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Fact check: No, banana stalk and spots don't indicate whether it was 'chemically ripened'

Chris Mueller   | Paste BN

The claim: Shoppers can see whether bananas are 'chemically ripened'

A Feb. 5 Facebook post (direct link, archive link) shows side-by-side photos of two bunches of ripe bananas: One bunch has green stems with black dots covering the bananas, and the other has brown stems and no brown dots.

"Green stalk with brown spots means they were chemically ripened," the post says. "Black stalk (means) naturally ripened."

The post was shared more than 1,000 times in three days.

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Our rating: False

There is no difference – visual or otherwise – between bananas allowed to ripen naturally and those treated with ethylene gas, a chemical that bananas also naturally produce on their own, experts say. Many producers expose bananas to ethylene gas to control the ripening process before they're sold to consumers. 

Banana ripening is triggered by naturally produced ethylene gas

Banana ripening is triggered by a chemical called ethylene, which the fruit naturally produces on its own, Robert Paull, a plant physiology professor at the University of Hawaii at Manoa, told Paste BN. 

"This same chemical, ethylene, is used by the major wholesalers to control banana ripening so they can display fruit at a similar stage of ripeness," Paull said.

Bananas are picked when they're horticulturally mature – fully formed, but still hard and light green in color – so they can be shipped, Jonathan Crane, a professor and associate director of the Tropical Research and Education Center at the University of Florida.

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"Once here, the bananas can be gassed with ethylene to trigger the ripening process so they ripen at the same time," Crane said.

If the bananas aren't gassed with ethylene, they would still eventually produce ethylene on their own, he said.

A 2019 study published in the International Journal of Food Science says "most studies suggest that there is no difference in biochemical composition and sensory quality in bananas treated with chemicals that induce ripening from naturally ripened bananas."

Paull said the same.

"It would be difficult to tell the difference between fruit ripened with ethylene and those allowed to 'naturally' ripen," Paull said. "The 'naturally' ripened might be slower to ripen and less uniform."

Brown spots show ripeness, experts say

The brown spots that appear on the peel of bananas simply show it's in an "advanced stage of ripeness," Paull said.

Crane agreed, saying the brown dots – called "sugar spots" – show the banana is fully ripe and sweet.

The color of the stem isn't indicative of whether a banana was chemically ripened, as the post claims, but "is more a function of the relative humidity during ripening," Paull said.

"Lower relative humidities lead to dehydration and darling of the stem, as well as a duller overall fruit," he said.

Steven Sargent, a horticultural sciences professor at the University of Florida, told Paste BN that the stem and peel naturally lost moisture as the banana ripens, which accounts for the drier stems in the post's right image.

In the U.S., organically produced bananas can still be treated with ethylene gas. But both organically produced and conventionally grown bananas get the same ethylene treatment to start the ripening process, Sargent said.

"In my experience, it is virtually impossible to make a blanket statement from images such as these because we do not know the history of these fruits," he said.

USA TODAY reached out to the social media user who shared the post for comment. 

Reuters also debunked the claim.

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