Anatomy and physiology of smell in wine tasting.

The sense of Smell in wine tasting

Two of our five senses respond to the chemical stimuli from our surroundings: taste and smell. Both depend on chemical interaction, known as chemoreception. Taste is: contact chemoreception, because to sensing the taste of anything requires contact with it. Smell is: remote chemoreception, it is airborne, and can be sensed from a distance.

The Sense of Smell – press to watch Video  

(from The Sense of Smell (Brief Overview for Primary/Secondary Grade Students) http://www.youtube.com/watch?v=dIDBG-UPRUI

In 1990 BBC books published a small (soft cover) book, by Jilly Goolden, titled “The Taste of WINE“, for me it was one of the basic ABC’s to wine tasting. It meticulously described all the “Smells of wine”, not TASTE (divided by country of origin, grape variety, local blends etc.). Semantically, it follows the title of the reference book by Emile Peynaud: The Taste of Wine: The Art Science of Wine Appreciation (1984). Both books are titled mistakenly: The taste of wine. But it is by the aromas of wine (the sense of smell) that wine is “tasted”. It occurs mainly by accumulating information from smelling the wine in the glass before tasting and retro-nasally through the back of the mouth as the wine is swirled in the mouth, It is here that vapors of wine smells travel via the Nasopharynx to the olfactory bulb, and finally translated in the form of flavour by the brain. The human tongue (sense of taste) is limited to the primary tastes perceived by taste receptors on the tongue: sour, bitter, salty, sweet and savory (Umami). The wide array of fruit, earthy, floral, herbal, mineral and woody flavours perceived in wine derive from aroma notes which are interpreted in our brain through chemical information obtained by the primary receptor cells in the olfactory membrane.

.In professional wine tasting,  a distinction is made between wine odors:  “aromas” and “bouquet“.

Aroma is used to describe the smells of a young wine, or of fermenting wine must, and represent odors mainly from the fruit, vegetable and mineral families.

The term Bouquet refers to the smells that arise from the chemical reactions of fermentation and aging of the wine in the bottle as part of the wine aging process, these are more complex kind of smells, combined together to induce an odor from our memory bank of smells (ground coffee, cigar box, leather, Tarte tatin, toasted bread, compost, caramel, toffee, mint etc.)

          

Apart maybe from wines made from the Muscat grape no wine smells like the juice of the grapes variety it is made from. Aroma refers to the smells unique to a certain grape variety, and is most readily demonstrated in varietal wines–such as Raspberries and blackcurrants with Cabernet Sauvignon, exotic fruits and canned Leeches with Gewürztraminer or Gooseberries and freshly cut grass in Sauvignon Blanc. These are smells that are commonly associated with a young wine.

As wine ages chemical reactions between the acids, sugars, alcohols and phenolic compounds, create “new smells” that are known as a wine’s bouquet. These can include honey in an aged Sauternes or mushrooms even truffles in a Pinot noir, and others listed above. The term bouquet can also be expanded to include the smells derived from fermentation and exposure to oak. Wine aromas are sub-divided into three categories-primary, secondary and tertiary aromas.

Primary aromas are those specific to the grape variety itself. Secondary aromas are those derived from alcoholic fermentation and oak aging. Tertiary aromas are those that develop through bottled aging.

Wine contains volatile and non-volatile compounds that contribute to the overall wine aroma. The majority of volatile compounds responsible for aroma combine with sugars in the wine to form odorless glycosides. Through the process of hydrolysis, caused by enzymes or acids in the wine, the odorless compounds revert into an aromatic form, thus the act of tasting wine is essentially an act of smelling vaporized aroma compounds

 Of the human senses, the sense of smell is the most precise, with high sensitivity to minute amount of odorant. It is also the most fragile. Most of us have experienced detecting an aroma of bread baking, even from a long distance and certainly in the bakery, yet after a fairly short but continuous exposure of just a few minutes, that same smell is less noticeable. This “fatigue” is really an accommodation process of the sense of smell by means of sensory adaptation and occurs in other senses as well.

                                   

Since olfaction is connected directly to the Limbic system in our brain that supports a variety of functions, including emotion, creativity, long-term memory, and olfaction. Being primarily responsible for our emotional life, the formation of memories and smells in the same brain center facilitates connection of certain emotions that were evoked with a certain odor “background” a memory of that smell will be unconsciously related to an emotion. A connection between emotion memory and smell is created in our brain. The memory/olfaction connection plays a major role in the ability to relate (by association) wine odors to groups of smells fruity floral vegetal etc. which is a basic requirement in wine tasting. In fact of all our senses, the sense of smell is the most intimately connected with the brain.

The amount of odors in wine and their inner intricacies present a huge vocabulary from which to choose when coming to describe a wine.  Ann C. Noble of University of California, Davis, formulated an aroma aid called the “Aroma Wheel”. It divides the various wine aromas to groups and sub groups within them covering the most commonly aromas encountered in table wines this was a means to try and “standardize” terms used to describe wines to a point that wine tasters, wine journalist, wine novices and readers of wine articles will “know” what was meant by a certain description:

The Aroma Wheel provides a visual graphic of the different categories and aroma components that one can encounter in wine.

