The gustatory papillae are stimulated by the wine's molecules.
When we swallow the wine, its vapours go back to the throat towards the nasal cavity.
The olfactory bulb transmits the stimulus to the brain under the form of nervous signals.
In the cortex, the nervous signals are interpreted by the hippocampus. The hippocampus stores all our memories and, by association to other flavours, decodes the flavour we are tasting.

The tasting of the wine ends only when we feel it through our taste. In the mouth we feel not only the wine’s flavour, but also tactile and thermal sensations. Tactile sensations derive from the wine’s acidity, flow, roughness and sugar content. Thermal sensations are divided into cold, pseudo-cold (effervescence), heat and pseudo-heat (alcohol).

In tasting, these sensations are not assessed in isolation because the balance between them is what makes the wine pleasant. Balance is also evaluated assessing the acidity, alcohol content and quality of the tannins.

Some areas in the mouth are more sensitive to certain flavours. On the tip of the tongue we taste sweet things. Salty things are tasted on the front and sides of the tongue. On the back and sides of the tongue we feel what’s acid. At the very back of the tongue, we feel what’s bitter. It is important to let the wine flow through all the areas of the mouth and let it stay there for some seconds to assess its intensity. The ideal is to slightly open the mouth and inhale some air, which will be exhaled by the nose. But you should also pay attention to the flavour that stays in the mouth after swallowing the wine, known as aftertaste. Good wines have a long finish (aftertaste).  

Faults in wine

Oxidised: excessive contact with air (during fermentation, in wood or bottle) has made the wine loose its aromas and flavour.

because of the acetic acid in the fermentation tank or wooden barrel, the wine gets a sour smell.

sulphur dioxide is used to protect wine from oxygen; however, if too much is used it will impart a spicy flavour and a smell of burnt matches.

sometimes the cork is attacked by moulds and alters the wine’s taste, making it smell like must and dust.