I ran across a short article over at Scientific American, and while it didn’t contain too much information that isn’t already known, it did describe some new research that says that the genetic diversity in how we perceive aromas may be larger than we previously thought (which seemed large already).
Here it is, and it shows just how difficult the job is for someone studying the human senses. How do you know that a particular panelist is responding to an odor the same way another is? Well, you don’t really.
Some practical examples of this have been seen in the threshold tests I’ve performed with the panel regarding diacetyl. Some panelist’s thresholds are down below 30ppb, while others are well over 100ppb, and there are even 1 or 2 who may be totally anosmic to it (meaning they have no ability to detect it at any concentration). Training a panel to be good diacetyl tasters can be tricky since finding a concentration of diacetyl for a flavor standard that is appropriate for the whole panel is pretty much impossible.
Another example comes from the flavor standard “indole”, which has been known to elicit a floral jasmine-like aroma for a certain portion of the population, while the rest of the population smells fecal material. That part is interesting enough, but what’s even more so is that, for me, I can smell it both ways. Like an optical illusion, I can “flip” my brain’s interpretation of this aroma back and forth at will. It’s really an interesting experience to be smelling a nice flowery flavor standard one second, then in the next second your nose is full of poop.
PS: Indole arises in fermentations which have become contaminated by coliform bacteria (those usually associated with sewage and waste-water), and tends to be most common when adjunct sugars are used which are themselves contaminated.