I have never made liquid nitrogen. I do make dry ice ice cream about 4 times a year. Kids love the carbonation. My daughter says it is like an automatic root beer float (even though we don’t make it root beer flavored). Here is the procedure I keep for our Demo Squad (of course, with me, they are required to fill out a risk assessment form before the demo):
What To Do
A. Crush the dry ice into little pieces.
1. Place in paper bag and smash with a mallet
B. Mix all other ingredients in a large bowl
A. Shake the dry ice into the ice cream, a little at a time
1. Mixing in between additions
B. When adding more dry ice, it will start to harden, and get more difficult to mix.
C. Continue adding dry ice until the ice cream reaches the desired consistency.
D. Remove stray chunks of dry ice with a small fork, or spoon
1. Once all dry ice been removed, enjoy
3. Post Demo Clean Up
A. Clean the bowls and spoons
B. Put dry ice away in a -90oC freezer, or let it sublimate in a fume hood
Dry Ice is frozen carbon dioxide, which is part of the earth’s atmosphere. The temperature of dry ice is -78.5oC, so it can help things freeze and be kept frozen. When breaking up the chunks of dry ice at normal temperature of the atmosphere, the ice will turn from a solid to a gas through sublimation. When the dry ice is added to the ice cream mixture, the mixture will start to thicken up, a little at a time, and there will be some CO2 bubbles forming. When you get to the consistency that you want, stop adding the dry ice, or it will become harder to stir, and hard to scoop. When done at the consistency you want, scoop out the dry ice pieces that didn’t break up, so you don’t eat any (this could lead to asphyxiation or cause other health affects). Then make a bowl or a cup with whatever toppings you want. The tangy flavor is from the CO2 that bubbled through the liquid ice cream mixture.
Dry Ice is a cryogenic material which has a boiling temperature of less than -73oC. It can cause tissue damage and asphyxiation due to oxygen displacement. It also poses as a fire hazard if the oxygen is condensed out of the atmosphere. Dry ice ice cream is simple to freeze so insulated gloves are appropriate. Try to stand back while breaking the chunks or handling or have a fan available to keep air circulating so you don’t breathe in large amounts of the CO2.
I wonder - could you do similar with crushed dry ice? Sounds like a weekend project to me …..
Thanks for the recipe, David. In the absence of LN2, that’d freeze up nicely in an ice cream freezer, too.
Debbie M. Decker, CCHO, ACS Fellow
Immediate Past Chair, Division of Chemical Health and Safety
University of California, Davis
Birkett's hypothesis: "Any chemical reaction
that proceeds smoothly under normal conditions,
can proceed violently in the presence of an idiot."
I have made liquid nitrogen ice cream for years with no problems. Here is the link to my procedure http://www.chymist.com/Liquid%20N2%20ice%20cream.pdf
Remember, you are working with a cryogenic fluid. Safety procedures must be followed as well a food safety procedures..
At the ACS meeting in Boston, the RSC hired the Wiches of Boston to make liquid nitrogen ice cream at their booth in the exposition. They used my recipe. http://www.chymist.com/Liquid%20N2%20ice%20cream.pdf
David A. Katz
Chemist, Educator, Expert Demonstrator, Science Communicator, and Consultant
Programs and workshops for teachers, schools, museums, and the public
133 N. Desert Stream Dr. * Tucson, AZ 85745-2277 * USA
voice/fax: (520) 624-2207 * email: dakatz45**At_Symbol_Here**msn.com
Visit my web site: http://www.chymist.com
--- This e-mail is from DCHAS-L, the e-mail list of the ACS Division of Chemical Health and Safety. For more information about the list, contact the Divisional secretary at secretary**At_Symbol_Here**dchas.org
Previous post | Top of Page | Next post