Prosecco is produced using the Charmat Method, in which the secondary fermentation takes place in stainless steel tanks. Here, carbonation occurs biologically from the decomposition of sugar from added yeasts.
The must then undergoes slow fermentation in pressurized, stainless steel tanks (autoclaves). To achieve the proper balance of flavour, aroma, elegance, consistency and fine perlage, the wine is kept in these tanks from 20 days (frizzanti) to 3 months, and can go up to 6 months for Cuveè and Prestige.
Charmat Method History
Maumèné was the first person who thought to speed up the fermentation process by fermenting sparkling wines in large vessels rather than bottles. In the mid 1800s he built an “Afroforo” machine, consisting of a fermentation tank which siphoned the wine off and bottled it. The method was difficult to reproduce on an industrial scale. The Italian, Martinotti then took Maumèné’s idea, industrialised and employed wooden tanks, but the system was still not effective enough.
Finally, Frenchman Eugène Charmat found a way to turn Martinotti’s idea into a successful industrial system by using stainless steel tanks (autoclave), coated on the inside with a vitrified glaze resistant to attack by wine and sulphuric acids.