New research from a pair of Danish scientists at Aarhus University has found the bitter characteristics of coffee can make a person more sensitive to sweetness. The study found this effect was independent of caffeine and helps explain why many people enjoy the experience of bitter dark chocolate with coffee.
To test the effect of coffee on a person’s sense of taste and smell, the researchers recruited 156 subjects. Following baseline tests to establish initial taste and smell levels, the subjects consumed a lukewarm espresso. Soon after, all the subjects were then instructed to drink a small cup of tap water to cleanse their palettes, before undergoing the taste and smell tests a second time. No changes to the sense of smell were seen in the study, but the research did reveal sweet tastes were amplified following the coffee consumption.
"When people were tested after drinking coffee, they became more sensitive to sweetness, and less sensitive to bitterness," says Alexander Wieck Fjældstad, co-author on the new research.
This result was unexpected as prior studies have suggested acute exposure to bitter tastes generally inhibit perceptions of sweet tastes. For example, caffeine and quinine, two compounds found in coffee, have been previously found to directly inhibit the activity of certain sweet taste receptors.
The researchers conducted the experiment a second time with decaffeinated coffee and saw the same results. This suggests caffeine plays no particular role in altering taste sensations after drinking coffee.
"We already know that our senses have an effect on each other, but it's a surprise that our registration of sweetness and bitterness is so easily influenced,” says Alexander Wieck Fjældstad. "It's probably some of the bitter substances in the coffee that create this effect.”
Exactly how coffee generates these particular changes in taste sensitivity is not explored in the study. The researchers do note the discordancy between these results, and that prior research into the way specific bitter compounds suppress the perception of sweet taste suggests there is an unknown combination of compounds in coffee that result in this dynamic change to bitter-sweet taste.
Alongside helping explain why the classic combination of bitter dark chocolate and coffee is so desirable, the research offers new insights into how dynamic our taste perception is. Plus, the study points to new kinds of food additive research that could amplify sweet taste perception without increasing sugar content in foods.
"More research in this area could have significance for how we regulate the way in which we use sugar and sweeteners as food additives,” adds Wieck Fjældstad. “Improved knowledge can potentially be utilized to reduce sugar and calories in our food, which would be beneficial for a number of groups, including those who are overweight and diabetes patients.”
The new study was published in the journal Foods.
Source: Aarhus University via EurekAlert