Washington, Jan 23 : A team of scientists from the Monell Center and Tokyo University of Agriculture has used a new molecular way to find chemical compounds from common foods that activate bitter taste receptors in humans.
The study provides a practical means to manipulate food flavour in general and bitter taste in particular.
"Identification of bitter taste compounds and their corresponding receptors opens doors to screening for specific bitter receptor inhibitors," said senior author Liquan Huang, PhD, a molecular biologist at Monell.
"Such inhibitors can be used to suppress unpleasantness and thereby increase palatability and acceptance of health-promoting bitter foods, such as green vegetables or soy products," Huang added.
Scientists have identified 25 different human bitter receptors from human genome sequences.
But, only some of these can be activated by known chemical compounds. The remainders are 'orphan receptors,' meaning that the compounds that bind to and activate them have not been identified.
Therefore, it is not clear how these orphan receptors add to bitter taste perception.
The researchers 'deorphanized' several bitter receptors by demonstrating that peptides from fermented foods can specifically stimulate human bitter taste receptors expressed in a cell culture system.
Fermented foods, such as cheese or miso, are characterized by bitter off-tastes. These foods also contain abundant quantities of peptides, which are short chains of amino acids, the building blocks of proteins.
The findings show that the molecular identities of chemical food components responsible for the bitterness of fermented foods and demonstrate that bitter-tasting peptides are detected by human bitter receptors in an analogous manner to other bitter compounds.
"Information on how food constituents interact with receptors is needed to design and identify inhibitors and enhancers that can be targeted towards specific bitter compounds. Our findings may help make health-promoting bitter foods such as broccoli more palatable for children and adults," says Huang.
The study is published in the journal Biochemical and Biophysical Research Communications.