Researchers found that consuming caffeine can alter the way people perceive tastes. Participants of the study were also unable to determine if their beverages were caffeinated or not based on their alertness levels, implying a certain level of placebo effect.
Altered Taste Perception
If you've ever wondered why coffee seems best paired with sweet pastries such as donuts and cakes, evidently, researchers have wondered about that too. A team of researchers from Cornell University found that caffeine actually has the effect of altering taste perception, specifically sweetness.
Researchers conducted their test by dividing 107 participants into two groups. During the first part of the experiment, one group was given decaffeinated coffee, while the other drank coffee with 200 milligrams of caffeine. Both groups had the same amount of sugar added to their beverage.
Interestingly, sensory testing revealed that although caffeine had no effect on umami, sour, salty, and bitter perception, participants who were given caffeinated beverages described their coffee as less sweet. As a result, this could lead an individual to crave for sweets afterward.
Caffeine Placebo Effect
In the second part of the test, researchers made an interesting observation. Participants of both groups were asked to report on their levels of alertness and were evidently unable to determine whether what they consumed were caffeinated or not.
As it turns out, both groups reported the same level of alertness but no significant increase in reaction times, pointing to a certain level of placebo effect in response to consuming coffee.
"Just the action of thinking that you've done the things that make you feel more awake, makes you feel more awake," said Robin Dando, senior author of the study. Likewise, he likened the participants' reactions to Pavlov's famous classical conditioning experiment where a simple sound stimulus caused the dogs to salivate.
Adenosine Receptor Antagonist
Caffeine is a powerful antagonist of adenosine receptors, which are responsible for inducing feelings of relaxation and sleepiness. What happens when an individual drinks coffee is as these receptors are suppressed, the individual in turn feels more energized.
However, as per the results of the study, it turns out that caffeine also affects how the individual perceives taste.
Now this is not saying that consuming caffeine will make a person eat more sugary food items. It merely means that taste perception directly after drinking coffee will likely be altered if only for a certain period and that the lessened sweetness of the beverage may lead to sugar cravings afterward.
The study is published in the Journal of Food Science.