The Chemical Senses
In class today Doctor Herz referred to taste and smell as the "chemical senses," because they are used to detect and perceive the actual molecules of a substance in a way that the brain can understand -- the chemical senses literally sense chemicals. However, detecting a substance first requires that it be internalized (whether in the mouth or nose), which contributes to the perception of these senses as "lower." Personally, though, I think its really cool that our bodies come equipped with their own molecular scanners. That is, after all, what these chemical senses are doing when they analyze the molecular composition of a substance.
Taste and smell are designed so that they detect different types of substances and provide information about them -- smell detects small hydrophobic and lipophilic molecules in the air while taste detects the hydrophilic molecules dissolve in our saliva. This difference in what the two senses detect helps explain those things that smell so good to us, yet taste awful. Like incense. Have you ever tried to eat incense? I don't suggest it -- the molecules that you can taste taste like dirt. What I find fascinating, however, is not when these two molecular scanners send different messages about the same substance, but when they work together to create an entirely different experience -- flavor, the perception of smell and taste together. Taste consists of five flavors, but the number of substances and combinations of substances that we can smell is innumerable, which means that while flavor starts with the five tastes, odor can create an infinite variety of flavor. The real spice of life, then, is odor.
Reading a little bit about coffee tasting, I found that one common practice is to take a sip of a coffee, identify immediate flavor impressions, then take a sip of water. This clears the palette of taste but those sticky smell molecules remain and the more subtle aromatics can be assessed separately of taste. These tasters dismiss the basic bitter taste as superfluous and prioritize the odors that make each brew unique. In my own life, I know I'll be paying more attention to the aromatic dimension of flavor; I just hope I don't get too many strange looks in the dining hall as I hold my nose while I eat to separate the tastes from the odors. Now that I know how my two molecular scanners are working together, I'm curious to explore how they produce the flavors I love.
Fascinating connections you make! I like the analogy you drew to how coffee tasters filter out bitterness to pay attention to the nuances that really count, just as we generally do with the "smell" of oxygen and nitrogen, etc.
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