Destemming separates the grapes from their stems. When stems are not sufficiently ripe, they run the risk of adding unpleasant, green tannins to the wine, or a grassy taste. Nevertheless, stems can be left on when ripe to enrich a wine’s palette of aromas, to add quality tannins to wines that are lacking or to cellaring wines, and to add extra complexity.
The principle :
The grapes are harvested as late as possible, then pressed and stored for over six years. During this time, the yeast that is naturally present on the surface of the grapes will proliferate and create a precious "veil" that will give this cellaring wine its colour and its taste.
The purpose of crushing is to open the grapes to foster fermentation and the flow of aromas from the skin into the pulp. Classic vinification. However no sulphur dioxide is added as this would destroy the germs that are needed to produce yellow wine. Settling is also to be avoided as it would leave these germs at the bottom of the vat.
No time to settle for yellow wine. Settling would leave precious germs at the bottom of the vat. These gems are plentiful at the end of maturation and play an essential role in maturing the wine. No sulphur dioxide is added either, as it would destroy the germs.
Oxygen triggers the fermentation of must. Sugar is transformed into alcohol in a vat for about ten days at temperatures varying between 15°C and 20°C. Such relatively low temperatures foster the release of subtle aromas and curb the formation of yeast.
Malolactic fermentation by lactic bacteria often commences spontaneously. It transforms the slightly hard malic acid into softer, rounder, lactic acid. This transformation makes the wine suppler and less aggressive. It also stabilises the wine, because lactic acid is less reactive than malic acid. In the Jura, the main region where yellow wine is made, malolactic fermentation only takes place in the spring due to the harshness of winter.
The white wine thus obtained is decanted and poured into oak barrels that have generally already contained either yellow wine or Burgundy in order to take advantage of the flora that has developed in the slats of wood. The wine is stored for a precise period of time: six years and three months exactly, after which time the traditional "Percée du Vin Jaune" – the pre-bottling yellow wine festival - can take place.
During the long period of maturation there is no topping up to compensate for wine that has evaporated. This allows the wine to come into contact with an increasing volume of oxygen. Yeast gradually rises to the surface to form a protective veil. As the cellars are not underground, temperature and hygrometry vary with the seasons, giving the veil a very specific look year after year. During this period, under the combined effects of developing yeast and oxidation, the wine develops all of its savours and dons its unique bronze-tinted gown.
Yellow wine is put in 62-cl bottles called "clavelins". Yellow wine is for laying down. It keeps very well, with the great vintages reaching the ripe old age of one hundred.