault), but is attributable to the loss of pigment over time.
Holding the stem of the wine glass, trace an “o” pattern without lifting the base from the table. This whirlpool effect draws oxygen into the wine and releases alcohol and organic aromatic compounds. Aerating the wine in this manner creates an invisible cloud of aromatics within the bowl of the glass.
Note: Make sure to hold the glass by the stem. Holding the bowl of the glass will rapidly heat up the wine, throwing it out of balance. The surest way to identify a rookie is the way they hold the glass!
The path to understanding wine lies with your sense of smell. Close your eyes, shut your mouth, and inhale. Breath deeply and clear your mind.
The sense of smell, also known as olfaction, provides most of the essential information about a wine. Grape varietal, winemaking styles, faults, and all major winemaking techniques can be identified by olfaction.
While some of this information is also present on the palate, a large portion can be detected only through our olfactory system. Wines will often taste dramatically differently than they smell. A wine that smells like a barnyard may taste of bright cherry. A wine that smells of lavender may taste of burnt rubber. This is due to the curiously haphazard organization of the human sense of taste.
Wine aromas will develop with exposure to oxygen. The fullest expression of the wine will develop over time. Most professional tasters find it helpful to repeat the process of swirling and sniffing at least three times. But be careful: our olfactory system will experience “nasal fatigue” after 30 seconds of smelling the same aroma.
Take a small sip, then whisk in air through pursed lips. Allow the wine to rest on your tongue for five or more seconds, then swish it around to cover your gums, inside of the cheeks, and the roof of your mouth. This action provides a direct and intense interaction with the wine. It accomplishes two things. First, by coating your tongue with the wine you engage as many taste receptors as possible. Second, by breathing in such a silly way — akin to slurping or gargling — some of the wine will be turned into a mist. These volatile molecules then float up into the nasal cavity, triggering your sense of smell.
This is very effective because your sense of taste is a composite of information from several different organs: your tongue, your nervous system, and your nose. As we progress in this program, you will come to understand these interactions more thoroughly.
Taste is obviously key to wine tasting, but not for the reasons you may think. Mainly, it provides information about a wine’s alcohol, acids, and tannin levels. Known as the “ABT”s (for acid, body and tannin), these are the building blocks of both winemaking and winetasting. One can identify wines by comparing the specific levels of each of these elements in a wine. Alcohol is perceived as weight in the mouth (body), acid as tartness, and tannin as bitterness.
This is the moment in which a skilled taster collects his or her thoughts on what has just been experienced, and attempts to synthesize a description of the wine’s profile.
This is also the time to consider if the wine flavor evolves and adapts after swallowing, and how long the taste lingers. A sign of a high quality wine is a long, pleasing aftertaste that lasts at least 15 seconds. A persistent finish can last over 45 seconds while its flavors continue to evolve and develop on the palate.
While it takes experience to identify a quality wine by its finish, a wine expert will be most focused on two elements: complexity and balance. Complexity occurs when a wine exhibits multiple layers of flavors and taste sensations. Balance is described as the condition where no elements overwhelm the overall profile of the wine. Most people are able to identify a wine of high quality even if they cannot describe the specific sensations involved. However, a skilled professional is able to deconstruct each element of the experience and quantify the results in a manner that sets them apart from a wine novice.
THE PHYSIOLOGY OF AROMA & TASTE
A main component of the Foundation program is understanding the elements of sensory evaluation as they relate to taste, i.e., the aromas, flavors, and tactile sensations we experience when tasting wine. We also want to correlate the physiological responses (the “Five Esses” described above) to the inherent characteristics of the grape. The goal is to understand the interaction of our senses with the complex organic structure of wine.
What we refer to as “taste” is a combination of stimuli generated by three separate but integrated anatomical systems: the olfactory bulb, the tongue, and the trigeminal nerve. Each is an important aspect of our ability to discern the basic elements of wine.
The olfactory bulb is actually a gland composed of millions of microscopic cells found at the top of our nasal cavity. It is adjacent to our limbic system where emotions and memories reside. When we eat or drink, aromatic molecules enter our nasal cavity. These are then filtered through the olfactory bulb and elicit an aroma memory pinpointing their identity.
We call this process olfaction. Odor compounds, which must be volatile to reach the olfactory bulb, can take two different pathways: orthonasal stimulation or retronasal stimulation. The former is triggered by odor compounds traveling through the nostrils to the olfactory bulb. Retronasal olfaction, on the other hand, occurs when odor compounds travel internally through the mouth to reach the olfactory bulb.
A common practice used to test the difference between the orthonasal and retronasal stimulation is the jelly bean test. While pinching your nose shut, chew a jelly bean for a few seconds. Mid-chew, release your fingers from your nose. The flavor compounds can be immediately sensed and smelled. This is the stimulation of the retronasal pathway.
Of the three anatomical tools we depend on for taste, the tongue has a limited but critical role. It responds to the five taste sensations through receptors scattered on its surface. The taste sensations are: bitter, salty, sour, sweet and savory (umami). Note: the location of these receptors is subject to individual variations. Food scientists now believe that you can detect all of the sensations throughout your tongue. If you would like to give this hypothesis a try, use a sour candy coated with tartaric acid, such as a sour Jolly Rancher. Once the candy hits your tongue, you may detect the sour quality before it even reaches the sides of your tongue. This demonstrates that receptors are scattered throughout the tongue’s surface and vary by individual.
