Reduction comes about in the winemaking process. This is the opposite of oxidative winemaking – in the ways that the winemaker has stopped the wine coming into contact with air as much as possible. Like mentioned below, a bit of contact with oxygen can be beneficial to wines. Reduction is where the winemaker has gone too far in the other direction. Winemakers will often choose to be reductive so that they can preserve the primary fruit flavours – this is a technique largely used in cheap white wines. It will also be used combined with higher sulphur dioxide levels used in the wines to preserve the wine in as fresh as state as possible. 

What does it taste/smell like?

The worst examples smell putrid and have rotten egg or cabbage flavours. Though usually reduction will smell metallic to most people, and can be perceived as harsh on the palate.

You can often fix this issue by putting the wine in contact with copper, as the reductive aromatic particles will attach to the copper particles. So get out the copper bowl, pots and coins and just pour the wine on top. You’ll be surprised at how fresh the wine will be after doing so.


Volatile Acidity (V.A.)

Volatile Acidity is most common in wines that have been treated to higher temperatures in transport. All wines have low natural levels of Volatile Acidity yet on heat this is amplified. 

What does it taste/smell like?

When the level of Volatile Acidity is amplified in a wine it starts to smell like vinegar or nail polish remover.



Brettanomyces, or Brett for short, is actually a yeast that can infect wineries or winemaking equipment such as tanks or barrels. If wine comes into contact with the Brett yeasts then in becomes infected too.

What does it taste/smell like?

Brett will give the wines animal/rancid or earthy notes, as well as a plaster or damp material smell. On top of this the wines will often appear duller in both colour and aroma. At small quantities of Brett infection it can benefit some bigger red wines adding an earthy complexity that some drinkers enjoy.


Sulfur Dioxide

Sulfur Dioxide has been the preservative of choice by winemakers for the last 20 centuries. It can be applied into the wine in numerous ways from burning sulphur candles, liquid or powder forms. All wines need some level of preservative to stop the wines from oxidising (read about this below). There is currently a real interest in natural or low-sulphur wines – these use natural preservatives like tannins and sulphides (a natural preservative that comes about as a by-product of the grape’s fermentation) to protect the wines.

You will undoubtedly find higher levels of sulphur in cheap, supermarket wines as they are made to be simplistic and fresh – both characteristics that sulphur helps to preserve. Higher quality wines, and European wines in general, will have much lower sulphur contents due to regulations. Wines with high residual sugar, like dessert wines, will have the highest amount of sulphur added to them.

What does it taste/smell like?

High levels of sulphur will give the wines a ‘struck match’ or smokey aroma. At low levels sulphur could give the wines some complexity yet at higher levels it will interfere with the wines primary aromatics. The match or smokey aromas can often be overwhelming to wine drinkers.

NOTE: The words sulphur and sulphites can be used interchangeably.