New research from the Japanese company indicates that calcium channels on the tongue may be the targets of compounds that can enhance taste, according to results published in The Journal of Biological Chemistry.
“This is the first report indicating a distinct function of the calcium-sensing receptor in human taste perception,” write the researchers, led by Yuzuru Eto.
Kokumi concept
The findings tap into the Japanese concept of kokumi, which refers to this balance and taste complexity. Kokumi taste foods contain various compounds that have no taste themselves, but can enhance the basic sweet, salty and umami taste sensation they co-exist with. Kokumi compounds include calcium, protamine (found in milt), L-histidine (an amino acid) and glutathione (found in yeast extract).
The new research has implications for food formulation, said the researchers, by creating healthy foods that contain minimal sugar or salt but still elicit strong taste.
Writing in JBC, Eto and colleagues examined how glutathione and other molecules resembling glutathione interact with the calcium channels and relates to the receptors that sense sweet and umami (savoury) tastes.
Tasty findings
The test compounds were diluted in water flavoured with salt or sugar and asked a trained panel of taste testers to rate how strong the flavours were.
The results showed that molecules that induced the largest activity in calcium receptors also elicited the strongest flavour enhancement in the taste tests, said the researchers.
The researchers identified “a large number of calcium-sensing receptor agonist gamma-glutamyl peptides, including glutathione (gamma-Glu-Cys-Gly) and gamma-Glu-Val-Gly, and showed that these peptides elicit the kokumi taste.”
Additional study showed that calcium ions, protamine, polylysine, and l-histidine could also elicit the kokumi taste. On the other hand, a compound that antagonizes the calcium-sensing receptor was found to significantly suppress the kokumi taste.
Commenting on the implications for taste biology, the researchers noted that calcium channels are found in the gastro-intestinal tract as well, suggesting they may be important in other aspects of eating, such as food digestion and absorption.
Source: The Journal of Biological Chemistry
January 8, 2010, Volume 285, Pages 1016-1022, doi: 10.1074/jbc.M109.029165
"Involvement of the Calcium-sensing Receptor in Human Taste Perception"
Authors: T. Ohsu, Y. Amino, H. Nagasaki, T. Yamanaka, S. Takeshita, T. Hatanaka, Y. Maruyama, N. Miyamura, Y. Eto