Taste Science

When I first started studying taste and smell, I was fascinated by individual differences in taste sensitivity and what they might mean for individual differences in personality and performance. Consequently I have a treasure trove of data about the value of these individual differences for daily life.

I have even saved at least one marriage! The husband was quite a wine connoisseur, and frustrated by the fact that his wife didn’t get it. A taste testing later, and it was clear that the wife was a mildly sensitive taster, and wasn’t biologically equipped to make the flavor distinctions he could make, distinctions that are the pride and joy of wine connoisseurs everywhere. The wife enjoyed wine, but had been put off by her husband’s frustration with her.

IMPORTANT POINT: you can ENJOY food and beverages even if you are a mildly sensitive taster!

Even with “education” there will be a limit to what you can experience and talk about. Which is perfectly OK, because the point is enjoyment - how the food makes you feel - you don’t need a mouthful of highly sensitive receptors to get a pleasurable feeling.

Our PROP studies

We initiated our studies in the classical way, using PROP (6-n-propylthiouracil) as our probe for differences in taste sensitivity. The participants in these studies were primarily Cornell students, though we also went elsewhere to collect data from healthcare workers among others.

Some people can taste PROP, and some people can't - for very sensitive tasters, the taste of PROP is very intense, a nasty bitter chemical, whether administered in water or on a piece of filter paper. By contrast, people who can't taste PROP say it tastes like water if it's in a solution, and like paper if it's on a filter paper.

How does the ability to taste PROP relate to taste sensitivity?

There are at least three, factors which determine how strong PROP will taste to you:

First, you have to have the active gene for the ability to taste PROP. People who have the active gene will taste the bitterness of PROP, whereas people who have an inactive gene will not taste anything, because their taste bud cells don't have a receptor that can bind to PROP and send the binding message to the brain. People who have one copy of the active gene and one copy of the inactive gene will be intermediate in their sensitivity to PROP. In addition, sensiivity to PROP decreases with age, according to Mennella and her collegues at the Monell Chemical Senses Center in Philadelphia, PA [Mennella JA, Pepino MY, Duke FF, Reed DR (2010) Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38. BMC Genet 11: 60. doi: 10.1186/1471-2156-11-60]

The second factor is the number of taste buds on your tongue: the more taste buds you have in your mouth, the stronger PROP tastes to you, provided you can taste PROP at all.

The third factor involves attention. The more attentive you are to any stimulus, the stronger it may seem.

We found that people with high taste sensitivity as measured by PROP experience other tastes, and usually smells, too, as being very strong. They are also able to distinguish individual flavors in a mixture very well. For people with low taste sensitivity, tastes, smells, and flavors are not as strong, and they come as a "package deal." In sum, I believe that what PROP sensitivity is measuring is primarily the number of functional taste buds, confounded by the genetics of PROP receptors.

How does the strength of mint flavor relate to general taste sensitivity?

In the past several years, we have been using the flavor of peppermints as a substitute of PROP in measuring taste sensitivity, because peppermint flavor is more pleasant, and measures more aspects of flavor. The response to peppermint involves not only taste (for the sweetness), but also smell (to identify the mint), and sensitivity to trigeminal activation (= the cool feeling of mint). Most foods present some combination of these kinds of sensations, so we believe that testing with peppermints reflects general flavor sensitivity more successfully than does PROP.
When we test with peppermint, we score the intensity of flavor and the intensity of the cooling "rush" of sensation people may get in the back of the throat and the nose. This colling rush is due to the activation of the trigeminal nerve endings in the taste buds and in the nose.

We find that people can be divided into four groups: a group for whom the mint is mild, and who don't get the rush; a group for whom the mint is very strong, and who do get a rush; and finally two groups for whom the peppermint is moderately strong: one group does get the rush, and the other doesn't.

People who find the peppermint moderately strong but who don't get the rush are similar to the mildly sensitive tasters in many of our psychological and behavioral tests, so the general outline of the differences among taster groups given below (which refers to PROP) also applies reasonably well to the peppermint results.

How many taster types are there and in what ways do they differ?

The following table shows the different taster types and some of the characteristics we have found:

And what about children?

We have found that children are more sensitive than their parents...this may explain why many children are often picky eaters! Here is a graph showing the differences between children ages 3-5 years and their parents in their mean responses to PROP. The vertical scale shows the intensity of the response - the higher the number, the more intense the response.

Since we carried out this research, Julie Menella and her colleagues at the Monell Chemical reported similar findings [Mennella JA, Pepino MY, Duke FF, Reed DR (2010) Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38. BMC Genet 11: 60. doi: 10.1186/1471-2156-11-60].

Continue on for my work on taste sensitivity and wine preferences