We can observe wine, smell it, taste it, and associate it with scents, aromas, and even memories that revolve around certain characteristics.
These characteristics, which are different for each wine, are the characterizing element of the process by which it was obtained, of the attention devoted both in the cultivation and production stages. In short, the wine conveys our sensations, memories, and pleasures given mainly by the organoleptic qualities of the wine itself.
But what are these organoleptic qualities?
They are those certain characteristics perceived by our senses, in particular for the wine they are mainly represented by color, aroma, and flavor that activate sight, smell, and taste respectively.
As mentioned in a previous article, color, for red wines is given by anthocyanins present in the marc (skins), while for white wines, coloration is given by flavones, leucoanthocyanins, catechins, and chlorophyll. For example, catechins are colorless but through oxidative reaction they allow the wine to darken.
So important are the organoleptic qualities that, for example, DOC and DOCG wines must undergo organoleptic analysis before they are sold, with returns in the controls over the years varying depending on the certification.
Often organoleptic analysis and tastings begin with observing the color, which is different for each wine, clearly, this can give us some general information about the possible composition; clarity, transparency, and fluidity will be evaluated.
Instead, below we will tell about the characteristics that give us direct sensations and are related to the wine’s aroma and taste.
Wines are composed of more than 200 different substances, which is why it is often difficult to distinguish the different scents. These also come together to form the so-called aromatic “bouquet,” which represents, precisely, the set of smells that we perceive. This varies for each wine and also depends on the type of storage.
The main molecules that give wine these characteristics are usually organic molecules such as polyols, terpenes, ethers, and many others.
Primary compounds
As a reminder, one can distinguish primary aromas, which come directly from the vines, secondary aromas from fermentation, and tertiary aromas, which come from aging, in barrel or bottle.
Terpenes are among the main aromatic compounds in wine and represent primary aromas. The term aromatic is already present in the chemical composition of the compound, where it is said that it can be “aromatically active.” Among the most relevant terpenes in bouquets, we find chemical compounds that, already from their names, recall certain scents, among them: linalool, geraniol, citronellol, and nerol. In fact, these give the wine floral and fruity aromas reminiscent of, geranium, rose, lemongrass, and citrus fruits. These scents are often found in grape varieties such as Malvasia and Moscato.
Relevant compounds then follow thiols. In fact, many of these compounds do not give properly pleasant odors, quite the contrary. But some thiols can give pleasant scents reminiscent of tropical fruits and boxwood; these are often found, for example, in Cabernet Sauvignon, Merlot, Gewurtztraminer, and others.
High concentrations can sadly give very unpleasant odors, often associated, for example, with cat urine, and yes! These odors become perceptible during alcoholic fermentation.
Regarding flavor, we can distinguish compounds on the basis of flavor type: sweet, soft, sour, tannic, savory, and bitter.
Sweet is mainly given by sugars such as fructose, glucose, and sucrose. In greater quantity is fructose, which, unlike glucose, is retained after fermentation.
Soft is given by alcohols including ethyl, methyl, propyl, glycerol, pectins, and others. Alcohols impart softness to a dry feel as they absorb water.
Glycerol, which is formed in fermentation, binds with pectins, ethyl alcohol, and other compounds giving a velvety character to the wine.
Acidity comes from compounds present in both pre-fermentation and post-fermentation. These include tartaric, malic, citric, lactic, succinic, citric, and others among the fixed and acetic and propionic acids among the volatile.
In particular, tartaric gives the wine liveliness, freshness, and color, malic gives body and is sometimes said to “allappa” (feeling your mouth dry) if present in high amounts. Citric gives a slightly acidic taste, and from its fermentation are formed succinic, which gives flavor and slight bitterness, acetic, which must not exceed 1 g/l by law, and lactic, which gives softness to the wine.
We often hear that a wine is tannic. This feeling defines the astringency of wine because tannins, which are polyphenols, give a dry mouthfeel.
Sapidity is given by chlorides, phosphates, citrates, malates, and others that, being salts, give precisely a saline sensation to the wine. These of course are partially covered by the acids that mask their presence.
Bitterness is given by organic and inorganic substances, mainly for the “positive” bitterness we have tannins and quinones, for the “negative” bitterness we have acrolein that comes from bacterial transformations.
Finally, the liveliness of wine is given by the carbon dioxide that is produced during alcoholic fermentation.
Depending on the quantity produced we distinguish wines: still, sparkling or sparkling. Highly valued in white wines, in red wines, it increases astringency.
