The newest “pet” in the wine world is pétillant naturel, known in geek speak as “pét-nat”. It’s a cute term for a natural wine with a bit of fizz that can be quite foamy when opened, and ranges from bone dry to a little on the sweet side. But, although it is trendy, pét-nat is not new.

One could call it retro because the tech­niques involved in this style of wine are very old: méthode ancestrale is said to be the earliest traditional way of making sparkling wine. Most likely, this was hit upon accident­ally, when it was noticed that fermentation had been slowed or stopped by unexpectedly cold weather. A French winemaker would have bottled his wine, assuming that it was ready. When opened, it would have been discovered that ferment­ation had restarted in the bottle and that it now contained bubbles. Méthode ancestrale precedes the méthode traditionnelle technique used to make champagne.

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What makes pét-nat wines distinct is that no sugar is added; fermentation depends on natural yeasts on skins of the grapes, and bubbles are a by-product of fermentation. The tricky part is in bottling the wine at just the right time: what I call the “wine interrupted” moment, when most or all of the natural sugars in the grapes have been consumed by the natural yeasts, but fermentation is still vibrant.

It sounds easy, but there are a few things to watch out for. One is the sediment (the lees) left over from fermenting grapes – fermenting lees could increase the pressure in a bottle to exploding point. With méthode traditionnelle, disgorgement removes this problem. This starts with riddling, whereby a bottle is gradually spun from upright to an upside-down position, so that sediment migrates to the bottle’s neck. The bottle is then chilled to almost freezing and opened so that a small amount of wine, including the part with the sediment, is allowed out. If no disgorgement takes place, which is often the case for pét-nat wines, a light filtering (at the very least) should be carried out before bottling.

Pét-nat wines are bottled without the addi­tion of any sulphur dioxide as a preservative. It is essential to have absolute cleanliness in the winery to avoid oxidation and other spoilage issues. These wines are meant to be enjoyed young.

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So how to tell them apart from other spark­ling wines? Usually, pét-nat wines come with a crown cap – like a bottle of beer. A bottle of pét-nat wine is slightly heavier than a usual wine bottle, being thicker to withstand higher pressure (perhaps two to four atmospheres).

Pét-nat wines are lower in alcohol than other wines and refreshing, with vibrant fruit flavours – if done right – and they are easy on the wallet. They are excellentas an aperitif, matching well with savoury flavours that are not too spicy.

Blanquette de Limoux, from the Languedoc, is believed to be the first sparkling wine from France. Records from 1531 show that monks at the abbey of Saint-Hilaire had figured out how to consistently make sparkling wine. Grapes used in today’s Blanquette de Limoux are the same as those used then: mauzac, clairette, chenin blanc and chardonnay.

Australia too is a good source of pét-nat wines, with many young winemakers producing adventurous offerings. The most memorable bottle that I tasted on a recent tour of the country was made from nebbiolo, and called Pat-Nat by Little Reddie, after the winemaker, Pat Underwood.

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The wine was the palest shade of blush pink with gentle bubbles, and tasted of slightly dried cherries, mulberries and a hint of earthy licorice. The back label declared “nothing added, nothing taken away”; the front label featured a rather risqué, black-and-white photo of Underwood – naked and standing on a barrel, with only a strategically placed diamanté to cover his embarrassment.

Because there are no rules governing which grapes may be used for pét-nat wines, they are for the adventurous taster. They can be pleasant surprises, and a great topic of discussion for wine geeks.