I want to say up front that I haven’t tried this recipe myself yet. But I have gotten so many requests for it along the lines of “Have you heard about making ice cream in a bag?” or “My kids made ice cream in a Ziploc bag at school.” that I decided to go ahead and post this. As you will see its a very simple process and I have it on good authority that kids love the simple magic of it. Each Ziploc bag makes a cup of ice cream (2 servings). I can see this as a fun kid’s party activity. Though come to think of it 15 kids and liquids hmm… PLEASE NOTE STEP 5: This mixture gets very, very cold while freezing.
Since I have published this I have gotten feedback from friends that this technique works quite well. See the videos at the end of the post. If you don’t have an ice cream maker I urge you to try this method. You should be able to make up to pint of any recipe on this site with no difficulty especially if you use rock salt rather than table salt.
- 1 quart size, freezer ready, Ziploc bag
- 1 gallon size, freezer ready, Ziploc bag
- 3/4 cups of table salt. Rock or Kosher works even better.
- 2 cups of ice
- 1/2 cup cream
- 1/2 cup milk
- 1/4 cup sugar
- 1/4 teaspoon vanilla
- Add all the ingredients to the quart Ziploc bag. Try to remove some of the air and seal it securely. Mix the ingredients together by gently shaking and rocking the bag. “Gentle” may want to be emphasized here.
- Add the ice into the gallon ziplocTM bag.
- Add the salt (sodium chloride) to the bag of ice.
- Place the sealed ice cream bag inside the gallon bag of ice and salt. Seal the gallon bag securely.
- Gently rock the gallon bag from side to side. It’s best to hold it by the top seal or to have gloves or a cloth between the bag and your hands because the bag will be cold enough to damage your skin.
- Keep rocking for between 10-15 minutes at which point the mixture should have solidified into ice cream.
- Serve. This is a no lose activity because at worst you will end up with a vanilla “milk shake” and happy kids irregardless of how solid the ice cream actually ends up getting.
Why it works.
Ice needs energy to melt, to phase change from a solid to a liquid. It draws that energy out of the ice cream mix (and little hands if they aren’t holding the bag by the zipper seam!) causing it to get cold. Adding salt to the ice lowers it’s temperature of freezing so that even more energy than usual is needed to get it to melt. This cause the ice to get colder and draw out more energy, faster from the ice cream mixture causing it to freeze.
This recipe is based on one by Anne Marie Helmenstine, Ph.D., in the Science Projects section of About.com. You can read the full post here.
My friends Kristi and Alex decided to try this out with their son Max and as you can see from the short iPhone videos below the process works as advertised. They doubled the recipe and added some thawed out frozen strawberries. I don’t see why you couldn’t make any recipe on this website using this method.
Max tumbling the ice cream while it freezes.
The moment of truth.
Enjoying the fruits of their labor.