Sancerre is one of the Loire Valley wine region's most easterly appellations and arguably its most prestigious. Once a name associated with light-bodied red wines, since the mid-20th century Sancerre has been world famous for the crisp, herbaceous style and marked minerality of its Sauvignon Blanc. It still produces red and rose wines, exclusively from Pinot Noir, but these represent only about one-fifth of its annual production.
The distinctively smoky, gunflint character of Sauvignon Blanc from this area is an intrinsic part of the Sancerre palate and is referred to locally as pierre a fusil. This aroma is the reason that Sauvignon in the eastern Loire has taken the pseudonym Blanc Fume - which explains the Fume of Pouilly-Fume, just across the Loire. It is complemented by the appellation's other key mineral, calcium, which is present in the form of limestone in the soils and as a 'chalky' flavor in the wines.
Until phylloxera wiped out vast tracts of vineyard in the 1860s, Sancerre and its immediate neighbors grew mostly Gamay and Pinot Noir. When the solution to the phylloxera epidemic was identified – grafting European vines onto American rootstocks – Sauvignon Blanc vines proved more responsive than these red varieties. Thus, Sauvignon came to be the most widely planted variety in Sancerre, bringing the fame that the parish enjoys today.
The area demarcated as 'Sancerre' encompasses Sancerre itself and 14 parishes on the left bank of the Loire – from Montigny in the south to Bannay, 14 miles (22km) to the north. There were nearly 6900 acres (2800ha) of vines producing Sancerre wine in 2005, roughly double the acreage recorded when the title was introduced in November 1936.
In true French style, the terroir here is credited with the very particular aroma and flavor of Sancerre and it has been intricately studied and mapped. The key soil types are divided into limestone, marlstone, clays of various compositions and the all-important flint. Limestone and flint are the two most important. Both have excellent heat-retention and light-reflecting properties, helping the vines to achieve optimal ripeness in the cool growing season. The mineral qualities traditionally found in both Sancerre and Pouilly-Fume wines are neatly encapsulated by the two descriptors 'flinty' (pierre a fusil) and 'chalky', and are typically linked to the soil type of the vineyard where the grapes were grown.
While less fruit-driven than many modern styles of Sauvignon Blanc (from Marlborough or the Casablanca Valley, for example), there is a reliable fruity element in almost all Sancerre wines. This tends towards gooseberry and citrus characters, which work in harmony with the wines' high acidity and complement the minerality rather than dominating it.