Marvelous Tricks of the Tongue

By Julianne Glaser

All would agree that savoring a delicious meal is one of life's great pleasures. But have you ever considered how we taste the intricate flavors of food and spices? Why some foods are sweet while others burn?

The Versatile Tongue 

We can detect five basic tastes—sweet, sour, bitter, salty and umami (savory) — through taste buds located primarily on the tongue, but also on the roof of the mouth and back of the throat. Did you know that our tongues are also sensitive to temperature, pressure and chemicals triggered by certain foods that can create unusual "gustatory" experiences? Research sheds light on how certain foods can effectively trick your tongue with unexpected sensations.

The Unusual Sensations of "Non-taste" Taste Buds

Chemesthesis enables the tongue to sense temperature, pressure and chemicals through "non-taste" receptors that connect to nerve fibers in the brain. These chemoresponsive receptors are stimulated by unique compounds in certain spicy, "piquant" foods that cause a burning sensation or minty foods that cause a cooling sensation.

Sanshool, a compound found in Szechuan peppercorn, binds to chemoresponsive touch receptors on the tongue causing the mouth to gently tingle and become progressively numb. Similarly, capsaicin, a compound found in hot peppers, binds to receptors on the tongue that perceive pain as well as those that detect temperature to create the sensation of spicy heat. These same receptors are also activated by piperine found in black pepper and allyl isothiocyanate found in mustard and radishes. Ever notice how spicy food tastes spicier when you enjoy an alcoholic beverage? Ethanol actually lowers the temperature at which the capsaicin receptors are activated and increases pain perception.

Despite the burning and pain sensations, these compounds don't actually harm the tongue. In fact, those who frequently eat spicy food actually desensitize their receptors and lessen their reactions to spicy foods. The capsaicin desensitization phenomenon has led to the development of capsaicin creams that alleviate arthritic pain as chemoresponsive receptors run throughout the skin not just the mouth.

At the opposite end of the sensation spectrum is the cooling sensation from foods containing peppermint or menthol. Like sanshool and capsaicin, peppermint and menthol transmit sensation to the brain via the trigeminal nerve, allowing you to quite literally feel your food.

Taste, aroma and chemesthesis combine to create unique and distinct food flavors and sensations that may well explain why some like it hot!