How to Make Ice Cream in a Zip Lock Bag

Your ice cream will be different from the store-bought kind.

Water normally freezes at 32 degrees Fahrenheit, but not when salt is added. This basic scientific reaction and some simple ingredients make it possible to create delicious ice cream in a zip-lock bag. There's a simple explanation. Adding salt to ice causes the ice to melt, and anything in contact with the ice loses some of its heat energy and becomes colder -- in this case allowing a milk mixture to freeze into ice cream.

Things You'll Need

• 1 tablespoon sugar
• 1/2 cup milk or chocolate milk
• 1/4 teaspoon vanilla
• Small zip-lock bag (pint)
• Large zip-lock bag (gallon)
• Ice cubes
• 6 tablespoons rock salt

Instructions

1. Measure and add the sugar, milk and vanilla to the smaller zip-lock bag. Seal the bag securely. A half cup of milk will make roughly one scoop of ice cream, so adjust the recipe according to the number of scoops you need.

2. Fill the large bag between 1/2 and 3/4 full of ice. Add the rock salt.

3. Put the small bag inside the large bag and seal the large bag.

4. Shake the large bag until the milk mixture has solidified into ice cream, which takes roughly five minutes. Do not shake too violently or you risk puncturing the small bag.

5. Remove the small bag and clean off the salt and ice. Unzip the bag, dump your ice cream in a bowl and serve.

Tips & Warnings

• Use chocolate milk for a different flavor.

References

• Kaboose: Homemade Ice Cream in a Bag
• Teach Net: Make Ice Cream in a Plastic Bag
• Education: Science Activity: Making the Coolest Ice Cream; J. Abruscato