Everyone thinks they know what flavor is, but do they really?
We experience flavor every single time we eat. However, have you ever considered what those flavorful sensations actually mean?
Flavor is quite important to our survival — it keeps us eating healthy food and steers us away from things that may make us sick. For example, ripe fruits taste sweet, while old and rotten foods taste bitter, and we are attracted to salty foods because we need sodium in our diet, but we don’t overly like sour as a taste, which includes unripe fruit and spoiled protein.
Your mouth recognizes five tastes — sweet, salty, sour, bitter, and savory (or umami) — but flavor is actually a mixture of both taste and smell. Remove one or the other, and flavor is diminished. Since flavor is technically a chemical reaction, taste and smell receptors in our nose and mouth are stimulated by the chemicals in the foods we eat.
Taste receptors are found all over the mouth and they pick up all of the five tastes, but taste buds are are located just on the top surface of the tongue, the back roof of your mouth, and on the epiglottis (the flap in the back of your throat that keeps swallowed food from entering your windpipe).
Taste buds sit on papillae, which are small projections that cover the tongue. They are cup-shaped and packed within them are gustatory cells — the ones that pick up taste — and have hair-like filaments (cilia) extending from the center.
Food first makes contact with the taste buds, the cilium picks up the taste molecules and transfers them to the gustatory cells, which pass the information to nerve fibers that travel to the brain where taste is perceived.
Our noses are much more sensitive than our tongues — there are nearly 40 million olfactory (smell) neurons in our nose that pick up odors from the air. Smell makes up 80 percent of flavor and in fact, without smelling, it’s really quite difficult to tell the difference between fruits with similar textures such as an apple and a pear.
Roughly 4.5 million North Americans have hyposmia (reduced ability to smell) or anosmia (the inability to smell), and nearly everyone has experienced temporary anosmia when congested with a cold.
Olfactory cells are found high up in the nose. They are completely covered in cilia, and the cilia are covered with olfactory receptors. The olfactory epithelium (the odor-receiving tissue in the nose) is only about one inch wide by two inches long, and millions of receptor cells are packed in this tiny region.
SEE ALSO: Is the Sense of Taste All in Your Head?
When we smell something, nerve fibers from olfactory receptor cells meet up at the olfactory bulb — a structure in the front of the brain that processes smell. Since the pathway between the nose and brain is so short, it explains why we can smell something almost instantly.
The olfactory bulb is also very close to the hippocampus — a part of the brain responsible for memory — which is why certain smells can bring back vivid memories from years and years ago. Women tend to have better olfactory senses than men and they are often more sensitive during ovulation and pregnancy!
Everything that tastes distinctive about food, isn’t taste at all, it’s aroma.
As you now know, the perception of flavor is exceptionally complex, and even though we tend to think of the aroma of a particular food as just one thing, it is actually a combination of several flavor compounds. In fact, there are thousands of flavor chemicals! The classes of flavor compounds are: Acids, Alcohols, Aldehydes, Esters, Ketones, Lactones, Phenols, Pyrazines, Terpenes and Sulfur Compounds. In other words, a lot!
However, to simplify things, sensory scientists have developed what is known as the flavor wheel — a way to create a flavor profile. However, the characteristics that make up the flavor wheel change based on the food being tasted.
Here is an example of a flavor wheel for coffee:
Photo credit: Andy Ciordia/Flickr (CC BY-NC 2.0)
Source: Joachim, David, Andrew Schloss and A. Philip Handel. (2008). The Science of Good Food. Toronto, Ontario: Robert Rose Inc.