Oh no! My wine has a strange smell!

Recognize the situation? Ever experienced the feeling? You open a bottle – Even worse, it is your favourite wine – You take a first sniff in the glass and you realise – Something’s not right. It can even happen that you notice something’s not right before you start pouring.

Actually, what a wine looks like, how it tastes and how it smells, boils down to chemistry. We will try to explain some of the most common causes of “strange” smelling wine. In this blog post you find a short version of the article that has been distributed to subscribers of the 200+ Wine Grapes app.

Please also note that not everybody shares the view that “strange” equals “bad”. Some claim that what is described below makes the wine more interesting. You have to judge for yourself, once you encounter it.

The wine smells like wet newspaper or a humid, unventilated cellar

If the wine’s odour reminds you of opening the door to a frowsty cellar, you’re most likely facing what is called Cork taint or Cork defect. Noticeable is that the odour will increase as the wine starts reacting with the air.

Cork taint’s “real name” is TCA or Trihcloranisole, and it can be found in approximately one out of fifty wine bottles. The problem applies only to the bottles sealed with a tap made from cork.

The wine? No, you don’t want to drink that. Throw it and open another bottle.

The wine smells of acetone or nail polish remover

If you are met by a stinging scent that reminds of nail polish remover, or something similar to acetone, your wine is likely to have developed what is called Volatile acidity (VA). Your wine has – or at least is about to – turn into Vinegar.

The process as such is a natural part of the fermenting process. It is caused when bacteria react with Oxygen that the Acetic acid is created.

What to do with a wine that has this problem? There should not be any risk for your health, but better avoid it if you feel unsure about it.

Note that while the Volatile Acidity process is unwanted in your wine, it is a necessity for producing vinegar.

There’s a smell (and taste) of Petroleum

Sometimes you find that a wine has a fragrance of petroleum. Some call this a defect. By others it is viewed as adding an interesting effect to the wine. It is called TDN and is the result of a chemical process in the grapes. It has nothing to do with the ground partly consisting of slate.

Other factors that also will increase the amount of TDN are high acidity levels and age. You can expect to find TDN in wines made from grapes with naturally high acidity, especially when they are aged, for example in aged Riesling wines from Alsace.

Is a “Petroleum” wine drinkable? Definitely. Then it is up to you to decide if you like it or not.

This wine smells like a sweaty (!) horse

If your wine has an aspect that reminds you of a sweaty horse – sometimes also referred to as the wine being “Mousy” – you have most likely been bestowed with a so called Brettanomyces wine. Brett (as it sometimes is called), is far less appreciated than is “Petroleum” (above).

Brettanomyces is one of several natural yeasts that can be used (e.g. intentionally) or occur (e.g. unintentionally) in the fermentation process. It is however not so easy to control the fermentation if you use natural yeasts. The way to avoid unwanted influence during fermentation is to use an industrially produced yeast instead.

Can you drink a “Brett-wine”? If nothing else is wrong with it, of course. If you like it or not is another question.