Dangerous desserts: Liquid nitrogen treats aren't always safe to eat

Beware of a novelty treat made of colorful breakfast cereal and liquid nitrogen, found at fairs, amusement parks, and ice cream shops. Trademarked as Dragon’s Breath, the dessert may be sold under different names—but you’ll recognize it as a cup of bright, multicolored, cereal puffs that emanate a smoldering “smoke.”

“Liquid nitrogen is poured all over the cereal, flash freezing it and creating a fog that spills out as if it’s coming from a bubbling cauldron,” a Los Angeles Times article described. “Skewer the sweet and crunchy puff, toss one into your mouth, and you’ll start breathing out a cloud of smoke for a few seconds.”

Sounds like fun? Maybe—unless you accidentally drink some liquid nitrogen that may remain in the bottom of the cup. Then your stomach will fill up with gas, inflate like a balloon, and likely burst from the pressure.

Accidental ingestion

That’s what happened to a 13-year-old boy in Korea, according to a case report published recently in Clinical Endoscopy. Immediately after eating such a treat at an amusement park, he complained of severe abdominal pain and shortness of breath. He was rushed to the emergency department.

He was in respiratory distress upon examination, his breath coming in shallow, rapid gasps. His abdomen was severely distended and tender. X-ray and computed tomography scan confirmed a large volume of pneumoperitoneum.

He was immediately taken to the operating room. Exploratory laparotomy revealed he had a large amount of gas under tension. A linear perforation 4 cm long was found in the angular notch of the lesser curvature of his stomach, through which a large amount of food had been expelled.

After surgeons repaired the perforation, the boy was transferred to the intensive care unit for close observation. Oral intake was resumed on the fourth day after surgery, with no complications, and the boy was discharged 4 days later.

“As seen in this case, it can be hazardous to accidentally ingest liquid nitrogen,” the authors of the report concluded. “Our 13-year-old patient was in critical condition and has been left with a 20-cm scar on his abdomen.”

A public health problem?

Nitrogen is one of the most abundant elements on the planet and makes up about 78% of the Earth’s atmosphere. It’s a gas at room temperature, but when compressed and cooled, it becomes a liquid. When liquid nitrogen reaches its boiling point (-320° F), it evaporates and turns rapidly back into a gas, expanding nearly 700 times in size.

Although rare, this boy’s case isn’t the only reported incident of accidental ingestion of liquid nitrogen. A 2013 report described the case of an 18-year-old girl who drank an alcoholic shot containing liquid nitrogen. She was taken to the hospital and underwent a total gastrectomy with Roux-en-Y reconstruction. Owners of the bar where she was served the smoking drink later admitted in court that they failed to ensure the shot was safe to consume.

“Public health bodies must be aware of, and monitor, the use of liquid nitrogen in this way and consider regulation to prevent further injuries,” the case report authors concluded.

Safety precautions

Back at the Los Angeles ice cream shop that claims to have originated the Dragon’s Breath dessert, a sign at the counter warns: “Nitrogen Liquid can be dangerous. Pls do not touch or ingest nitrogen liquid.”

But if the dessert is made properly, there should be no danger of accidentally ingesting liquid nitrogen, explained Mindy Levine, PhD, associate professor of chemistry, University of Rhode Island, Kingston, RI.

In addition to her day job as an organic chemist, Dr. Levine also runs a science-themed party planning business. One of the highlights of her science-themed party: ice cream made using liquid nitrogen.

“The key to ensuring that liquid nitrogen is not left [behind] is to mix the ice cream thoroughly so that all of the liquid nitrogen evaporates before consumption,” she told MDLinx. “Thorough mixing as well as waiting a few minutes prior to consumption is sufficient to ensure that no liquid nitrogen remains.”

Currently, no food safety guidelines appear to exist in the United States for the use of liquid nitrogen in food preparation. Also, there are no particular restrictions on buying it, although some distributors may require the purchaser to sign a waiver.

“Liquid nitrogen is a wonderful substance for scientists and medical professionals,” Dr. Levine added. “It can also be used by kitchen chemists, restaurant owners, and other people in food and beverage production, but people should understand the very real need to be careful with such usage. It is extremely cold, can cause injury, and should be treated with appropriate caution, especially if being used by untrained personnel.”

So, “caveat cenator”—let the diner beware.