Caffeine is undoubtedly the best-known bitter component in coffee. However, this is not the main element responsible for the bitter taste of the beverage.
A recent study led by the Leibniz-Institute for Food Systems Biology and the Technical University of Munich (TUM) gives new insights into the molecular interactions between bitter substances and bitter receptors, and the importance of the discovery goes beyond taste perception.
The team examined five different bitter coffee constituents using a cell-based testing system, a type of artificial tongue, and docking analyses. The tests included the bitter substance called mozambioside identified in Arabica beans, its roast product bengalensol, and the well-known coffee compounds kahweol, cafestol, and caffeine.
According to the study results, the research team believes that mainly two of the 25 human bitter taste receptors react to the coffee’s constituents. Whereas a relatively high caffeine concentration is required to stimulate the receptors TAS2R46 and TAS2R43, considerably smaller amounts of the other four substances are needed.
Lead author Tatjana Lang from the Leibniz-Institute for Food Systems Biology stated that the caffeine concentration required to activate the bitter taste receptor TAS2R43 to the same degree as bengalensol or mozambioside was about 30 and 300 times higher, respectively.
Further findings conducted by the researchers imply that the bitter substances contained in coffee interact with each other. These results showed that kahweol and mozambioside exhibit similar binding properties for the bitter taste receptor TAS2R43. The team assumed that kahweol could reduce the bitter taste obtained by TAS2R43 by suppressing more effective bitter substances at the receptor.
Maik Behrens, head of the research group Taste Systems Reception & Biosignals at the Leibniz-Institute, stated that they found out that both types of receptors are present not only in taste cells. The receptor TAS2R43 is also present in the stomach, and conjunction with caffeine plays a part in the control of gastric acid secretion.
According to Veronika Somoza, director of the Leibniz-Institute for Systems Biology, many people do not possess the bitter taste receptor TAS2R43 due to a genetic variation. This phenomenon could explain the differences in individual coffee taste perception or its tolerability.
