Every now and then, we will encounter a mother whose milk does not freeze, or occasionally does not freeze.  Back in January of 2014, there was a brief discussion about whether the amount of sugar in milk will keep it from freezing.  So, my daughter and I just did an experiment on lactose and human  milk freezing.
As I am not breastfeeding at this time, I acquired some frozen milk from another woman.  My daughter and I added the following amounts of lactose to 4 ounces (120ish ml.) of thawed milk in breast milk storage bags, and put them in the freezer: 1/8 tsp, 1/4 tsp, 1/2 tsp, 3/4 tsp, 1 tsp, 1 1/2 tsp.  They all froze solid within 4 hours.  So, we can conclude that if a mother's milk isn't freezing, it's probably not because her milk has more lactose than usual.  (1 tsp. is approximately 5 ml, I believe.)  
I chose the amounts based on the amount of lactose added to the Weston A. Price formula, which works out to 2 tsp added to 4 ounces of cow milk and water to bring up the lactose to human milk levels (or so they say), and we just needed extra, not doubled.
Julie Tardos
 ==== Anything worth doing is even worth doing badly.

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