A research group at the Graduate School of Okayama University, in collaboration with the Tokyo Dental College Junior College, discovered that chloride ions, one of the constituents of salt, act on sweet and umami receptors to induce the sense of taste.
The taste caused by salt has a mysterious property.For example, salt water with a concentration of about 0.8 to 1%, which is close to the concentration contained in miso soup, is perceived as a delicious salty taste.About 10 years ago, a psychology research paper reported on the phenomenon that a salt solution that is about 20 to 1 times thinner feels sweeter.However, until now, it was completely unknown why this phenomenon occurred.
In 2017, the research group clarified the three-dimensional structure of the gustatory substance sensor region of taste receptors T1r2a-T1r3 possessed by medaka.In this research, it was found that there is a pocket bound with chloride ions in the immediate vicinity of the pocket bound with amino acids, which are taste substances detected by receptors in medaka fish.This chloride ion-binding pocket is located in T1r3, a common component of sweet taste receptors and umami taste receptors.
Furthermore, it was found that chloride ions induced a sweet taste nerve response via sweet taste receptors in mice and were perceived as a taste sensation.The concentration at which chloride ions act on these receptors and gustatory nerves is as low as a fraction of the concentration at which salty taste receptors sense salt (sodium ions). It was almost the same as the concentration of a thin saline solution that feels the "sweetness" of
Excessive or insufficient intake of salt affects health.The results of this research will provide new knowledge about how salt is perceived in the sense of taste, which greatly affects salt intake.
Paper information:[eLife] Chloride ions evoke taste sensations by binding to the extracellular ligand-binding domain of sweet/umami taste receptors
