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/> >