Human milk can be stored at different temperatures (from romm temp, to 
freezing temp.) or can be stored pasteurized or a combination of this 
techniques.
The reason to proceed to this manipulation are concerns about 
preservation, infection transmission and preservation of various activities.
Each method has different effects, on all three issues, and on the 
different main components of milk.
On the whole, if long term storage is the goal, cold storage (low 
temperature) seem to be the better compromise (but not perfect!) for the 
different aspects.
Pasteurization, on the other hand, is better for healty reason, but 
compromize more the bioactivity of milk.
(info from S:E: Buescher presentation on Manipulation and Sotrage of 
Human Milk, ref. available).

In bovine milk, bioactivity is usually not an issue (bovine milk is 
bioactive for calf, not for humans, so we do not care). Preservation and 
health security are the main concerns.
Usually pasteurized milk is the norm. Recently in Italy raw milk has 
become relatively available, but has rised concern because it has cause 
infection from O-157 (a potentially lethal bacteria for humans, not 
pathological for cow).
However, even pasteurization methods for bovine milk are different, and 
have different effects on milk.
I do not know standards for other countries, in Italy it has "recently" 
changed from Holder pasteurization (65.5°C for 30 min.) to HTST (High 
Temperature Short Time 72°C/16 sec).
When I used to live in Japan, I remember I could find more then one kind 
of milk pasteurization (Holder, HTST, UHT, and 75°/3 sec). Each of them 
had different organolectic characteristic.
I usually preferred very much the low temperatures kind, as they had the 
lesser impact on milk taste. But they were those which lasted less in 
the refrigerator, a few days at most, against the 10 or more of the 
highest temperatures.

This is to say that I would not compare bovine milk processing method to 
human milk processing/storage method, because there are huge differences 
both in objective and in method.

I think that there is research showing that bacteria proliferation does 
occur after a certain time, and this could be a problem for an infant.
Hygiene conditions at the moment of expression are an important factor 
for the probability of contamination, and therefore have a huge impact 
on subsequent bacteria proliferation (and probably on the result of 
studies).
Another thing to consider is that usually infants are less 
immuno-competent than a healthy adult, and some extra care should be 
employed in handling "food" for them. More so if the milk is for premies 
or immuno-compomised infants.

So, I think that even if there is no consensus about the guidelines for 
human milk storage, it still is an important issue to consider, and what 
should be said is perhaps that more research would be useful.
I would also say that in special situation (premies, ill child etc.) it 
would be better to be conservative (to be on the safe side), while with 
a term healthy babies it could be ok to be more relaxed about storage 
guidelines....

Micaela
LLL Leader,
Italy


Il 09/12/2010 6.54, Susan Lawrence ha scritto:
>>
>> I  always wonder about the breastmilk storage controversies/guidelines when
> I'm in the grocery store buying cow's milk, which usually has a "sell by"
> date 12 days or more from the purchase date (which I'm sure means at least a
> couple of weeks from when it left the cow udder).
> How can pasteurized pooled bovine milk be safe or tasty longer than
> immunologically active breastmilk?
> And what is the thing we are worried about? (taste? specific pathogens that
> in stored breastmilk that have been documented to cause identified illnesses
> in infants who were given "old" breastmilk?)
> If it's matter of deterioration of the immune factors, is that a reason to
> have mothers throw it out, given that the other infant food (formula) has
> none to begin with?
> How did the dairy industry come up with their "storage guidelines"?
>
> Susan Lawrence, LLLL, RN, IBCLC

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