I know a lot of people who will only drink white wine. There's a commonly held opinion that red wine is somehow more likely to cause that combination of ghastly feelings the next morning that we call a hangover. There may well be some truth in this; many red wines contain more alcohol than many whites and all red wines contain significantly more tannin, the chemical that preserves wine and leather. These naturally occurring tannins are not to everyone's taste - but they impart an edge to the wine that counterbalances the sweetness of the fruit and may well have allergenic effects on some.

In white wine that balancing job is done by the natural acidity. In a well-made white the sweetness, acidity and fruit will all be in an harmonious balance. Apart from the choice of grape which has a profound influence of the sort of wine a winemaker will produce, there are many other factors under his control that affect the final product. First there is the decision as to when to pick; the time of day affects the condition of the grapes, as of course does their level of maturity. Not all the bunches will have had the same exposure to the sun; some will be under-ripe, some over-ripe and some almost rotten. The winemaker has to choose whether to use them all or whether to hand sort the bunches, resulting in a much more expensive wine. Then the decision is made as to whether to include the skins in the fermentation or not. No skins results in a lighter, faster maturing wine that can be fresh and lively, but will be more prone to oxidisation. It won't last as long as wines fermented with the skins, so it can't develop into an interesting and complex wine.

Where the wine is fermented makes a difference to its final flavour. Strong, full-flavoured wines like white Burgundy are fermented in oak barrels, which imparts some oaky taste, but more commonly concrete, glass or stainless steel vats are used, which are neutral. And then there's the choice of yeast for the fermentation. It's common practice these days to kill off any naturally occurring yeasts with a dose of the wine-maker's all-purpose antiseptic - a dose of sulphur dioxide. Then the wine maker is free to choose a pure yeast strain that will give consistent results year after year. Lastly a wine may be allowed to develop a malo-lactic fermentation, which softens the sharpness of the wine.

Wine of the Week

Viognier 2001, Laurent Miquel.

If you're one of those people who is tiring of Chardonnays and Sauvignons, other grape varieties may titillate a jaded palate. Pinots and Semillons are increasingly common, and the great white grape of the Rhone, the Viognier, is gaining its fans. It's the grape that makes the wonderful Condrieu, and it produces a complex wine from a very small yield of grapes. This one is matured in oak and the fruit - almost apricot - is pronounced.

Available in selected Dunnes Stores, €10.99