Scientists discover the taste of fat, and it's not what you think

Move over sweet and sour, scientists say they've identified a distinct new taste: fat. And while fat has a reputation for making foods taste good (think bacon or french fries), researchers say in isolation it's not so appealing.

The taste of fat, which researchers call "oleogustus" (a combination of the Latin terms for oil and taste), is a distinct flavor and, as a new study in the journal Chemical Senses reports, quite unpleasant.

Identification of this new taste could provide insight into ways to fight obesity and how to develop food products to optimize health.

To see if people could identify the distinct taste of fat, volunteers sampled a variety of tastes, including non-esterified fatty acids (NEFA), free fatty acids that are the building blocks of fat, and sorted them into groups with similar tastes. All of the food samples in the study had the same texture and only a difference in flavor. The volunteers wore nose clips during the experiment so their sense of smell would not sway their perception of taste.

Participants grouped the samples into piles that they self-identified as sweet, sour, salty and bitter. The bitter pile included nebulous flavors that participants could not quite label, such as umami (often described as meaty or savory) or fat.

In a second experiment, participants sampled only from the bitter pile, were able to isolate fat as its own flavor, and it was described as bitter and unpalatable.

"They were struggling to say something that they don't have a word for," the lead author of the study, Dr. Richard Mattes, a professor of food and nutrition at Purdue University, told CBS News. "They said things like irritating, nauseating -- generic terms to say this is really unpleasant."

Mattes suggested that the taste of fat might have been so unpleasant because of the high concentrations of flavors used in the study. He likened it to the same way bitter stimulus is unpalatable, except when it is used in lower concentrations or put in the right context like in coffee or wine.

Thus high qualities of the fat taste are a warning sign that food is bad or rancid.

"Depending on the form of fat in food, you either get a message that promotes or discourages ingestion," Matte said.

Mattes believes that his work could help to improve the quality of fat modified products and how we understand taste.

"Taste, perhaps is not quite as limited a sense as we thought," he said.