The area most famous for this type of wine is of course Champagne, and that is well to the north in France (north-east of Paris). It is the cooler wine growing regions that produce the best sparklers. This is because we require relatively unripe grapes for the wine - indeed cynics would say, with some justification, that the Champagne growers invented sparkling wine because they could not make such good still wine as their compatriots further south in France, notably in Bordeaux and Burgundy.
The basic requirement is for grapes that when fermented fully will yield around 11% alcohol by volume in the base wine. There must be no residual sugars left in the wine. Under the right conditions some wine growing regions can regularly produce well over twice this sugar level in their grapes to produce a very strong sweet wine - an obvious example is Sauterne.
The wine is made from clean, disease-free grapes, and fermented in our stainless steel tanks without any preservative (sulphur dioxide). At all times it is handled with loving care and attention. The grapes we use are from Seyval Blanc vines. These have a fairly neutral taste, high acidity, and the vine is very disease resistant. The more usual Champagne vine varieties Pinot Noir, Pinot Meunier and Chardonnay do not perform particularly well in our climate.
Once the fermentation is complete we clear the wine by natural settling of the dead yeast cells (the lees), and then filter the wine to remove any yeast and bacteria. We return it to a steam-cleaned tank, and make up a fresh yeast starter culture. Once this is going strongly we add a small quantity of sugar (24 grams per litre) and the fermenting yeast to the base wine, and immediately bottle it in strong Champagne-type bottles capped by a crown cork. The bottles are laid down to store. The yeast ferments the small amount of sugar in the bottles to produce a little more alcohol, but carbon dioxide is also produced, and unlike in a normal fermentation this gas cannot escape. It therefore dissolves in the wine, and pumps up the bottle pressure to 6 bar (90 lbs/sq.in.). The wine now has its sparkle!
We now need the taste. This comes from leaving the wine to mature. The yeast dies, and settles on to the side of the bottle. In time it starts to decompose in a process known as autolysis. This produces the earthy flavour which is the essential character of this type of wine. The longer the wine is left on its lees the better as the process only really starts after about 9 months. Our 1992 vintage was left on the lees for three years, which is the longest we have left a wine for yet (and longer than most other sparklers of its type). The wine now has its taste!
The wine should be kept cool, undisturbed, and in the dark. Within reason the longer the wine is kept in contact with the lees the better, but the ideal time for termination will depend on the quality of the wine itself, most aspects of which can be traced back to the quality of the grapes. The best Champagnes do not contain Pinot Meunier grapes for example because these are chosen for early maturing properties. Champagnes are usually matured for between 5 and 8 years, but they have been in the business longer than us and have had the time to build up the stocks! Also we use a different grape variety – namely Seyval Blanc, and are still acquiring knowledge on how the wine performs during maturing.
At the time chosen for the end of lees contact we have to remove the lees from the bottle, to leave a clear sparkling wine, and put in the champagne cork. For this we have to send the wine away to someone with the right (expensive) equipment for 2-3 weeks. There are four stages in the process:
The wine is ready for drinking in a few days, though it will continue to improve over a period of about 6 months.