Cool Chemistry: Students make ice cream with liquid nitrogen
By OLIVIA BARTLETT
Daily Mining Gazette Writer, Houghton, Michigan

A Lake Linden-Hubbell student stirs a combination of milk, sugar and vanilla flavoring with liquid nitrogen to make ice cream Friday inside the Department of Materials Science & Engineering at Michigan Tech University. Twenty students from Lake Linden-Hubbell attended the day-long department tour and activities, which concluded with ice-cream making.

HOUGHTON - After 20 minutes of tedious work, Tyler Stemler reached his boiling point. He brushes away cloudy vapor from a bucket and looks inside. "Anybody want some ice cream," Stemler shouts out to his Lake Linden-Hubbell High School classmates during a liquid nitrogen ice cream project Friday at Michigan Tech University.

Nitrogen has a boiling temperature of 320.4 below zero. Yowza, that's cold! But it's perfect for turning milk, sugar and vanilla flavoring into delicious ice cream in minutes. Ruth Schultz Kramer, an engineer/scientist for the Department of Materials Science & Engineering instructed the cooks.

She chose Stemler and four other volunteers to take turns mixing ingredients, stirring and adding the nitrogen - safely stored in a metal tub. Any spillage could mean freezer burn to the skin. "The instructions say, before indulging, to allow excess liquid nitrogen to boil off before serving," she says, smiling. The students dress in aprons, thick gloves, long sleeved-shirts and protective eye wear.

Their classmates mutter about trying the chemically-cooked cream. "Is this healthy to eat," asks Jenna Judnich. Says Kramer, "The air we breathe is about 80 percent nitrogen, so it must be pretty safe." Stemler holds the bucket sturdy while his classmate, Corey Steinhoff, stirs fast to insure the ice crystals will stay small. If not, the concoction will resemble melted ice cream that has been frozen.

Whenever it gets too thick, Judnich pours in more nitrogen. The classmates aw and ooh at the sight of clouds emerging from the bucket. The haze means the nitrogen is at work - boiling, yet freezing the other ingredients. After ten minutes of stirring, Kramer checks the students progress. "It's getting there," she says. "I bet they're awfully close to being done." After scooping both flavors into bowls, the students taste the treat. Some students were hesitant. "I didn't think you could use (nitrogen) for something you'd be eating ... I thought it was poisonous," said Vienna Chapin. Chapin's friend, Jenny Rheault, was impressed with the outcome. "It's bubbly yet flavorful," she said. "I'm surprised ... I thought it would come out worse than it did, but it's awesome!"

The liquid nitrogen ice cream project concluded a day-long tour of the Department of Materials Science & Engineering Friday. Students also had the opportunity to see how aluminum foil is made, cast molten metal into a desired shape, alter the properties of steel, use an electron microscope and meet with faculty and students in the department.