Coffee Flavor Altered by Color of Coffee Cups, Study Shows

There are many variables that can influence the flavor of a cup of coffee: the variety of the coffee beans, the darkness of the roast, and of course how much cream or sugar is added. But researchers have now shown that the cup in which coffee is served can impact a drinker’s perception of its taste, as well.

A new study demonstrates that coffee tastes sweeter when served in a clear mug, as opposed to a white one. Coffee served in a blue mug is perceived as being of moderate sweetness.

“The color of the mug really does seem to have an impact,” Charles Spence, head of a lab at Oxford University and one of the study’s three authors, told the Washington Post. “We found a particularly significant difference between the white mug and the clear one.”

In the experiment, researchers had 18 participants drink the same type of coffee from three mugs. The mugs were all of similar shapes, but were white, blue and clear, respectively. The drinkers rated each cup of coffee on sweetness, aroma, bitterness, quality and acceptability.

The coffee was rated as being sweeter when drunk out of the transparent mug, and more bitter or “intense” when drunk out of the white mug.

The Science Behind the Senses

There’s extensive evidence linking color to palatability. In the 1940s, psychologist Louis Cheskin was able to increase margarine sales when he suggested that it be colored yellow (to resemble butter).

Similarly, the most direct application of the current research is in the coffee industry. “[T]he colour of the mug should be considered by those serving coffee as it can influence the consumer’s multisensory coffee drinking experience,” the study’s authors write.

But underlying those practical applications, why might the color of a cup or plate change a diner’s perception of taste?

One theory rests on two factors: that certain tastes are associated with certain colors of foods, and that humans perceive color not absolutely, but in relation to other colors.

For example, red is associated with sweetness because red fruits are often ripe and sweeter than their green counterparts, Spence explained to the Post. And a red strawberry will appear more red on a white plate than it would on a colored plate. This can lead to a strawberry served on a white plate seeming sweeter than one served on a dark plate.

Spence and his colleagues have a hunch — though more research will be required to confirm it — that people associate the color brown with bitterness. “The white mug may have influenced the perceived brownness of the coffee and this, in turn, may have influenced the perceived intensity (and sweetness) of the coffee,” the researchers write.

The full study is published in the journal Flavour.