For generations, scientists thought the human tongue could detect only four basic tastes: sweet, sour, salt and bitter.

Then a fifth was discovered, "umami" or savory. Now, researchers have identified a previously-unrecognized "sixth taste" – fat.

Fat should be considered the sixth taste and can be called oleogustus, according to a study from Purdue University.

Special tasters were brought in to sample food created for the experiments at Purdue University and more than half of the 28 tasters could distinguish fatty acids from the other tastes, according to a study published in the journal Chemical Senses.

Past research showed fat had a distinct feel in the mouth, but scientists removed texture and smell clues and people could still tell the difference.

Study author Richard Mattes, a Purdue nutrition science professor said that the taste of fat should not be confused with the feel of fat, which is often described as creamy or smooth.

“The fatty acid part of taste is very unpleasant,” Mattes said. “I haven’t met anybody who likes it alone. You usually get a gag reflex.”

But generally, some people's inability to perceive fat taste is why some say there's not enough evidence to say fat is a true taste.

When it comes to fat, scientists know what the stimuli are: fatty acids — the building blocks of oil, butter and lard. And scientists also know that we have taste receptors for these fatty acids in our mouths and intestines.

A team in the United States has located a chemical receptor in the taste buds on the tongue that recognizes fat molecules, and found that its sensitivity varies between individuals.

The finding may help to explain why some people consume more fatty foods, as they are less aware of the taste as they eat.

The researchers hope their discovery can be exploited to combat obesity by increasing people's sensitivity to fat in their food.