Reductive or oxidative? The role of oxygen in winemaking
One of the most important decisions in winemaking is how much oxygen reaches the wine during fermentation and maturing. There are three broad directions: excluding oxygen, a little oxygen, and deliberate contact with air.
Reductive winemaking
The winemaker tries to keep oxygen away: using stainless-steel tanks, cooling and sulphur-dioxide protection. The result is a fresh, fruity wine with a clean taste.
Oxidative winemaking
The wine is deliberately and controllably in contact with air, for example in a barrel that is not topped up. This gives it a deeper, nuttier, honeyed, spicier character, and it can be matured for longer.
Between the two extremes
Barrel maturing lies between the two: oak lets a little oxygen through, which makes the wine rounder.
When the oxidative character is the essence of the style
There are wines that are deliberately left in contact with air. One is the traditional dry Szamorodni, which matures in a barrel that is not topped up, often under a thin film of yeast, and acquires a nutty, spicy, sherry-like character. The yellow wine of France's Jura region (vin jaune) belongs here too. These wines are not faulty: here the oxidative character is the essence of the style.
The vessel matters too
- Stainless steel: neutral, adds no flavour and lets no oxygen in; the basic tool of the fruity style.
- Oak barrel: lets a little oxygen through, and adds flavour.
- Concrete egg and amphora: let a little oxygen through but add no flavour; they support a mineral, clean style.
