No Ice Cream Machine? No Problem! How to Make Ice Cream in a Ziploc Bag.

By Marcella Soewignjo Edited by Francesca-Lauren Seguin

No Ice Cream Machine? No Problem! How to Make Ice Cream in a Ziploc Bag.

Materials:

• 1 sandwich Ziploc bag

• 1-gallon Ziploc bag

• 1 cup of half and half

• ½ teaspoon of vanilla extract

• 3 cups of ice

• ⅓ cup of salt (preferably rock salt)

• 1 ½ tablespoons of sugar

• Ice cream toppings (optional)

Steps:

1. Making the ice cream bag: In the sandwich-sized Ziploc bag, place 1 cup of half and half, ½ teaspoon of vanilla extract, and 1 ½ tablespoons of sugar, and make sure to seal the bag tightly.

2. In the larger gallon Ziploc bag, place 3 cups of ice and ⅓ cup of salt.

3. Place the smaller ice cream bag into the large Ziploc bag filled with ice and salt. This step is why it is super important to make sure the smaller ice cream bag is sealed nice and tight! Otherwise, you may find yourself with some super salty ice cream.

4. Seal the large gallon Ziploc bag.

5. Shake the bag for about 10 minutes until the mixture in the smaller ice cream bag is fully hardened.

6. Voila! Once the ice cream in the smaller bag is fully hardened you can remove the small bag from the larger Ziploc bag, open it up and serve your ice cream! You can also add your favorite ice cream toppings for some extra flavor.

The science behind at-home ice cream making. Why does this work so well?:

You may be wondering how the ice in your large gallon Ziploc bag was able to get cold enough to allow your liquid ice cream mixture to harden so quickly. Remember how during the winter we use salt on the roads to make sure they don’t get slick with ice? This works because salt lowers the temperature at which water melts, causing snow to melt quickly and the roads to be free of ice. This temperature is also called the melting point. When we add salt to the large gallon Ziploc bag, it causes the melting point of the ice to lower, which causes the ice to melt quickly. When something melts, it takes heat away from the surrounding environment. As the ice in the bag melts, it takes away heat from the mixture in the smaller Ziploc bag containing our ice cream mixture, causing it to quickly freeze. You can also feel the heat being taken away from your hands! As you were shaking the large Ziploc bag, you might have felt that your fingers started to get very cold. This is because as the ice was melting in the bag, it was also taking away some of that heat from your own hands!