What's new

Microwave caramel

By Pat, 14 November 2012 Activity

If you’re looking for a sweet activity, this one’s the sweetest! Make yourself some caramel, and learn all about the chemistry of caramelisation.

food safety hazard iconhot hazard iconSafety: This activity involves heat and a microwave. Ask an adult for assistance. Use clean hands and clean equipment when cooking.

Oven mitts, bowl, whisk, can of condensed milk.

You will need these items.

You will need

  • Can of sweetened condensed milk
  • Large, microwave-safe bowl
  • Whisk
  • Microwave
  • Oven mitts

What to do

Condensed milk in a bowl, in a microwave.

Empty the can of condensed milk into the bowl and microwave on medium for 2 minutes.

  1. Open the can of condensed milk and pour into the bowl.
  2. Place the bowl into the microwave. Cook the condensed milk on a medium setting for 2 minutes. Note: Watch the milk the whole time. As it heats, the milk may rise up and flow over the sides. If it does, stop the microwave and allow the bowl to cool for 30 seconds. Then restart the microwave.
  3. After 2 minutes, remove the bowl while wearing the oven mitts and place it to one side, on a cleared bench. Carefully use the whisk to gently stir the milk, mixing it thoroughly.
  4. Return the bowl to the microwave, and heat on medium for another 2 minutes.
  5. Continue to repeat this process until the milk turns a caramel brown colour.
  6. Whisk the mixture until you have a smooth caramel.

    Whisking the condensed milk.

    After 2 minutes, remove the bowl from the microwave and carefully mix with the whisk.

  7. Allow the caramel to cool, and then enjoy!

What’s happening?

When something changes colour, it usually means that a chemical reaction has occurred. That’s what happens in this activity. The pale condensed milk turns brown due to chemical reactions.

There are two similar chemical reactions happening here. They are called caramelisation and the Maillard reaction. In caramelisation, the white sugar molecules in the condensed milk break down and reform new chemicals, which are brown.

Mixing the light brown caramel until smooth.

Repeat this process until the milk turns a light brown colour. Whisk until smooth.

In the Maillard reaction, a similar process occurs. The protein in the milk reacts with the sugar to form new chemicals which are also brown. Both the Maillard reaction and caramelisation result in the milk turning a lovely golden colour. Many foods, such as bread and meats, turn brown when cooked as a result of these reactions.

This chemical reaction needs heat. If we just left the condensed milk in the bowl, and never heated it, it wouldn’t form the caramel. Many chemical reactions need a bit of energy, often in the form of heat, to give them a kick start.


Caramelisation and the Maillard reaction are used all the time in cooking. Almost any time when food turns brown, it is because of caramelisation or the Maillard reaction. This includes cooking meat, browning onions and baking bread. These reactions are important in giving food flavour and making it taste good.

Using heat to make chemicals react is also commonly used in industry. A huge range of products, including steel, gold, plastics and medicines, are made using chemical reactions that need heat.

If you’re after more scientific recipes for kids, subscribe to Double Helix magazine!

Subscribe now! button


  1. I tried this with my daughter – it took us slightly more than 2 min for the experiment to work, but once it did it was cool seeing it change to the brown color. Then we enjoyed tasting it!


Leave a Reply

By posting a comment you are agreeing to the Double Helix commenting guidelines.

This site uses Akismet to reduce spam. Learn how your comment data is processed.