The main grape used to make Prosecco is a white grape called Glera, and this is what gives Prosecco its characteristically fresh and aromatic flavour. The Glera base wine may then be mixed with a small quantity of other grape varieties to give further complexity to the final product. All Proseccos must be at least 85 per cent Glera; this is usually blended with other local grape varieties such as Verdiso, Perera, and Bianchetta, or even Pinot Bianco, Pinot Grigio or Chardonnay. Most Proseccos are blends, but after a really exceptional harvest some winemakers produce ‘pure’ Prosecco, made from 100 per cent Glera grape.
Glera has been cultivated in this little patch of North-East Italy since at least the eighteenth century. In 1772, Italian scholar Francesco Maria Malvolti mentioned the Glera grape in an article for the Giornale d’Italia, in which he praised the quality of local viticulture. Until recently, this grape was known as ‘Prosecco’, but in 2009 was officially renamed Glera (one of its old synonyms) in order to avoid confusion between sparkling wines produced inside and outside the DOC/DOCG zone. This renaming effectively prevents those producers outside the DOC/DOCG zone from mislabelling their sparkling wine as ‘Prosecco’. Sparkling wine producers in the IGT zone are instead encouraged to name their produce ‘Glera’, after the grape variety.