There are five categories for taste: salty, sour, sweet, bitter, and umami. Everyone has an innate sense of what tastes they prefer. For example, no one is born liking sour and bitter, and everyone is born liking sweet and salty and umami. Even though we are born with these preferences, we can override them. For instance, no one innately likes coffee since it is bitter; therefore people override their innate response to dislike coffee considering there are other favorable benefits that one can get from consuming coffee, such as energy from caffeine. Also, it is programmed into our genes to be very sensitive to sour and bitter and not as sensitive to sweet, salty, and umami. We are innately more sensitive to sour and bitter compounds because these represent the compounds that have a greater risk of being hazardous to our health, considering poisons can be very bitter. We are less sensitive to sweet, salty, and umami compounds because these compounds represent easily obtainable/digestible calories.
The tongue has a very complex anatomy. There are four different types of taste papillae on the tongue: fungiform, foliate, circumvallate, which all contain taste buds, and filiform.
The filiform papillae are thin pointed protrusions that are simply there to help your tongue hold onto the food in your mouth. Fungiform papillae look like mushrooms and are located on the tip and sides of the tongue. Circumvallate papillae are the biggest papillae and look like wide round bumps that have a ditch surrounding it. These papillae are located in a V shape at the very back of the tongue. Foliate papillae are not present in humans, although are present in some other animals. These papillae look like a stack of folds on the rear sides of the tongue. There is a widely known theory that certain spots on the tongue can taste certain compounds better than other spots on the tongue. For example, this theory states that the tip of the tongue can taste sweet compounds better than the rest of the tongue, although this is not true. Very recently it was discovered that this theory is a myth, and all parts of one’s tongue can taste about the same since the receptors on one’s tongue for difference compounds are uniformly distributed across the tongue. This leads into the topic of taste buds/receptors. These taste buds are embedded in the epithelial tissue of the papillae. The taste buds are connected to nerves, therefore they are able to detect the particular flavor compound at hand and send a signal to the brain telling it what you are tasting. Therefore, if something binds to a sweet taste receptor then you will perceive that as being sweet, because only sweet compounds can bind to sweet taste receptors. The trigeminal nerve also runs through the oral and nasal cavities and provides a signal to the brain for when one tastes chemical irritants, such as a chili pepper. With all these papillae, taste buds, and nerves, the human tongue is capable of tasting a variety of flavor compounds.
Although between humans there is great variation in taste perception. The population is divided into three groups when discussing the topic of taste perception: supertasters, normal tasters, and non-tasters. Supertasters make up 25% of the population and the density of their taste papillae is 165 . Supertasters are twice as sensitive to flavors in comparison to the normal taster. Women tend to be supertasters more than men. Some believe this is due to the fact that women must be able to detect bitter compounds very easily to help them avoid consuming poisons and toxins while pregnant. Having this superior tasting ability helps them be able to protect their child much better than if they were just a normal taster. Normal tasters make up 50% of the population and the density of their taste papillae is 127Non-tasters make up 25% of the population and the density of their taste papillae is 117 The non-tasters do not detect bitter foods easily, therefore they do not avoid bitter foods. Being a non-taster could lead to obesity and possibly diet related diseases, such as diabetes. Being a non-taster leaves one susceptible for becoming overweight because they also cannot taste sweet and salty compounds as good as the rest of the population, therefore they consume more sugar and salt than they should be. Non-tasters also have a benefit of consuming a wider variety of foods, due to their lack of taste receptors they can deal with bad tasting foods that are very healthy for one to consume. Being able to consume these bitter tasting foods lowers ones risk for developing cancer. Hence, there are positive and negative sides to being a non-taster.