By Ezen Choo
PhD candidate
Cornell University
Background: Multiple reports have detailed the presence of adenosine receptors in sweet sensitive taste cells. These receptors are activated by endogenous adenosine in the plasma to enhance sweet signals within the taste bud. Caffeine is actually a powerful antagonist of this receptor and many people consume it in their daily lives when they drink coffee and tea. Thus, we wanted to know if caffeine had some effect on the basic tastes.
Objective: The objective of this study was to examine how caffeine delivered in a cup of coffee could influence the sense of taste through inhibition of adenosine receptors in the taste buds.
Study Design: One hundred and seven (107) healthy men and women were randomly assigned to 2 groups, sampling decaffeinated coffee supplemented with either 200mg of caffeine, about the level found in a strong cup of coffee, or an equally bitter amount of quinine. Panelists then performed sensory testing, with the session repeated with the alternative condition in a second session on a separate day. The Study was conducted in November 2016 at the Sensory Evaluation Center. Thank you to all those who participated in the study!
Results and Implications: Panelists who consumed caffeine rated sucrose solutions as less sweet, while there was no effect on the other basic tastes. Panelists were also unable to discern whether they had consumed the caffeinated or non-caffeinated coffee, with ratings of alertness increased equally, but no significant improvement in reaction times, highlighting coffee’s powerful placebo effect. This work validates earlier observations in rodents in a human population and tackles an area we feel has not yet been considered in human taste research before. This could be a part of why it is popular to consume sweet treats/cookies with a cup of coffee or tea.
Note from the editor: If you have questions about this study, contact Ezen at <ec649@cornell.edu>.
