Preparing expressed breastmilk

Expressed breastmilk gives your baby all the benefits of breastmilk, even when you’re apart. Handling and preparing expressed milk with care helps protect its nutrients and keeps your baby safe.

• Wash your hands thoroughly before handling expressed milk or feeding equipment.
• Use clean bottles, teats, and feeding equipment every time. Breastmilk, like other food, can grow germs, particularly after freezing and thawing. Wash bottles, teats, spoons, cups or other feeding equipment need in hot, soapy water and rinse well. If not using straight away you can air-dry or dry with new paper towel or cloth.
• Never use a microwave to thaw or heat breastmilk. It can create hot spots and damage nutrients in the milk.
• Don’t overheat or boil breastmilk.
• Only heat or warm breastmilk once. Discard any leftovers after feeding.

Frozen breastmilk may be in a bottle, storage bag or other container. 

• Thaw in the fridge: This can take several hours or overnight.
• Thaw quickly in warm water: If you need breastmilk sooner, stand the container in a bowl of warm (not hot or boiling) water and gently move it around until thawed. As the water cools, add a little hot water to the bowl and keep moving the container until it all becomes liquid. You may need to then put the milk into a clean feeding container.   
• Never thaw at room temperature: This can allow germs to grow.
• Do not refreeze thawed milk

Milk that has been thawed in the fridge can be  

• stored for 24 hours in the fridge OR
• kept for no more than 4 hours at room temperature OR
• used immediately to feed the baby.  

• To heat cold or defrosted expressed milk: Stand the bottle or bag in a container of hot (not boiling) water until the milk feels warm to the touch. Swirl gently to mix.
• Test the temperature: Drop a little milk on your wrist. It should feel warm, not hot.
• Avoid microwaves: Microwaving can create hot spots and damage nutrients.
• Don’t heat breastmilk more than once.

It's not essential to warm the milk to feed your baby. Some babies may be fine with having cooler milk, especially as they get older. 

• Offer small amounts: Prepare only what your baby needs for each feed.
• Discard leftovers: Any milk your baby doesn’t finish should be thrown away.
• If your baby needs more: Prepare a fresh small amount.

Some mums notice a change in the taste and smell of their breastmilk after it has been stored in the fridge or freezer. This maybe be caused by lipase, a natural enzyme in breastmilk. The milk is still safe and nutritious but some babies may refuse it. It’s not common but if this happens with your expressed milk, it will usually keep happening. 

You can stop the enzyme from changing the taste by scalding your breastmilk straight after expressing. 

• Heat the milk gently on the stove, not in the microwave, until it reaches 70 to 80°C.
• If you don’t have a thermometer, look for steam rising and tiny bubbles around the edges. The milk should be very hot but not boiling (boiling is over 100°C).
• Keep the milk at this heat for about 2 minutes, then remove from heat.
• Cool the milk quickly by placing the container in a bowl or sink of ice and water.
• Store the milk as usual.

Does scalding affect breastmilk? 
Scalding may reduce some of the protective properties of breastmilk. However, the milk is still nutritious and safe, and scalding is often better than having milk refused or thrown away.
 

© Australian Breastfeeding Association February 2026