Watermelons can offer a nice explosion of flavor in your mouth, but they shouldn’t be spontaneously combusting.
Oddly enough, that’s exactly what some fans of the popular fruit are worried about following several consumer reports of foaming watermelons this summer.
Emily Durbin, a Florida resident, posted about one such ominous-looking fruit this week on a Facebook group “Mommy Needs A Recipe!”
Durbin shared a photo of a sizeable watermelon perched on her kitchen counter with white foam oozing out of it.
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“We bought this watermelon YESTERDAY at Walmart. My husband left for work around 6 am & when I walked in the kitchen around 9 am, this is what I walked into. The white stuff was a foamy bubbly substance. The yellow juice was chunky & thick. The odor was absolutely FOUL. It reminded me of vomit,” she wrote in the post.
When Durbin picked up the fruit to toss it in the trash, she said she felt “rumbling on the inside” but was perplexed because the watermelon hadn't been around “any heat sources.” Durbin did not respond to a request for comment from TODAY.com.
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Many Facebook users commented on Durbin’s post to say they had also experienced an exploding watermelon in recent weeks.
“My melon was on the counter and it must have already been bad when I got it and the next day I came down to an awful smell and rotten melon everywhere it was disgusting and anytime I get something I cut it up right away now,” one wrote.
Another left the following comment: “This happened to me once. It wasn’t leaking yet but when I cut into it it literally exploded. The biggest bang I’ve ever heard and scared the crap out of me.”
Earlier this month, Maine’s Bangor Daily News published a story about exploding watermelons, detailing another incident involving a watermelon that Maine resident Julie Raines purchased.
So, yes, foaming fruit is trending, but why? And should we be concerned? TODAY.com consulted several food safety experts to get to the root of the bizarre phenomenon. Here’s what we found out.
What causes watermelons to foam and explode?
Keith Schneider, Ph.D, professor in the Food Science and Human Nutrition Department at the University of Florida, tells TODAY.com this isn’t the first time he’s heard of foaming or exploding watermelons.
“This is probably due to the heat. The fruit, if slightly damaged, can begin fermenting. If enough fermentation occurs, which produces gas, enough internal pressure may build up for the watermelon to crack or pop,” Schneider says.
He explains that “excessive summer heat” can wreak havoc on the quality of some produce, calling it an “unexpected consequence of climate change.”
As part of the fermentation process, if certain microorganisms are introduced into the watermelon, they convert sugar into alcohol.
“It’s the same process that happens in beer and wine making. The offshoot of this process is CO2 gas. The thing that puts the bubbles in your beer,” Schneider says.
Eventually, an explosion can take place, especially “if the wound heals over and pressure is allowed to build up,” he explains.
Even if these watermelons aren't actually fermenting, Dr. Steve Reiners, a professor of horticulture in the School of Integrative Plant Science at Cornell, says a “bacterial or fungal/mold disease has gotten into the fruit.”
“Normally the inside of the fruit is protected by the rind but there are a few diseases that may find their way inside soon after the flower experiences fruit set (bees bringing pollen to the flowers),” the professor explains. “Sometimes the part of the fruit where the flower was attached does not close entirely, and a small passage allows the disease to enter. It's likely worse in rainy conditions.”
The fruit will usually not explode in this scenario, Reiners says, unless the entry hole is “entirely plugged up.”
“More typically you will see the melon oozing out the bottom,” he says. “When I have had melon trials in the past, it’s not unusual for me to pick up a couple of fruit to weigh and have the entire inside of the fruit flow out on my boot.”
Are foaming watermelons safe to eat?
Foaming watermelons are neat to look at — and great fodder for social media — but they’re not exactly good to eat.
“The watermelon is undergoing decay, so it's best to bring it back to the store and get a replacement or just toss it,” Schneider said.
Reiners also recommends letting your sense of smell guide you in these scenarios.
“Basically, our noses are pretty good at telling us what is safe to eat and if a fruit smells bad, it’s rotting. Trust your nose,” he says.
Luckily, you don't typically have to worry about plant diseases causing humans to get sick, but Reiners adds that a “soft rot bacteria” could make you “a bit uncomfortable,” so it’s best not to eat it.
“Plus, if the fruit has a small hole, it is possible that human pathogens could enter, especially if heavy rains have moved water from areas where animals are present. Growers are always careful to keep fruits and veggies as safe as possible but occasionally, and very rarely, a potential human pathogen like E. coli or salmonella could enter,” he says.
In 2011, Food Safety News reported on a recall of Del Monte melons due to salmonella exposure.
“While other pathogens such as E. coli O157:H7 and Listeria can find their way into many crops, Salmonella seems to be the bacterial pathogen of greatest concern with melons. Salmonellosis can be a severe illness and the infection leads to complications with reactive arthritis and other chronic diseases in about 15 percent of cases," the outlet wrote at the time.
How should you store watermelons?
Hoping to avoid your own foaming fruit incident? Proper food storage practices can help. Here are a few tips:
- Leave watermelon out of direct sunlight to extend the shelf life.
- Leave the entire watermelon in the fridge until it’s ready to eat.
- Store leftovers in the fridge once you cut into the watermelon.
“A watermelon is basically sugar water and if kept at room temperature, the fruit will respire and use oxygen and the internal sugars to ‘breathe.’ So a warm fruit will lose sugar more quickly and be less sweet. Kept in the fridge, you can store for a week to 10 days,” Reiners says.
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