Researchers at the Leibniz Institute for Food Systems Biology at the Technical University of Munich have made significant strides in understanding why coffee tastes more bitter to some individuals than others. Their study, published on January 29, 2025, uncovers a new group of bitter compounds in roasted Arabica coffee and explores the role of genetic predisposition in taste perception.
While caffeine has long been recognized for its bitterness, this research reveals that decaffeinated coffee also retains a bitter flavor due to other compounds. The team identified a previously unknown class of roasting substances, focusing on a compound named mozambioside, which is approximately ten times more bitter than caffeine.
As the lead investigator, Roman Lang, noted, 'Our investigations showed that the concentration of mozambioside decreases significantly during roasting, prompting us to explore whether its breakdown products could also influence coffee's taste.'
The research team discovered seven different degradation products of mozambioside that form during the roasting process. These compounds activate the same bitter taste receptors as mozambioside, with three exhibiting a stronger effect. However, the concentrations found in brewed coffee are typically too low to produce a noticeable taste on their own. Instead, it is the combination of mozambioside and its degradation products that leads to the perception of bitterness among tasters.
Genetic testing revealed that individual taste sensitivity varies, with some test subjects possessing defective variants of the TAS2R43 gene, which is crucial for bitter taste perception. Lang emphasized the implications of these findings, stating, 'The new insights enhance our understanding of how roasting affects coffee flavor and could lead to the development of coffee varieties with tailored flavor profiles.'
These discoveries not only advance flavor research but also hold potential significance for health research, as the physiological roles of bitter substances and their receptors in the body remain largely unexplored. With millions of coffee drinkers worldwide, the implications of this research could resonate on a global scale.