Sparkling wine
All sparkling wines start life as still wines and have the sparkle added later. The crucial factor in the quality of every sparkling wine is how the fizz is added.

The fermentation process naturally produces carbon dioxide gas (CO2) - the waste product of the yeasts devouring the sugars. In still wine making this gas is allowed to escape. In sparkling wines, the CO2 is retained, dissolving within the wine the wine which is kept under pressure. When it is released, the CO2 bubbles to the surface. The method for producing a wine filled with CO2 varies from the very time-consuming and expensive Champagne method of natural, secondary fermentation in individual bottles, to the inexpensive and easy method of squirting industrial CO2 into cheap, still wine.

The Champagne method The Champenois are justifiably proud of their wines and the age old methods used in their creation. Legend has it that the method was invented by a monk and winemaker named Dom Pérignon. Champagne itself can come only from a very well defined area in the north east of France, but many quality wines are made using the “Méthode Champenoise” (this term is no longer allowed on labels, so the term “traditional method” is often used instead). First of all, a high quality, dry white wine is made (usually from a blend of chardonnay, pinot noir and pinot meunier grapes) with “ordinary” tank fermentation. Once the wine is complete it is placed into special, heavyweight bottles and a fresh dose of yeast and sugar is added. The bottles are then capped and placed in the cool cellars of the winery for up to 2 years. During this time, a secondary fermentation takes place. The yeasts and sugars create CO2 that, because it is in a sealed container, cannot escape so dissolves into the liquid. In the early days Champagne production was a dangerous business - cellars were destroyed by exploding wines. Controlled production methods and stronger bottles have eliminated that risk. The problem with this technique is the deposit of dead yeast cells that collects in the bottle. In still wines these would simply be filtered

out, but since that would also remove the bubbles, another method had to be found. This process is known as Remuage: an action whereby each bottle is shaken lightly, revolved and its position adjusted, so that over the course of a few weeks the bottle ends up upside-down with the dead yeast cells captured in the neck of the bottle.

The Remueur can precisely adjust 40,000 bottles per day. At this stage the inverted bottles are carefully transported to a freezing tank. The necks are dipped in, just to the level of the gathered sediment, which freezes into a solid “plug” of dead yeast cells. The caps are removed and the gas pressure shoots the plug out. Depending on the style of wine being made (dry, medium or sweet) the bottles are topped up with a “dosage” of reserved wine and sugar.

The bottles are corked, wired and at that stage, the Champagne is complete. Though this process is long, expensive and labour intensive, no other method produces wines with such fine and persistent bubbles and such a creamy complexity on the tongue.

The Tank method
This is a different process by which good quality bubblies can be made. Here the secondary fermentation still takes place naturally, by adding new yeast and sugar to a finished wine, but instead of taking place in bottles, the wine is held under pressure in large sealed tanks so that the equivalent of several thousand bottles re-ferment at the same time. The wine is cleared of sediment and bottled under pressure, directly from the tank. The bubbles are a little larger and disperse more quickly, but the tank method can produce good results.
The transfer method
This is a less common system for creating a sparkling wine. Here, secondary fermentation takes place in individual bottles - like Champagne - but instead of the expensive remuage process, the wine is cleared by filtration and is then pumped, under pressure, into clean bottles.

Sweet (or dessert) wines Like sparkling wines, there are a variety of methods for making sweet wines. These vary from cheap and easy, to some of the most labour intensive and expensive processes in the wine making world. We are talking here about fully sweet wines, often drunk with desserts, though the French like to partner the finest foie-gras with a luscious Sauternes - perhaps the king of sweet wines. Like so many aspects of wine making, the discovery that grapes left on the vine until they rot can produce beautiful wines, was probably yet another accident. Botrytis is a fungus which may attacks grapes, usuallyin

the cool of late autumn. It occurs in the early morning mists which form in vineyards sited near large bodies of water. The fungus wraps itself around the grapes and spores puncture the skin, drawing off water and leaving the grape shrivelled.

If left unchecked, botrytis will kill grapes and can be a big problem to vine growers. In some unique locations (Sauternes in France, parts of Germany and Austria for example) the vineyards are sited such that they also get maximum exposure to the sun.

In good years, the warmth of the sun as it rises kills off the fungus, leaving the grapes shrivelled and unsightly, but tasting delicious: full of the sugar and glycerine which was left behind.

Vineyards for botrytis wines are harvested by hand, so that only those individual grapes affected by the “noble rot” are selected. Often the same area will be picked over several times so that grapes can be picked in ideal condition. The wine is then made using the normal method for white wines, but the high sugar and glycerine content means that the wine is sweet, luscious and full-bodied. Because grapes high in natural acidity are used (sémillon, sauvignon blanc, riesling, gewürztraminer) the wine is not at all cloying. Though sweet, the best wines are balanced and full of subtle flavours that linger on the palate.

Botrytis wines are always expensive and often bought by the half bottle. With the unpredictability of the harvest and the labour intensive methods used, it is perhaps easy to see where the money goes.

Other sweet wines and methods of production
Some other sweet wines are produced from grapes that are over-ripened, but not rotted. This can be done by simply leaving the grapes on the vine for longer than usual, or harvesting the grapes as normal but leaving them spread out to dry on mats so that they shrivel in the sun and air. One interesting, rare and expensive form of sweet wine is the ice-wine (in German, Eiswein) of Germany, Austria and Canada. Here the grapes are left on the vine into the dead of winter - often into the new year. On a suitably freezing cold night the grapes are harvested. Most of the water content of the grapes has turned to ice and this is expelled from the grapes leaving only the sugars and acids behind in the pulp. A wine is made from this which is very luscious and sweet.

Another group of sweet wines are sweet because fermentation is stopped at a fairly low alcohol level.