Our sense of smell is remarkable and allows us to perceive the aromas of a wine and recognize its characteristics during a tasting.

After visual analysis, the second step in tasting a wine involves an olfactory evaluation – consisting of two main moments. First, the intensity of the wine’s bouquet is evaluated and then the complexity and type of aromas perceived. Through this analysis, it will be possible to understand, for example, the evolution of wine or some stages of the production process. Here are some of the main concepts and terms to learn more about this topic.

What is the sense of smell?

Smell is one of the five senses that perceives odorous stimuli: through chemoreceptors on the olfactory cells present in the nasal mucosa, it sends signals to the cortex through a complex system of neural pathways and is closely linked to taste. The sense of smell is certainly the most primordial sense organ, linked to reproduction and the search for food. Since there are more than 300 genes that code for olfactory receptors, not all people perceive the same smells, having a different sensitivity: some certainly have a better and more articulated sense of smell!

Pathologies that can affect the sense of smell can be quantitative and qualitative. Quantitative pathologies are caused by hyposmia: for example, with ageing there is a progressive, physiological decrease in perceptive capacity.  Anosmias are instead temporary or permanent diseases, where the sense of smell is reduced and can affect all ages: for example, unfortunately, anosmia can occur if someone has been infected by COVID-19. Inevitably, these disorders also affect the sense of taste.

The primary aromas of wine: the varietals

Primary aromas are pre-existing wine aromas, i.e. which are present in the grape skin and which are transmitted to the wine during its evolution, helping to give it its bouquet. In fact, the skin of thegrape contains odorous substances, represented above all by terpenes and many precursors of the so-called varietal aromas, linked to sugars. During alcoholic fermentation, thanks to the autolytic action of yeasts that breaks down the molecules, the volatile aromas are released, perceptible to the nose. Aromas are primary when they are characteristic of the grape, for example:

  • Some so-called aromatic grape varieties, such as Moscato, Malvasia, Gewurztraminer or Brachetto, have the characteristic of having these varietal aromas also in the flesh of the grape. The most important aromatic grapes are:
    • Gewurztraminer (Cultivated in Italy, Alsace, California. Oregon, Austria, Australia and South Africa)
    • Riesling (cultivated in Germany, Alsace, Austria, Hungary, Australia, Canada)
    • Moscato or Muscat or Moscatel (a lot of biotypes cultivated in Italy, France, Est Europe, Spain)
    • Malvasia (cultivated in Greece, Italy, Canary Island, Madeira)
    • Torrontes (cultivated in Argentina)
  • Younger wines, or when the grapes have been harvested a little earlier than the perfect ripening time, have aromas leaning more towards fresh fruits and flowers, for example in white wines, aromas such as the Granny Smith apple, Acacia and Hawthorn.
  • Depending on the evolution of the wine, or if the grapes have been harvested when overripe, the fruit will be perceived as more mature. For example, this can be tasted in white wines with hints of yellow peach, melon and Golden apple.

The secondary aromas of wine: the fermentation aromas

Secondary aromas are linked to specific processes that occurred during winemaking. These can be prefermentation aromas, which derive from the pressing of wine, and fermentation aromas, deriving from the fermentation of wine and generated by ethyl alcohol, carbon dioxide and types of yeasts.

For example, malolactic fermentation transforms the sourer malic acid into lactic acid, giving a more delicate and less acrid flavor to the wine. Generally, fermentation aromas give the wine floral, fruity, dried fruit and jam aromas.

The tertiary aromas of wine: post-fermentation aromas

Tertiary aromas develop during the evolution and aging of wine. These are obtained through initial oxidation in containers (barriques, barrels, amphoras), after which they are transferred to the bottle, that is an oxygen-free environment where numerous chemical processes take place.

During this stage, spicy, toasted and more wild aromas are given to the wine: these hints are the decisive ones that characterise wines with a long aging and maturation. 

What is meant by olfactory intensity and how is it evaluated?

Intensity is defined as the global impact that the aromas of a wine have on the sensory organs. Intensity is the first thing that is perceived during an olfactory evaluation: this depends on the quantity of aromas in the wine and its temperature; in fact, it is always recommended to taste a wine at the indicated temperature. To better understand the concept, the comparison with a bunch of roses is used, whose olfactory intensity will certainly be much greater if there are 100 roses rather than 20.

Intensity is evaluated with the glass still, placing it approximately under the chin, trying to appreciate how the aromas affect the nasal mucous membranes: a more or less intense wine will be defined according to the quantity of aromas perceived.

8 February 2022 hOn