Why Kids and Adults Taste Blueberries -- and Sweets -- Differently

A new study shows how kids can taste tiny differences in sweetness.
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 Kyle McDonald via Flickr

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Katharine Gammon, Contributor

(Inside Science) -- It's one of the sublime pleasures of summer: stuffing your face full of ripe, juicy berries. The ability to taste the intense sweetness of summer fruit is actually a skill, and according to a new study, kids are just better at it than adults.

“Kids live in a different sensory world than adults,” said Julie Mennella of the Monell Chemical Senses Center in Philadelphia, an author of the study. “When it comes to sweet taste, children are really vulnerable. They use sweet in deciding what they like -- and it can be used for good.”

In the new report, researchers from Monell and the University of Florida offered two harvests of blueberries to 49 children and their mothers. They tested three different varieties of blueberries. When asked to pick their favorites, adults and children chose the sweetest berries picked during the first harvest fairly equally, but in the second harvest, the children -- aged 6 to 16 -- picked the sweeter fruit, while the adults like each variety equally. The study was published last month in The Journal of Food Science.

Mennella says that science can help parents channel the sweet preference to a food humans evolved to like – healthy fruits. Young children are more tolerant of both sweetness and saltiness. Somewhere in mid-adolescence, those windows narrow.

“It’s a really smart biologic response,” said Mennella. “Sweet taste is a signal for calories, and salt is a signal for minerals.”

It all comes down to kids’ taste buds, said Kathryn Medler, a biologist at the University of Buffalo who studies taste and who was not involved with the blueberry study. “Taste cells in the tongue and cheeks turn over continuously -- and as you age, that process breaks down,” she said. “So kids really do taste things more intensely than teenagers or adults.”

Medler added that most people don’t appreciate how critical the sense of taste is for survival. When she asks students which sensory system they’d be willing to lose, most choose taste. “But if you lose [the] taste system, it’s really hard to survive. If we were living out in the middle of nowhere, we’d be a lot more cautious about what we consume,” she said.

And the sense of sweet taste, in particular, may be a signal for other issues. People who are obese often have dysregulation in the taste system, where they don’t taste sweet things as well as people of normal weight. “We don’t know which comes first: the problem in system, or obesity. But we know it gets out of whack.”

To get berries to market that are sweet, farmers have to pick at the exact right time -- but that can be a delicate dance, explained Mark Gaskell, a blueberry researcher at the University of California, Davis school of agriculture, who also wasn’t involved with the new study.

Gaskell says sunlight, day length and temperature all affect how sweet the fruit will ultimately be, but farmers who have to send their fruit on a multiple-day journey will often pick less ripe berries, with so-called red shoulders, and let the color develop during the journey. Picking too early means the flavor and color isn’t there, but picking too late could lead to mushy, unmarketable berries. “As with most berries, there has to be a compromise between the visual part and the flavor part,” said Gaskell.

Gaskell has been part of a group expanding the production of blueberries in the U.S., and it has been successful: Consumption of the fruit has increased fifteenfold over the past two decades, according to the U.S. Department of Agriculture.

Even so, research has shown that from the age of two onward, an American is more likely to eat a manufactured sweet than a fruit on any day, said Mennella.

Mennella said it’s important for people to realize that the child consumer isn’t the same as the adult consumer. “Children aren’t the same, and an appreciation of those differences can help them get on a healthy track. Parents can cater their preferences to the foods they should be eating,” she says. Blueberries may be a gateway fruit for getting kids to move away from candy and toward natural sugars. 

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Katharine Gammon is a freelance science writer based in Santa Monica, California, and writes for a wide range of magazines covering technology, society, and animal science.