Bake Your Ice Cream
Did you ever bake your ice cream? An insulated bag or a cooler filled with ice can keep a treat like ice cream cool. Using the same principles, it is even possible to bake ice cream in a hot oven and have it come out frozen! This activity will teach you how.
- Two round bowls that can be placed in the freezer, preferably identical
- Plastic film or plastic wrap
- Ice cream
- Sponge cake, about one inch larger in diameter than the diameter of the bowls
- Three egg whites at room temperature
- One cup of white sugar
- Half teaspoon cream of tartar
- Handheld electric mixer
- Mixing bowl
- Two cake pans, one at least the size of the sponge cake
- Oven mitts
- Knife to cut the cake
- To create an ice cream mold, cover the inside of a round bowl with two layers of plastic film or plastic wrap and fold the excess over the rim. The plastic will make it easy to remove the ice cream from the bowl.
- Repeat previous step with the second bowl.
- Fill the molds with ice cream. If your ice cream is too hard, leave it out for a few minutes and try again. Press the ice cream down so there are no air pockets left inside, and level the top surface.
- Place the molds filled with ice cream in the freezer for at least 30 minutes. This ice cream will be placed in a hot oven later in the activity.
- Preheat the oven to 400° F.Any idea how you can place ice cream in an oven heated to 400° F without it melting?
- Pour the egg whites into a mixing bowl and ask an adult to help you whip them with an electric mixer at medium speed. Watch how the translucent liquid egg white becomes a white foam.Did you see how the volume of the egg whites changed in the process? Why would this be?
- Add the cream of tartar and ask the adult to keep whipping until soft peaks form when you lift up the beaters. The peaks will curl over, which is fine.
- Add a small amount of sugar and ask an adult to whip it into the foam using the high-speed setting. Repeat this until all the sugar has been added and is dissolved into the egg whites. If the mixture looks shiny and peaks stay standing up when the beaters are taken out, you have done it right! This mixture is called meringue.
- Ask the adult to unplug the electric mixer, remove the beaters. You can wash the beaters with the other tools later.
- In a moment, you will assemble the cake. Start this about 20 minutes before you plan to eat it. Check if your oven has preheated before you start assembling.
- To assemble the cake, place your sponge cake in the middle of your cake pan.
- Take one ice cream-filled mold out of the freezer and use the plastic to take the ice cream out of the mold. Turn the ice cream over and place it, flat side down, in the middle of the sponge cake. Remove the plastic.
- Use a spatula to cover the ice cream and the visible parts of the sponge cake with a thick layer of meringue.
- Ask an adult to place the pan with your cake in the preheated oven. Leave it in for about 10 minutes, until the outermost layer of meringue turns brown.What do you expect to happen with the ice cream in the middle of the cake? What do you expect to happen with just ice cream when placed in a hot oven?
- To test your prediction, take the second ice cream-filled mold out of the freezer, remove the mold, and turn the ice cream over onto a second cake pan. Remove the plastic and ask an adult to place this pan in the oven. Observe what happens.
- When the cake is done, ask an adult to take it out of the oven. You can leave the pan with just ice cream in a little longer, as it was put in later. Turn the oven off.
- Cut a quarter of your cake and look inside.Is the ice cream still cold and hard, or did it turn into a liquid? How is it different compared to the ice cream that is still in the hot oven? What do you think kept the ice cream in the center of the cake cold, and why did it keep the ice cream cold?
Was the ice cream in the center of the cake still hard and frozen? Did the uncovered ice cream melt quickly when placed in a hot oven? This is expected.
Sponge cake and the meringue both have plenty of air bubbles trapped in them. This layer of stationary air keeps the heat out. It is a good thermal insulator, and as such, it does not easily let heat flow through it. In this way, it protects the cold ice cream underneath—at least, for some time. If you left the cake in the hot oven for too long, the ice cream center would eventually warm up and melt. As you probably observed, without the protection of sponge cake and the meringue, this happens way faster.
Insulated bags or coolers often use a stationary layer of air to keep heat from flowing through the walls, much like the cake and meringue!
Heat is the energy that automatically flows from a higher temperature to a lower temperature. This energy can flow in three ways. Sometimes, it is carried by a movement of fluids (liquids or gases) known as convection. An example is when hot air in your oven flows to colder areas. Other times, radiation carries this energy. When the grill in your oven glows red, you can feel it radiate heat. Direct contact is the third way this energy can flow from one place or object to another.
We can prevent this energy flow by using thermal insulators, which are made of materials that hinder the flow of heat. An insulator can keep the heat out, like in a cooler or insulated bag, or in, like in a Thermos® or an igloo.
To keep ice cream solid inside a hot oven, you need to protect it with thermal insulators. Luckily, some baked desserts are excellent insulators. Sponge cake and meringue are good examples because they have plenty of air bubbles trapped in them. This layer of stationary air keeps the heat out. Similarly, stationary air can keep the heat in. Examples are cardboard cups, down feathers, or layered clothing.
Ask an Expert
For Further Exploration
- Do you think you can make small ice cream-filled cakes with cookies on the bottom? What type of cookie would you take? Try it out and see if it works!
- Why would the recipe call for baked cake as bottom layer? Would putting the ice cream on batter and baking the batter and the meringue all at the same time work as well? If you feel unsure, try it out!
- Use items you find around the house to make an insulator that can keep a cup of ice cream cold for 20 minutes. To measure the performance of your creation, take two identical ice cubes and place one inside and one outside the insulator. Wait 10 or 20 minutes, then compare how much the ice cubes weigh, or how much melted water they provide. The more your ice cube weighs compared to the one that was not insulated, or the less water it provides, the better your creation works!
- MS-PS3-3. Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
- MS-PS3-4. Plan an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample.
- Blog Post: Kitchen Science Roundup!