Bitterness is known to be the most complex taste sensation with twenty-five taste receptors

being members of G-protein-coupled TAS2R receptor family. Many nutritionally important

compounds may contribute to unpleasant bitter taste. Importantly, consumers live in their own

personal sensory worlds, which may result in their expressing individualized food preferences.

Caffeine is a very common reference compound for bitter taste and found in food as well. The

objective of this study was to investigate the effect of genetic variation in TAS2R38, TAS2R16

and TAS2R19 bitter receptors on taste intensity of caffeine.

Data was collected in our sensory laboratory (ISO 8589, University of Turku, Compusense

Cloud) with untrained and volunteer Finnish participants (n = 115, age 21–75, 88 females, 27

males). The caffeine samples (0.36 mM-3.6 mM) were prepared to active-carbon filtered water

and stored before serving following good laboratory practices and high hygienic protocol. The

participants were asked to spin a sample around the mouth for few seconds before rating the

intensity using a continuous graphical scale anchored from 0 (none) to 10 (very strong). All the

subjects provided written informed consent and were genotyped for their TAS2R38, TAS2R16

(rs846672, rs1308724) and TAS2R19 (R299C).

Our results show that there are differences between the participants in rating the intensity of

different caffeine samples. Most of the subjects were able to separate weak and strong

samples. In TAS2R16 there was a trend that participants with C/G or C/A and their combination

were the most sensitive to caffeine in stronger concentrations. Interestingly, people possessing

the AAV form of the TAS2R38 were most sensitive to caffeine, but their number was relatively

low in this study. Therefore genetic variation in taste perception may contribute to differences in

taste sensation of caffeine also. Moreover, this difference may mediate in preference and

consumption of caffeine-rich products.