Gustatory stimuli

Taste is perceived by the specific organs of the tongue: the taste buds. These buds only detect 4 elementary flavours: acid, bitter, sweet and salty tastes. The rest are simply tactile, chemical and thermal sensations, involving the lips, palate and cheeks (but not in detecting flavours).

The four tastes cannot be appreciated at the same time given the fact that the buds specific to each taste are located on different parts of the tongue: sweet on the tip; acid and salty in the centre, at the sides; bitter at the back. Several seconds can go by between the sensations of sweetness and bitterness.

The sweet taste is the easiest to accept; the other sensations, in a pure state, are not pleasant and are only accepted if they balance out the sweet taste.

In wine, the four elementary flavours are due to:

• Sweetness: alcohol, glycerol and sugars (residual or not).
• Acidity: free organic acids (primarily tartaric, malic, citric, acetic, lactic and succinic).
• Saltiness: salified organic acids.
• Bitterness: polyphenols (particularly tannins).

The gustatory analysis is conducted on the basis of the following parameters:

• Frankness, non-interference from outside tastes - smells.
• Body - volume.
• Harmony or balance.
• Persistence or duration of the sensation. This varies from 2 to 3 seconds for a short wine to 20 seconds for an extraordinary wine.
• Final sensation: overall quality.

The following stages comprise a gustatory analysis:

• Attack: the initial sensation perceived during the first 2 - 3 seconds. This is generally marked by a sweet taste.
• On the palate: the other flavours rapidly conceal the sweet taste, highlighting or harmonising one with another (peaks, edges or balances).
• Finish and aftertaste: aroma - taste which lasts for more or less time after swallowing or spitting out the wine.

The evaluation of these three stages comprises the frame or structure of the wine. Based on the wine's structure, it will be rated from fragile to powerful, encompassing such intermediate terms as thin, closed, delicate, light, intricate, full-bodied, robust, structured and solid. Covering this structure is the meat, the consistency.

Red wines are primarily judged on their tannin strength and quality. In other words, the tannin concentration is assessed (rated from smooth or light to rough, with intermediate terms such as condensed, structured, chewy, hard or firm), and also the tannin grain is analysed (which gives rise to expressions such as silky, velvety, thick, solid, rustic or coarse). It is therefore possible to have a weak wine, but with a rustic, unbalanced tannin content. The highest quality wines have a high tannin content with a fine, elegant grain.