Making Ice Cream With Liquid Nitrogen

This is a favorite demo for small groups (20 or so), but it can be scaled up for large classes.

The idea for this came from a Scientific American article (Kurti & This-Benckhard, Sci. Amer. 1994, 270 (4), 66-71) on science in the kitchen. It makes good ice cream for two reasons:

1. The mix freezes very quickly, so you get small crystals and a very creamy texture.
2. The evaporating LN2 aerates (nitrogenates?) the mixture, so it doesn't end up as a frozen lump.

This demo ties in nicely with thermodynamics and phase changes.

Liquid Nitrogen Ice Cream (makes about 1/2 gallon)

cream base:
	4	cups	heavy cream
	1 1/2	cups	half and half or milk
	1 3/4	cups	sugar
berry mixture:
	1	quart	mashed strawberries
	1/2	cup	sugar

Use gloves and goggles when doing anything with liquid nitrogen. Keep all the ingredients cold, and make sure the sugar is dissolved in the cream base.

Pour the cream base into a large bowl. Add one to two liters of liquid nitrogen and stir vigorously with a stout-handled spoon. (Wimpy spoons will break.) When the cream has thickened, add the berry mixture and more nitrogen, if necessary. Continue to stir until the nitrogen has evaporated and the fog has disappeared.

This recipe does not keep well, and is best consumed immediately. If it begins to melt before everyone is served, simply add more liquid nitrogen and stir.

About Liquid Nitrogen

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