Semillon is a paradoxical grape, as much of its appeal stems from its susceptibility to rot. Sure, the idea of rot may conjure up nasty images, but in winemaking, rot isn't necessarily a negative. Grapes can be affected by two types of rot: grey rot and noble rot, also known as Botrytis. While the former is a destructive force, diminishing yields and making wines taste moldy, noble rot causes grapes to shed water while still on the vine, thereby concentrating sugars and acids. The thick skins of the Semillon make the grape prone to noble rot, but certain vintages, where improper climatic conditions occur, can be affected by the latter.
Concentration of sugars and flavors are critical because Semillon is the key component of one of the world's famous sweet wines, Sauternes. Some Sauvignon Blanc is usually blended in to provide a little acidity and freshness. Made in the Sauternes region of Bordeaux, producers rely on Botrytis in the Semillon to deliver the characteristic honeyed nectars of the wine. In years when neither type of rot develops, producers are stuck with a sweet wine lacking real complexity and texture. Even worse are the years when grey rot strikes. Furthermore, harvest of the grape requires great care, with multiple passes through the vineyards necessary to pick Botrytis-affected clusters and even individual berries. Consequently, Sauternes is not an inexpensive wine, but we're convinced that with foie gras, there's nothing better. Here, the acidity and sweetness of the wine provide the perfect counterpoint to the rich density of foie gras. We like the producers Chateau d'Yquem and Climens.
Semillon is also also used to make dry wines in Bordeaux, again blended with Sauvignon Blanc. Here, the Sauvignon is usually the dominant partner, with Semillon used to add softness and richness to counter the brisk characteristics of Sauvignon. Introduction of Semillon generally makes these wines more age-worthy. For top examples of Bordeaux blends featuring Semillon prominently, look to the legendary Chateaus Haut-Brion and Laville Haut-Brion.
Outside of France, Semillon has a long history in Australia. Hunter Valley, Australia's oldest wine region, is home to a number of producers making single-varietal Semillon. Here, Semillon is usually unoaked, and wines have orchard fruit characteristics. Try wines from Brokenwood and Margan. These dry Semillons will be reliable partners for seafood and white meats.