Sparkling Wine, Sekt, Semi-Sparkling: What's What?

How Much Pressure Do Sparkling Wine, Sekt, and Semi-Sparkling Wine Have?

Anyone who hears a cork pop is hearing physics at work. Inside the closed bottle, carbon dioxide is dissolved in the wine and pushes against the glass and closure. EU law measures this excess pressure at 20 degrees Celsius and requires that it comes from dissolved carbon dioxide. This figure determines under which name a beverage may be sold. The governing rule is Regulation (EU) No. 1308/2013, whose Annex VII lists all categories of wine products.

The thresholds are clearly drawn. Sparkling wine begins at 3 bar, quality sparkling wine at 3.5 bar, and semi-sparkling wine ranges between 1 and 2.5 bar. For comparison: a car tire typically holds between 2 and 2.5 bar. Champagne typically sits around 6 bar, roughly double the minimum threshold. The narrow band between 2.5 and 3 bar doesn't belong to any category.

Pressure also determines the packaging. Sparkling wine bottles have thick glass and a deeply indented base to safely contain six bar of pressure. The mushroom-shaped cork is secured by a wire cage, called a muselet. Semi-sparkling wine gets by with lighter glass and simpler closures, often a screw cap or a cork held down by string.

What Turns a Sparkling Wine into a Sekt?

In everyday speech, many people call anything fizzy Sekt. Legally, the word is more specific: in Germany and Austria, it denotes quality sparkling wine, the fifth category on the EU list. The minimum pressure rises to 3.5 bar, though 3 bar suffices for bottles under 25 centiliters. The cuvée—the finished blended base wine before the second fermentation—must bring at least 9 percent total alcohol. For simple sparkling wine, 8.5 percent is enough.

Then there's time. For quality sparkling wine, Delegated Regulation (EU) 2019/934 prescribes a minimum production period, counted from the start of the second fermentation: six months if that fermentation takes place in a pressure tank, nine months if it ferments in the bottle. The wine must remain in contact with the lees for at least 90 days, or 30 days in tanks equipped with stirring devices. In both categories, the carbon dioxide must come from fermentation.

The word Sekt, however, says nothing about origin. A German winery may produce Sekt from base wines sourced from other EU countries. Only additions like Sekt b.A. (from a designated region) tie it to a specific place. Quality sparkling wine with a protected designation of origin, or PDO, must also have at least 10 percent actual alcohol. This category includes Sekt b.A., Champagne, Cava, and Prosecco DOC.

Sparkling Wine with Added Carbon Dioxide: How Do You Spot It?

Some of the cheaper products are made entirely without a second fermentation. The winery simply injects carbon dioxide from a gas cylinder into a still wine, much like a soda maker. EU law has its own category for this: sparkling wine with added carbon dioxide. It too needs at least 3 bar, but may only be made from wine without a protected designation of origin.

The label must state "made by the addition of carbon dioxide." Such a beverage can never be called Sekt, since quality sparkling wine requires that all the carbon dioxide come from fermentation. This one sentence reveals whether the bubbles grew naturally in the wine or were injected into it. It says nothing yet about taste, but everything about the method.

Semi-Sparkling, Pét-Nat, and Asti: The Borderline Cases

Below the sparkling wine threshold sits semi-sparkling wine, at 1 to 2.5 bar. It must have at least 7 percent actual alcohol and may be sold in containers up to 60 liters. Here too, a version exists with added carbon dioxide. Italian frizzante wines and many of the Seccos found on German supermarket shelves belong to this group. They fizz more gently, and their sweetness level is indicated using the same terms as for still wine.

Pét-Nat, short for pétillant naturel (naturally sparkling), has no legal category of its own. It ferments only once and is bottled before that fermentation finishes. Depending on how much pressure builds up in the bottle, it's legally classified as either semi-sparkling or sparkling wine.

Aromatic quality sparkling wine occupies a special position. It's made from fragrant varieties like Muscat, requires only 3 bar, and needs at least 6 percent actual alcohol with 10 percent total alcohol, the remainder staying in the wine as sugar. The best-known example is Italian Asti. Anyone who knows these categories can read a label faster than any marketing copy.