The benefits of breastfeeding are well known, and the storage of breast milk undoubtedly greatly facilitates the continuation of breastfeeding, making it more flexible in terms of time and space.
The key to storing breast milk mainly involves two aspects: safety and effectiveness. To achieve these two key points, it is necessary to maintain cleanliness of the equipment used, use it as soon as possible, and refrigerate or freeze it in a timely manner. Therefore, the refrigerator is a good helper that many breastfeeding families will use.
But did you know, how does the slight difference in temperature in the refrigerator affect the shelf life of breast milk? What is the difference between placing breast milk in different parts of the refrigerator? How do different storage containers affect the composition of breast milk? After a power outage, how should the shelf life of breast milk be calculated?
Today, let’s delve into these details one by one and clarify them.
How long can breast milk be stored in the refrigerator?
The shelf life of breast milk is related to factors such as temperature, storage location, and hygiene conditions. Under different conditions, the shelf life and best usage period vary slightly.
Let’s take the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics (AAP), and the Academy of Breastfeeding Medicine (ABM) as examples, these three authoritative organizations have the following recommendations for the shelf life of breast milk for term infants:
You can refer to any of the above institutions. In general, these institutions have at least reached a consensus on the following aspects:
At room temperature ≤25°C, 4 hours
In the refrigerator at ≤4°C, 4 days
In the freezer at < -18°C, 6 months. At ≤-20°C, it can reach 12 months.
Within this period, the “safety” and “effectiveness” of breast milk achieve a better balance. It is not ruled out that with more research, there will be changes in the future.
Does refrigerator storage affect the quality of breast milk?
It depends on what you compare it to.
If compared to formula milk, several organizations including ABM and CDC
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unanimously suggest that as long as it is reasonably preserved, even if the nutritional and immune components of breast milk are somewhat lost, its overall value is still incomparable to formula milk.
If compared to fresh milk, refrigerated storage will more or less result in some loss of nutritional components or immune activity components of breast milk.
The impact of refrigerated storage (≤4°C)
The impact of frozen storage (≤-18°C)
These two tables may look a bit complex, but they can be simply summarized into three points:
1. Loss of breast milk components
Whether refrigerated or frozen, it will cause some loss of breast milk components. But as the saying goes, even after freezing for 12 months, breast milk is still better than formula milk.
2. Prioritize refrigeration
Compared to freezing, refrigeration can better preserve the integrity of breast milk – the composition of fresh breast milk stored at 4°C for 4 days has hardly changed. Therefore, if you can finish it within 4 days, choose refrigeration. Breast milk that exceeds 4 days can also be used(ABM guidelines suggest a maximum of 8 days), but the bioactivity will decrease significantly.
3. Consume frozen milk as soon as possible
If you estimate that you can’t finish it within 4 days, just freeze it.
Freezing is also the fresher the date, the better it is preserved, so although you can freeze breast milk for up to 12 months, it is best to consume it within 1-3 months. Even the landlords should try not to store too much surplus food.
In addition to changes in composition, the method of storing breast milk also needs to consider the baby’s situation. For example, premature babies and full-term babies need different components in breast milk. Relatively speaking, premature babies need more immune active substances in breast milk, so refrigeration is advocated. Also, some babies refuse frozen breast milk but are willing to accept refrigerated breast milk.
In summary, the choice of breast milk storage method needs to take into account both the breast milk and the baby’s factors.
Keep these three points in mind for higher quality breast milk in the refrigerator
If you want the expressed breast milk to have less bacterial growth and better retention of nutrients and immune factors, then pay attention to the following three links during the milking and storage process:
Hygiene during milking (Refer to NICU mothers’ breast milk collection strategy)
1. Hand hygiene
Wash your hands before each milking, clean the inside of your fingernails, and wipe the nipple area with water (avoid using soap).
2. Cleaning
It is recommended to use a dedicated container for collecting and storing expressed breast milk. After each use, all breast milk storage equipment that comes into contact with milk should be washed with hot water and soap/dishwasher detergent, and rinsed thoroughly.
Before cleaning, make sure to take apart all the accessories and use a bottle brush to gently clean the small gaps.
3. Disinfection
Disinfect the breast milk storage tools once a day. Note that disinfection must be done after “cleaning” in point 2. The CDC recommends the following two disinfection methods, choose one:
①Steam: Use the microwave sterilization bag according to the manufacturer’s instructions, or a dedicated steam device (However, the FDA believes that the current microwave sterilization devices on the market may not meet its definition of “sterilization”[10]).
②Boil: Take apart the parts that can be safely boiled, put them into a pot, and cover with water. Put the pot on the fire and boil for 5 minutes. Use a clean pair of tongs to take out the parts.
No matter which disinfection method is chosen, the parts should be thoroughly air-dried afterwards. The disinfected parts, along with the pot and bottle brush, can be placed on a clean, unused dish towel or paper towel, in an area away from dirt and dust. It is advisable to avoid drying or patting items with a dish towel, as this may spread bacteria to the items.
Container selection
It is not recommended to use containers commonly used in hospitals for collecting specimens, such as urine cups.
