I was hoping that someone more erudite than I would reply to you, but until
they do, here goes:

The O E D says as one of the alternative uses of the word:
"1. The powdery residue, composed chiefly of earthy or mineral particles,
left after the combustion of any substance."

The food is heated until all the carbon and nitrogen organic compounds have
been converted to CO2 and other gases.  The ash is the complex of
unvolatilised metals that remains:  calcium, boron, potassium, iron and so
on.  Astonishingly, silica is found, sometimes in relatively large
proportion, despite it being so insoluble;  grasses are particularly apt to
accumulate silicate, mainly in the edges of their blades, so converting them
to efficient micro-hacksaws;  for example, Spartina pectinata, Rip-gut
Cordgrass.

Metals are important in our diet, for many of our enzymes contain an atom of
one or other rare metals at their center, and we cannot do without them:
cobalt, for example.  Lead is not used in the human body (as far as I know)
but the oft-reviled seleium is.  Hope this helps        Geoff

-----Original Message-----
From: Kathy Partridge <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Sunday, October 25, 1998 8:47 PM
Subject: [P-F] Ash?


>Hi all,
>
>Can someone explain what "ash" is? The foods in the USDA database all have
>an "ash" component. What is that? It sounds like it's some kind of
>by-product of the analysis process. Is it usable by the body? Do I "count"
>it when I'm figuring percent of calories or nutrients on a dry weight
basis?
>
>TIA!
>
>
>Kathy Partridge
>mailto:[log in to unmask]
>Artworks website: <http://www.borg.com/~atelierk/>
>