If your baby rejects frozen breastmilk, it's often due to a metallic/soapy taste from high lipase or oxidation; try mixing it with fresh milk, adding a drop of alcohol-free vanilla, serving it cold, or scalding milk before freezing to prevent it, and use unwanted milk for baths or baby food once solids start.
Background: Infant refusal to feed previously frozen human milk is thought possibly attributable to lipase, an enzyme that cleaves fatty acids from milk triglycerides potentially changing the taste of the milk.
Mixing frozen with fresh, scalding and adding alcohol free vanilla have all been reported to work if baby doesn't take it straight up.
Even when breast milk is stored correctly, it can sometimes develop a distinct smell or taste over time due to a natural enzyme called lipase, which breaks down fats in the milk. Some babies don't mind this change, but others, especially if they're sensitive, can become fussy or uncomfortable after drinking it.
You can scald your milk (lots of info on how to do this if you search), but personally I just freeze ASAP and it seems mostly fine. When giving baby thawed milk I add 1 drop of alcohol free vanilla extract per frozen oz to ensure it tastes better.
It's best to defrost frozen breast milk slowly in the fridge before giving it to your baby. If you need to use it straight away, you can defrost it by putting it in a jug of warm water or holding it under running warm water. Once it's defrosted, give it a gentle shake if it has separated. Use it straight away.
The "4-4-4 rule" for breast milk is a simple storage guideline: fresh milk is good for 4 hours at room temperature (up to 77°F/25°C), for 4 days in the refrigerator (39°F/4°C or colder), and up to 4-6 months (or longer) in a standard freezer (0°F/-18°C). It's a handy mnemonic, though some organizations like the CDC recommend up to 6 months in the freezer and the AAP up to 9 months, with deeper freezers offering even longer storage.
Stored milk has time for the lipase to take effect resulting in changes to taste and smell. Some women report a soapy or metallic smell while others notice a distinctly fishy whiff. This usually doesn't occur in freshly expressed milk.
The 5-5-5 rule for breast milk is a simple guideline for storage: freshly expressed milk lasts up to 5 hours at room temperature, up to 5 days in the refrigerator, and up to 5 months in a standard freezer, though the CDC notes it can be frozen for up to 12 months for best quality within 6 months. Always label containers with the date and time, use small batches (2-4 oz), and place milk in the back of the fridge or freezer for consistent temperature.
Previously frozen breast milk has similar nutrient and antibody content to fresh milk. It does lose a small amount of those qualities but can still provide a baby with the nutrition it needs.
Rule #2: The Breast Milk Storage Guidelines.
The 4-4-4 Rule. Or the 6-6-6 rule. Basically, breast milk is good at room temperature for 4 or 6 hours, in the refrigerator for 4 or 6 days, and in the freezer for 4 or 6 or 12 months.
Symptoms include:
The longer milk is kept at room temperature or even in the refrigerator before being frozen, the more lipase activity it will have. Milk that has a high level of lipase can develop a soapy smell and taste, but is not harmful to the baby.
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Scald your breastmilk to reduce high lipase.
Deep freezer.
You can store freshly expressed breast milk in the back of a deep freezer for up to 12 months. But it's best to use the frozen milk within six months.
A single breastfeeding session might produce between 54-234 mL/1.82-7.91 oz of milk. A mom might nurse between 4-13 times every day depending on the baby's appetite, how much milk is removed each session, and other external factors. The average breastfeeding session lasts between 12-67 minutes.
Common Breast Milk Storage Mistakes to Avoid
If exclusively pumping, the first 12 weeks aim for pumping every 2-3 hours, which is about 8x per day. Pumping more than that will be harder to manage your schedule plus it can increase nipple soreness and pain. All of this combined can contribute to lowering your milk supply.
When lipase is overactive, as in the case of high lipase breast milk, it can cause some unexpected smells or tastes that are more pronounced in refrigerated or frozen breast milk. Essentially, the breast milk might start to smell soapy, which is why your baby may suddenly reject it.
High lipase activity in breast milk can cause the milk to develop a soapy or metallic taste and smell when stored. This change occurs because the enzyme breaks down the fats in the milk more quickly, releasing fatty acids that alter the milk's flavor.
Is it still safe to offer the “soapy” smelling milk to my baby? If your little one doesn't mind the taste and will drink it without resisting, then it is perfectly safe to use. However, it is important to differentiate between spoiled milk and high lipase.
As newborns get older, they'll nurse less often, and may have a more predictable schedule. Some might feed every 90 minutes, whereas others might go 2–3 hours between feedings. Newborns should not go more than about 4 hours without feeding, even overnight.
At around 6 weeks, many moms introduce the pump and follow the Magic 8 method — pumping 8 times in 24 hours to help build and maintain milk supply.
According to Verywell Family, it is safe to combine breast milk from different pumping sessions if the milk is collected and stored under clean conditions and the baby is full-term and healthy. However, it is not recommended to combine milk that has been stored for more than 24 hours.