October 9, 2012
Liquid Nitrogen And Food: A Potentially Lethal Concoction
April Flowers for redOrbit.com - Your Universe Online
In the UK last week, an 18 year old woman's birthday celebration ended in emergency surgery to remove her perforated stomach. The cause: a cocktail prepared using liquid nitrogen. The tragedy has prompted an intense look at the use of liquid nitrogen in food and beverage preparation.
Gaby Scanlon ingested the "correctly prepared Jagermeister drink made with liquid nitrogen" at her 18th birthday celebration. Shortly thereafter she began to feel sick, "becoming breathless and developing severe stomach pain." When Gaby reached the hospital, she was diagnosed with a perforated stomach, which had to be removed.
Dr. Malcolm Povey, professor of food physics at Leeds University, explains what probably happened to Gaby.
"The liquid nitrogen would rapidly change into gas and blow the stomach up like a balloon," he said. "The idea that people put this stuff in drinks is just unbelievable."
At a boiling point of -196C, liquid nitrogen is used for a variety of industrial applications including coolant for computers, to remove skin growths and cancers, and in cryogenic studies where scientists examine the effects of very cold temperatures on materials.
Top restaurants have increasingly used it as a method for instantly freezing food and drinks, or creating a cloud or vapor special effect. Chef Heston Blumenthal made the avant-garde cooking technique famous with his nitro-scrambled egg and bacon ice cream and nitro-parched aperitifs at his Berkshire, UK, restaurant, the Fat Duck.
Since then, it has become a popular technique at restaurants and dozens of recipes have shown up on the internet.
University of Bristol's School of Physics Professor Peter Barham says that liquid nitrogen is "simply the harmless gas nitrogen, which has been cooled to such a low temperature that it becomes a liquid".
If not handled properly, Barham says, the liquefied gas can cause frostbite or cryogenic burns. Using it in cooking is fine, as long as proper safety measures are taken.
"If liquid nitrogen is added to a liquid such as an ice-cream mixture, it cools the liquid rapidly while it boils away and produces a cloud of vapor. The technique is used by some restaurants to prepare instant ice creams at the table - the rapid freezing produces an ice cream with particularly small ice crystals which has a very smooth texture," he says.
Ingesting liquid nitrogen should never be done, and it is essential that all the liquid has evaporated before any food or drink prepared with it is used.
Gaby Scanlon's tragedy has prompted the UK's Food Standards Agency to issue a warning, telling consumers to "take care when drinking cocktails made with this substance."
Director of public health for the county of Cumbria, Dr. John Ashton said that Gaby was "the victim of an irresponsible alcohol industry that's now competing on gimmicks." The police say the bar involved has suspended selling drinks prepared with liquid nitrogen and is cooperating with the investigation.
John Emsley, science writer and fellow at the Royal Society of Chemistry, says that if more than a "trivial" amount of liquid nitrogen is swallowed the results are disastrous.
"If you drank more than a few drops of liquid nitrogen, certainly a teaspoon, it would freeze, and become solid and brittle like glass. Imagine if that happened in the alimentary canal or the stomach. The liquid also quickly picks up heat, boils and becomes a gas, which could cause damage such as perforations or cause a stomach to burst," he says.
Emsley asserted he would be surprised if someone could swallow liquid nitrogen. "It would be extremely cold in anyone's mouth - people would want to spit it out immediately," he says.
Emsley believes the liquid nitrogen is safe in the hands of chefs and bartenders trained to use it, he suggests that there should be a very strong warning not to "play" with it. "It can be a bit of a novelty in the hands of experts, but it would be a different territory in the hands of the general public."
"If you put your finger in liquid nitrogen, it would go rock solid and fall off," he says.
David Morris, Tory MP for Morecambe and Lunsdale, UK, has called for a ban on drinks made with liquid nitrogen following Scanlon's ordeal. "I would like to see these drinks banned from sale so we do not see anyone else's son or daughter injured or even killed."