The gustatory examination is performed on the palate, and involves not only the sense of taste but also the sense of touch, to confirm balance of basic flavors, as well as texture and body.

Wine tastes are simpler than smells. They are sensed on the tongue, which, through the taste buds, detects four basic flavors:

Sweetness
Acidity
Saltiness
Bitternesss

The most important for evaluating a wine are sweetness and acidity. Saltiness is barely perceptible and serves mainly to heighten sweet and acidic flavors. A hint of bitter adds interest to certain wines but pronounced bitterness is a negative factor. Each flavor is sensed most strongly by certain parts of the tongue. But in each case there is a time lag from the moment the wine enters the mouth and the point when the taste is registered. Also each flavor remains evident for a length of time that determines its persistence.

Wine Sweetness Scale

The degree of sweetness (or dryness) in Italian wines is measured on a scale of grams of sugar per liter, subdivided in four basic categories:

Secco (less than 6 grams of sugar per liter) is distinctly dry
Abboccato (6 to 20 grams) is lightly sweet or mouth filling
Amabile (20 to 45 grams) is medium sweet
Dolce (more than 45 grams) is fully sweet.

When a wine seems too sweet, it may be referred to as sticky or cloying. The term liquoroso applies to wines of varying degrees of sweetness that, in some cases, are naturally strong and, in others, are fortified with alcohol.

Wine Acidity Scale

The degree of acidity is the other key factor in wine taste. A mature wine of balanced flavor will usually have 0.5 grams per liter of total or fixed acids. A young white wine may have 0.6 to 0.7 grams or, if it's especially tart or zesty, up to 0.8 grams. A wine with more than 0.8 grams usually too acidic to be enjoyable. Over 0.9 grams is sour. A wine with less than 0.5 grams will taste flat or flabby since it lacks the brac.

Sweetness

It is detected mainly at the tip of the tongue by so-called fungiform papillae sensitive to sugars, alcohol and glycerine. The sensation of sweetness is first in the taste sequence, with a time lag of about one second and a persistence of up to 10 seconds.

Acidity

It is detected mainly along the sides of the tongue by foliate papillae sensitive to the different types of acids in wine. The six main types and their taste effects are: tartaric (hardness); malic (sour apples); citric (sharp, lemony); succinic (a salty bitterness that causes salivation); lactic (milky tartness); acetic (acrid, vinegary). The sensation of acidity is second in the taste sequence, with a time lag of about 2 seconds and a persistence of up to 12 seconds.

Saltiness

It is detected mainly at the upper front part of the tongue by foliate papillae sensitive to salts, which in wine derive from mineral or organic acids. The sensation of saltiness has a time lag of about 2 seconds while persistence is of little relevance.

Bitterness

It is detected mainly at the back of the tongue by circumvallate papillae sensitive to certain phenolic substances, tannins and esters. The bitter sensation is the last to be perceived with a time lag of about 3 seconds and a persistence of up to 15 seconds. This lingering effect accounts for the bitter aftertaste described in certain wines.

Hile the sense of taste is confined to the tongue, the entire oral cavityhas some sense of touch. The parts most sensitive to the tactile impressions of wine are the upper, center part of the tongue and the soft areas of the palate, the pharynx, the larynx and the gums. The center of the tongue contains filiform papillae that feel rather than taste. Experts often seem to chew on a mouthful of wine while analyzing the sensations of:

Texture
Astringency
Temperature
Body
Prickle, in sparkling wines