Making your own dessert doesn’t always require a bulky kitchen appliance or hours of waiting for a freezer to do its work. One of the most satisfying culinary experiments you can perform in your own kitchen is learning how to make ice cream with a bag of ice. This method is not just a fun activity for families or a quick way to satisfy a sugar craving; it is a fascinating lesson in chemistry and physics that results in a delicious, creamy reward.
The Magic of Science in a Plastic Bag
To understand how to make ice cream with a bag of ice, you first have to understand the role of the salt. You might have noticed that when you simply put a bag of liquid cream on top of ice, it stays liquid for a very long time. This is because the freezing point of water is 32 degrees Fahrenheit. However, the freezing point of the cream mixture is actually lower than that of pure water because of the dissolved sugar and fats.
When you add salt to the bag of ice, you are performing a trick called freezing point depression. The salt lowers the freezing point of the ice, forcing it to melt. As the ice melts, it absorbs heat from its surroundings to fuel the phase change from solid to liquid. In this case, the closest source of heat is your bag of ice cream mix. By drawing the heat out of the cream, the salt-and-ice mixture drops to temperatures as low as 0 degrees Fahrenheit, which is more than cold enough to freeze your dessert in a matter of minutes.
Essential Ingredients and Supplies
Before you begin your frozen adventure, you need to gather your materials. The beauty of this method is that most of these items are likely already in your pantry.
For the Ice Cream Base
- 1/2 cup of half-and-half (or a mix of heavy cream and whole milk)
- 1 tablespoon of granulated white sugar
- 1/2 teaspoon of pure vanilla extract
- Optional mix-ins like mini chocolate chips or crushed cookies
For the Freezing Station
- 1 large bag of ice (enough to fill a gallon-sized bag halfway)
- 1/2 cup of rock salt or kosher salt
- 1 gallon-sized resealable plastic bag
- 1 quart-sized resealable plastic bag (heavy-duty freezer bags are best)
Protective Gear
- A pair of winter gloves or a thick kitchen towel (the bag will get dangerously cold!)
Step-by-Step Instructions
Once your ingredients are laid out, the process moves quickly. Follow these steps carefully to ensure a smooth, grit-free texture.
Preparing the Cream Mixture
Take your quart-sized bag and pour in the half-and-half, sugar, and vanilla extract. If you are adding fine mix-ins like cocoa powder, add them now. Squeeze as much air out of the bag as possible before sealing it. This is a critical step; excess air can cause the bag to pop during the shaking process. For extra security, many experts recommend placing this bag inside a second quart-sized bag to prevent any salt water from leaking in.
Setting Up the Ice Bag
Fill your gallon-sized bag about halfway with ice. If you have a choice, crushed ice is superior to large cubes because it has more surface area, which leads to faster cooling. Pour your salt over the ice. Give the bag a quick shake to distribute the salt so it can begin reacting with the ice immediately.
The Shaking Process
Place your sealed cream bag into the large bag of ice and salt. Seal the large bag tightly. Now comes the hard work. Wrap the bag in your towel or put on your gloves. Shake the bag vigorously for 5 to 10 minutes. You want to keep the inner bag moving so that the cream freezes evenly rather than forming one large block of ice on one side.
The Big Reveal
After about 8 minutes, feel the inner bag. If it feels firm and holds its shape when squeezed, your ice cream is ready. If it still feels liquid, keep shaking for another 2 to 3 minutes. Once it reaches the consistency of soft-serve, remove the small bag from the ice.
Crucial Tips for Success
The most common mistake when learning how to make ice cream with a bag of ice is ending up with salty dessert. To avoid this, use a paper towel to thoroughly wipe down the outside of the small bag—especially around the seal—before you open it. Some even suggest a quick rinse under cold tap water.
Another tip involves the type of dairy you use. While you can use Vitamin D milk, the fat content in half-and-half or heavy cream provides a much smoother mouthfeel. Lower-fat milks tend to create more ice crystals, resulting in a texture that is closer to an ice milk or a granita than a traditional premium ice cream.
Creative Flavor Variations
Once you have mastered the basic vanilla recipe, you can experiment with endless combinations.
- Chocolate Lovers: Add 1 tablespoon of chocolate syrup or cocoa powder to the base.
- Strawberry Fields: Mash two fresh strawberries and mix them into the cream before sealing the bag.
- Mint Chip: Add a drop of peppermint extract and a teaspoon of mini chocolate chips.
- Coffee Break: Stir in half a teaspoon of instant coffee granules for a sophisticated treat.
Remember that adding large chunks of fruit or candy can sometimes slow down the freezing process, so it is often better to add those as toppings after the ice cream has hardened.
FAQs
Can I use regular table salt instead of rock salt?
Yes, you can use table salt, but it is not as efficient. Because table salt has much finer grains, it dissolves almost instantly, which can cause the temperature to drop too rapidly and then rise again. Rock salt or kosher salt is preferred because the larger crystals dissolve more slowly, maintaining a consistently low temperature for the full duration of the shaking.
Why is my ice cream not getting hard?
There are usually two culprits: not enough salt or too much air. If the ice isn’t melting significantly, you need to add more salt to lower the temperature further. Also, ensure you are shaking vigorously; the movement is what incorporates air and ensures every part of the cream touches the cold outer walls of the bag.
Is it possible to make this dairy-free?
Absolutely. You can substitute the half-and-half with full-fat canned coconut milk or oat milk. Almond milk works as well, but because it has a high water content, the resulting ice cream will be more “icy” and less “creamy.” Coconut milk provides the best non-dairy texture due to its high fat content.
How do I store the leftovers?
Ice cream made in a bag is best enjoyed immediately. Because it doesn’t contain the stabilizers found in commercial brands, it tends to freeze into a solid, un-scoopable brick if placed in a standard home freezer for long periods. If you must store it, put it in an airtight container and let it sit on the counter for 5 to 10 minutes to soften before eating.
Can I make a larger batch in one bag?
It is tempting to double the recipe, but it is generally not recommended for the bag method. A larger volume of liquid takes much longer to freeze, and your arms will likely tire out before the center of the mixture reaches the proper consistency. It is much more efficient to make several small bags simultaneously if you are serving a group.