4/17/2013

Science In A Scoop: Making Liquid Nitrogen Ice Cream

Robyn Sue Fisher's ice cream shop, Smitten, in San Francisco's Hayes Valley, may at moments resemble a high school chemistry lab, but that's because Fisher uses liquid nitrogen to freeze her product.

Nitrogen is "a natural element," she notes. "It's all around us."

What makes it essential to Smitten is the ability to make ice cream fresh to order. You walk up and ask for a chocolate, or a blood orange with pistachio. The liquid nitrogen freezes the ingredients together, and your cup or cone is ready about a minute later.

Because servings are made on the spot, each one requires just a few ingredients. Normally, ice cream needs gums, egg yolks or other stabilizers and emulsifiers to keep it frozen on its months-long journey from manufacturer to distributor to store to your home freezer