Microwaves action on milk for infants (fwd)

[Hao Xiao]

> 
> Contrary to what other respondents have stated,
>  there is some theory behind this concern.  Amino acids,
> which are the building blocks of proteins in all living organisms,
> occur in two spatial configurations that are often referred to as
> D and L.  However, the form used with very few exceptions in
> organisms is the L form; that is the form that occurs in milk
> as a nutrient.
> 
> However, microwaves can "racemize" amino acids, that is, interconvert
> the D and L forms.  I do not know the theoretcial basis of this

What is the % of free amino acids in milk as compared to protein? Or how 
the microwave can "racemize" peptide bonded amino acids? 

> as I'd have expected the microwave energy to be too low to do this,
> but I've seen reports of it being done and it has been proposed as the
> basis of an industrial method for interconversion.  Indeed, I did get
> a student of mine to check it out a few years ago, and she did
> manage to get it to occur.
> 
> To get back to the milk, I did see a letter to Lancet a few years back
> reporting that D amino acids could be detected in microwaved milk.
> Right at this moment I can't find the reference.  Of course, what
> you want to know is how important is this.  The loss of nutrient
> quality is probably small; the D amino acids formed from essential
> amino acids will be unavailable for use in making proteins in the baby.
> Normally, we destroy any D amino acids we encounter.  The only concern
> is that babies almost certainly have a more limited ability to cope
> with D amino acids, and one of them, D - proline is somewhat
> neurotoxic. The risk might be entirely hypothetical, but there is
> a potential mechanism for it.  Why microwave the milk anyway? It's easy
> to warm the amounts required for a baby by standing it in hot water.
> 
> David Fell
> 
> =========================================================
> 
> David Fell,
> School of Biological & Molecular Sciences,
> Oxford Brookes University,
> Oxford OX3 0BP,           Tel. +44 (0)1865 483247
> UK                        FAX  +44 (0)1865 484017
> 
> daf at bms.brookes.ac.uk
> 
> 
>