The grapes are harvested during the first weeks of September when the organoleptic qualities (sugars, acidity and aromatic substances) have reached maturity and are perfect for producing sparkling and semi-sparkling Prosecco. After the harvest, the grapes have been picked by hand in their individual vineyards and then brought to the winery. The ﬁrst step is pressing, which provide the separation of the grape stalk and the grapes. It takes place in special presses that crush the grapes softly, extracting only the free-run must.
Vinification takes place thanks to natural yeats , which when added to the must trigger alcoholic fermentation: sugars contained in the grapes has been transformed in alcohol and CO2. The action of the yeasts (fermentation) lasts for around 15/20 days at a maximum temperature of 18°C to preserve the delicate aromas of the original grapes. After fermentation the ageing process begins and the wine is racked and filtered to make it clear.
According to the type of Prosecco we want to produce, there are different operation doing it. Prosecco Tranquillo is bottled, while the Frizzante and Spumante varieties continue to the final unique stage of the natural secondary fermentation.
The secondary fementation is carry out in two ways.
Using the classic method, the wine is bottled with a mixture of sugar and yeast. The bottles (made by a thick glass which can support the pressure of 4-8 atmospheres) are closed with a special stopper, a cylinder (the so-called “bidule”, or cartridge) placed with the opening facing down towards the wine, over which the better-known crown cork is applied. The bottles are then arranged horizontally in racks and keep in the dark for some months or years.
In the next stage the bottles are tilted and head down, in this way the lees (yeasts) that have amassed along the inside of the bottle are gradually moved towards the “bidule”. Later, the neck of the bottle is immersed in a liquid solution cooled to -25° C. After a short time the part of the wine immersed in the solution freezes and forms a cylinder of ice, containing all of the deposit that has formed whilst the wine has been maturing on its lees. At this stage the bottles are uncork and the cylinder ice is remove.
Using the Italian method or Martinotti-Charmat, the secondary fermentation and the production of CO2 takes place in stainless steel tanks. Towards the end of the secondary fermentation, which lasts a minimum of 30 days, the temperature is lowered to stop fermentation, this causes the yeasts to die and fall to the bottom. The sparkling wine is left for a period of between 1 and 6-9 months on the lees and then filtered, cleaned and transferred to a second tank from where it is bottled. Corking and muzzling take place immediately afterwards.