A wine’s aroma is one of its most important characteristics. It depends on the grape variety, the vinification techniques used, the style of the wine, its age, the contact it has had with oak or other types of wood and a few other factors. A wine’s aroma is often a reflection of its condition at a certain moment. It reveals whether it is ready to drink, whether it needs to age more or we have been too late to drink it at its peak condition. In terms of pleasant aromas, the diversity is great and consumer choices vary depending on their individual preferences.

Wine faults (or unpleasant odours) also vary a lot and they can be caused by the health state of the grapes as well as chemical and microbiological processes taking place during fermentation and storage. The degree of their expression can reduce the quality of a certain batch of wine or even make it unacceptable for consumption. Wine faults can very rarely be adjusted for or disguised. Therefore, it is very important to prevent them from appearing altogether or identifying them in the very beginning.

Some of the most common wine faults on the nose are related to the presence of undesirable microorganisms, oxidation, or poor cork quality used for bottled wines.

Problems caused by microorganisms can lead to sour aromas, the reason for them being harmful yeast or bacteria; odours of pickled vegetables or sauerkraut are usually caused by harmful bacteria; odours of barnyard and wet mop are caused by a yeast called Brettanomyces and, therefore, referred to as “Brett”. The protection against this group of defects is associated with the excellent hygiene of the grapes, production facilities and strict control.

Oxidation due to untimely or excessive contact with oxygen from the air is a common problem. When oxidation takes place during fermentation, aromas of cooked fruit, compote, marmalade or cooked dried fruit occur quickly. If the oxidation occurs gradually during wine storage and maturation and goes beyond certain limit, notes of dried fruit, wet hay, tea, herbs mark the end of life of a certain batch of wine. Preventing oxidation is related to protecting the wine against contact with air, storing it in completely filled vats and storing the bottles horizontally at a relatively low temperature of about 13-15о С.

When wine is bottled using low quality or poorly stored cork, the contact between the cork and the wine results in aromas of moldy cork, dirt, stale and rotten wood. This problem, in fact, affects 3-5% of all wines closed with cork and it is extremely difficult to foresee or prevent it. That is why metal screw caps, silicone or glass stoppers are often used. Another possibility, although a controversial one in terms of quality and tradition, is using the “bag in a box” packaging which is designed to protect the wine over longer periods of time without the risk of oxidation and the occurrence of faulty aromas.

The aromatic profile of a wine is one of its defining characteristics which is why it needs to meet high and clearly defined standards.

Assoc. Prof. Hristo Spasov