Dear Colleen,
I did a lot of inquiring about this subject 2 years ago when I returned
to work 1 day a week and my youngest (third) needed frozen EBM.  My
husband complained about the sour smell and refused to give it to my
daughter unl
ess I did some detective work.  I don't have anything in writing, but I
contacted a milk bank in Connecticut and they have had many similar
experiences.  The basis for the sour smell is a change in the make up
of the fatt
y acids when frozen and thawed.  It is perfectly harmless, and usually
the caregiver is more annoyed by the smell than the baby.  Babies
usually drink it without a problem.  It doesn't happen in all moms milk
either, who
knows why- probably the unique composition of the fats from mother to
mother.  If I get a chance, I will find the name of the milk bank in
Connecticut (USA) and post it, but if someone from the milk bank reads
this, pleas
e respond.  Thanks.

Sincerely,
Sharon A. Rapoza, RN, BSN, IBCLC