It is normal for pumped milk to vary in color, consistency and scent depending on your diet. Stored milk separates into layers. Cream will rise to the top. Gently swirl the warmed bottle to mix the milk layers.
You can continue to add small amounts of cooled breastmilk to the same refrigerated container throughout the day. Avoid adding warm milk to already cooled milk.
Pumped milk may be added to frozen milk provided it is first chilled and the quantity is less than what is frozen.
Freeze milk in 2 - 5 oz portions. Small amounts will thaw more quickly. You will waste less milk this way and will avoid over-feeding. Liquids expand when frozen. Be sure to leave some extra room at the top of the container so the bottle or bag won't burst.
Seal containers tightly. Write the date on a piece of tape on the bag or bottle. Use the oldest milk first.
Some mothers report their defrosted breastmilk has a soapy taste or odor. This is due to a normally occurring enzyme, lipase, which helps to digest the fat content of the breastmilk. To avoid this from occurring, scald the breastmilk (do not bring to a boil) on a stove until tiny bubbles appear along the sides of the pan; do this before it is frozen. The scalding process will neutralize the enzyme preventing the soapy taste or smell.
Thaw milk overnight in the refrigerator, or hold the bottle under warm running water to quickly thaw. You can also place the sealed container in a bowl of warm water for 20 minutes to bring it to body temperature.
Thawed milk is safe in the refrigerator for 24 hours. DO NOT REFREEZE.
(All the information from this post can be found on the Medela website)