Finally, we consider the tactical sensations experienced on the palate. The mandibular nerve is one of three branches of the trigeminal nerve that register sensations on the tongue. It transmits responses from the mouth, lower lip, teeth, gums, and the floor of the mouth to the brain. These various stimuli experienced on the tongue are called the mouthfeel of a wine, a catchall for qualities such as texture, weight, temperature, and astringency.
Your brain receives this information, then summons specific memories associated with the organic compounds in the grapes and the esters created at fermentation (described in detail below). It associates those esters with flavor and taste sensations. With novice wine drinkers this may cause information overload as the brain attempts to right itself and process familiar sensory input in a new format.
The inherent difficulty in understanding taste and aroma is not surprising when we consider that nearly 100,000 odors can be detected by a given sense receptor. This is our detection threshold. However, many of us do not even recognize a fraction of these odors. With training, an average individual can learn to identify about 1,000 odors. We describe this as an individual’s recognition threshold. While it seems as if some students are naturally gifted at explaining taste and aroma, they have simply increased their ability to identify and name aromas following a sensory stimulus.
To summarize, “flavor” is the complex interpretation of aromatics or flavors (via the olfactory bulb); taste sensations (registered on the tongue); and sensations, or mouthfeel (triggered by the trigeminal nerve).
THE SOURCE of AROMA
Once we establish the mechanics of how we smell, the obvious follow-up question becomes: Where do the aromatic molecules in wine come from? We hear and read all sorts of descriptions assigned to the aromas people find in a glass of wine, from caramel and eucalyptus to balsamic, toast, and diesel fuel. How is this possible considering those elements are never actually used in the creation of wine?
The aromatic molecules we filter through our olfactory bulb can come from three sources: 1. chemical compounds present in grapes prior to fermentation; 2. microbial reactions during winemaking; and 3. the type and length of aging. These are described as primary aromas, secondary aromas, and tertiary aromas, respectively. The first two are the key factors in shaping wine aromas and can be grouped in four primary categories: pyrazine, terpenes, esters, and aldehydes.
This group of compounds originates in the grapes themselves and is not subject to microbial action during fermentation or aging. Pyrazines produce clean, fresh, floral aromas in varietals such as Sauvignon Blanc and Semillon, as well as the jalapeno pepper we associate with New Zealand Sauvignon Blancs. They may also lend wine a “green” aroma, often expressed as green pepper, but sometimes as olive, dried sage, dried oregano, or other dried herbs. Cabernet Sauvignon and Merlot are two grapes with a distinct pyrazine character. The less sun exposure received by ripening grapes, the more this quality will be apparent in the final wine.
Terpenes constitute the largest group of organic compounds in grapes. Noteworthy examples include linalool, limonene, and citronelle. These are responsible either singly, or in combination, for generic floral aromas like rose and lavender. They also contribute to fruit aromas, such as orange peel in wines from the Muscat family of grapes; lemon in many Mediterranean white wines; lime in German Riesling; New Zealand Sauvignon Blanc’s under-ripe grapefruit; and the melon common in Chardonnay from California and Australia. It also can be found in the mushroomy aromatics of wines from Italy’s Piedmont. Other terpenes include methyl keton (acacia flowers); damascanone (roses); licorice in red wines; and a combination of terpenes forming the petrol and diesel fuel in Riesling.
Esters are naturally present in grapes as they ripen. The esters we detect in wine, however, are mostly formed during fermentation as a result of microbial action with yeast. Esters react with acids and alcohol to form the flavor compounds in wine. Like terpenes, they account for many of the myriad fruit flavors in wine. Esters mimic the smell of other natural aromas. Fruit aromas associated with esters include the strawberry and raspberry of classic Pinot Noir, Grenache, and Syrah, as well as the blackcurrant or cassis in Cabernet Sauvignon and Syrah. Pear and bubblegum flavors of carbonically-macerated Beaujolais are tied to amyl acetate, as are the floral nuances of apple blossoms. Other esters include rose oil (phenethyl acetate), lavender, and some Muscat derivatives (linalyl acetate), acetone, i.e., nail polish remover (ethyl acetate), and soap (ethyl laurate).
These are formed by microbial activity and by oxidation during the aging process. We sense aldehydes as tart, under-ripe red cherries in Pinot Noir and darker cherries in Sangiovese, Cabernet, and Syrah. Peachy flavors in Viognier, Riesling, and New World Chardonnay are the result of piperonal. In older, more oxidized wine, aldehydes impart a nutty characteristic.
There are many more aromas to be found in wine, of course. One of the more important are mercaptans derived from sulfurs formed during fermentation. A low level of mercaptans in certain wines (Sauvignon Blanc in particular) can evoke passion fruit and tropical melons; when disproportionately high they can become pungent, like cat pee. Ethyl mercaptan can be perceived as earthy, or have the smell of a freshly struck match. Dimethyl mercaptan has varied tones: stewed vegetables, truffles, or mushrooms.
Finally, there are those familiar aromatics created by barrel aging and other phases of production which too often are lumped under the heading of “oaky”. Vanillin is found in oak itself, as are the lactones that come off as coconut. Toasty flavors are imparted by aldehydes in new oak. Clove, cinnamon, butterscotch, and caramel can all be linked to the interaction of compounds in wine and the composition of barrels during aging. Each of these qualities can be attributed to a specific reaction during the post-fermentation stage of winemaking.