Oleogustus is the name given to the sense of fat taste that researchers believe should be added as the sixth sense of taste alongside salt, sweet, sour, bitter and umami.

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Fat was as distinctive a taste as sweet in the study.

The findings are from researchers at Purdue University in West Lafayette, IN, and published online in Chemical Senses, a journal of chemoreception.

Richard Mattes, PhD, distinguished professor of nutrition science at Purdue and one of the study authors, says:

"The taste component of fat is often described as bitter or sour because it is unpleasant, but new evidence reveals fatty acids evoke a unique sensation satisfying another element of the criteria for what constitutes a basic taste, just like sweet, sour, salty, bitter and umami."

Prof. Mattes, who specializes in studying the mechanisms and function of taste, believes there are real-world implications for the idea of a sixth basic taste.

"By building a lexicon around fat and understanding its identity as a taste, it could help the food industry develop better-tasting products and with more research help clinicians and public health educators better understand the health implications of oral fat exposure. "

Tastes grouped together by study participants

The conclusion was reached by a study of 102 participants who placed cups of solutions of varying tastes into different groupings, and fatty tastes were given distinct separation.

Because there are no familiar words to ask people to use to describe the taste of fat, the participants were given cups of solutions containing a compound that tasted salty, sweet, umami, bitter, sour or fatty and asked to sort them into groups of similar taste qualities.

Odor, texture and appearance were all controlled. Sweet, salty and sour samples were readily separated by the panelists.

Because bitter tends to describe any unpleasant taste sensation, the fatty samples were initially grouped with bitter. But the participants then grouped the fatty acids separately from the other samples when asked to sort samples including only bitter, umami and fatty stimuli.

The study authors conclude: "These data added to the totality of evidence on 'fat taste' now provide a comprehensive body of evidence supporting the existence of another basic or primary taste quality for selected fatty acids (fat taste), whose oral activity should thus be considered when examining the health consequences of fatty acid signaling."

The researchers explain their rationale for naming the new taste "oleogustus."

"Following the precedent set for umami," write the authors, "which was derived from Japanese to mean delicious taste (umai: delicious/savory, mi: taste), we propose the term 'oleogustus.' The Latin term, 'oleo' is a root for oily or fatty and 'gustus' refers to taste.

"The term oleogustus would provide a word easily recognized as pertaining to taste by those in the field, but not easily confused with other sensations of fat perception."

Other research being undertaken by Prof. Mattes with collaborators is analyzing the genetics of fat taste at the Denver Museum of Nature & Science's Genetics of Taste Lab, using data from more than a thousand participants.