News & Articles, Read Our Blog

Paul’s Wine Tip! What causes Oxidation in Wine?


Oxidation, in wine terms, refers to a group of chemical reactions that occur when the wine comes into contact with air.

We all know that oxidization can ruin any wine, but what causes this? Well, the answer is simple: oxidization is the result of too much air contact with the wine or insufficient sulfite levels. This can occur at any point during the winemaking process, as of course, it does with the finished product. For example, oxidization can occur during the racking process, and as such, it is important to minimize how many times you rack your wine, as well as to use either our vaccuvin system to remove excessive CO2, or rent one of our Home Vintner degassers.

Excessively whipping is another way you can oxidize your wine. “Whipping” refers to the mechanical stirring tool that quickly stirs the wine and will often churn up the wine and result in foam. This adds an excessive amount of unnecessary oxygen to the wine and should be avoided at all costs.

Storing your wine with poor-quality corks allows for the opportunity for wine to become oxidized very quickly. It is important to only purchase reputable, high-quality corks, such as those sold at any of our locations.

Another common mistake that can result in the deterioration of the quality of your wine due to air contact is leaving large air space in the carboy for a prolonged period of time. Even airlocks will eventually dry out, so to avoid this use our trick: run a hose from the airlock into a wine bottle full of water if the carboys will be left alone for a long period of time.


So what exactly does air contact do to your wine? Well, oxidization casues a particular odor, which is primarily due to the presence of acetaldehyde, which is the result of the oxidation product of ethanol. Without any sulfite, even the best-stored wine will be affected, as colour and aroma compounds interact with any oxygen that may be present.

With oxidation, the fruity aroma  disappears and is replaced by an aldehyde aroma, similar to the aromas found in sherry, though sherry is deliberately oxidized. As oxidation proceeds, red wines change from bright red through to brick red and finally to brown. White wines will change colour also, from yellow through gold to brown.

Oxidization that takes place extremely gradually, such as during aging, has the potential to add complexity to the wine and and be considered desirable. What we wish to avoid is too much too soon. Our wine, our corks and good storage conditions will give the best results possible.

Related Posts