Art and Science seem to be colliding at this point…

I hadn’t thought to link the adaptation and habituation process to the transformation of flavour experienced during cooling.

Adaptation has to do with how we perceive aromas and tastes. Here’s a simplification about how aromas work: there are areas within your aromatic receptors that are designed to detect specific odor chemicals. Think of them as a hole of a specific shape, ready to accept a peg of the same shape. Once the peg “fits” into the hole, your body knows that particular chemical has been detected, and sends the signal to your brain. As more of that hole-shape get filled with more pegs, your brain knows there is more of that aromatic chemical in the environment, and the smell appears “stronger”. Problem is, it takes a while for these receptors to clear themselves out, and once all the “holes” are filled with “pegs”, you can no longer perceive that particular aroma. In practice, once you hypersaturate your nose with a particular aroma, you actually physically lose the ability to perceive it for a while. Dr. Acree demonstrated it for me in this way. He showed me a Sauvignon Blanc from New Zealand which had a strong green bell pepper note in the nose. After a sip, he then handed me a small piece of actual green bell pepper, which I chewed and swallowed. I then returned to the wine, which tasted DRAMATICALLY different. The green pepper note was gone, and I could taste nuances in the wine that were previously obscured by the green pepper note. Amazing. We then repeated the experiment with a Gverstraminer and a lychee. Similar result. Dr. Acree explained that this is a major factor when tasting anything over time- you gradually become “adapted” to the tastes and aromatics, and your body loses the ability to perceive some of the flavors, making other less-intense flavors seem to “appear” out of nowhere.

Habituation has a similar effect, but happens in your brain. There are all sorts of stimuli around us all the time- sounds, smells, sights, etc. Our brains learn to screen certain stimuli out, once we have registered them. This happens dramatically with smells. For example, when you walk into your house, you may smell the odor of floor cleaner. Within a few minutes, you can no longer smell the cleaner. The aroma hasn’t disappeared- it’s just that your brain is screening it out. If you walk outside, and “de-habituate” yourself, you can return and smell the cleaner again.

With both habituation and adaptation, our “instrument” (our sense of taste and smell) changes over the course of our interaction with the flavorant (in this case, coffee). In other words, our ability to perceive the coffee is changing, even as the coffee itself is changing (as has been outlined above). Our mouth and throat become coated with coffee, and the vapors rise retronasally through our nasal cavity, and continue to stimulate our taste buds and aromatic receptors. As we become habituated and adapted, previously hidden flavors seem to “emerge” over time.

In other words, as the coffee itself is changing over time, and so are we. The first time you taste a coffee, it will taste different than the second or fourth our eighth. Step away, some of the habituation and adaptation clears up, and returning to the coffee it seems radically different again. It’s really difficult to separate what is intrinsically changing about the coffee (due to changes in aromatic volatility, chlorogenic acid breakdown, etc.) and what is changing about our perception of the coffee.

Peter G

p.s. I couldn’t agree more that we need more food scientists “at the table” in the coffee industry. Dr. Acree himself is enthusiastic about coffee, and he attended the Symposium last year. That’s not enough, however, which is why we are working on getting the Global Coffee Quality Research Initiative- which could actually fund academic research on coffee quality- started. Apologies for the shameless plug, but we’re going to need a lot of support throughout the community in order to really get this thing going. We’ll get food scientists involved in quality coffee as soon as we can fund and direct their research- plain and simple.