Can You Microwave Milk? How Do You Heat It Up Safely?

Microwaves provide a quick and convenient way of heating up milk, but the trick is to do so gradually and in bursts. 

Less is more every time here, otherwise you risk either scorching the milk, or creating an unholy mess as it spills over into the inside of the appliance.

In this guide, I’ll explain why it’s perfectly OK to heat up in milk in the microwave, while answering some common questions as we go.

Is It Safe To Microwave Milk?

If your milk is store-bought and pasteurized, it is perfectly safe to microwave it. 

Just make sure you keep it chilled at all times, and pay close attention to the shelf life printed on the container.

As a general rule, you can expect unopened milk to last 5-7 past its listed date (2-3 days once opened).

When it comes to playing it safe though, you should always avoid heating milk more than once. If you’ve any left over, the best advice all round is to discard it. It’s just not worth the risk.

For the most part, your biggest concerns won’t be safety-related but instead:

  • Scorching on the bottom of the heating container. This is never going to taste nice, so be mindful of how long the milk’s been heating for.
  • Skin forming on the surface of the milk. This mix of proteins and fats can be stirred back in, but will alter the texture – unpleasantly so for many of us.

So with that in mind, let’s move onto the right way to heat milk in a microwave, and avoid these problems.

How To Heat Milk In The Microwave

Slow and steady is the most important thing to remember when you’re heating milk this way.

It’s a bit of a pain having to stop, stir and start again, but doing so will help you avoid scorching the milk or having it boil over in the microwave.

Step 1: Pour your milk into the – microwave-safe – container, and make sure you leave a little space at the top. When it gets close to boiling, the milk will expand quickly and you’ll appreciate having a little breathing room here!

Step 2: Select a medium heat and set a timer for 15 seconds.

Step 3: After 15 secs open the microwave and stir the milk.

Step 4: Repeat this process of 15 seconds heating / stirring until the mil is beginning to steam but not boil.

There you go! Pretty simple stuff really, but in the rest of this guide I’ll go into a little more detail about how the process works, and how you can get better results from your microwaved milk.

What Happens When You Microwave Milk?

Microwaves work by generating electromagnetic radiation waves. 

These waves agitate the molecules in the milk, causing them to move and create heat energy.

Some of this heat energy escapes as humidity, while most of it simply circulates through the rest of the liquid, resulting in an evenly heated drink.

What Happens If You Microwave Milk Too Long?

The simple answer? You make an enormous mess of your microwave! When milk approaches its boiling point it very quickly expands. It gets scalding hot too, and it gets everywhere.

You can avoid this problem somewhat by using a container that’s larger than the volume of milk you want to warm up.

It’s also worth microwaving the milk in smaller bursts, and sticking around to check on the progress. It can get away from you before you know it!

Can You Get Sick From Microwaving Milk?

There is nothing about the process of microwaving milk – or any other product – that can make you sick, when compared directly with any other method.

In other words, if your milk is pasteurized and within its use-by date, it’s as safe to heat in the microwave as it is on the stovetop, or in a frothing jug.

A powdery mug of hot chocolate on a saucer, sitting on a wooden table

How To Microwave Milk For Hot Chocolate

You’ve got two options for making hot chocolate in the microwave:

  • Heat the milk in its entirety, and then add the hot chocolate or cocoa powder.
  • Add the chocolate powder halfway through the heating process. Expect this method to take a little longer.

How To Microwave Milk Without Curdling

The likely culprit here is the milk itself. Once it approaches its use-by date, the chance of the milk curdling in the microwave increases rapidly.

If it’s at all possible, try using your freshest milk to get the best results in the microwave.

How To Microwave Milk Without Skin Forming

I can’t think of many things that are less appealing than skin on milk, but there are a few ways of preventing this.

  • Use skimmed milk. Without any fat to work with, a skin can’t form!
  • Create a “cartouche” from wax paper. This should be the same diameter as the milk container and floats on top of the surface to prevent a skin from forming.

How To Microwave Milk For Lattes

It’s very difficult to achieve a smooth finish on microwaved milk, but you can whip up a froth pretty easily.

  • Add the milk to a mason jar, filling only to the halfway point (you need lots of room for the actual froth, remember).
  • Put the lid firmly on the mason jar and then shake it as hard as you can for around 20 seconds.
  • Remove the lid, put the mason jar in the microwave, and then blast it for around 30 seconds. Give it another 10-15 seconds after that if you want to get it to a higher temperature.

Don’t expect perfect results here, but you can make a surprisingly good specialty coffee using this rough-and-ready method!

Wrapping Up

Although the process seems simple, it’s important to take things slowly when you’re heating up milk in the microwave.

Remember to heat in shorter bursts and stir regularly too. Don’t hang onto any milk you’ve heated, but no longer need either!