Your morning coffee might be the jolt you need to make it to work without drowsily forgetting to put on your pants, but that caffeine may also be temporarily be dulling your taste buds, possibly leaving some folks still jonesing for something sweet.

Scientific coffee breaks

In a study published today in the Journal of Food Science, researchers at Cornell University looked into whether consuming caffeine affected how people perceive flavors in food and drink.

Study participants drank cups of sweetened hot coffee served at 140 degrees Fahrenheit. Some of the coffee was caffeinated, while the remaining cups contained decaf. Subjects were then asked to note the sweetness level of the brew and also their own alertness level.

This was not a gourmet coffee experience: All of the beverages in the study were made from Folgers decaf instant coffee and Coffee-Mate sweetened creamer. Every cup had the same amount of sugar and coffee.

The researchers used an interesting method to precisely control the amount of caffeine that study participants received. Everyone drank decaffeinated coffee, and then the researchers added either 200 mg of caffeine or an amount of quinine that would add the same amount of bitterness.

Participants received either caffeine or quinine in their coffee on the first day, and then the other substance on the second. Otherwise, it could simply be the bitterness of the caffeine affecting how sweet participants thought their coffee was.

How sweet it is

Participants rated their drinks as less sweet on average when they contained caffeine compared to when they didn’t, showing that caffeine itself may affect our senses.

“When you drink caffeinated coffee, it will change how you perceive taste – for however long that effect lasts,” Robin Dando, assistant professor of food science at Cornell University, explained. “So if you eat food directly after drinking a caffeinated coffee or other caffeinated drinks, you will likely perceive food differently.”

Keep that in mind the next time you order a giant pastry along with your syrup-sweetened double latte.

Also of interest was the fact that test subjects were generally unable to accurately determine whether they had just consumed caffeinated or decaf coffee.

“We think there might be a placebo or a conditioning effect to the simple action of drinking coffee,” said Dando. “Think Pavlov’s dog. The act of drinking coffee – with the aroma and taste – is usually followed by alertness. So the panelists felt alert even if the caffeine was not there.”

Dando says the mental association of drinking coffee with being more awake may be strong enough to provide that effect: “Just the action of thinking that you’ve done the things that make you feel more awake, makes you feel more awake.”

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