By taste

Wines may be also classified by their primary impression on the drinker’s palate. They are made up of chemical compounds which are similar to those in fruits, vegetables, and spices. Different grape varieties are associated with the aromas and tastes of different compounds. Wines may be described as ’dry’ (meaning they are without obvious sugar), off-dry, fruity, or sweet, for example. The sugar content of grapes can be measured in brix, at harvest, and this determines the combined level of alcohol and residual sugar (in the absence of chaptalisation). Sweetness is in actuality 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 tiny amount of residual sugar.

Specific flavors may also be sensed, at least by an experienced taster, due to the highly complex mix of organic molecules, such as esters, that a fully vinted wine contains. Experienced tasters will also distinguish between flavors characteristic of a specific grape (e.g., Cabernet Sauvignon and black currant) and flavors that are imparted by other factors in winemaking, either intentional or not. The most typical intentional flavor elements in wine are those that are imparted by aging in oak casks, and virtually every element of chocolate, vanilla, or coffee are actually a factor of oak and not the native grape. Banana flavors are almost always imparted by use of a specific yeast, and are not characteristic of any grape. Many people are very sensitive to animal scents in wine, and with possible exception of mourvedre almost all of these flavors, whether viewed positively or not, are the result of natural yeasts producing these scents.

Generally an experienced taster will distinguish between the aromas that the natural grape produces--called primary qualities--and the bouquet that is imparted by secondary effects such as winemaking practices or aging.