Not a fan of coffee? Science may be able to explain why. Researchers have uncovered how genetics may play a role in determining how bitter coffee tastes.
The research team at the Leibniz Institute for Food Systems Biology at the Technical University of Munich identified a new group of bitter compounds in roasted Arabica coffee and investigated how they influence its bitter taste.
Although caffeine is known to have a bitter taste, decaffeinated coffee is also bitter therefore showing that other substances contribute to coffee’s bitter flavour profile.
The research team explored mozambioside contained in Arabica beans, another compound class linked to bitterness. It tastes about 10 times more bitter than caffeine and activates two of the approximately 25 bitter taste receptor types found in the human body, including the TAS2R43 and TAS2R46 receptors.
“However, our investigations showed that the concentration of mozambioside decreases significantly during roasting, so that it only makes a small contribution to the bitterness of coffee,” says Principal Investigator Roman Lang.
”This prompted us to test whether roasting produces breakdown products of mozambioside are also bitter and could affect coffee’s taste.”
The research team found that seven different byproducts of mozambioside are formed during roasting and are all found in coffee in varying concentrations.
Notably, these byproducts were found to activate the same bitter taste receptor types as mozambioside, with three of them having an even stronger effect on the receptors than the original compound.
However, the researchers found that the concentrations of these roasting products measured in brewed coffee were too low to induce a noticeable taste on their own and were only detected in combination with mozambioside.
Eight out of 11 test subjects perceived the combination of mozambioside and its byproducts to have a bitter taste. One person found the taste astringent and two did not perceive any particular taste.
Interestingly, a genetic test showed that taste sensitivity depended on the genetic predisposition of the test subjects: two people had both copies of the TAS2R43 gene variant defective. Seven had one intact and one defective variant of the receptor and only two people had both copies of the gene intact.
The researchers say that these results may help to influence the roasting process and open up new possibilities for developing coffee varieties with coordinated flavour profiles.
