Why does coffee taste bitter? It comes down to its molecular profile. Specifically, bitter tastants are detected by taste receptors like TAS2R43.
Using advanced imaging techniques, a team of researchers at the University of North Carolina (UNC) School of Medicine has shown how the receptor binds to chemical compounds in your morning brew, a process that results in a bitter — sometimes acrid — flavor.
“In this work, we solved the structures of TAS2R43 bound to bitter compounds and showed, in molecular detail, how this receptor detects bitter molecules,” first author Yoojoong Kim, a post-doctoral research associate at UNC, explained in a statement.
The researchers say the findings, published in Nature Structural & Molecular Biology, could support the development of new therapeutic approaches and provide a way to reduce the bitterness of food and medicines, thereby improving flavor and making pills easier to swallow.
Read More: Brewed for Longevity: Drinking Coffee Linked To Healthy Aging in Women
Understanding Bitter Taste Receptors
Food can be broken down into five basic tastes: sweet, umami, sour, salty, and bitter. (Although, according to researchers writing in Nature Communications, there may also be a sixth: ammonium.) These basic tastes can explain our preference for carbohydrates and proteins (sweet and umami) and our aversion to chemicals and spoiled foods (sour and bitter), and can help us maintain a healthy balance of sodium (salt).
When it comes to determining whether something is bitter or not, we rely on approximately 26 known taste receptors. These can be found on the tongue as well as in other areas of the body, such as the intestines, lungs, heart, and brain — a fact that underscores their role beyond taste perception.
Previous research has shown that caffeine activates several of these bitter taste receptors, including TAS2R43, while other compounds — or tastants — in coffee, such as mozambioside, cafestol, kahweol, and bengalensol, activate TAS2R43 and TAS2R46. Kim et al.’s research focused on taste receptor type 2 member 43 (TAS2R43).
The team was able to create extremely detailed images of TAS2R43 using a technique called cryogenic electron microscopy, which enables researchers to make 3D images of biomolecules — such as DNA, RNA, cells, and viruses — by rapidly freezing them at ultra-low temperatures and mapping their structures with electrons. (The technique earned its inventors the Nobel Prize in 2017.) From this, the researchers could determine how TAS2R43 recognizes coffee tastants, such as caffeine, mozambioside, and cafestol.
A Pathway To New Therapies
Aside from affecting the flavor of your flat white, TAS2R43 and other bitter taste receptors play important roles in gut function and metabolism, and help protect the body against harmful microbes.
“Bitter taste receptors are thought to be important for detecting toxins, pathogens, and harmful bacteria in the airways, gut, skin, and organs, initiating immune responses, clearing pathogens, regulating immune cells, influencing hormone secretion, and aiding digestion,” Bryan Roth, a professor in the Department of Pharmacology at UNC, said in a statement.
As such, Kim and Roth believe the discovery could pave the way for new therapeutic strategies targeting a range of conditions and diseases.
“In the long term, this could help guide the development of new therapeutic strategies for diseases involving airway defense, gut function, inflammation, or host responses to microbes, while also improving our ability to control bitter taste in foods and medicines,” said Kim.
This article is not offering medical advice and should be used for informational purposes only.
Read More: Is Coffee Good for You or Not?
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article includes information from a study published in Nature Structural & Molecular Biology: Structural insights into coffee bitter taste perception by TAS2R43 receptor
- This article includes information from a study published in Nature Communications: The proton channel OTOP1 is a sensor for the taste of ammonium chloride
- This article includes information from The Nobel Prize: Nobel Prize in Chemistry 2017
