I have no answers - I am trying to think about ice-cream making, and what I
know is that besides alcohol, sugar is the next thing that bothers
freezing. If you put a lot of sugar in the mix it is more difficult for it
to freeze. And some kind of sweetener, like corn syrup and lactose, lower
the freezing point further.
I am not saying that the not-freezing milk was containing corn syrup! but
that perhaps, to find the answer we should be able to verify some of the
chemical characteristic of the milk.
Here some explanation of the phenomenon (freezing point depression)
http://www.all-science-fair-projects.com/print_project_1151_38
From this rather detailed book (unfortunately not completely available) I
gather that together with milk salts (?), lactose is a very important
component of freezing point depression in ice-creams, and if I understand
correctly, its interaction with proteins - especially whey - increases the
complexity of the the freezing point determination
http://books.google.it/books?id=hz9U9nzy-rQC&pg=PA72&lpg=PA72&dq=lactose+freezing+point+depression&source=bl&ots=8qChGxt9aH&sig=Vd6TOEj_cacPZm6aYHwYzPH0lw8&hl=it&sa=X&ei=kR_HUtaCK8fMywPQ-oDgAg&ved=0CDIQ6AEwAA#v=onepage&q=lactose%20freezing%20point%20depression&f=false
I have no answers, and I think that something must be very peculiar in the
non freezing milk, but I suppose we could probably get some good hint from
a chemist with knowledge of ice-cream making!
And to solve the mystery, probably some good chemical lab analysis could
help a lot.
Warmly (even though speaking of cold ice-creams),
Micaela
Italy
On Fri, Jan 3, 2014 at 9:05 PM, Watson, Leanna <[log in to unmask]>wrote:
> This topic seems to come up every once in a while on LACTNET, and no one
> seems to have any answers. The usual suspects of alcohol or especially
> high fat or sodium content, or a defective freezer are brought up, but then
> everyone shrugs and goes on to the next subject.
>
> This is especially interesting to me because it happened to me personally
> on several occasions while my son was in a PICU long term following heart
> surgery and significant complications. There was a huge walk in breastmilk
> freezer (they had a 75 bed NICU)and I was pumping 8x/24 hours, obtaining
> 8-12 oz at each session. I was freezing lots and lots of milk (much of it
> ended up at the Georgetown Milk Bank in Washington DC!). I was fastidious
> about sanitation, and did not drink alcohol at all. I would have milk not
> freeze, despite being in the freezer for 48 hours. The milk pumped at the
> session prior to, and after, the non-freezing milk froze fine. The
> non-freezing milk was very cold, but not frozen. Eventually it would
> freeze, after 48-72 hours. There is even a 15 year old LACTNET post from
> the hospital IBCLC about my case, and there was substantial suspicion that
> I was drinking, but not disclosing it. (That was not the case.) I was
> encouraged by the physicians to dump this milk out of an abundance of
> precaution, especially with a very compromised baby, which I did while he
> was ill. However, when he was out of PICU I fed it to him without concern.
>
> I would implore those interested in research to PLEASE explore this topic.
> It happens often enough that the subject finds its way to LACTNET on a
> semi-regular basis. Clearly there are much more instances of it happening
> in "the wild" than are brought up to IBCLCs, much less on LACTNET. There
> is still so much we don't know about lactation and breastmilk and this is
> one of those things!! My professional opinion now is that I would advise
> the mother to continue to use this milk, as I believe even unusually
> appearing/behaving breastmilk is safe and normal unless and until proven
> otherwise.
>
> Leanna Moore Watson, BS, IBCLC, RLC
> International Board Certified Lactation Consultant
>
>
>
>
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