Santa Margherita

Prior to the alcoholic fermentation, must is essentially sugary water. The action of the yeasts changes the sugars into alcohol. In order to obtain sweet wines, therefore, all that is required is to limit this process. The most commonly used technique is to interrupt the fermentation when the desired alcohol level has been reached and there is still a substantial quantity of unfermented sugars. The must is filtered using a very fine mesh to trap the yeasts, then the fermentation is allowed to start up once again: this operation is repeated several times and gradually becomes weaker and slower.
The process for wines made from dried grapes (“vini passiti”) is rather different. In this case, the grapes undergo natural or artificial drying, and their sugars thus become more concentrated because of the evaporation of their water content.
Once they have reached the required degree of drying, the grapes are vinified as for white wine (or for red wine, if the grapes are dark-skinned) with a fairly slow fermentation at low temperatures so as not to cause the aromas to be affected. The wine will also have to remain quite a long time in the cellar in order to refine its character. These types of wine may be considered mature after three to four years.
One of the most famous examples is Tuscan Vin Santo, which is made from the best bunches of grapes. These are allowed to dry on mats or trelliswork, generally in attics which are well aired all year round and where temperatures vary markedly. The wine’s long maturation takes at least three years, in small barrels (“caratelli”).
Moscato Rosa (a sweet red wine from the Trentino and Friuli areas) is, on the other hand, left to overripen on the vine. The alcoholic fermentation takes place in small vessels and, after the malolactic fermentation, the young wine is sweetened with concentrated must. The wine is then left to age in small barrels for 2-3 years.
The so-called botrytized wines are another matter again: these are obtained from grapes attacked by Botrytis Cynerea or “noble rot”. This mold causes changes inside the berries themselves that alter the grapes' metabolism, causing a substantial increase in aromatic substances. In certain cases it is possible to add ethyl alcohol or concentrated must to these wines in order to increase their alcoholic strength. The vinification is similar to the process used for wines made from dried grapes.