A sixth sense of taste should be added along with the list of salt, sweet, sour, bitter and umami, Purdue University researchers believe. Meet oleogustus, the name given to the sense of fat taste. Triglycerides, molecules made of three fatty acids, comprise the bulk of the fat we eat.
Richard D. Mattes, distinguished professor of nutrition science, said:
“Triglycerides often impart appealing textures to foods like creaminess. However, triglycerides are not a taste stimulus. Fatty acids that are cleaved off the triglyceride in the food or during chewing in the mouth stimulate the sensation of fat."
Mattes specializes in the study of mechanisms and function of taste. He hopes for practical applications for the idea of a sixth basic taste:
“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. 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. “
“Oleo” is the Latin root word for oily or fatty, and “gustus” refers to taste, which is why researchers proposed “oleogustus” as a way to refer to the sensation. But the taste of fat should not be confused with the feel of fat, Mattes said, which is often described as creamy or smooth. The term oleogustus could becaome an easily recognized word at least by those in the taste field.
“Fatty taste itself is not pleasant. When concentrations of fatty acids are high in a food it is typically rejected, as would be the case when a food is rancid. In this instance, the fat taste sensation is a warning to not eat the item. At the same time, low concentrations of fatty acids in food may add to their appeal just like unpleasant bitter chemicals can enhance the pleasantness of foods like chocolate, coffee and wine,” said Mattes.
102 study participants were given numerous cups of solutions, each with a compound that tastes salty, sweet, umami, bitter, sour or fatty. The participants were asked to sort the solutions into groups based on which had similar taste qualities. Odor, texture and appearance were all controlled for so they were not a factor.
Panelists segregated sweet, salty and sour samples without difficulty, confirming they understood the task. At first, the fatty samples were grouped with bitter because since is the most common word used for unpleasant taste sensations. However, when asked to sort samples including bitter, umami and fatty stimuli, panelists grouped the fatty acids together and separately from the other samples, Mattes said.
Cordelia A. Running, Bruce A. Craig and Richard D. Mattes
Oleogustus: The Unique Taste of Fat
Chem. Senses (2015) doi: 10.1093/chemse/bjv036