Pétillant-Naturel Ciders and Wines

What are pétillant naturels?

Pet-nat, short for pétillant naturel, is a type of natural sparkling wine that is made by bottling the wine before it has finished fermenting, allowing carbon dioxide to naturally carbonate the wine. Think cloudy champagne! Utilizing natural carbonation creates a beverage with more persistent carbonation in the glass therefore a higher quality product. If you feel like nerding out on carbonation then check out this article by Scientific American. Both pet-nat and natural cider are known for their rustic, funky flavors and are gaining in popularity among wine and cider enthusiasts.

Why produce undisgorged pet-nats?

One advantage of producing the undisgorged pet-nat is that they are generally more cost-efficient to make than other traditionally naturally sparkling wines and producers can charge more money for these bottles because of their perceived quality. This is because they require less intervention from the winemaker or cider maker. For example, pet-nat can be bottled directly from the fermenting tank, which eliminates the need for expensive equipment like a disgorging line or expensive processes that involve a lot of labor and loss like hand disgorging. Check out a this video of machine disgorging.

Story Time! The problems associated with undisgorged pet-nets..

You have been eagerly waiting until the spring for your favorite winery to release their new pét nat wine. When you finally got your hands on a bottle, you couldn't wait to crack it open and taste the bubbly goodness.

As soon as you loosen the crown cap, the liquid erupts from the bottle like a geyser, showering you and everything around you with sticky foam.

You are surprised and a little embarrassed, but you can't help but laugh at the ridiculousness of the situation.

Unfortunately, the gushing bottle has become all too common with the pét-nat style. Many makers would argue that hands off production is the style when really the method of production is bottling the cider with primary fermentation sugars from the fruit to create a sparkling cider/wine that finishes fermentation in the bottle. This is also commonly referred to as Méthode Ancestral.

How many of your customers have had this experience with your pétillant-naturel ciders and wines?  Would you be willing to change your methods to create a pétillant-naturel cider/wine that did not gush and still was undisgorged?

The solutions to “gushers”

There can be many causes as to why your bottle has become a gusher and it can be very complicated. Here are the top three common problems that I see when making an undisgorged pétillant-naturel.

1. Insufficient gross lees removal from the fermentation process prior to bottling.

You must remove the majority of gross lees using racking and light filtration prior to bottling. Yes, you heard me right! Light filtration! I have found that filtration around 4 micron is sufficient to remove the majority of particulates from fermentation that will cause excessive carbon dioxide nucleation and gushing at lower carbonation levels(<= 5.0 g/L CO2) . In order to do this you will need to cold crash your fermentation just above your bottling target grams/Liter of sugar remaining. This is certainly a little complicated because you do want your fermentation to restart after you filter.

2. Potassium bitartrate crystals from grapes

Do you have naturally occurring tartaric acid in your pet nat? If so, you will need to cold stabilize your wine and hold it for two weeks to make sure you have chemically stabilized the liquid before bottling. Potassium bitartrate crystals in the bottle will eventually form and create nucleation points for carbon dioxide if the wine is not cold stabilized. Again, this is complicated because you will need to restart your fermentation.

3. Bottling with too much sugar remaining

When bottling with too much sugar remaining, you are really susceptible to creating a gusher due to the differences in atmospheric pressure between the bottle and the surrounding environment. Typically, I aim for just 9 g/L of residual sugar when bottling. This residual sugar will be consumed by the yeast and converted into alcohol and carbon dioxide (CO2) in the closed bottle. 9 g/L results in roughly 2.2 volumes of CO2 or 4.4 g/L of dissolved CO2. A carbonation level between 2-2.5 volumes works very well for undisgorged pétillant-naturels.

Theoretically, 4.04 g/L of glucose results in roughly 1 volume/ 1.96 g/L of carbon dioxide. For those that want to read more about naturally sparkling wines, check out Virginia Tech’s Review of Méthode Champenoise Production for more information on creating naturally sparkling wines.

In Summary

Ultimately, the key to creating a great pét-nat is to start with a goal in mind. I create custom plans, products and processes to work for your operations and workflow. Feel free to connect if you would like to know more about the pétillant-naturel process.