Destemming separates the berries from their stems. If the latter are not sufficiently ripe they may add unpleasant green tannins to the wine, or a grassy taste. Nevertheless, the stems can be kept if they are ripe, in which case they enrich the wine’s range of aromas, add quality tannins to wines that are lacking or to cellaring wines, and add extra complexity.
Vin Doux Naturel
The principle :
To make a Vin Doux Naturel, or "vin muté", alcohol is added to the must during fermentation in order to halt the action of the yeast and hold on to some of the residual sugar. The main grape varieties for these natural sweet wines are Muscat à Petits Grains, Muscat from Alexandria, Grenache, Macabéo and Malvoisie.
The aim of crushing is to burst the grapes so that they release the maximum amount of juice and substances (tannins, colour) to get fermentation off to a good start.
Oxygen triggers the fermentation of the must. Fermentation gradually takes the sugar level of the must to 252 grammes per litre, at which point mutage can take place: 96% neutral grape alcohol is added in proportions varying between 5 and 10% of total volume. This stops the action of the yeast before it has been able to transform all of the sugar into alcohol. This is how Vins Doux Naturels hold on to some of the fruit’s natural sweetness.
In general, Vins Doux Naturels (of the Ambré, Tuilé and Hors d’Âge varieties) are matured in contact with the air in wooden casks or vats for between 30 months and sometimes up to 20 years... This does not apply to Muscat and some red Vin Doux Naturels intended to be drunk young, however. Sometimes, the "aging" of the wine is accelerated by a period of time spent outside the cellar: - in 600-litre barrels (demi-muids) placed outdoors; - in glass demijohns placed outdoors for one year at most, before the maturation process is rounded off in tuns or casks indoors. Whether consumed young or mature, a VDN will always have 15% ABV and be rich, stable and unique.