Plastic Bag Ice Cream In 3 Easy Steps
1-3 hours
Ages 5+
What Will You Make?
If you shake cream and ice long enough, it turns into ice cream. Sweet! But just how much shaking, and for how long?
What Will You Learn?
You’ll learn to use salt to lower the freezing point of water and how to get the creamiest ice cream by making an emulsion.
Mix Your Ingredients
Step 1
Pour ¼ cup milk, ¼ cup heavy cream, 1 Tbsp sugar, and ¼ tsp vanilla into a quart zip-top freezer bag. Seal the quart bag.
Step 2
Now place your ice cream bag into a gallon zip-top freezer bag with 4 cups of ice and 4 Tbsp of salt. Seal the gallon bag with everything inside.
Step 3
Set aside this first bag of ingredients and ice, and prepare two more the same way.
Whole Lotta Shakin'
Step 1
Once prepared, gently shake the second bag for 10 minutes.
Shake the third bag vigorously for 10 minutes.
Don’t shake the first one at all.
Step 2
Pour or scoop out the contents of the three bags and compare the results.
Fast and Slow
Step 1
How did your shaking affect the overall completeness (how frozen it is) and smoothness of your ice cream? Which technique created the smoothest ice cream?
What Is Happening Here?
What Makes Ice Cream Creamy?
This ice cream is made of sugar, fat, ice crystals, and air. Ice cream’s creaminess depends on the size of the ice crystals that form during freezing — the more you shake, the smaller the ice crystals become and the more air is incorporated into the ice cream. Doing both makes for a creamier cream!
Why Does Shaking Some Dairy in a Bag Make Ice Cream?
Ice cream is an emulsion, which means small droplets of one liquid dispersed or spread throughout another. Think salad dressing: Oil and vinegar don’t dissolve, but they can disperse into an emulsion with the help of a whisk. When you shake the bag, it emulsifies the ice cream, dispersing the ice crystals, fat molecules, and air.
Why salt? Salt lowers the melting temperature of the ice; the colder the icy solution around the ice cream, the faster the cream freezes.
What Is Next?
More Frozen Treats
Are you dairy free? Try a refreshing Cranberry Pomegranate Sorbet instead? Or learn to make ice cream with liquid nitrogen!
MATERIALS
- Quart zip-top freezer bags
- Gallon zip-top freezer bags
- Milk, ¼ cup
- Heavy cream, ¼ cup
- Sugar, 1 Tbsp
- Vanilla, ¼ tsp
- Ice, 4 cups
- Salt, 4 Tbsp
