gonneke van veldhuizen <[log in to unmask]> wrote:

> What I still will try to find is any kind of research on the effect of
> shaking (by hand) a container with human milk on the integrity of
> proteins and, if that is changed, how that might change the nutritional
> and/or protecting properties of the milk. 

My partner (who did a whole lot of milk handling in our house) is a
molecular biologist/chemist (post PhD) who works with cell cultures and
antibody solutions routinely. He snorted out loud at this idea that the
usual handful of shakes of a smooth-walled milk container in a domestic
setting, below the foaming threshold, would be noticeably harmful to the
milk. You have to agitate a liquid fairly hard and long to disrupt
robust live cells or antibodies, without the aid of other chemicals,
heat, beads, etc. 

I've also never managed to make butter with shaking  - though I tried
once, with a very creamy bottle, out of interest, and did eventually
manage to produce some sort of visible change in the milk. It took a LOT
of work. Think about a woman who runs for the bus ... not only does the
milk not turn to something else inside her breasts, but her jostled
blood and brain and organs seem to do pretty fine, too. And think about
eggwhites: you can't produce a nice white whipped eggwhite by dropping a
carton of eggs, or by jostling the contents up and down in a jar a
couple of times.

There is more formal work on the effects of agitation, because
scientists very often need to either preserve cells and proteins in a
solution, or want to deliberately disrupt them. Try a google scholar
search using terms like "mechanical agitation" and "disrupt" or
"denature" and add terms like proteins/antibodies/cells. Even Wikipedia
will give you a start:

http://en.wikipedia.org/wiki/Cell_disruption

http://en.wikipedia.org/wiki/Denaturation_%28biochemistry%29

Freezing and longer-term fridge storage was of far more concern in terms
of destroying cells and other components (antioxidants etc) for me, and
I also made sure there was no significant surfactant residue in bottled
after washing. Feeding milk as fresh as possible is a good priority in
my opinion, however that word "possible" is important -  older milk or
mishandled milk is never worse than substitutes unless it is truly
spoiled. And the woman is rather uncommon who can happily discard
containers of milk without being worried that that they will equal
containers of substitute at some point in her baby's life.

Therefore, the "intervention", the one requiring the extraordinary
evidence, is the discarding of human milk and its substitution with AIM.
People who think it should be discarded under these various
circumstances are the people who should be under the burden of producing
the evidence for their stance.

Lara Hopkins

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