Judging color is the first step in tasting a wine

Wine tasting is the sensory examination and evaluation of wine. Wines are made up of chemical compounds which are similar or identical to those in fruits, vegetables, and spices. The sweetness of wine is determined by the amount of residual sugar in the wine after fermentation, relative to the acidity present in the wine. Dry wine, for example, has only a small amount of residual sugar. Inexperienced wine drinkers often tend to mistake the taste of ripe fruit for sweetness when, in fact, the wine in question is very dry.

Individual flavors may also be detected, due to the complex mix of organic molecules such as esters and terpenes that grape juice and wine can contain. Tasters often can distinguish between flavors characteristic of a specific grape (e.g., Chianti and sour cherry) and flavors that result from other factors in wine making, either intentional or not. The most typical intentional flavor elements in wine are those that are imparted by aging in oak casks; chocolate, vanilla, or coffee almost always come from the oak and not the grape itself.

Banana flavors (isoamyl acetate) are the product of yeast metabolism, as are spoilage aromas such as sweaty, barnyard, band-aid (4-ethylphenol and 4-ethylguaiacol), and rotten egg (hydrogen sulfide). Some varietals can also have a mineral flavor, because some salts are soluble in water (like limestone), and are absorbed by the wine.

Wine aroma comes from volatile compounds in the wine that are released into the air. Vaporization of these compounds can be sped up by twirling the wine glass or serving the wine at room temperature. For red wines that are already highly aromatic, like Chinon and Beaujolais, many people prefer them chilled.