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Making Ice Cream with Snow Legend credits Roman Emperor Nero as the first to make ice cream.
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Making Ice Cream with Snow

Legend has it that the Roman emperor, Nero, is credited as the first person to make ice cream. Nero commanded slaves to bring snow down from the mountains, which was then used to freeze the flavored cream mixture. The secret was to lower the freezing point of snow in order to freeze the cream. How? The scientific secret is SALT! Here’s a scientific recipe that you can use at home to make your own ice cream.

Materials

- 1 gallon size zipper-lock bag
- 2 quart size zipper-lock bag
- Half & half or milk
- Snow or crushed ice
- Salt
- Vanilla
- Sugar
- Towel (or winter gloves)
  1. Fill the gallon size bag half full with crushed ice.
  2. Add about 6 tablespoons of salt to the ice. Seal the bag and mix for 5 minutes. You’ll need to wear your gloves when you’re handling the bag. If you’re curious as to why you have to wear gloves, measure the temperature of the mixture with a thermometer. The salt and ice mixture gets down to about 14 degrees F (-10 degrees C)!
  3. Use the quart size zipper-lock bag to mix the following ingredients:
    • 1/2 cup of half & half cream (or milk)
    • 1 tablespoon sugar
    • 1/2 teaspoon vanilla extract
  4. Seal tightly, allowing as little air to remain in the bag as possible. Too much air left inside may force the bag open during shaking.
  5. Place this bag inside the other quart size bag, again leaving as little air inside as possible and sealing well. By double-bagging, the risk of salt and ice leaking into the ice cream is minimized.
  6. Place the two bags inside the gallon size bag with the ice and seal the bag. Wrap the bag in the towel or put your gloves on, and shake and massage the bag, making sure the ice surrounds the cream mixture. Five to eight minutes is adequate time for the mixture to freeze into ice cream.
  7. You’ll be able to feel the consistency of the ice cream mixture through the bag. When it feels frozen enough to eat, remove the inner bags and rinse it well with water. You don’t want any salt water accidentally getting into your ice cream.
  8. Use your spoon to eat the ice cream right out of the bag!

How does it work?

What does the salt do?
Just like we use salt on icy roads in the winter, salt mixed with ice in this case also causes the ice to melt. When salt comes into contact with ice, the freezing point of the ice is lowered. The lowering of the freezing point depends on the amount of salt added. The more salt added, the lower the temperature will be before the salt- water solution freezes. For example, water will normally freeze at 32 degrees F. A 10% salt solution freezes at 20 degrees F, and a 20% solution freezes at 2 degrees F. When salt is added to the ice (or snow), some of the ice melts because the freezing point is lowered. Always remember that heat must be absorbed by the ice for it to melt. The heat that causes the melting comes from the surroundings (the warmer cream mixture). By lowering the temperature at which ice is frozen, you were able to create an environment in which the cream mixture could freeze at a temperature below 32 degrees F into ice cream.

Additional Info

Freezer bags work best because they are thicker and less likely to develop small holes, allowing the bags to leak. You can get away with using regular Zip-loc bags for the smaller quart sizes, because you are double-bagging. Especially if you plan to do this indoors, we strongly recommend using gallon size freezer bags.

Did You Know? In 1846, Nancy Johnson invented the hand-cranked ice cream churn and ice cream surged in popularity. Then, in 1904, ice cream cones were invented at the St. Louis World Exposition. An ice cream vendor ran out of dishes and improvised by rolling up some waffles to make cones.

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