Glera

Glera is the grape behind Prosecco, and it only acquired that name in 2009. Until then the variety itself was called Prosecco, which made the name impossible to protect — anyone anywhere could plant the grape and sell the result under the same word. The solution was to rename the vine Glera and reserve Prosecco for wine from a defined area in north-east Italy. It was a legal manoeuvre rather than an ampelographic discovery, and it worked.

The grape is vigorous, high-yielding and moderately acidic, with delicate aromas of pear, white peach, honeysuckle and cream. Those aromatics are fragile, which dictates how the wine is made. Prosecco is produced by the tank method, with the second fermentation happening in a sealed pressurised vessel over a few weeks rather than in individual bottles over years. That keeps the fruit fresh and primary. Bottle fermentation and long lees ageing, which build the toast and brioche of Champagne, would simply bury everything Glera has to offer.

Quality varies more than the category's reputation suggests. The flat, fertile plains produce oceans of unremarkable wine; the steep hills of Conegliano and Valdobbiadene, where the vines are worked by hand on slopes too sharp for machinery, produce something considerably more precise, with real mineral cut beneath the fruit. The distinction is on the label if you know to look for it.

There is also a small traditionalist strand making col fondo — refermented in bottle and left undisgorged, so it pours cloudy and tastes dry, yeasty and savoury. It is the older style, and the least like the drink most people picture.

The DOC hierarchy is the most useful thing on a Prosecco label and the least understood. Plain Prosecco DOC covers a vast area across the Veneto and Friuli. Conegliano Valdobbiadene DOCG is the original hill zone, worked by hand on slopes too steep for machinery. Rive indicates a single hillside within it, and Cartizze is a small, famously expensive subzone of about a hundred hectares.

The sweetness scale runs counter-intuitively. Brut is the driest commonly sold, Extra Dry is sweeter than Brut, and Dry is sweeter still — a legacy of nineteenth-century terminology that nobody has been willing to fix. Most commercial Prosecco is Extra Dry.

Col fondo is the traditional style and the most interesting: refermented in bottle, left on its lees and sold undisgorged, so it pours cloudy and tastes dry, yeasty and savoury. It is closer to what the region drank a century ago than anything on a supermarket shelf.