We all know cooking is chemistry, so of course ice cream is all about science, too! Make a tasty treat and explore different scientific concepts, like freezing point depression, supercooling, and cryogenics using liquid nitrogen or dry ice.
Ice Cream in a Bag
Ice cream in a bag is a classic science ice cream project that is perfect for kids, but also offers a quick fix for adults with a craving. Start with any ice cream recipe and two plastic zipper bags. The ingredients go into the inner bag, while the outer bag contains ice and salt. Salt works the science magic, producing freezing point depression when a bit of the ice melts. This chills the inner bag well below the freezing point of water, making ice cream. You don’t even need a freezer for this project, as long as you have ice!
Liquid Nitrogen Ice Cream
There is more than one way of making an instant slushy. You can use supercooling, where you place juice or a soft drink in the freezer, chill it below its freezing point, and then make the liquid freeze on command. Or, do a variation of the ice cream in a bag project and use ice with salt to freeze the slushy.
Dippin’ Dots Science Ice Cream
Dippin’ Dots are a variation of liquid nitrogen ice cream. The twist is that you use different ice cream colors or flavors and drip them into the nitrogen rather than pouring it over the top. Chocolate and vanilla are two great recipes to combine, or get inexpensive rainbow sherbet from the store, separate out the colors, and let them melt. The project instructions even include a variation that does not require liquid nitrogen.
Snow Ice Cream
Make snow ice cream either using snow as an ingredient or as a means of chilling an ice cream recipe. When the recipe itself contains snow, the finished product has a memorable “winter” texture and flavor. If you use snow as the coolant, add salt for getting the temperature icy cold.
Dry Ice Ice Cream
Dry ice ice cream works a lot like liquid nitrogen ice cream in that the dry ice freezes the recipe. The dry ice undergoes sublimation, changing from a solid directly into carbon dioxide gas (no liquid phase). Because carbon dioxide is more reactive than nitrogen, some dissolves, reacts with the ingredients, and even forms bubbles. The resulting science ice cream has fizzy texture and a bit of an acidic flavor. Take advantage of the unique flavor profile by adding lemon or lime as a flavoring.
Hot Ice Cream
Hot ice cream is a surprising science treat that starts out as a steaming hot solid and melts as it cools toward room temperature. Methylcellulose is the ingredient responsible for the effect. It bonds with itself and forms a gel at high temperatures, but interacts with water as it cools. This makes the gel collapse. Heating it once again causes it to firm up. Play with your food and test it for yourself.
- Atkins, Peter (2006). Atkins’ Physical Chemistry. Oxford University Press. ISBN 0198700725.
- Debenedetti, P. G.; Stanley, H. E. (2003). “Supercooled and Glassy Water”. Physics Today. 56 (6): 40–46. doi:10.1063/1.1595053
- Kroger, Manfred (2006). “What’s All This We Hear about Molecular Gastronomy?”. Comprehensive Reviews in Food Science and Food Safety. 5 (3): 48–50. doi:10.1111/j.1541-4337.2006.00003.x
- Pedersen, U.R.; et al. (August 2016). “Thermodynamics of freezing and melting”. Nature Communications. 7 (1): 12386. doi:10.1038/ncomms12386