Flavor and aroma in wine are closely linked. In fact, Dr. Marion Baldy who teaches a University-Level course in the evaluation of wine, jokingly refers to her class as the “Winesmelling Course”. What you taste in a given wine depends most heavily on cooperation from your sense of smell. The rich, complex odors and flavors of wines are for the most part sensed by the olfactory epithelium a specialized patch of millions of nerve endings at the top and rear of the nasal cavity, above and behind the nose. Sometimes wine tasters suck a stream of air through a portion of wine they have taken into their mouth, bubbling it through the wine in the process. This volatilizes the aromatic components in the wine so that they are carried into the epithelium and amplified.
But once a wine has been tasted, how do we describe what we’ve perceived?
We all describe odors differently probably because of our differing life experiences and our varying abilities to perceive scents. In particular, it becomes challenging for most of us to place a name on a particular odor once we’ve encountered it again. This brings up a issue in the tasting and evaluation of wines How do we communicate consistently with one another
the flavors aromas found in wines?
To address this issue, Professor Ann Noble of the University of California, Davis developed the wine aroma wheel in the 1980s. Similar tools existed in the beer and scotch whisky industries, I am told. Professor Noble used the approach of grouping similar aromas into descriptive categories, which were then organized into groups by origin and/or similarity of smell and displayed in the circular format shown in Figure 1. This provided a common “catalog” of descriptive and commonly perceived wine aromas a lingua franca which allows our epitheliums to relate to one another.
Figure 1: The Wine Aroma Wheel
There are 12 fundamental groupings of aromas in the “catalog”, each of which has two or three sub-categories related to the fundamental. These sub-categories, in-turn, have multiple specific descriptors which pin-point an aroma. Often, the specific descriptors have reference-standards; pure essence of that aroma that can be brewed, extracted, or otherwise reproduced.
Recipes for making aroma standards can be found in article by NobLE, A.C.et al, in the American Society for Enology and Viticulture 38:143-146( 1987). Additionally, colored, plastic laminated copies of the wine aroma wheel (copyright ACNOBLE 1990) may be obtained from A.C.Noble, Dept. Vit and Enology, Univ. California, Davis, CA 95616; FAX 916 752 0382; email firstname.lastname@example.org; phone 916 752 0387.
On an editorial note aromas in wines can be pleasing to one person and offensive to another. Some folks enjoy an “earthy” wine or a “microbiological” wine (something I might call funky). A little bit of one component can be complex and interesting, whereas a lot can be a flaw. Its all a matter of taste, after all, isn’t it? Also these terms are just an attempt by academics to standardize perceived aromas so that they can be accurately discussed. Too often, this sort of tool risks usage in a snobbish or intimidating way in all cases I feel one should first concentrate on what’s tasted and smelled and enjoyed in the wine. Keep these “standard” terms as a backdrop to your tasting experience, not a facade.
So where in wine grapes do these aromas come from? Certainly human intervention in the wine growing process, or the introduction of human-made elements can effect the flavors and aromas in wines. But surprisingly mother nature can imbue in her fruit many surprising aromas some of which may seem man-made but they are entirely natural. I thought it would be instructive to list the twelve fundamental categories of the aroma wheel and relate some of my thoughts and experiences on just what happens in the vineyard or the winery that can produce each effect.
|Fruity||Can be caused by cooler fermentation temperature, strain of yeast used, or by carbonic-maceration fermentation (Beaujolais style)|
|Nutty||Sur Lie againg of wines (storing wine on its spent yeast cells after primary fermentation) can introduce a nuttiness or yeastiness to the wine|
|Vegetative||Can be caused by underipe fruit, or by herbaceousness introduced in whole-cluster fermentation|
|Caramelized||Sometimes extracted from barrel aging in newer, toasted French oak barrels. Toasting of oak creates a non-fermentable sugar which can be perceived as caramel.|
|Woody||Can be caused by aging in oak barrels, particularly barrels that have seen several seasons of use. The non-fermentable sugars and other new oak aromas are leached out of the barrel after about 3 seasons of use, leaving only “neutral” wood components behind to effect the wine.|
|Earthy||Can be caused by naturally occurring or “wild-yeast” fermentation|
|Chemical||Can be caused by over use of sulfur dioxide or by over exposure of wine to air (as occurs when head-space in barrels are not keep topped up with fresh wine).|
|Pungent||Sometimes can be caused by high-alcohol content in wine (derived from high-sugar content of grapes when harvested).|
|Oxidized||Caused by over exposure of wine to air, as occurs when head-space in barrels are not kept topped up with fresh wine, or through cavitation of a pump when moving a delicate wine from tank to bottling line.|
|Microbiological||Can be caused by lack of proper cleaning procedures in winery operations and by little or no use of Sulfur-Dioxide, the anti-microbial / anti-oxidative compound used in winemaking.|
|Floral||Most often floral wine components are produced in the grape skins and pulp by mother nature. Floral aromas can also arise when alcohols & acids combine during fermentation to produce esters. Cooler fermentation temperatures retain these volatile esters, whereas hot fermentation temperatures cause them to “blow off”. Floral aromas also can occur during bottle aging of wine, developing a so-called “bottle bouquet.”|
|Spicy||Can be picked up from soil constituents by a particular clone of grape. Sometimes spiciness is derived from prolonged skin contact during pre-fermentation maceration. Too long of a soak on the skins produces astringency|