Caffeine is naturally bitter, but molecules formed during coffee roasting appear to mask this taste when interacting with it.
Although decaf drinkers may disagree, caffeine is an essential component of a cup of coffee. This compound is extremely bitter when isolatedbut regular coffee is not.
In a new one, published on Wednesday in Journal of Agricultural and Food Chemistry a team of scientists investigated why — and explains that the answer may lie in interactions between caffeine and other molecules coffee, calls melanoidinasproduced during the roasting process.
Previously, tasters had described caffeine as very bittereven with a medicinal flavor. Still, a cup of coffee often feels pleasant in the mouth.
As this extremely bitter taste disappears, Oliver FrankJohanna Kreissl e Michael Gigl they wanted to understand why. “Our work explains why coffee drinks do not taste like caffeine, despite the concentration of caffeine in coffee being far above the threshold of perception”, explains Gigl to .
Through a series of tests with the help of a panel of trained tasters, researchers found that caffeine has to interact with other molecules present in coffee that significantly reduce its bitterness.
In truth, the coffee masked the characteristic taste of caffeine until researchers added ten times the normal amount of caffeine present in a typical drink.
To identify the coffee molecules responsible for this effectthe team carried out taste tests with caffeine in a solution combined with additional compounds: chlorogenic acid, present in coffee beans, and/or melanoidins, which are products of Maillard reaction that occurs during roasting.
The panel of tasters concluded that when both compounds were combined with caffeine, the bitter taste was reduced by about half. Frank suspects that caffeine and melanoidins form a complex that, due to their size, prevents them from interacting with the bitter taste receptors on our tongue.
The strength of the bond between caffeine and melanoidins could vary depending on different roasting processes, although more studies are needed on this point.
“One multiplicity of bitter stimuligenerated during the roasting process, converges into the unique bitter flavor of coffee drinks”, concludes Gigl.
This knowledge can guide new investigations into these unique interactions and even contribute to better coffee productssuch as flavorings or instant coffees.
