I found this:
http://www.kidsource.com/maternal.conn/ ... orage.html
Storage
There are several containers available for storing breastmilk. These include specially designed plastic bags, plastic bottles or glass containers. There are advantages to each.
1. If you are going to freeze your breastmilk, leave some space at the top of the container. Breastmilk, like most liquids, expands as it freezes.
2. When using plastic bags, use those designed for breastmilk collection. Before storing, fold the top several times and seal with freezer or masking tape.
Place smaller bags in a larger bag to help protect against punctures. Medela's CSF bags come with twist ties for easy sealing and don't need to be double bagged.
3. Mark the date and amount on each container.
4. Freeze your milk in two ounce to four ounce portions. Smaller amounts thaw quicker, and you will waste less milk if your baby consumes less than you anticipated.
5. You may continue to add small amounts of cooled breastmilk to the same container throughout the day. Chill in the refrigerator until evening. Then, freeze in appropriate amounts.
6. You may also add to previously frozen milk. First refrigerate all freshly expressed milk until cold, and then add to the frozen milk. The newly added milk must be of a lesser amount than the previously frozen milk.1
7. If you carefully washed your hand before pumpIng or expressing, your breastmilk will be safe for a few hours at room temperature, 68'F. Immediate refrigeration, however, is recommended.2
8. Fresh milk may be stored in the refrigerator for up to 72 hours3 at 39'F.
9. Frozen milk may be stored in the back of the freezer portion of a refrigerator-freezer for up to six months4.
10. Frozen milk may be stored in a -20'C deep freezer for up to 12 months5.
11. Defrosted milk may be kept for up to 24 hours in the refrigerator6.