How to freeze breast milk using Japanese freezer bags

Here I show you how to freeze breastmilk using Japanese freezer bags. As the instructions are in Japanese, you may be tempted to go ahead and open the bag with your fingers (like I did!), but there is actually a technique of opening these bags to avoid contaminating the inside of the bag.

The following is a brief translation of the instructions for Pigeon 80ml freezer bags.

Instructions on how to open and use the freezer bag:

Open the chuck
Tear the top off the bag
Slide seal back and forth with fingers to open the seal (DO NOT insert your fingers into the top to open the seal. This will contaminate the inside which is sterile)
While holding the top of the bag on the outside edges, pull down the bottom of the bag to open up inside
Pour breast milk in, squeeze out air and seal the bag
Roll down the top 3 times and stick on label

Thawing instructions:

To thaw, place freezer bag in container of warm water (40°C)
Open bag from bottom-end & pour into sterile bottle

Other information (as written on the instructions for Pigeon 80ml freezer bags):

Freeze for max 3 weeks (-18°C)
Use sterile bottles
Freezer bags are sterile inside, so don’t contaminate with fingers
If take with you outside, keep frozen until use

Pigeon 80ml freezer bags (bought on Amazon Japan website)

Freezer bag

Step 1 – Open the chuck

Step 2 – Tear the top off the bag

Step 3 – Slide seal back and forth with fingers to open the seal (DO NOT insert your fingers into the top to open the seal. This will contaminate the inside which is sterile)

Another photo demonstrating sliding with fingers to open the bag

Step 4 – While holding the top of the bag on the outside edges, pull down the bottom of the bag to open up inside

Step 5 – Pour breast milk in, squeeze out air and seal the bag

Step 6 – Roll down the top 3 times and stick on label.

Place labeled freezer bag containing breast milk in container and place in freezer at -18°C (Pigeon instructions recommend using breast milk within 3 weeks).