Basic taste

From ArticleWorld

Basic taste is one of the body’s senses. Humans and other animals have the ability to taste by means of taste buds located on the upper surface of the tongue. The “apparent taste” of something is a combination of what is sensed in the mouth and what is smelled via the olfactory bulb in the nose.

Types

As of now, there are five different tastes recognized by the Western world. These are bitter, sour, sweet and “umami”, or the taste known as “savory”. Umami is a taste sensation that has been recognized by the Asian world for a long time. Soy sauce, fish sauce and mushrooms have the umami flavor. Some scientists are investigating the possibility that a sixth receptor on the tongue carries the taste of fat. Others recognize “pungent” and “spicy” as possible taste sensations. There is no actual map on the tongue where certain tastes are sensed. Instead, all tastes are recognized throughout the tongue.

Physiology

The sensation of salt occurs by ions channels in the cells of the tongue that respond to the presence of sodium and sometimes to potassium and other salt ions. Sour tasting depends on ion channels that detect hydronium ions (H3O+) which come from acids in the food. Sweetness is detected by “sweetness receptors” or G receptors on the taste buds. There are several types of G receptors for sweetness that, when activated differently, are able to discern differences in sweetness.

Bitterness is detected by G receptors similar to those involved in the sensation of sweetness. There is a genetic variation among people that allow some people to detect bitterness in a substance while others do not sense the bitterness as much. A particular synthetic substance called phenylthiocarbamide (PTC) can be extremely bitter to some and tasteless to others, depending on their genetic makeup.

Umami or savoriness is produced by fermented or aged substances. It is detected by the presence of glutamates in food. One food additive known to add the umami flavor is monosodium glutamate (MSG), which is often found in Asian cooking. Glutamates are detected by specific G receptors on the tongue.

The tongue and mouth can also sense temperature through the somatosensory system and pungency, a type of warm sensation from alcohol or capsaicin. Capsaicin is what makes hot peppers such as Cayenne pepper so hot. This sensation is derived from nerve cells with ion channels that are the same channels that detect heat.