“Pét-Nat,” or “pétillant naturel,” is the term given to sparkling wines made with a single fermentation. Fermentation is started in-tank, then the wine is put into a bottle and topped with a crown cap, like those on beer or glass soda bottles. The yeast in the bottle will continue to ferment the sugar in the grape juice, and the carbon dioxide that is a byproduct of fermentation has nowhere to go, except into the wine itself, yielding a sparkling wine.
“Pétillant naturel” translates to “naturally sparkling,” and is the method that produced the world’s first sparkling wines, though initially this was unintentional. Yeasts will become dormant if the temperature drops too low, so in olden days, in non-temperature-controlled winemaking facilities, winemakers might think that wines were done fermenting, due to this dormancy. They would bottle their wines, and when spring rolled around with its warmth, the yeast would come out of dormancy and additional fermentation in the bottle would occur. Exploding bottles, due to the extreme pressure caused by the carbon dioxide build-up, was a true problem, and physical hazard.
Pressure inside a bottle of champagne is five to six atmospheres of pressure, which requires a heavy bottle and a cork with wire cage. The pressure in a pétillant naturel wine is usually under five atmospheres, and is controlled by allowing enough of the fermentation to happen prior to putting the wine into bottle, in order to not yield higher levels of pressure.
Pét-Nat differs in production and style from other methods of producing sparkling wines, due to its single fermentation, and to the fact that the spent yeast cells, called the lees, are usually left in the bottle. This can lead to the wine being hazy or cloudy when opened and poured. In contrast, wines like champagne are made by creating a dry still wine, then bottling that wine along with some grape juice and yeast, which will trigger a second fermentation in the capped bottle. After the champagne is aged sufficiently according to the style, the bottles are inverted and the lees settle in the neck of the bottle. The wine is then flash-frozen, and the bottle is opened, propelling the frozen lees out of the bottle due to the high pressure. This process is called “disgorging,” which results in a clear wine.
Champagne production is time-consuming, requires special equipment, and requires more labor, compared to pétillant naturel production. Pétillant naturel wine production is a much more streamlined and quicker process. Wine production has fewer steps, and if the wine is not filtered to remove the lees, once the wine is in the bottle, the work is done. The wine finishes its fermentation and then it rests, before being labelled and made available for sale.
Another difference between pét-nat and champagne is the riskiness. Champagne production is very formulated, as a still wine gets a precise amount of grape sugar and yeast added to the bottle to allow for the second fermentation. The still wine has been tasted, and the winemakers can predict the outcome. For pét-nat, the outcome is less predictable, as the wine is partially fermented when it is put in bottle.
Pét-Nat wines can be made from any grape or combination of grapes, whether red or white. There are no requirements or regulations, beyond the winemaker’s imagination and vision. Champagne production is limited by law to only those approved grapes for its production, including Chardonnay, Pinot Noir, and Pinot Meunier.
When it comes to a taste comparison of Pét-Nat to Champagne, the Pét-Nat will be more rustic, lightweight, and unpolished. Champagne will be more refined, with more yeasty, toasty notes, due to its extended time in contact with the lees. Grab a bottle of Early Mountain Pét-Nat Blanc 2019 and Bauget Jouette Carte Blanche Champagne NV, and do your own comparison.