This is the most common method of producing Prosecco. Once the grapes have been harvested they are transported to the winery, where specially designed machinery presses the grapes very gently, so that only the free-run juice from the heart of the grape is extracted (100 kilograms of grapes should give no more than 70 litres of wine). This cloudy juice, known as the ‘must’, is then allowed to settle in a stainless-steel tank, where it is kept at a cold temperature for around ten to 12 hours.
Once the cloudy part of the must has settled, natural yeast is added to the clear liquid and the fermentation process begins. The addition of yeast encourages the natural sugars in the grape juice to convert into alcohol. This first stage of the fermentation process usually takes between 15 and 20 days, during which the tank is kept at a constant temperature.
The base wine produced in this first stage is then blended with other types of wine before being submitted to a second phase, known as the prise de mousse. It is during this phase that the still wine is transformed into a sparkling wine. After being carefully blended and tasted, the still wine is introduced into pressurised, stainless-steel tanks, along with yeast and sugar, which stimulate the production of bubbles of carbon dioxide in the wine. As soon as the wine has reached the desired alcohol level, it is cooled and filtered, and all of the yeast used in the fermentation process is removed. Some of the residual sugar is kept to give it a bit of sweetness, and finally the Prosecco is bottled under pressure, to ensure that it keeps its bubbles. This part of the production process tends to take around 30-40 days.