Some of the world’s most glorious dessert wines would not exist but for a tiny airborne fungus. Folk tales abound about how its transformative powers were discovered, but most have to do with absent farmers returning late in the autumn to their vineyards to find an apparently ruined harvest, but making the wine just the same.
Botrytis cinerea is that fungus, and it typically appears when warm, humid conditions persist as harvest approaches. Clinging to the ripe grape, the fungus pierces the skin causing water to escape and concentrate the grape sugar.
When fermentation progresses to a level exceeding 14% alcohol, the yeasts are no longer able to survive, leaving residual sugar in the finished wine. The mold itself imparts a unique honeyed aspect to sweet ambrosia (nectar of the Gods), contrary to what one might expect from its appearance.
Just as a little mold has given us some of our favorite cheeses, so we can thank our lucky stars for botrytis which has brought us Sauternes, Trockenbeerenauslese, Sélection de Grains Nobles and wines labeled “botrytized.”
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