The wheel breaks down wine aromas into 12 basic categories and then sub-divides them into different aromas that fit those main categories:

    Fruity – Aromas like blackcurrant, apricot, apples and plums

    Vegetative – Aromas like Green pepper, asparagus or artichoke       

    Floral – Aromas like rose, acacia, or Jasmine

    Spicy – Aromas like cloves, cinnamon or anise

    Microbiological – Aromas like yeast and lactic acid

    Nutty – Aromas like pine nuts walnut and hazelnut

    Caramelized – Aromas like butterscotch and molasses

    Woody – Aromas often imparted by oak like vanilla and coffee

    Earthy – Aromas such as mushroom compost and mildew

    Chemical – Includes aromas like sulfur and petroleum or nail varnish

    Pungent – Aromas like alcohol and vinegar                                                  

    Oxidized – Aromas like Sherry or acetaldehyde                                                                    

Aroma Wheel: property of Aromaster wine aroma kits  http://www.aromaster.com/product/wine-aroma-wheel/

A drawback of the wheel is that it does not contain terms used to describe the sense of touch on the palate, like texture or astringency, which affect the overall “tasting experience” and are a major factor in determining a wine’s quality, balance.

 Prior to tasting the wine, a good swirl of the glass releases wine odorants into the glass bowl. Some glasses are specifically designed to enhance aromatic qualities and characters of different wines, these assist in capturing more aromatic compounds within the glass for the taster/sniffer, to detect. Wines served at warmer temperature will be more aromatic than wine served cooler due to heat’s ability to increase the volatility of aromatic compounds in the wine. Swirling aerates, the wine and increases available surface area, increasing the amount of volatilized aromatic molecules. Some subtle odors can be hidden by a more dominant smell that arise after swirling, so most professional tasters will sniff the wine briefly first before swirling.

The deeper our nose is stuck inside the glass, the greater the chance to capture the specific wine aromas.  Our nose can detect and distinguish between thousands of different smells, which increase by means of training through exposure.

When wine is sipped, it is warmed in the mouth and mixes with saliva to vaporize the volatile aroma compounds. These compounds are then inhaled “retro-nasally” through the back of the mouth to where it is received by the millions of nerve receptor cells in the olfactory bulb. An average human can be trained to distinguish between thousands of smells but can usually name only a handful at a time when presented with a wide variety of aromas. Professional wine tasters will use their vast “library” of memorized aromas, for those with a lesser collection of memorized odors a visual aid like the aroma wheel.

Detecting an aroma is only part of wine tasting. The next step is to describe or communicate what that aroma is verbally. In this step subjective nature of wine tasting is most prominent. Different individuals have their own way of describing familiar scents and aromas based on their unique smell experiences, memories and “smell vocabulary”. Furthermore, there are varying levels of sensitivity and recognition thresholds among humans of some aromatic compounds. This is why one taster may describe different aromas and flavors from another taster sampling the very same wine.

In 1981, as a result of his research into vocabulary used to describe wine, Jean Lenoir created Le Nez du Vin®, a unique and learned combination of written works and collection of bottled aromas covering a large array of odors which form a part of the scents of wine.

“Le Nez du vin is a The 54 Aroma Master Kit has been the reference for wine aromas vocabulary. Our sense of smell is very delicate and highly sensitive. Practice through daily training allows us to recognize and identify the 54 aromas most commonly present in wine; thus, improving our appreciation and enjoyment of wine. These are the typical aromas found in red and white wine (including Champagne) from France and around the world. They give us an indication of the wine’s origin, the grape variety as well as the vineyard, the winemaking techniques used and the aging conditions. Memorizing these aromas provides an accurate and coherent vocabulary to further stimulate our appreciation of fine wines”

The 54 Aromas of Le Nez Du Vin are:

23 Fruit Aromas, 6 Floral Aromas, 10 Vegetal Aromas, 5 Spices, 3 Animal Aromas and 7 Grilled Aromas (full list could be found in: http://www.winearomas.com/master_kit.html

“It is widely accepted that sensory interactions can, and do, occur during wine consumption. To this concern, many studies have dealt with aroma-taste interactions which have been attributed to physicochemical interactions in the product itself, interactions at the receptor level or cognitive interactions. Although the understanding of these interactions has grown during the years and it has been demonstrated that they are strongly product-dependent, investigations have seldom gone beyond that of model solutions with a reduced number of components (volatile and/or nonvolatile molecules). Recently some investigations carried out in this field have been conducted with more complex matrices in an attempt to simulate interactions in real wine samples. The aim of this chapter is to review these latest advances in the research of wine sensory interactions, and to highlight the magnitude, relative importance and qualitative nature of such sensory effects.” (From: Sensory Interactions in Wine: Effect Of Nonvolatile Molecules on Wine Aroma and Volatiles on Taste/Astringency Perception  Authors:  (María-Pilar Sáenz-Navajas, Eva Campo, Dominique Valentin, Purificación Fernández-Zurbano, Vicente Ferreira).

The “correct” scent of wine can quite easily be reached at the winery level but the quality of wine starts at the flavour’s level which is a combination of taste and smell add to those the sense of touch on our palate and the balance of the wine can be judged to give a complete view of the wine’s quality.

Next post of the sense of taste continues “our” journey through the symphony of senses in relation to wine tasting.

YOUR WINEGUIDE