White wine making
The majority of white wines are made from green or yellow-skinned grapes, however if the juice is separated from the skins gently and quickly, white wines can also be made from black-skinned grapes.
Upon entering the winery, the grapes are crushed and destemmed, and the skins are then separated from the juice before fermentation as the colours, flavour compounds, phenolics and tannins found in the skins are usually not wanted in white wines. The grape juice, or must, is now ready for fermentation.
The fermentation usually takes place in inert vats, such as stainless steel, but can sometimes be done in oak barrels of varying sizes. Barrel fermentation can add additional complexity to a wine's aromas and flavours, with oaky and toasty aromas being most apparent. To start the fermentation, yeast is added to the wine, along with sulphur dioxide to prevent oxidation.
When the alcoholic fermentation is complete, the wine may undergo a secondary fermentation - the malolactic fermentation - to convert the harsh malic acid into the softer lactic acid. This is not always desirable, as some wines may be better suited to the fresher, crisper natural acidity, so the winemaker will prevent the malolactic fermentation from taking place.
The wine may then undergo lees stirring. This is the stirring of the natural sediment that forms during fermentation. The purpose of lees stirring is to add additional flavour and texture complexity to the wine.
The wine will then undergo racking to remove the lees, ready to be blended, if necessary. The wine is fined (the process of removing solids from the wine using a coagulate), stabilised and bottled. Alternatively, if the wine is destined for barrel maturation, it will be racked into oak barrels, prior to bottling.
Main white wine grapes
Chardonnay is one of the most widely grown grapes varieties in the world, as it adapts well to different soils and climates. Its spiritual home is in Burgundy, where it produces some of the world's greatest wines. It is also produces great wines in Champagne, Australia, California, Oregon, Chile, Argentina, New Zealand and South Africa. In cooler climates it produces dry wines with flavours of green apple and citrus fruit with high acidity. In warmer climates it tends towards tropical fruit flavours (pineapple, banana) and medium acidity. Chardonnay is often fermented and / or aged in oak, and can age very well.
Sauvignon Blanc is a hugely popular and widely planted variety. It is typified by its crisp, high acidity and pungent aromas of gooseberry, capsicum and vegetal notes. In warmer climates it can also have aromas and flavours of ripe tropical fruit, citrus fruits and minerals. It is at its best in the Loire, particularly in Sancerre and Pouilly Fumé, Bordeaux, where it is often blended with Sémillon, and New Zealand. It also produces some fantastic wines in Chile, South Africa, California and Australia. It is normally unoaked to retain its freshness, but oaked examples are becoming more common.
Pinot Gris (Pinot Grigio) has seen its popularity soar over recent years, due mainly to inexpensive, light bodied, crisp and refreshing wines from Northern Italy. At its best, Pinot Gris produces wines with pear, citrus and tropical fruits with honeyed & spicy notes. It can also make excellent sweet wines with dried fruit, apricot and honey flavours. Pinot Gris is at its best in Alsace, North-East Italy and increasingly in cool-climate regions such as New Zealand, Tasmania and Oregon.
Pinot Blanc gives medium bodied wines with green apple, pear and citrus fruit flavours which are dry and have high acidity. It prefers cool climates and is a speciality of the Alpine regions of Alto Adige & Friuli in Northern Italy. It is also widely grown in Alsace.
Chenin Blanc produces some of the greatest sweet wines of the Loire Valley - think Bonnezeaux, Quartes de Chaume and Coteaux de Layon. But it also produces some exceptional dry wines, both in the Loire and further afield, notably South Africa where it is one of the most widely planted white grape varieties. In cool climates it produces dry wines with green apple and leafy notes with high acidity. It also produces sweet wines with tropical, dried fruit and honey flavours, and high balancing acidity. In warmer climates it tends to have flavours of citrus and stone fruits with high acidity.
Sémillon is a very flexible variety with a range of styles from light bodied and dry to full and sweet. In its dry capacity, it produces wines with citrus fruit, vegetal notes and a waxy or oily texture. As a sweet wine it tends to have tropical fruit flaxours with honey and sometimes a nutty edge. Sémillon is one of the great white varieties or Bordeaux, both in the dry wines and the famous sweet wines of Sauternes. It is often blended with Sauvignon Blanc and Muscadelle, and can be oaked or unoaked. It is equally at home in Australia, most notably in the Hunter Valley, but also in Margaret River where it is often blended with Sauvignon Blanc. There are also good examples from elsewhere in France and in South Africa.