Do you know the difference between passerillage & botrytis? Sweet wines can be made with grapes affected by one or both. But what’s the difference?
Well, passerillage is the French word that describes grapes that have dried, shrivelled or raisined on the vine. This concentrates the sugars in the grape and reduces the water content.
So how is that different to botrytis?
Well, botrytis is a fungus that potentially has a huge effect upon the quality of a wine. That’s because it can go one way or another.
Under damp, wet conditions it can turn almost ripe or damaged grapes to what we call ‘grey rot’. That’s very bad news for the grower as too much grey rot in your grapes and the quality is severely compomised.
When the conditions are better however, ripe, healthy grapes attract botrytis in its good form, ‘noble rot’.
Noble rot or ‘pourriture noble’ makes some of the best and most delicious sweet wines in the world.
It’s very weather dependent. Ripe, healthy grapes, misty mornings that allow the fungus to spread to other healthy grapes, sunny afternoons that ensure dampness doesn’t get trapped in between the grapes turning it to grey rot.
In very hot, dry years we’re more likely to see passillerage than noble rot. That’s because when the weather conditions are hot and dry, it won’t spread. In damp wet conditions, it’s a worry.
Vineyards that produce fine sweet wine are often located close to rivers such as in the hills of the Layon, the Coteaux du Layon, or Coteaux de L’Aubance, Vouvray, Sauternes, Barsac and Tokaji in Hungary. These areas are perfect for the production of wine sweet wines affected by botrytis.
Noble rot changes the chemical composition of the grapes. The fungus feeds on the nutrients in the grape and gives the grapes an aromatic profile that is quite different to wines made from raisined grapes.
Generally growers in the Loire try to avoid using any grapes affected by noble rot in their dry wines because they are looking for a purity of flavour. When it comes to sweet wines however, noble rot is always welcome if the weather conditions allow it and the grapes remain healthy late into the season.
Ice wine does not use grapes affected by noble rot. It’s grapes are picked when frozen so the juice that leaves the press is extremely high in sugar but with no botrytis.
In Italy, passerillage is known as passito. Here, grapes are picked and left to dry over a period of weeks until the water content in the bunches has severely reduced and the concentration of sugar has increased.
They are all delicious and when the balance of residual sugar is spot on, just fabulous!
