The Science of Ice Cream

Making Ice Cream At Home

With a few simple ingredients, we can make delicious ice cream at home and learn about the science behind it. 

Ingredients:

• Sugar
• Milk and heavy whipping cream.
• Vanilla extract
• Salt
• Ice cubes 

Materials:

• Quart and Gallon Ziploc bags
• Measuring Cups
• Oven Mitts

Process:

• Add ¼ cup of sugar, ½ cup of milk, ½ cup of heavy whipping cream, and ¼ teaspoon of vanilla extract to a quart Ziploc bag and seal the bag well.
• Add four cups of ice cubes and ½ cup of salt to the gallon Ziploc bag.
• Place the quart Ziploc bag inside the gallon Ziploc bag and seal it tightly.
• Put on oven mitts and shake the gallon Ziploc bag well for five minutes. 
• Feel the quart bag as you continue to shake to feel the change in texture.
• Homemade ice cream is ready to enjoy!

Science Behind Ice Cream

Let’s look at the exciting science that goes behind making ice cream.

• Freezing Point: 
  • Normally, water freezes into ice at a temperature of 32 degrees Fahrenheit. 
  • Adding salt to the ice lowers its freezing point, allowing it to melt at a lower temperature than normal. 
  • The super-cooled mixture of salt and ice in the gallon bag helps freeze the ice cream mixture in the quart bag.
• Emulsions: 
  • An emulsion is a mixture of two or more liquids that don’t usually mix.
  •  Ice cream is an emulsion of fat (from the heavy whipping cream & milk), air, and water. 
  • The shaking process adds air bubbles into the mixture, giving it a light and fluffy texture. 
  • The fat from the cream coats the ice crystals, preventing them from growing too big and giving the ice cream a smooth consistency.
• Crystallization: 
  • The ice cream mixture freezes as it comes into contact with the cold water and salt mixture in the gallon bag, forming tiny ice crystals. 
  • Shaking helps distribute the ice crystals evenly, creating a creamy texture.
  • Ice cream stays frozen because of the ice crystals that form when the water in the ice cream base freezes.

Fun Facts

Here are some interesting facts about ice cream:

• Ice cream was invented in China.
• Gelato is an ice cream made with less air and fat than traditional ice cream, making it denser and more flavorful.
• When cold ice cream comes into contact with the roof of your mouth, a “brain freeze” occurs, causing blood vessels to shorten and expand, leading to a quick headache-like feeling.
• It takes 12 pounds of milk to make one gallon of ice cream.
• Vanilla ice cream was introduced to the United States when Thomas Jefferson discovered the flavor in France and brought the recipe to the United States.

Review

Let’s quickly recap what we learned about the science behind ice cream:

• What is the normal temperature at which water freezes into ice? 32 Degrees Fahrenheit
• What can be added to water to lower its freezing point? Salt
• What is ice cream an emulsion of?  Fat, Air & Water
• While shaking the Ziploc bag, what gets added to the ice cream mixture to make it light and fluffy? Air Bubbles
• What helps ice cream stay frozen? Ice Crystals from the Water