Premature infants should not use milk storage bags as much as possible, as this can cause excessive loss of live cells in breast milk. Priority should be given to glass and polypropylene (PP) bottles, as these two types of containers have relatively less ability to adhere to fat-soluble nutrients, IgA, and various white blood cells when storing milk.
Silicone, glass bottles, or steel containers can also be chosen. However, when using steel containers, there is a significant decrease in cell count and cell survival rate.
When choosing plastic containers, pay attention to the type of plastic. Let’s first understand the classification of plastics. The current standard is the plastic material guide issued by the Society of the Plastics Industry (SPI). In addition to the manufacturer’s instructions, you can also find the corresponding logo on the bottom/side of the bottle, as shown in the following figure:
Among them, number 7 is a large category of plastic materials, including Tritan, PESU (PES), PPSU, and PC materials, etc.
At present, the baby milk storage bags on the market in our country are mainly made of materials 1, 2, and 5. Baby bottles are mainly made of material 5, as well as Tritan, PESU, and PPSU materials in category 7.
As long as you follow the instructions, you can rest assured that these materials are used for milk storage.
It is important to avoid using PC material in category 7, as it releases bisphenol A, which may cause obesity, lung diseases, endocrine disorders, and other issues. The national standard of our country clearly stipulates that PC material shall not be used for the production of materials or products in contact with infant food, but it is not ruled out that there are still some PC containers circulating in the market. Be careful to avoid them when purchasing.
Placement in the refrigerator
Many people mistakenly believe that the inside of the refrigerator is a uniform temperature environment. In fact, no matter which refrigerator you choose for your home, the temperature distribution in the refrigerator and freezer is within a wide range, which has been confirmed in many studies.
For example, even if the refrigerator temperature is set to 4°C, the temperature fluctuation in different corners may be between 0.9~14°C, which differs from the recommended < 4°C for breast milk refrigeration.
Therefore, to achieve the best infection control and preserve the quality of breast milk, the following should be done:
Note ⚠️
1. Set the temperature of the refrigerator to less than 4°C and the freezer to less than -18°C. If the freezing temperature is less than -20°C, the shelf life of breast milk is instantly extended to 12 months.
2. When refrigerating, do not place it on the refrigerator door, but put the breast milk in the deepest part of the refrigerator. Because the temperature fluctuation when opening the door can reach 10°C, which accelerates bacterial proliferation. In addition, it is best to place it in the upper layer. Because most of the evaporators in the refrigerator are located in the upper back part of the refrigerator, and the temperature nearby is the lowest.
3. When freezing, do not place it on the refrigerator door, just put the breast milk in the back of the freezer.
4. Set aside a compartment in the refrigerator for storing breast milk, or use a storage box. The CDC recommends regular cleaning of the refrigerator.
Roll it up a bit more! There are these details in milk storage
1. Leave space when using a bottle
Since the volume of breast milk increases after freezing, do not fill the bottle too full, but leave at least 2.5cm of height to avoid the bottle bursting and causing a large disaster scene…
2. Expel air when using a milk storage bag
Milk storage bags also need to reserve at least 2.5cm of space. After filling, you can easily expel most of the air with the edge of the table, delaying the oxidation reaction.
3. Freezing milk storage bags, horizontal and vertical have their own advantages
Freezing horizontally, the milk storage bag will become a thin piece, and after freezing, it can be stood up for storage in a storage box. While standing upright, although it takes up more space, the contact area between breast milk and the storage bag is reduced, and the “wall hanging” breast milk will also be reduced.
4. A portion of breast milk should be controlled within 30-120ml
I personally like the small bag of 30-60mL, which is very flexible to combine and can prevent the waste of thawed breast milk.
5. Mark the milliliters
Over time, or after freezing deformation, it is difficult to estimate how much breast milk is in one bag.
6. Mark the date
In principle, follow the “first in, first out” principle when using it. Of course, if there is too much stored milk, you can use the one within 3 months as appropriate – the closer the breast milk is to the baby’s age, the more it can adapt to the baby’s growth and development needs in theory.
7. During a power outage, try to close the refrigerator door
If the refrigerator door is not opened, the food can be safely refrigerated for about 4 hours. If the freezer door is not opened, the food can be safely frozen for about 48 hours when full; about 24 hours when half full.
After the power is restored, it is also possible to check the condition of the breast milk in time –if the frozen breast milk has begun to thaw but still contains ice crystals, it can be refrozen. If the breast milk has completely thawed into a liquid but still feels cold, it can be placed in the refrigerator and consumed the next day.
Finally, I hope that everyone doesn’t store too much surplus food. If the milk is really too much to pump, it is likely to be over-lactation, and it is necessary to scientifically reduce milk production under the guidance of professionals to return to a comfortable state of supply and demand balance.
Of course, mothers who have too much milk can use breast milk to mix with rice flour, make snacks, and focus on not wasting. If it is really too much to drink, it is also possible to consider donating to a milk bank (for more information: Is there any difference between a child eating their own breast milk and donated breast milk? The answer may surprise you), making your journey of breastfeeding more meaningful.
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