The Martinotti Method (or Charmat Method) autoclave refermentation.
Until the late 1800s, the Classical Method was the only method used for the production of sparkling wines. In 1895 Federico Martinotti devised a production method characterized by lower costs and much shorter production times. This method involves mass fermentation of the base wine in stainless steel containers under pressure (autoclaves) at a controlled temperature. The method was later improved and patented by Frenchman Eugéne Charmat some 15 years later, and is now universally known as the "Charmat Method."
Characteristics of "Charmat" sparkling wines
Secondary fermentation in autoclaves lends itself particularly well to the production of fresh and fragrant sparkling wines particularly from aromatic grape varieties, as it allows a more effective extraction of aromas and flavors in a significantly shorter period of time than the classic method. In addition, the particular olfactory notes due to the long sojourn on the lees, characteristics of the classic method, would contrast with the primary aromas of aromatic grape varieties, creating an olfactory profile that is not quite harmonious. Sweet sparkling wines, often made from aromatic grape varieties, find this method best suited to their production. The speed of the process and its economy also allows the production of quality sparkling wines at a much lower cost.
The Charmat or Martinotti method in detail
To produce a sparkling wine using the Martinotti method (or Charmat method), as with the classic method, one can start with a cuvée of base wines, which is introduced inside stainless steel autoclaves where a rapid fermentation is started that will last at least 30 days and can last up to 80 days. Marketing will not take place until several months after the start of refermentation so as to stabilize the product. The longer the period of time on the yeasts before their separation, the more complex sparkling wine will be the result; this is when we will hear the term Metodo Charmat Lungo. On the other hand, the Charmat method lends itself to the production of large volumes of product, making sparkling wine "on demand" from refrigerated musts that undergo a double fermentation cycle within the same autoclave, from which the finished sparkling wine comes out, which is filtered and bottled at isobaric pressure (i.e., at the same pressure as it exits the autoclave).
The stages of the Charmat or Martinotti method
Most of the stages of sparkling wine making using the Charmat method (Martinotti method) take place under isobaric conditions (under pressure) so as not to disperse the carbon dioxide developed during the fermentation processes. The detailed sequence is:
Fermentation and/or blending of base wines
Addition of sugars, mineral salts and selected yeasts
Racking and filtration under isobaric conditions
What about long charmat method?
The long Charmat method is a middle ground between the classic method and the short Charmat method, and the duration of the wine's stay with the yeasts is 9 to 15 months, which results in a product with a more pronounced yeast aroma and finer perlage. The long Charmat method may also involve the addition of liqueur d'expédition after refermentation. This method of sparkling wine making was developed by winemaker Nereo Cavazzani in the late 1970s. The duration is not the only difference from the more popular "short" Charmat. In fact, propeller agitators are installed inside the autoclave, which have the task of putting fermentation sediments back into suspension. This promotes a more important wine structure and a more complex sensory profile, more similar to those of sparkling wines produced with the classic method.
Main wines produced with the Charmat or Martinotti method
The most famous sparkling wines produced with the Charmat method range from Prosecco to Moscato d'Asti and Moscati in general, Brachetto, Lambrusco and many others.
The Charmat method and sweet wines
The Charmat method for sweet wines is based on fermenting the must of generally aromatic grapes, such as Moscato Bianco and Brachetto, by interrupting fermentation through sterilizing filtration and thus obtaining a naturally sweet sparkling wine with a low alcohol volume. Note that in this case, one starts in an autoclave directly from the must rather than from the base wine.