Ice Cream in a Can
Answers to questions found on page 6.

If you put the ingredients in a container and freeze them without mixing, what would happen?

It would freeze into one solid block... you can try it if you'd like... just don't plan to eat it!

 

Why is churning or mixing needed to make ice cream?

Milk particles are surrounded by globules of fat. These fat globules need to be broken apart so the sugar and vanilla can become part of the mixture. The churning allows the particles to mix as they freeze creating a texture that can be scooped with an ice cream scoop.

 

Why is salt put in with the ice?

Ice cream freezes at -3°C (or 27°F), but ordinary ice starts to melt at 0° C (32° F). If the tub contained just ice by itself, it would soon melt into an ice-water mixture and the ice cream would not freeze. That's where the salt comes in. Salt lowers the freezing point of water. Mixing salt with ice makes a substance that has a freezing point of -5° C (23° F), and that's cold enough to freeze the ice cream. Why the ice-water mixture has a lower freezing point is complex and requires the knowledge of advanced phsyics. Let's save that for high school!

Ice Cream Recipe

1 cup milk
1 cup whipping cream
1/2 cup sugar
1/2 teaspoon vanilla
1 cup rock salt

Put all ingredients in a 1-pound coffee can with a tight-fitting plastic lid. Place the lid on the can. Secure with duct tape. Place the can with the ingredients inside a 3-pound coffee can that has a tight-fitting plastic lid.

Fill the space between the cans with crushed ice. Pour at least 1/2 cup of rock salt over the ice. Place the lid on the larger can. Roll back and forth on a table or cement slab for 10 minutes. Open the outer can. Remove the inner can, wipe it off, and then remove the tape and lid.

Using a rubber spatula, stir the mixture. If not yet solid, repack the smaller can in the larger container and fill with ice and 1/2 cup salt. Roll back and forth for five more minutes. Serve immediately. Makes about three cups.

Did You Know?
Alfalfa is a type of clover.

For more information on alfalfa check out www.calhay.org.