Non Ouillé

What it is

Non ouillé (pronounced non-wee-YAY) is a French winemaking technique where a barrel is not topped up after the normal evaporation losses during ageing. The opposite of ouillé (topped up), the default practice in almost every wine region. Central to the production of Jura’s vin jaune and the wider sous-voile style.

In ordinary cask ageing the winemaker periodically refills the barrel to keep the air gap above the wine small, slowing oxidation. In non ouillé ageing that air gap is deliberately allowed to expand, making space for a living yeast veil (in Jura le voile, comparable to sherry’s flor).

Why non ouillé works

Three factors converge:

1. Air gap above the wine: at least 25% of the barrel volume stays empty. Far larger than in ouillé ageing (where the air gap is minimised).
2. Yeast veil formation: the specific yeast strain that lives in Jura cellars (related to sherry’s Saccharomyces beticus) grows on the wine surface once alcohol sits at 13-14% and humidity is high enough.
3. Controlled oxidation: the yeast veil shields the wine from aggressive oxidation while allowing micro-oxidation. Result: nutty, hazelnut and curry notes without the colour shift typical of full oxidative profile.

Cahier des charges requirements

For vin jaune INAO sets out:

• Minimum ageing: 6 years 3 months in cask without topping
• Cask size: 228L (classical Burgundy oak)
• Loss tolerance: up to 38% of the original volume may evaporate (“angels’ share”)
• Bottle size: 62 cl (the specific “clavelin” bottle, sized to the remaining volume after ageing)
• Grape: 100% Savagnin
• Minimum alcohol: 13.5% at cask entry

A normal 228L barrel delivers around 140-160L to the bottler after 6 years 3 months of non ouillé ageing. The rest has evaporated or oxidised despite the veil.

Beyond Jura

Sous-voile-comparable techniques exist elsewhere, though not always under the name non ouillé:

• Sherry soleras in Marco de Jerez: comparable air gap (max 5/6 fill), flor ageing. No exact 6-year rule.
• Tokaj (Hungary): dry szamorodni works comparably, with a yeast veil on Furmint
• Vernaccia di Oristano (Sardinia): flor ageing on Vernaccia di Oristano grape
• Sherry beyond Spain (Cyprus, South Africa): historical attempts at non ouillé ageing, limited volume quality

Frequently asked questions

What’s the difference between non ouillé and oxidative ageing?

Non ouillé creates the conditions for sous-voile ageing: a yeast veil on the surface that protects the wine from aggressive oxidation. Pure oxidative ageing (as in oloroso sherry or Marsala) has no yeast veil and lets the wine sit in direct contact with oxygen. Non ouillé is therefore not a synonym for “oxidative”; it is a controlled intermediate form.

Which wines undergo non ouillé?

Primarily vin jaune and Château-Chalon (Jura). Beyond that some Côtes du Jura blanc tradition and Arbois tradition. A handful of producers outside Jura experiment with it (Domaine du Pélican, and some natural-wine-oriented producers in France).

Why is the clavelin bottle 62 cl?

The clavelin (62 cl) is legally fixed as the exact amount left from 1 litre of wine after 6 years 3 months of non ouillé ageing. The ~38% loss is formalised in the bottle size itself, which partly expresses Jura’s vin jaune uniqueness.