What percentage of flavor is smell?

You may have heard people say that “taste” is really something like 80% smell. At our World Tea Expo 2016 workshop I was asked whether this were a fact.

The truth is that we can’t do such a calculation. The purposes of taste and smell are quite different from each other: taste gives us the nutritional value of an ingesting, while smell allows us to know what it is we are ingesting. Together with trigeminal sensation which serves as a sort of volume dial, each makes a necessary contribution to flavor. One modality without the others simply can’t lead to the full perception of flavor.

I think that the reason why this notion of percentage comes up is that the effect of holding one’s nose when tasting something is quite astonishing. Suddenly you lose the full richness of a flavor, to have it rush back once you let go.

It is much harder to “hold” your tongue the way you can hold your nose, so we don’t have an everyday way to experience the loss of taste. Still, loss of taste buds means loss of flavor as surely as does loss of smell. As a physician I have been with many a patient who has lost his or her taste buds—whose tongue, due to chemotherapy for example, is devoid of taste papillae. Patients with this condition complain that food has no flavor and that food aromas, when sniffed, are dampened and often unpleasant.

Taste, smell, and trigeminal sensations are only three of the peripheral sensory inputs that influence flavor. Vision and hearing also contribute, and you will get more flavor from a food if you are hungry than if you are sated, so the internal state of the body is also figured in. We also consciously or unconsciously compare our memories and expectations with the information given by our senses to determine how flavorful something is. 

In other words, what we experience as flavor is the product of the brain’s analysis of all manner of inputs, and its attribution of flavor to sensations coming from the mouth. That’s why it’s impossible to parse the sources of flavor in terms of percentages.