What is Flavor?
Flavor is defined by Merriam-Webster in several ways; however, the best definition to apply to food is the blend of taste and smell sensations evoked by a substance in the mouth. It is a succinct statement, but there is a lot going on with that definition; let’s break it down. “Blend of taste and smell sensations”. This statement is discussing the anatomy of a flavor (which we will get to later). There are two major components of flavors: the taste is what occurs in the mouth, on the tongue. The smell, of course, is what happens in the nasal passage. The second part of the definition “a substance in the mouth” is a bit more difficult to explain; and is the source of the flavor industry. These substances are a variety of materials that induce some sort of response in the brain; such as, Sweet, Fruity, Cooked, etc.
Let’s leave the substances portion for later and get back to the Anatomy.
The Anatomy of Flavor
As discussed above, flavors consist of two major sensorial perceptions: Taste and Smell. We are all quite familiar with our five senses, but Taste and Smell are far more complex that most people consider. When it comes to Flavor Perception, most believe that everything happens in the mouth (much like our definition states above). However, this idea would be incorrect. Taste is the Flavor Perception that occurs in the mouth and is made up of five effects: Sweet, Sour, Salty, Bitter and Umami.
Try the following experiment for a great hands-on example of how these two senses work together to form Flavor Perception.
Take a piece of sugary candy (Jelly Beans work well as they are small and have strong flavors), hold your nose and begin eating the candy. What do you notice? You probably taste some sugar (Sweet) and maybe some sourness, but I imagine the type of flavor (i.e. watermelon, apple, grape…) is not very recognizable. Now release your nose and continue to chew and swallow. Do you get the flavor as soon as you release your nose? Why does this work? What is happening here?
Like I said, the only Flavor Perception occurring in the mouth is Taste. When you release your nose, and allow the air to flow through your nasal passage, the Smell portion of the flavor is allowed to reach the receptors so that your brain can interpret the flavor.
What are Receptors?
Receptors are small cells lining your tongue (taste buds) or your nasal passage, which are exposed to the environment and send signals to your brain for interpretation into Taste and Smell. Receptors in the mouth are activated by particular materials that the brain can relate to the 5 characteristics of taste: Sweet, Sour, Salty, Bitter and Umami. One great example is Sugar. Sugar attaches to the receptor on the taste bud which sends a signal to the brain, your brain interprets this signal and you perceive Sweetness. Taste buds have a sparing amount of receptors, not all are known, but mechanisms for Sweet and Bitter are highly publicized in the academic community.
In the nasal passage (Smell), the receptors use the same concept, but on a completely different set of materials and a completely different magnitude. There are estimated to be somewhere between 300-400 smell receptors (aroma receptors) in humans, which is why we are able to distinguish such an immense variety of different foods. Your brain interprets all the different signals sent from the receptors and relates it to a previous experience. The first time you taste/smell something, your brain associates the unique characteristics to that food; often relating back to something that is similar but different. A good example would be when you taste a new variety of apple; it is still an apple and your brain already associates it with that but the differences become synonymous with the variety.
Flavor Perception is a highly complex process involving a multitude of senses and materials, which the brain interprets and is commits to memory for future reference. This article is a brief overview of the background that gives rise to an enormous flavor industry, responsible for flavoring all types of products. In future articles, I will discuss the details of these different concepts; concepts such as, flavor materials, natural vs artificial ingredients, biological pathways of perception and more.