Whether it’s red, white or in between, all wine is fermented grape juice. But white wine is made differently from any other sort.
When the grapes destined for white wine have ripened sufficiently in the vineyard, they are picked and crushed. At this point, whites destined to be fuller bodied often spend a day or two before fermentation in contact with their skins, pulp and sometimes stems. To make less assertive whites, winemakers cleanse the juice of pulp, stems, seeds and skins. With white wine, the idea is not to extract color and tannin from the skins, as it is with red wine, but to retain fruitiness and freshness.
In either case, the juice is then put into a large tank, commonly temperature-controlled stainless steel, but sometimes wood. If the winemaker does not rely on ambient yeast, yeast is added.
Fermentation
Fermentation begins and the yeast converts the sugar in the grapes into alcohol and carbon dioxide. The winemaker then encourages or prevents a process called malolactic fermentation. It changes and softens the wine’s malic acid (from malum, Latin for apple) into lactic acid (like that in milk).
After fermentation, the winemaker has several choices, depending on the kind of white wine to be made:
- leaving the wine on its lees (spent yeast cells) will give the wine a creamy texture and tastes and aromas of butter
- chilling the wine to near-freezing temperatures (called cold stabilization) will prevent it from forming harmless but cosmetically unappealing crystals or cloudiness
- aging it in wood barrels versus leaving it in (inert) steel will dramatically affect its taste and aroma, adding marked vanilla, wood or even toasty flavors
- fining (filtering) it will make the wine clearer, but it may strip it of nuances of flavor.
Aging
If the wine is aged in barrels with its lees, the winemaker may choose to stir them up from time to time, allowing the spent yeasts to add even more flavor.
When it is ready – after an aging period of anywhere from a few days to a few months – the white wine is bottled and readied for shipment. Often the bottles rest for a period of time before they leave the winery.
White – and pink – from red
Finally, one very significant difference between red and white wine production is that, unlike with red wine which can be made from red grapes only, either white or red grapes can make white wine.
Of the several hundred wine grape varieties planted the world over, a mere three or four give red juice. It is possible to produce a white wine from red or black grapes if immediately after crushing them the winemaker separates the grape skins from the juice. It is from the skins of the grapes that a red wine gets its color. White wines often are made this way in Champagne.