Over the last 30 years people have become more sensitive to what they put into their bodies. The hazards of excessive smoking, fat consumption, and high blood pressure are now taken seriously.
Wine is one of the most natural of all beverages, but additives can be, and are included in wine The following are items that may turn up in your glass:
Acids
Cool climate vineyards rarely need to add acidity to wine. In hot climate areas the grapes often lack enough natural acidity and acid may be added to give balance. Most serious wineries add tartaric acid, the same type of acidity found naturally in wine. Less quality oriented wineries use pure citric acid, which gives the wine a lemon/lime taste.
Clarification Agents
A list of items can be poured into wine to coagulate suspended particles. These include dried ox blood, isinglass, casein (milk powder), kaolin (clay), bentonite (powdered clay), and the traditional egg whites. These fining agents are designed to make the wine brilliant and particle free. They are harmless, and top wineries in Europe and the New World either don't use them or use them minimally.
Oak
Many top quality red and white wines spend most of their lives aging in oak barrels. It is expected that wine stored that way will take on some of the vanillin flavours of the barrel. If not overdone, this adds flavour-complexity. Sometimes cheap wine are marginally enhanced by the addition of oak chips which provide a pungent raw flavour of wood.
Sugar
In most of the viticultural regions of Europe except for southern France, Portugal, and Spain, the law permits the addition of sugar to the fermenting grape juice in order to raise alcohol levels. This practice, called "chaptalization", is commonly performed in cool years where the grapes do not attain sufficient ripeness (where hot climates promote ripening, chaptalization is unnecessary). Judicious chaptalization raises the alcohol level one to two per cent.
Sulphates
All wines must now carry a label indicating whether they contain sulphites. Sulphite (also referred to as SO2 or sulfur dioxide) is a preservative used to kill bacteria and micro-organisms. It is sprayed on virtually all fresh vegetables and fruits, but a tiny percentage of the population is allergic to SO2, especially some asthmatics. The fermentation of wine produces some sulphur dioxide naturally, but it is also added by burning a sulphur stick inside the oak barrel to kill any bacteria. It is added again at bottling to prevent the wine from oxidizing. Quality wines should never smell of sulphur (a burning match smell) because serious winemakers keep the sulphur level low. Some wineries do not employ sulphites. When used properly, sulphites impart no smell or taste to the wine and, except for those who have a known allergy to them, are harmless to the general population. Used excessively, sulphites imparts the aforementioned unpleasant smell and a prickly taste sensation. Obviously people who are allergic to sulphates should not drink wine.
Tannin
Tannin occurs naturally in the skins and stems of grapes, and the content from the crushing of the grapes and subsequent maceration of the skins and juice is usually provides more than enough natural tannin. Tannin gives a red wine "grip" and "backbone", as well as acting as a preservative. However, on rare occasions tannin is added to a "spineless" wine.
Yeasts
Although many winemakers rely on the indigenous wild yeasts in the vineyard to start the fermentation, it is becoming more common to employ cultured yeasts for this procedure. There is no health hazard here, but increasing reliance on the same type of yeast for wines from all over the world leads to wines with similar bouquets and favours.
