NPR
The Salt

Scientists Discover A 6th Taste — And It's Quite A Disgusting Mouthful

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Olive oil gets filtered in an oil mill in a Portuguese oil farm near Evora. Rick Mattes says that if an olive oil's concentration of fatty acid rises above 3.3 percent, it's no longer considered edible. And it'll be brimming with oleogustus.
Francisco Seco, AP
Olive oil gets filtered in an oil mill in a Portuguese oil farm near Evora. Rick Mattes says that if an olive oil's concentration of fatty acid rises above 3.3 percent, it's no longer considered edible. And it'll be brimming with oleogustus.

Your attention please, everyone. Scientists have discovered a new taste — and its name is, well, a mouthful.

To the ranks of sweet, salty, sour, bitter and umami, researchers have added a sixth: "oleogustus." Announced in the journal Chemical Senses last month, oleogustus is Latin for "a taste for fat."

"It is a sensation one would get from eating oxidized oil," says Rick Mattes, a professor of nutrition science at Purdue University. He was on the team that made the discovery.

Now, when people think of the taste of fat, they're often thinking of a triglyceride, Mattes says.

"That's the overwhelming source of fat in the diet and, in fact, in our bodies as well. But that really provides a mouthfeel. That gives the richness, the creaminess, viscosity and so on," he explains. "But that is not the taste part. The taste part is when we cleave off part of that triglyceride, the fatty acid part."

And once it's been cleaved off, the taste that remains is not exactly pleasant. Found in high concentrations in rancid foods, oleogustus actually operates as a protective mechanism of sorts — offering a warning sign to stop eating whatever it is one is tasting. In this respect, it's a bit like bitterness.

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But Mattes is careful to offer a caveat.

"At very low concentrations, it may — we don't know this yet — but it may have exactly the opposite effect, the same way bitter stimuli, if you put it just in a glass of water, almost everybody would say it's unpleasant. But in the right context, bitterness adds to the overall appeal of chocolate, of coffee, of wine, many of the foods that we enjoy."

For the most part, though, oleogustus remains something of a paradox: fatty, but still not delicious. It may be tough to wrap your mind around, but most in the food industry already have, Mattes says.

"The food industry goes to great lengths to keep concentrations of these fatty acids below detection, because they are unpleasant," he says.

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