Pét-nat: Back to nature

© pixabay / User: Jill Wellington

The method is nothing new and yet it seems like the brilliant idea was discovered just yesterday: “Pét-nat,” a centuries-old winemaking method that produces a more-or-less sparking wine usually clouded by yeast.

Most recently, the rediscovery of the pétillant naturel (English: naturally sparkling) can be traced to winegrowers from the Loire, who caused a sensation with it in the 1990s. As was customary centuries ago in Languedoc, Champagne and many other wine regions of Europe, winemakers bottled their already-fermenting must and allowed it to finish fermenting in the bottle. A yeast-clouded wine that foamed — sometimes more and sometimes less — was the result.

Caution was advised when opening the bottles, since the yeasts and tartrate crystals still contained in the wine provided the pressurizing carbon dioxide plenty of crystallization points. The result: The carbon dioxide could relax all at once — in other words, it fizzed and foamed.

The pét-nat method is not new by any means. It originated at a time when the first glass bottles were coming into fashion and winegrowers were still filling bottles with fermenting wines and even fresh musts. At that time, people were still unaware of what happens during alcoholic fermentation and how it occurs quickly or slowly depending on cellar temperature. Because the bottles were tightly closed with corks and cords, the resulting carbon dioxide remained in the bottles and, once opened, resulted in foaming and refreshing bubbles of carbon dioxide — that is, if the bottles didn’t burst before that. So, it’s no surprise to learn that wines produced using this method were both rare and precious and gained immense popularity. Opening a bottle of pétillant naturel was a privilege long reserved for kings only.

Pét-nat profits from the trend toward natural wines

As a new trend based on ancient production methods, pét-nat wines have been gaining popularity for several years, even outside of France. “Naturally sparkling” is such an ideal match for the natural wine scene, the movement toward sulfur-free and virtually natural wines, that it was just a matter of time before the trend spilled over to all the world’s wine-growing countries. Biodynamic winegrowers in particular have enthusiastically taken up producing pét-nat.

The idea of simply leaving the must obtained during grape pressing to its own devices is entirely within the philosophy of going natural: There’s no artificial or technical intervention nor enological manipulation, and, what’s more, the wine stays in one bottle from beginning to end.

Production through single fermentation

The question is, what makes pét-nat wines so special and how do consumers react to them? Its uniqueness certainly lies in the winemaker’s decision to produce a sparkling, alcoholic beverage through a single fermentation. While the basis for producing a standard sparkling wine is a fully fermented base wine that no longer contains sugar, pét-nat is produced without adding sugar or sweet must.

Unlike sparkling wines, the production of pét-nat is based on a single fermentation that can start directly with sweet must. As a rule, however, a wine that is already fermenting is usually bottled, and the fermentation process can continue in the bottle until the rest of the sugar in the young wine is completely consumed. This results in a dry pét-nat with a brut nature sweetness level. The standard sparkling wine production process is somewhat different, with a precisely calculated amount of yeast and sugar added to the wine after the first fermentation in order to trigger the second one.

Referred to as “sparkling wine fermentation,” this process produces the carbon dioxide that provides the excess pressure needed for the characteristic fizzing and foaming. This all requires employing a sophisticated technique and a great many steps that are widely used in the two key production processes of the traditional and classical method and the tank fermentation method (also known as the Charmat method). The classical method has its origins in Champagne, however the term “Methode Champenoise” is exclusively reserved for sparkling wines from the Champagne region. 

Depending on the philosophy and goal of the winemaker, a pét-nat can be made as a slightly fizzy “still wine,” a tingling semi-sparkling wine or a vibrant sparkling wine. Wines with up to 2.5 bars of pressure are categorized as semi-sparkling, those with 3.0 bars and higher are considered sparkling. Most pét-nat wines today are sparkling wines, which, like Sekt (the legal term is quality sparkling wine), have more than 3.5 bars of pressure.

Must and pressure determine character

The basic process of pét-nat production can, of course, be altered to produce a number of varieties. If the bottles are filled with sweet must as a base, the must weight or sugar content of the must determines the degree to which the yeasts ferment the sugar in the pressure-resistant bottle. This can be excess pressure of 5 to 7 bar and a remaining sugar content of a few grams totaling up to 30, 40 or more grams depending on the final fermentation. This sugar content then consists mainly of fructose, since the yeast cells prefer to consume the glucose of the must first. The remaining fructose also lends a more intense fruity aroma to the “naturally fizzy” sparkling wines a more intense fruity aroma.

The starting point for all enological considerations is therefore the must selected for the pét-nat. Other critical factors include the degree to which fermentation or sugar consumption is allowed to proceed and the point at which the fermenting must or young wine is filled into the hermetically sealed bottles. The enologist can, as a result, let a must fermentation proceed and separate the fermented wine from the mash a few weeks later before bottling it as “partially fermented wine.”

Disgorging as the finishing touch

Pet Nat Wine
© Weingut am Stein / pure & naked

The product can be altered again even at the very end of the process. A pét-nat wine can also be disgorged using the method now considered standard for traditional products. As in the classic method, the bottle is turned upside down and shaken slightly to settle the yeast. The separated yeast collects in the neck of the bottle, which is then frozen in an ice bath to form a yeast plug; the plug is then removed using the disgorging process familiar from the classic method. Depending on the base wine and the yeast used, the product produced is more or less clear. It can even be sweetened by adding the dosage.

In pét-nat wines that haven’t yet been disgorged, the yeast settles on the bottom of the bottle over time and remains as a sediment, similar to the cloudiness of wheat beer.

Residual sweetness, excess pressure and more or less intense foam are certain aspects of pét-nat; the grape varieties and the type of starting must are others. A wide range of different pét-nat varieties are the result: from light, almost clear, fruity and yeasty varieties with more or less typical fermentation notes to dark brown, earthy-spicy varieties to wines with a nutty flavor. And all pét-nat wines have one thing in common: Once the wine is bottled, the biological fermentation process runs independently.

Those hoping to learn more about pét-nat, natural wine and its production will find everything they need at drinktec from October 4 through 8, 2021, at Messe München in Munich. Are you still looking for a platform to showcase your innovative products and services in this segment? Then join us at the next drinktec.

Dr. Hermann Pilz

Dr. Hermann Pilz has been in charge of the trade magazine WEINWIRTSCHAFT as chief editor for over 20 years. He loves writing about many different topics of the wine and spirits industry.