Wine basics
With most food and drink items, the label shows all the contents. Not so with wine. While 85 per cent to 90 per cent of wine is water, there are actually more than 1,000 identified components in a bottle. Here are the most important ones that give a wine its character and personality.
Fruit flavours will depend on the variety of the grape and the winemaking methods. For example, a sauvignon blanc will tend to have flavours such as gooseberry or green pepper. You may also pick up green pepper and leafy notes in cabernet sauvignon, flavours attributable to a chemical compound called methoxypyrazine.
Alcohol is a by-product of fermentation. The alcohol level of wines can vary from 7 per cent up to 15.5 per cent. These levels are partly determined by the sugar level in the grapes at the time of harvest. Lower alcohol white wines, including riesling from Germany's Mosel Valley, can range from 7.5 to 9 per cent, but chardonnay, or viognier, can have 14 or 15 per cent. Red grapes tend to be picked later than white grapes, resulting in higher sugar levels and more alcohol.
Acid is an important component of wine structure, and whites that have more generally taste more refreshing and vibrant. Piemonte red wines made from the nebbiolo grape are also highly acidic. Grenache and syrah/shiraz are reds at the lower end of the acidity scale.
Sugar balances high acid, and grapes naturally have high levels of it. Most sugar is converted into alcohol by fermentation. Dry red wines may have tiny amounts, as little as three grams per litre. On the other end of the scale are German dessert wines labelled trockenbeerenauslese (TBA), which can have more than 300 grams/litre.
Tannin is an important component derived from the grape skins, pips and stems as well as ageing in oak barrels. Tannins are important in providing structure to reds, adding to the life of the wine. While some reds are naturally high in tannin, such as cabernet sauvignon, others have less. Whites have lower tannin levels, as the juice is separated from the skin before fermentation.
