SciTech

How Things Work: Taste

Credit: Juan Fernandez/Staff Credit: Juan Fernandez/Staff

Taste is an integral part of people’s daily lives. With so many different reasons to eat or not to eat a certain food, taste vastly simplifies the decision of what to eat, and whether to keep eating. Yet scientists know less about taste than they do about hearing and sight. What makes it so complicated? How exactly does taste work?

The sensation one interprets as taste is not the product of the tongue alone — a person’s tongue, nose, ears, and eyes are all part of the sensory overload that people experience when they bite into a piece of food. According to WiseGeek.com, “What we perceive as taste is a complex interplay of smelling and tongue-tasting. The nose, tongue, eyes, and brain all evolved together to ensure that we consume the good stuff and keep out the bad stuff: rotten foods, poison foods, and other indigestibles.”

The tongue is the main organ of the somatosensory system — the system that controls the actual taste of food. In the tongue, there are specialized groups of cells known as taste buds. Almost 100,000 taste buds are located in the back and front of the tongue, while others are located in the sides and roof of the mouth. The tongue is special in that it can only perceive five tastes: sweet, sour, bitter, salty, and umami (meaty).

Evolutionarily, there is a reason people experience these particular tastes. Generally, basic tastes can be classified into two categories: good (appetizing) and bad (unappetizing). Donuts and chocolate, for example, taste good because they are sugar-rich and therefore sweet. Sweet foods, in terms of evolution, were seen as good items for humans to eat, especially in the hunter-gatherer days when fruits were a major part of human consumption. At the same time, bitter things were generally predictors for certain poisons, and the bitter taste served as a warning to not consume the food.

But the senses are obviously not limited to sweet, sour, salty, bitter, or umami. In fact, the most savory taste that people associate with food is directly related to its smell. For example, popcorn has a very distinct taste. When asked to describe it, an average person might say buttery or salty. Some might even describe it as crunchy, referring to the crunchiness of popped kernels. However, the only real taste that people pick up is saltiness. The buttery odor is associated with taste even though it is actually how the popcorn smells. Similarly, the associated texture — crunchiness — is based on mechanics and muscle nerves within our tongues.

According to the American Academy of Otolaryngology website, “Our body’s ability to sense chemicals is another chemosensory mechanism that contributes to our senses of smell and taste.” An example is the feeling of hotness or coolness that is associated with certain foods. People might say that a food is spicy, but in reality, it just generates a lot of heat within their mouth.

These hot and cold sensations people perceive are not tastes, but are detected by thermoreceptors within their mouths through chemesthesis. Chemesthesis is the ability of special receptors in people’s mouths to detect certain chemicals. If one were to place a chili pepper or a menthol strip in his or her mouth, heat would be generated or absorbed, and would activate the thermoreceptors. The brain then perceives the hot or cold sensation as a taste.

Moreover, eyes play a major role in deciding the taste humans perceive when eating a certain food. A 2008 article in the Chemosensory Perception journal suggested that food color may play a role in determining the taste humans associate with it. For example, if a person is given a flavored yet gray-colored popsicle, that person may claim that the popsicle tastes particularly bland.

Taste is not merely a way to see if one enjoys a certain food or not; it has an evolutionary reason behind its existence. Combined with information from other senses and other receptors, the sensations people attribute to taste provide a rich, delightful way to continue eating delicious food.