Everything You Need to Know About Storing And Feeding Expressed Breast Milk

There is no use crying over spilt milk, goes the old saying. But if you are a mum expressing your precious breast milk, you don’t want to see even a drop get spilled or wasted. So, what is the best way to store your precious ‘liquid gold’ and how long will it keep?

NOTE: The following instructions are for well, full term babies, if you are expressing for a premature or unwell baby, please check with your health professionals whether these are appropriate for your baby.

I’ve expressed but I’m out and can’t get to a fridge right now.

Breast milk is pretty amazing stuff, it will be fine to leave at room temperature for four hours (up to six hours on a cool day), then pop it in a fridge. If you are travelling, visiting or working and there isn’t a fridge handy, it would be helpful to take a cooler bag with ice packs. Your milk should be safe for 24 hours.

How long can I keep expressed milk in the fridge?

You will need to store breastmilk in a fridge at the back of the fridge where it is coolest – never in the door. The American Academy of Paediatrics advises you can keep expressed breastmilk in the fridge for up to eight days. However, the fats, enzyme activity and anti-infection properties will deteriorate the longer it’s left so it’s safest to use breast milk stored in the fridge during the first 72 hours (4 days).

How do I freeze breast milk?

If you won’t be using your expressed milk during the four days it is safe to keep in the fridge, it will need to be frozen within 24 hours. Firstly, you will need to cool your expressed milk in the fridge, if you are expressing very small amounts, you can mix cooled milk together over a day (cool each batch before mixing together), then freeze in an amount needed for a baby feed.

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Store expressed milk in either glass storage bottles with secure lids or breast milk storage bags – not sandwich bags, for instance, as the storage bags used need to be free of any chemicals that may leach into the breast milk while it’s in the freezer or being thawed.Label and date bags and leave a wee bit of space at the top of the bag to allow for expansion as the milk freezes. You can freeze breast milk in glass containers or other plastic containers that are BPA free. These need to be washed and rinsed or sterilised by boiling, then dried well before use.

You can store breast milk for two weeks in a freezer compartment in a fridge (below 15 degrees C); three months in a freezer with a separate door (below -18C) and 6 to 12 months in a deep freeze (below -20C).

What is the best way to thaw frozen breast milk?

Obviously feeding your baby freshly expressed milk will be the best option after feeding at the breast, so please feed this milk first before thawing frozen milk. To thaw your milk, it can be left to thaw over-night in the fridge, you can hold the bottle under warm running water or you can stand the bottle in a jug of warm (not hot) water.

To warm thawed milk, place it in a container of warm water until it’s a preferred temperature for your baby. Gently swirl the bottle of thawed milk to mix the fats and feed your baby (see here how to give a bottle to your breastfed baby).

Never thaw or heat expressed milk in a microwave – apart from potentially destroying nutrients, a microwave will heat milk unevenly so your baby could get burnt when drinking spots of hot milk.

My baby didn’t drink all his milk, can I reheat this?

If your baby doesn’t drink a full bottle of expressed milk, you might be wondering, do I have to discard the ‘left over’ milk? You can’t reheat this milk but you can offer it to your baby within the next hour. If it’s longer than this, (sorry) you will have to tip this milk out because there will be some transfer of bacteria from your baby’s mouth and this can contaminate the remaining milk.

The best way to avoid ‘spilt milk’ is to freeze expressed milk in smaller amounts – it’s easier to thaw a bit more milk than to watch it go down the sink.

Help! My frozen milk has gone ‘off’ .

“I had a stash of expressed milk in my freezer,” says Amber, “but when I thawed a bag the other day, my baby refused to drink it. I checked and it smelt and tasted ‘soapy’, so I thawed another bag and this one was ‘off’ too. I don’t get it. I followed the storage guidelines to a tee. And I need to express milk and have my baby drink it because I am going back to work in a couple of weeks.

What is happening?

If breast milk has actually gone ‘off’ it will smell rancid like sour milk but what Amber is describing sounds as though she could have an excess of ‘lipase’, an enzyme that naturally occurs in breast milk with some important beneficial functions, from breaking down fats in breast milk so fat soluble vitamins (eg Vitamins A and D)are more available to the baby to helping keep the fat particles well mixed with whey and keeping fat globules smaller so they are easily digested.

However, when a mum has an excess of lipase in breastmilk will mean that the fats in her milk will break down more quickly, giving the milk this soapy taste after it has been expressed. Although it won’t harm your baby, it’s very common for babies to reject this soapy tasting milk.

What’s a mum to do?

Before Amber decides there is no point expressing her breast milk or she ditches her entire freezer stash, there are some answers. Firstly, for mums like Amber with a high lipase content in their milk, the lipase enzymes can be inactivated by scalding breast milk as soon as it is expressed: heat breastmilk in a pot (at about 82 degrees ) until you see little bubbles appear at the edges of the pot – don’t boil the milk. Cool it quickly and freeze.

Don't waste your freezer stash! 

If your frozen milk is out of date or if it’s sour (it will smell and taste rancid, not just soapy), you will need to ditch it. But if it’s just soapy, you can try mixing some of this thawed milk with freshly expressed milk. Start with half thawed and half fresh and adjust from there. If your baby is older and eating family foods you can try mixing thawed milk into food or smoothies.

If your baby rejects the thawed milk even mixed with fresh milk and the thought of throwing out your liquid gold sees you literally crying over spilt milk, please don’t despair. You could make this marvellous mummy milk into a healing lotion that can help with dry itchy skin, sunburn, psoriasis, rashes and grazes. It will be gentle on delicate, sensitive skin and the antibacterial properties in breast milk can reduce secondary infection due to scratching.

Breastmilk Lotion

• 100 ml grapeseed oil • 1 tbsp beeswax (don’t overload the spoon) • Few drops of Vitamin E oil • 100 ml breast milk, at room temperature

Mix the oil and beeswax together and gently heat on low until the beeswax has just melted – this will take about 3 minutes in a microwave. Add the Vitamin E oil. Slowly pour in the breastmilk while whisking the mixture rapidly. The mixture should thicken as you whisk and will thicken more as it cools. Pour into a lidded container and store in the fridge for up to three months.