Many people start their day surrounded by the delicious scent of freshly brewed coffee. But after one sip, the disappointing reality sets in: coffee never tastes as good as it smells.
Professor Barry Smith, Director of the Institute of Philosophy of the University of London is currently exploring the perception of flavor. Last week, he was one of the lecturers at the British Festival of Science 2012 in Aberdeen and provided the audience with an answer for this puzzling question.
Prior to the festival he spoke with one of the bloggers of the festival, Julie Gould, about his interest in the research area of flavor perception. “It is a fascinating and complex area where we are learning more about our experience of tasting from sensory science…” he said. “What we call taste is in fact the result of inputs from touch, taste and smell that combine into a single unified experience that we either like or dislike. The effects of one sense on another go unnoticed in our experience and yet finding out about these interactions is telling us more and more about how our senses combine information.”
We often describe the texture of food when we describe its taste. Something may taste creamy, fresh or crunchy, “yet these descriptions are due to texture not taste,” Smith explains. The sensors on our tongue does provide information of taste, but it’s limited: “… the tongue can only give you salt, sweet, sour, bitter, savory and metallic; and yet you can easily recognize the flavor of strawberries, melon, mint, chicken…” Why?
What we think of as taste is largely the result of what we smell. Just hold your nose while eating and you will notice its major contribution to the experience of flavor. There seems to be something special about our sense of smell: it is the only dual sensory modality. Let’s get back to the “coffee paradox” to explain this mechanism.
Why does coffee never tastes as good as it smells? Speaking at the British Science Festival in Aberdeen Smith explains that we have two senses of smell. “One sense is when you inhale things from the environment into you, and the other is when the air comes out of you up the nasal passage and is breathed out through the nose,” told Smith, as quoted by the Telegraph. Thus the receptors in the nose can move into two different ways, which may cause different sensations.
Coffee is a perfect example of a mismatch between the two senses. When sniffing up the aroma of freshly brewed coffee, our smell receptors send out a different message to the brain than when exhaling while swallowing the coffee. This latter sense of smell is less receptive to the flavor of coffee. Therefore, we experience the smell of coffee as far more delicious than its taste.
Rozin, P. (1982). “Taste-smell confusions” and the duality of the olfactory sense. Attention, Perception, & Psychophysics, 31 (4) DOI: 10.3758/BF03202667
Smith B (2012). Perspective: complexities of flavour. Nature, 486 (7403) PMID: 22717402