Wine Arcana

Style

Straw wine

Also known as Vin de paille

Straw wine is made from grapes that are harvested and then dried before pressing. The name describes a production method, not one grape, colour, or fixed level of sweetness. Some grapes are placed on straw, but others are laid on racks or mats, hung, or dried in a ventilated room. The important distinction is that the fruit loses water after harvest, concentrating the remaining must; the exact supports and conditions depend on the local tradition.

Drying is different from noble rot and from a late harvest. Noble rot involves the action of Botrytis cinerea on ripe berries, which changes their chemistry as well as helping them lose water. A late-harvest wine leaves grapes on the vine for longer to gain ripeness and lose water in place. Straw wine begins with fruit picked for this purpose and dried off the vine; it need not be botrytized or unusually late-harvested.

How it is made

Growers select sound bunches at harvest, because drying concentrates defects as well as sugar. Air movement, temperature, humidity, time, berry condition, and the surface on which grapes rest control how quickly water leaves. Water loss concentrates acids and sugars, while the berry continues to respire and can consume malic acid during the process.1. “Postharvest Water Loss of Wine Grape: When, What and Why,” Metabolites, 2021, §3.2, review of water-loss techniques and berry metabolic changes.

The resulting grapes give less juice with more sugar per litre. If fermentation converts most of that sugar, the wine can become relatively alcoholic and dry; if fermentation stops earlier—because the producer chooses to retain sugar or because concentrated must becomes difficult for yeast to finish—the wine is sweeter and usually lower in alcohol than a fully fermented version of the same must. Sweetness therefore comes from the relationship between concentration and fermentation, not from drying alone. Yeast, temperature, nutrients, acidity, oxygen exposure, and the desired endpoint all affect whether fermentation is completed, arrested, or left with residual sugar.

The Jura example

In the Jura, vin de paille is a regulated mention attached to particular appellations, not a rule for every straw-dried wine. Under the adopted 2022 Côtes du Jura specification, eligible grapes are Chardonnay, Savagnin, Poulsard, or Trousseau. They must be hand-harvested by successive selections. Drying (passerillage hors souche) must last at least six weeks on straw beds or racks, or with bunches suspended in naturally or artificially ventilated rooms; heating the air is forbidden. The must’s sugar concentration at pressing must be more than 320 and less than 420 grams per litre.2. Ministère de l’Agriculture et de la Souveraineté alimentaire, Cahier des charges de l’appellation d’origine contrôlée « Côtes du Jura », sections VII–IX, homologated by the 20 September 2022 arrêté.

Those rules describe the raw material and the drying stage, while fermentation still determines how much of the concentrated sugar becomes alcohol. For Côtes du Jura vin de paille, the specification sets a minimum acquired alcohol of 14% by volume and a minimum total alcohol of 19%. Acquired alcohol is the alcohol actually present; total alcohol includes the potential alcohol from remaining sugar as well. The yield is limited to 20 hectolitres per hectare. The finished wine must be aged until at least 15 November of the third year after harvest, including at least 18 months under wood, and may be released to consumers from 1 December of that third year.2. Ministère de l’Agriculture et de la Souveraineté alimentaire, Cahier des charges de l’appellation d’origine contrôlée « Côtes du Jura », sections VII–IX, homologated by the 20 September 2022 arrêté.

The related Amarone della Valpolicella article shows another legally defined dried-grape method.

Sources